[llvm-branch-commits] [llvm-branch] r109616 - in /llvm/branches/Apple/williamson: include/llvm/Analysis/ScalarEvolutionExpressions.h.orig lib/Analysis/ScalarEvolution.cpp.orig lib/Transforms/Scalar/GVN.cpp.orig
Daniel Dunbar
daniel at zuster.org
Wed Jul 28 11:41:46 PDT 2010
Author: ddunbar
Date: Wed Jul 28 13:41:46 2010
New Revision: 109616
URL: http://llvm.org/viewvc/llvm-project?rev=109616&view=rev
Log:
Remove stray merge files.
Removed:
llvm/branches/Apple/williamson/include/llvm/Analysis/ScalarEvolutionExpressions.h.orig
llvm/branches/Apple/williamson/lib/Analysis/ScalarEvolution.cpp.orig
llvm/branches/Apple/williamson/lib/Transforms/Scalar/GVN.cpp.orig
Removed: llvm/branches/Apple/williamson/include/llvm/Analysis/ScalarEvolutionExpressions.h.orig
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/williamson/include/llvm/Analysis/ScalarEvolutionExpressions.h.orig?rev=109615&view=auto
==============================================================================
--- llvm/branches/Apple/williamson/include/llvm/Analysis/ScalarEvolutionExpressions.h.orig (original)
+++ llvm/branches/Apple/williamson/include/llvm/Analysis/ScalarEvolutionExpressions.h.orig (removed)
@@ -1,609 +0,0 @@
-//===- llvm/Analysis/ScalarEvolutionExpressions.h - SCEV Exprs --*- C++ -*-===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file defines the classes used to represent and build scalar expressions.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
-#define LLVM_ANALYSIS_SCALAREVOLUTION_EXPRESSIONS_H
-
-#include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Support/ErrorHandling.h"
-
-namespace llvm {
- class ConstantInt;
- class ConstantRange;
- class DominatorTree;
-
- enum SCEVTypes {
- // These should be ordered in terms of increasing complexity to make the
- // folders simpler.
- scConstant, scTruncate, scZeroExtend, scSignExtend, scAddExpr, scMulExpr,
- scUDivExpr, scAddRecExpr, scUMaxExpr, scSMaxExpr,
- scUnknown, scCouldNotCompute
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVConstant - This class represents a constant integer value.
- ///
- class SCEVConstant : public SCEV {
- friend class ScalarEvolution;
-
- ConstantInt *V;
- SCEVConstant(const FoldingSetNodeIDRef ID, ConstantInt *v) :
- SCEV(ID, scConstant), V(v) {}
- public:
- ConstantInt *getValue() const { return V; }
-
- virtual bool isLoopInvariant(const Loop *L) const {
- return true;
- }
-
- virtual bool hasComputableLoopEvolution(const Loop *L) const {
- return false; // Not loop variant
- }
-
- virtual const Type *getType() const;
-
- virtual bool hasOperand(const SCEV *) const {
- return false;
- }
-
- bool dominates(BasicBlock *BB, DominatorTree *DT) const {
- return true;
- }
-
- bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- return true;
- }
-
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVConstant *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scConstant;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVCastExpr - This is the base class for unary cast operator classes.
- ///
- class SCEVCastExpr : public SCEV {
- protected:
- const SCEV *Op;
- const Type *Ty;
-
- SCEVCastExpr(const FoldingSetNodeIDRef ID,
- unsigned SCEVTy, const SCEV *op, const Type *ty);
-
- public:
- const SCEV *getOperand() const { return Op; }
- virtual const Type *getType() const { return Ty; }
-
- virtual bool isLoopInvariant(const Loop *L) const {
- return Op->isLoopInvariant(L);
- }
-
- virtual bool hasComputableLoopEvolution(const Loop *L) const {
- return Op->hasComputableLoopEvolution(L);
- }
-
- virtual bool hasOperand(const SCEV *O) const {
- return Op == O || Op->hasOperand(O);
- }
-
- virtual bool dominates(BasicBlock *BB, DominatorTree *DT) const;
-
- virtual bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVCastExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scTruncate ||
- S->getSCEVType() == scZeroExtend ||
- S->getSCEVType() == scSignExtend;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVTruncateExpr - This class represents a truncation of an integer value
- /// to a smaller integer value.
- ///
- class SCEVTruncateExpr : public SCEVCastExpr {
- friend class ScalarEvolution;
-
- SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty);
-
- public:
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVTruncateExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scTruncate;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVZeroExtendExpr - This class represents a zero extension of a small
- /// integer value to a larger integer value.
- ///
- class SCEVZeroExtendExpr : public SCEVCastExpr {
- friend class ScalarEvolution;
-
- SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty);
-
- public:
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVZeroExtendExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scZeroExtend;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVSignExtendExpr - This class represents a sign extension of a small
- /// integer value to a larger integer value.
- ///
- class SCEVSignExtendExpr : public SCEVCastExpr {
- friend class ScalarEvolution;
-
- SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty);
-
- public:
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVSignExtendExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scSignExtend;
- }
- };
-
-
- //===--------------------------------------------------------------------===//
- /// SCEVNAryExpr - This node is a base class providing common
- /// functionality for n'ary operators.
- ///
- class SCEVNAryExpr : public SCEV {
- protected:
- // Since SCEVs are immutable, ScalarEvolution allocates operand
- // arrays with its SCEVAllocator, so this class just needs a simple
- // pointer rather than a more elaborate vector-like data structure.
- // This also avoids the need for a non-trivial destructor.
- const SCEV *const *Operands;
- size_t NumOperands;
-
- SCEVNAryExpr(const FoldingSetNodeIDRef ID,
- enum SCEVTypes T, const SCEV *const *O, size_t N)
- : SCEV(ID, T), Operands(O), NumOperands(N) {}
-
- public:
- size_t getNumOperands() const { return NumOperands; }
- const SCEV *getOperand(unsigned i) const {
- assert(i < NumOperands && "Operand index out of range!");
- return Operands[i];
- }
-
- typedef const SCEV *const *op_iterator;
- op_iterator op_begin() const { return Operands; }
- op_iterator op_end() const { return Operands + NumOperands; }
-
- virtual bool isLoopInvariant(const Loop *L) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (!getOperand(i)->isLoopInvariant(L)) return false;
- return true;
- }
-
- // hasComputableLoopEvolution - N-ary expressions have computable loop
- // evolutions iff they have at least one operand that varies with the loop,
- // but that all varying operands are computable.
- virtual bool hasComputableLoopEvolution(const Loop *L) const {
- bool HasVarying = false;
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (!getOperand(i)->isLoopInvariant(L)) {
- if (getOperand(i)->hasComputableLoopEvolution(L))
- HasVarying = true;
- else
- return false;
- }
- return HasVarying;
- }
-
- virtual bool hasOperand(const SCEV *O) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (O == getOperand(i) || getOperand(i)->hasOperand(O))
- return true;
- return false;
- }
-
- bool dominates(BasicBlock *BB, DominatorTree *DT) const;
-
- bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
-
- virtual const Type *getType() const { return getOperand(0)->getType(); }
-
- bool hasNoUnsignedWrap() const { return SubclassData & (1 << 0); }
- void setHasNoUnsignedWrap(bool B) {
- SubclassData = (SubclassData & ~(1 << 0)) | (B << 0);
- }
- bool hasNoSignedWrap() const { return SubclassData & (1 << 1); }
- void setHasNoSignedWrap(bool B) {
- SubclassData = (SubclassData & ~(1 << 1)) | (B << 1);
- }
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVNAryExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scAddExpr ||
- S->getSCEVType() == scMulExpr ||
- S->getSCEVType() == scSMaxExpr ||
- S->getSCEVType() == scUMaxExpr ||
- S->getSCEVType() == scAddRecExpr;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVCommutativeExpr - This node is the base class for n'ary commutative
- /// operators.
- ///
- class SCEVCommutativeExpr : public SCEVNAryExpr {
- protected:
- SCEVCommutativeExpr(const FoldingSetNodeIDRef ID,
- enum SCEVTypes T, const SCEV *const *O, size_t N)
- : SCEVNAryExpr(ID, T, O, N) {}
-
- public:
- virtual const char *getOperationStr() const = 0;
-
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVCommutativeExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scAddExpr ||
- S->getSCEVType() == scMulExpr ||
- S->getSCEVType() == scSMaxExpr ||
- S->getSCEVType() == scUMaxExpr;
- }
- };
-
-
- //===--------------------------------------------------------------------===//
- /// SCEVAddExpr - This node represents an addition of some number of SCEVs.
- ///
- class SCEVAddExpr : public SCEVCommutativeExpr {
- friend class ScalarEvolution;
-
- SCEVAddExpr(const FoldingSetNodeIDRef ID,
- const SCEV *const *O, size_t N)
- : SCEVCommutativeExpr(ID, scAddExpr, O, N) {
- }
-
- public:
- virtual const char *getOperationStr() const { return " + "; }
-
- virtual const Type *getType() const {
- // Use the type of the last operand, which is likely to be a pointer
- // type, if there is one. This doesn't usually matter, but it can help
- // reduce casts when the expressions are expanded.
- return getOperand(getNumOperands() - 1)->getType();
- }
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVAddExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scAddExpr;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVMulExpr - This node represents multiplication of some number of SCEVs.
- ///
- class SCEVMulExpr : public SCEVCommutativeExpr {
- friend class ScalarEvolution;
-
- SCEVMulExpr(const FoldingSetNodeIDRef ID,
- const SCEV *const *O, size_t N)
- : SCEVCommutativeExpr(ID, scMulExpr, O, N) {
- }
-
- public:
- virtual const char *getOperationStr() const { return " * "; }
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVMulExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scMulExpr;
- }
- };
-
-
- //===--------------------------------------------------------------------===//
- /// SCEVUDivExpr - This class represents a binary unsigned division operation.
- ///
- class SCEVUDivExpr : public SCEV {
- friend class ScalarEvolution;
-
- const SCEV *LHS;
- const SCEV *RHS;
- SCEVUDivExpr(const FoldingSetNodeIDRef ID, const SCEV *lhs, const SCEV *rhs)
- : SCEV(ID, scUDivExpr), LHS(lhs), RHS(rhs) {}
-
- public:
- const SCEV *getLHS() const { return LHS; }
- const SCEV *getRHS() const { return RHS; }
-
- virtual bool isLoopInvariant(const Loop *L) const {
- return LHS->isLoopInvariant(L) && RHS->isLoopInvariant(L);
- }
-
- virtual bool hasComputableLoopEvolution(const Loop *L) const {
- return LHS->hasComputableLoopEvolution(L) &&
- RHS->hasComputableLoopEvolution(L);
- }
-
- virtual bool hasOperand(const SCEV *O) const {
- return O == LHS || O == RHS || LHS->hasOperand(O) || RHS->hasOperand(O);
- }
-
- bool dominates(BasicBlock *BB, DominatorTree *DT) const;
-
- bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
-
- virtual const Type *getType() const;
-
- void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVUDivExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scUDivExpr;
- }
- };
-
-
- //===--------------------------------------------------------------------===//
- /// SCEVAddRecExpr - This node represents a polynomial recurrence on the trip
- /// count of the specified loop. This is the primary focus of the
- /// ScalarEvolution framework; all the other SCEV subclasses are mostly just
- /// supporting infrastructure to allow SCEVAddRecExpr expressions to be
- /// created and analyzed.
- ///
- /// All operands of an AddRec are required to be loop invariant.
- ///
- class SCEVAddRecExpr : public SCEVNAryExpr {
- friend class ScalarEvolution;
-
- const Loop *L;
-
- SCEVAddRecExpr(const FoldingSetNodeIDRef ID,
- const SCEV *const *O, size_t N, const Loop *l)
- : SCEVNAryExpr(ID, scAddRecExpr, O, N), L(l) {
- for (size_t i = 0, e = NumOperands; i != e; ++i)
- assert(Operands[i]->isLoopInvariant(l) &&
- "Operands of AddRec must be loop-invariant!");
- }
-
- public:
- const SCEV *getStart() const { return Operands[0]; }
- const Loop *getLoop() const { return L; }
-
- /// getStepRecurrence - This method constructs and returns the recurrence
- /// indicating how much this expression steps by. If this is a polynomial
- /// of degree N, it returns a chrec of degree N-1.
- const SCEV *getStepRecurrence(ScalarEvolution &SE) const {
- if (isAffine()) return getOperand(1);
- return SE.getAddRecExpr(SmallVector<const SCEV *, 3>(op_begin()+1,
- op_end()),
- getLoop());
- }
-
- virtual bool hasComputableLoopEvolution(const Loop *QL) const {
- return L == QL;
- }
-
- virtual bool isLoopInvariant(const Loop *QueryLoop) const;
-
- bool dominates(BasicBlock *BB, DominatorTree *DT) const;
-
- bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
-
- /// isAffine - Return true if this is an affine AddRec (i.e., it represents
- /// an expressions A+B*x where A and B are loop invariant values.
- bool isAffine() const {
- // We know that the start value is invariant. This expression is thus
- // affine iff the step is also invariant.
- return getNumOperands() == 2;
- }
-
- /// isQuadratic - Return true if this is an quadratic AddRec (i.e., it
- /// represents an expressions A+B*x+C*x^2 where A, B and C are loop
- /// invariant values. This corresponds to an addrec of the form {L,+,M,+,N}
- bool isQuadratic() const {
- return getNumOperands() == 3;
- }
-
- /// evaluateAtIteration - Return the value of this chain of recurrences at
- /// the specified iteration number.
- const SCEV *evaluateAtIteration(const SCEV *It, ScalarEvolution &SE) const;
-
- /// getNumIterationsInRange - Return the number of iterations of this loop
- /// that produce values in the specified constant range. Another way of
- /// looking at this is that it returns the first iteration number where the
- /// value is not in the condition, thus computing the exit count. If the
- /// iteration count can't be computed, an instance of SCEVCouldNotCompute is
- /// returned.
- const SCEV *getNumIterationsInRange(ConstantRange Range,
- ScalarEvolution &SE) const;
-
- /// getPostIncExpr - Return an expression representing the value of
- /// this expression one iteration of the loop ahead.
- const SCEVAddRecExpr *getPostIncExpr(ScalarEvolution &SE) const {
- return cast<SCEVAddRecExpr>(SE.getAddExpr(this, getStepRecurrence(SE)));
- }
-
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVAddRecExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scAddRecExpr;
- }
- };
-
-
- //===--------------------------------------------------------------------===//
- /// SCEVSMaxExpr - This class represents a signed maximum selection.
- ///
- class SCEVSMaxExpr : public SCEVCommutativeExpr {
- friend class ScalarEvolution;
-
- SCEVSMaxExpr(const FoldingSetNodeIDRef ID,
- const SCEV *const *O, size_t N)
- : SCEVCommutativeExpr(ID, scSMaxExpr, O, N) {
- // Max never overflows.
- setHasNoUnsignedWrap(true);
- setHasNoSignedWrap(true);
- }
-
- public:
- virtual const char *getOperationStr() const { return " smax "; }
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVSMaxExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scSMaxExpr;
- }
- };
-
-
- //===--------------------------------------------------------------------===//
- /// SCEVUMaxExpr - This class represents an unsigned maximum selection.
- ///
- class SCEVUMaxExpr : public SCEVCommutativeExpr {
- friend class ScalarEvolution;
-
- SCEVUMaxExpr(const FoldingSetNodeIDRef ID,
- const SCEV *const *O, size_t N)
- : SCEVCommutativeExpr(ID, scUMaxExpr, O, N) {
- // Max never overflows.
- setHasNoUnsignedWrap(true);
- setHasNoSignedWrap(true);
- }
-
- public:
- virtual const char *getOperationStr() const { return " umax "; }
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVUMaxExpr *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scUMaxExpr;
- }
- };
-
- //===--------------------------------------------------------------------===//
- /// SCEVUnknown - This means that we are dealing with an entirely unknown SCEV
- /// value, and only represent it as its LLVM Value. This is the "bottom"
- /// value for the analysis.
- ///
- class SCEVUnknown : public SCEV {
- friend class ScalarEvolution;
-
- Value *V;
- SCEVUnknown(const FoldingSetNodeIDRef ID, Value *v) :
- SCEV(ID, scUnknown), V(v) {}
-
- public:
- Value *getValue() const { return V; }
-
- /// isSizeOf, isAlignOf, isOffsetOf - Test whether this is a special
- /// constant representing a type size, alignment, or field offset in
- /// a target-independent manner, and hasn't happened to have been
- /// folded with other operations into something unrecognizable. This
- /// is mainly only useful for pretty-printing and other situations
- /// where it isn't absolutely required for these to succeed.
- bool isSizeOf(const Type *&AllocTy) const;
- bool isAlignOf(const Type *&AllocTy) const;
- bool isOffsetOf(const Type *&STy, Constant *&FieldNo) const;
-
- virtual bool isLoopInvariant(const Loop *L) const;
- virtual bool hasComputableLoopEvolution(const Loop *QL) const {
- return false; // not computable
- }
-
- virtual bool hasOperand(const SCEV *) const {
- return false;
- }
-
- bool dominates(BasicBlock *BB, DominatorTree *DT) const;
-
- bool properlyDominates(BasicBlock *BB, DominatorTree *DT) const;
-
- virtual const Type *getType() const;
-
- virtual void print(raw_ostream &OS) const;
-
- /// Methods for support type inquiry through isa, cast, and dyn_cast:
- static inline bool classof(const SCEVUnknown *S) { return true; }
- static inline bool classof(const SCEV *S) {
- return S->getSCEVType() == scUnknown;
- }
- };
-
- /// SCEVVisitor - This class defines a simple visitor class that may be used
- /// for various SCEV analysis purposes.
- template<typename SC, typename RetVal=void>
- struct SCEVVisitor {
- RetVal visit(const SCEV *S) {
- switch (S->getSCEVType()) {
- case scConstant:
- return ((SC*)this)->visitConstant((const SCEVConstant*)S);
- case scTruncate:
- return ((SC*)this)->visitTruncateExpr((const SCEVTruncateExpr*)S);
- case scZeroExtend:
- return ((SC*)this)->visitZeroExtendExpr((const SCEVZeroExtendExpr*)S);
- case scSignExtend:
- return ((SC*)this)->visitSignExtendExpr((const SCEVSignExtendExpr*)S);
- case scAddExpr:
- return ((SC*)this)->visitAddExpr((const SCEVAddExpr*)S);
- case scMulExpr:
- return ((SC*)this)->visitMulExpr((const SCEVMulExpr*)S);
- case scUDivExpr:
- return ((SC*)this)->visitUDivExpr((const SCEVUDivExpr*)S);
- case scAddRecExpr:
- return ((SC*)this)->visitAddRecExpr((const SCEVAddRecExpr*)S);
- case scSMaxExpr:
- return ((SC*)this)->visitSMaxExpr((const SCEVSMaxExpr*)S);
- case scUMaxExpr:
- return ((SC*)this)->visitUMaxExpr((const SCEVUMaxExpr*)S);
- case scUnknown:
- return ((SC*)this)->visitUnknown((const SCEVUnknown*)S);
- case scCouldNotCompute:
- return ((SC*)this)->visitCouldNotCompute((const SCEVCouldNotCompute*)S);
- default:
- llvm_unreachable("Unknown SCEV type!");
- }
- }
-
- RetVal visitCouldNotCompute(const SCEVCouldNotCompute *S) {
- llvm_unreachable("Invalid use of SCEVCouldNotCompute!");
- return RetVal();
- }
- };
-}
-
-#endif
Removed: llvm/branches/Apple/williamson/lib/Analysis/ScalarEvolution.cpp.orig
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/williamson/lib/Analysis/ScalarEvolution.cpp.orig?rev=109615&view=auto
==============================================================================
--- llvm/branches/Apple/williamson/lib/Analysis/ScalarEvolution.cpp.orig (original)
+++ llvm/branches/Apple/williamson/lib/Analysis/ScalarEvolution.cpp.orig (removed)
@@ -1,5842 +0,0 @@
-//===- ScalarEvolution.cpp - Scalar Evolution Analysis ----------*- C++ -*-===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file contains the implementation of the scalar evolution analysis
-// engine, which is used primarily to analyze expressions involving induction
-// variables in loops.
-//
-// There are several aspects to this library. First is the representation of
-// scalar expressions, which are represented as subclasses of the SCEV class.
-// These classes are used to represent certain types of subexpressions that we
-// can handle. We only create one SCEV of a particular shape, so
-// pointer-comparisons for equality are legal.
-//
-// One important aspect of the SCEV objects is that they are never cyclic, even
-// if there is a cycle in the dataflow for an expression (ie, a PHI node). If
-// the PHI node is one of the idioms that we can represent (e.g., a polynomial
-// recurrence) then we represent it directly as a recurrence node, otherwise we
-// represent it as a SCEVUnknown node.
-//
-// In addition to being able to represent expressions of various types, we also
-// have folders that are used to build the *canonical* representation for a
-// particular expression. These folders are capable of using a variety of
-// rewrite rules to simplify the expressions.
-//
-// Once the folders are defined, we can implement the more interesting
-// higher-level code, such as the code that recognizes PHI nodes of various
-// types, computes the execution count of a loop, etc.
-//
-// TODO: We should use these routines and value representations to implement
-// dependence analysis!
-//
-//===----------------------------------------------------------------------===//
-//
-// There are several good references for the techniques used in this analysis.
-//
-// Chains of recurrences -- a method to expedite the evaluation
-// of closed-form functions
-// Olaf Bachmann, Paul S. Wang, Eugene V. Zima
-//
-// On computational properties of chains of recurrences
-// Eugene V. Zima
-//
-// Symbolic Evaluation of Chains of Recurrences for Loop Optimization
-// Robert A. van Engelen
-//
-// Efficient Symbolic Analysis for Optimizing Compilers
-// Robert A. van Engelen
-//
-// Using the chains of recurrences algebra for data dependence testing and
-// induction variable substitution
-// MS Thesis, Johnie Birch
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "scalar-evolution"
-#include "llvm/Analysis/ScalarEvolutionExpressions.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/GlobalAlias.h"
-#include "llvm/Instructions.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Operator.h"
-#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/LoopInfo.h"
-#include "llvm/Analysis/ValueTracking.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/ConstantRange.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/InstIterator.h"
-#include "llvm/Support/MathExtras.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include <algorithm>
-using namespace llvm;
-
-STATISTIC(NumArrayLenItCounts,
- "Number of trip counts computed with array length");
-STATISTIC(NumTripCountsComputed,
- "Number of loops with predictable loop counts");
-STATISTIC(NumTripCountsNotComputed,
- "Number of loops without predictable loop counts");
-STATISTIC(NumBruteForceTripCountsComputed,
- "Number of loops with trip counts computed by force");
-
-static cl::opt<unsigned>
-MaxBruteForceIterations("scalar-evolution-max-iterations", cl::ReallyHidden,
- cl::desc("Maximum number of iterations SCEV will "
- "symbolically execute a constant "
- "derived loop"),
- cl::init(100));
-
-static RegisterPass<ScalarEvolution>
-R("scalar-evolution", "Scalar Evolution Analysis", false, true);
-char ScalarEvolution::ID = 0;
-
-//===----------------------------------------------------------------------===//
-// SCEV class definitions
-//===----------------------------------------------------------------------===//
-
-//===----------------------------------------------------------------------===//
-// Implementation of the SCEV class.
-//
-
-SCEV::~SCEV() {}
-
-void SCEV::dump() const {
- print(dbgs());
- dbgs() << '\n';
-}
-
-bool SCEV::isZero() const {
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
- return SC->getValue()->isZero();
- return false;
-}
-
-bool SCEV::isOne() const {
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
- return SC->getValue()->isOne();
- return false;
-}
-
-bool SCEV::isAllOnesValue() const {
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(this))
- return SC->getValue()->isAllOnesValue();
- return false;
-}
-
-SCEVCouldNotCompute::SCEVCouldNotCompute() :
- SCEV(FoldingSetNodeIDRef(), scCouldNotCompute) {}
-
-bool SCEVCouldNotCompute::isLoopInvariant(const Loop *L) const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return false;
-}
-
-const Type *SCEVCouldNotCompute::getType() const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return 0;
-}
-
-bool SCEVCouldNotCompute::hasComputableLoopEvolution(const Loop *L) const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return false;
-}
-
-bool SCEVCouldNotCompute::hasOperand(const SCEV *) const {
- llvm_unreachable("Attempt to use a SCEVCouldNotCompute object!");
- return false;
-}
-
-void SCEVCouldNotCompute::print(raw_ostream &OS) const {
- OS << "***COULDNOTCOMPUTE***";
-}
-
-bool SCEVCouldNotCompute::classof(const SCEV *S) {
- return S->getSCEVType() == scCouldNotCompute;
-}
-
-const SCEV *ScalarEvolution::getConstant(ConstantInt *V) {
- FoldingSetNodeID ID;
- ID.AddInteger(scConstant);
- ID.AddPointer(V);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- SCEV *S = new (SCEVAllocator) SCEVConstant(ID.Intern(SCEVAllocator), V);
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-const SCEV *ScalarEvolution::getConstant(const APInt& Val) {
- return getConstant(ConstantInt::get(getContext(), Val));
-}
-
-const SCEV *
-ScalarEvolution::getConstant(const Type *Ty, uint64_t V, bool isSigned) {
- const IntegerType *ITy = cast<IntegerType>(getEffectiveSCEVType(Ty));
- return getConstant(ConstantInt::get(ITy, V, isSigned));
-}
-
-const Type *SCEVConstant::getType() const { return V->getType(); }
-
-void SCEVConstant::print(raw_ostream &OS) const {
- WriteAsOperand(OS, V, false);
-}
-
-SCEVCastExpr::SCEVCastExpr(const FoldingSetNodeIDRef ID,
- unsigned SCEVTy, const SCEV *op, const Type *ty)
- : SCEV(ID, SCEVTy), Op(op), Ty(ty) {}
-
-bool SCEVCastExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- return Op->dominates(BB, DT);
-}
-
-bool SCEVCastExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- return Op->properlyDominates(BB, DT);
-}
-
-SCEVTruncateExpr::SCEVTruncateExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty)
- : SCEVCastExpr(ID, scTruncate, op, ty) {
- assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot truncate non-integer value!");
-}
-
-void SCEVTruncateExpr::print(raw_ostream &OS) const {
- OS << "(trunc " << *Op->getType() << " " << *Op << " to " << *Ty << ")";
-}
-
-SCEVZeroExtendExpr::SCEVZeroExtendExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty)
- : SCEVCastExpr(ID, scZeroExtend, op, ty) {
- assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot zero extend non-integer value!");
-}
-
-void SCEVZeroExtendExpr::print(raw_ostream &OS) const {
- OS << "(zext " << *Op->getType() << " " << *Op << " to " << *Ty << ")";
-}
-
-SCEVSignExtendExpr::SCEVSignExtendExpr(const FoldingSetNodeIDRef ID,
- const SCEV *op, const Type *ty)
- : SCEVCastExpr(ID, scSignExtend, op, ty) {
- assert((Op->getType()->isIntegerTy() || Op->getType()->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot sign extend non-integer value!");
-}
-
-void SCEVSignExtendExpr::print(raw_ostream &OS) const {
- OS << "(sext " << *Op->getType() << " " << *Op << " to " << *Ty << ")";
-}
-
-void SCEVCommutativeExpr::print(raw_ostream &OS) const {
- const char *OpStr = getOperationStr();
- OS << "(";
- for (op_iterator I = op_begin(), E = op_end(); I != E; ++I) {
- OS << **I;
- if (next(I) != E)
- OS << OpStr;
- }
- OS << ")";
-}
-
-bool SCEVNAryExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- if (!getOperand(i)->dominates(BB, DT))
- return false;
- }
- return true;
-}
-
-bool SCEVNAryExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
- if (!getOperand(i)->properlyDominates(BB, DT))
- return false;
- }
- return true;
-}
-
-bool SCEVUDivExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- return LHS->dominates(BB, DT) && RHS->dominates(BB, DT);
-}
-
-bool SCEVUDivExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- return LHS->properlyDominates(BB, DT) && RHS->properlyDominates(BB, DT);
-}
-
-void SCEVUDivExpr::print(raw_ostream &OS) const {
- OS << "(" << *LHS << " /u " << *RHS << ")";
-}
-
-const Type *SCEVUDivExpr::getType() const {
- // In most cases the types of LHS and RHS will be the same, but in some
- // crazy cases one or the other may be a pointer. ScalarEvolution doesn't
- // depend on the type for correctness, but handling types carefully can
- // avoid extra casts in the SCEVExpander. The LHS is more likely to be
- // a pointer type than the RHS, so use the RHS' type here.
- return RHS->getType();
-}
-
-bool SCEVAddRecExpr::isLoopInvariant(const Loop *QueryLoop) const {
- // Add recurrences are never invariant in the function-body (null loop).
- if (!QueryLoop)
- return false;
-
- // This recurrence is variant w.r.t. QueryLoop if QueryLoop contains L.
- if (QueryLoop->contains(L))
- return false;
-
- // This recurrence is variant w.r.t. QueryLoop if any of its operands
- // are variant.
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (!getOperand(i)->isLoopInvariant(QueryLoop))
- return false;
-
- // Otherwise it's loop-invariant.
- return true;
-}
-
-bool
-SCEVAddRecExpr::dominates(BasicBlock *BB, DominatorTree *DT) const {
- return DT->dominates(L->getHeader(), BB) &&
- SCEVNAryExpr::dominates(BB, DT);
-}
-
-bool
-SCEVAddRecExpr::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- // This uses a "dominates" query instead of "properly dominates" query because
- // the instruction which produces the addrec's value is a PHI, and a PHI
- // effectively properly dominates its entire containing block.
- return DT->dominates(L->getHeader(), BB) &&
- SCEVNAryExpr::properlyDominates(BB, DT);
-}
-
-void SCEVAddRecExpr::print(raw_ostream &OS) const {
- OS << "{" << *Operands[0];
- for (unsigned i = 1, e = NumOperands; i != e; ++i)
- OS << ",+," << *Operands[i];
- OS << "}<";
- WriteAsOperand(OS, L->getHeader(), /*PrintType=*/false);
- OS << ">";
-}
-
-bool SCEVUnknown::isLoopInvariant(const Loop *L) const {
- // All non-instruction values are loop invariant. All instructions are loop
- // invariant if they are not contained in the specified loop.
- // Instructions are never considered invariant in the function body
- // (null loop) because they are defined within the "loop".
- if (Instruction *I = dyn_cast<Instruction>(V))
- return L && !L->contains(I);
- return true;
-}
-
-bool SCEVUnknown::dominates(BasicBlock *BB, DominatorTree *DT) const {
- if (Instruction *I = dyn_cast<Instruction>(getValue()))
- return DT->dominates(I->getParent(), BB);
- return true;
-}
-
-bool SCEVUnknown::properlyDominates(BasicBlock *BB, DominatorTree *DT) const {
- if (Instruction *I = dyn_cast<Instruction>(getValue()))
- return DT->properlyDominates(I->getParent(), BB);
- return true;
-}
-
-const Type *SCEVUnknown::getType() const {
- return V->getType();
-}
-
-bool SCEVUnknown::isSizeOf(const Type *&AllocTy) const {
- if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(V))
- if (VCE->getOpcode() == Instruction::PtrToInt)
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- CE->getOperand(0)->isNullValue() &&
- CE->getNumOperands() == 2)
- if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(1)))
- if (CI->isOne()) {
- AllocTy = cast<PointerType>(CE->getOperand(0)->getType())
- ->getElementType();
- return true;
- }
-
- return false;
-}
-
-bool SCEVUnknown::isAlignOf(const Type *&AllocTy) const {
- if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(V))
- if (VCE->getOpcode() == Instruction::PtrToInt)
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- CE->getOperand(0)->isNullValue()) {
- const Type *Ty =
- cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
- if (const StructType *STy = dyn_cast<StructType>(Ty))
- if (!STy->isPacked() &&
- CE->getNumOperands() == 3 &&
- CE->getOperand(1)->isNullValue()) {
- if (ConstantInt *CI = dyn_cast<ConstantInt>(CE->getOperand(2)))
- if (CI->isOne() &&
- STy->getNumElements() == 2 &&
- STy->getElementType(0)->isIntegerTy(1)) {
- AllocTy = STy->getElementType(1);
- return true;
- }
- }
- }
-
- return false;
-}
-
-bool SCEVUnknown::isOffsetOf(const Type *&CTy, Constant *&FieldNo) const {
- if (ConstantExpr *VCE = dyn_cast<ConstantExpr>(V))
- if (VCE->getOpcode() == Instruction::PtrToInt)
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(VCE->getOperand(0)))
- if (CE->getOpcode() == Instruction::GetElementPtr &&
- CE->getNumOperands() == 3 &&
- CE->getOperand(0)->isNullValue() &&
- CE->getOperand(1)->isNullValue()) {
- const Type *Ty =
- cast<PointerType>(CE->getOperand(0)->getType())->getElementType();
- // Ignore vector types here so that ScalarEvolutionExpander doesn't
- // emit getelementptrs that index into vectors.
- if (Ty->isStructTy() || Ty->isArrayTy()) {
- CTy = Ty;
- FieldNo = CE->getOperand(2);
- return true;
- }
- }
-
- return false;
-}
-
-void SCEVUnknown::print(raw_ostream &OS) const {
- const Type *AllocTy;
- if (isSizeOf(AllocTy)) {
- OS << "sizeof(" << *AllocTy << ")";
- return;
- }
- if (isAlignOf(AllocTy)) {
- OS << "alignof(" << *AllocTy << ")";
- return;
- }
-
- const Type *CTy;
- Constant *FieldNo;
- if (isOffsetOf(CTy, FieldNo)) {
- OS << "offsetof(" << *CTy << ", ";
- WriteAsOperand(OS, FieldNo, false);
- OS << ")";
- return;
- }
-
- // Otherwise just print it normally.
- WriteAsOperand(OS, V, false);
-}
-
-//===----------------------------------------------------------------------===//
-// SCEV Utilities
-//===----------------------------------------------------------------------===//
-
-static bool CompareTypes(const Type *A, const Type *B) {
- if (A->getTypeID() != B->getTypeID())
- return A->getTypeID() < B->getTypeID();
- if (const IntegerType *AI = dyn_cast<IntegerType>(A)) {
- const IntegerType *BI = cast<IntegerType>(B);
- return AI->getBitWidth() < BI->getBitWidth();
- }
- if (const PointerType *AI = dyn_cast<PointerType>(A)) {
- const PointerType *BI = cast<PointerType>(B);
- return CompareTypes(AI->getElementType(), BI->getElementType());
- }
- if (const ArrayType *AI = dyn_cast<ArrayType>(A)) {
- const ArrayType *BI = cast<ArrayType>(B);
- if (AI->getNumElements() != BI->getNumElements())
- return AI->getNumElements() < BI->getNumElements();
- return CompareTypes(AI->getElementType(), BI->getElementType());
- }
- if (const VectorType *AI = dyn_cast<VectorType>(A)) {
- const VectorType *BI = cast<VectorType>(B);
- if (AI->getNumElements() != BI->getNumElements())
- return AI->getNumElements() < BI->getNumElements();
- return CompareTypes(AI->getElementType(), BI->getElementType());
- }
- if (const StructType *AI = dyn_cast<StructType>(A)) {
- const StructType *BI = cast<StructType>(B);
- if (AI->getNumElements() != BI->getNumElements())
- return AI->getNumElements() < BI->getNumElements();
- for (unsigned i = 0, e = AI->getNumElements(); i != e; ++i)
- if (CompareTypes(AI->getElementType(i), BI->getElementType(i)) ||
- CompareTypes(BI->getElementType(i), AI->getElementType(i)))
- return CompareTypes(AI->getElementType(i), BI->getElementType(i));
- }
- return false;
-}
-
-namespace {
- /// SCEVComplexityCompare - Return true if the complexity of the LHS is less
- /// than the complexity of the RHS. This comparator is used to canonicalize
- /// expressions.
- class SCEVComplexityCompare {
- const LoopInfo *LI;
- public:
- explicit SCEVComplexityCompare(const LoopInfo *li) : LI(li) {}
-
- bool operator()(const SCEV *LHS, const SCEV *RHS) const {
- // Fast-path: SCEVs are uniqued so we can do a quick equality check.
- if (LHS == RHS)
- return false;
-
- // Primarily, sort the SCEVs by their getSCEVType().
- unsigned LType = LHS->getSCEVType(), RType = RHS->getSCEVType();
- if (LType != RType)
- return LType < RType;
-
- // Aside from the getSCEVType() ordering, the particular ordering
- // isn't very important except that it's beneficial to be consistent,
- // so that (a + b) and (b + a) don't end up as different expressions.
-
- // Sort SCEVUnknown values with some loose heuristics. TODO: This is
- // not as complete as it could be.
- if (const SCEVUnknown *LU = dyn_cast<SCEVUnknown>(LHS)) {
- const SCEVUnknown *RU = cast<SCEVUnknown>(RHS);
-
- // Order pointer values after integer values. This helps SCEVExpander
- // form GEPs.
- bool LIsPointer = LU->getType()->isPointerTy(),
- RIsPointer = RU->getType()->isPointerTy();
- if (LIsPointer != RIsPointer)
- return RIsPointer;
-
- // Compare getValueID values.
- unsigned LID = LU->getValue()->getValueID(),
- RID = RU->getValue()->getValueID();
- if (LID != RID)
- return LID < RID;
-
- // Sort arguments by their position.
- if (const Argument *LA = dyn_cast<Argument>(LU->getValue())) {
- const Argument *RA = cast<Argument>(RU->getValue());
- return LA->getArgNo() < RA->getArgNo();
- }
-
- // For instructions, compare their loop depth, and their opcode.
- // This is pretty loose.
- if (const Instruction *LV = dyn_cast<Instruction>(LU->getValue())) {
- const Instruction *RV = cast<Instruction>(RU->getValue());
-
- // Compare loop depths.
- unsigned LDepth = LI->getLoopDepth(LV->getParent()),
- RDepth = LI->getLoopDepth(RV->getParent());
- if (LDepth != RDepth)
- return LDepth < RDepth;
-
- // Compare the number of operands.
- unsigned LNumOps = LV->getNumOperands(),
- RNumOps = RV->getNumOperands();
- if (LNumOps != RNumOps)
- return LNumOps < RNumOps;
- }
-
- return false;
- }
-
- // Compare constant values.
- if (const SCEVConstant *LC = dyn_cast<SCEVConstant>(LHS)) {
- const SCEVConstant *RC = cast<SCEVConstant>(RHS);
- const ConstantInt *LCC = LC->getValue();
- const ConstantInt *RCC = RC->getValue();
- unsigned LBitWidth = LCC->getBitWidth(), RBitWidth = RCC->getBitWidth();
- if (LBitWidth != RBitWidth)
- return LBitWidth < RBitWidth;
- return LCC->getValue().ult(RCC->getValue());
- }
-
- // Compare addrec loop depths.
- if (const SCEVAddRecExpr *LA = dyn_cast<SCEVAddRecExpr>(LHS)) {
- const SCEVAddRecExpr *RA = cast<SCEVAddRecExpr>(RHS);
- unsigned LDepth = LA->getLoop()->getLoopDepth(),
- RDepth = RA->getLoop()->getLoopDepth();
- if (LDepth != RDepth)
- return LDepth < RDepth;
- }
-
- // Lexicographically compare n-ary expressions.
- if (const SCEVNAryExpr *LC = dyn_cast<SCEVNAryExpr>(LHS)) {
- const SCEVNAryExpr *RC = cast<SCEVNAryExpr>(RHS);
- unsigned LNumOps = LC->getNumOperands(), RNumOps = RC->getNumOperands();
- for (unsigned i = 0; i != LNumOps; ++i) {
- if (i >= RNumOps)
- return false;
- const SCEV *LOp = LC->getOperand(i), *ROp = RC->getOperand(i);
- if (operator()(LOp, ROp))
- return true;
- if (operator()(ROp, LOp))
- return false;
- }
- return LNumOps < RNumOps;
- }
-
- // Lexicographically compare udiv expressions.
- if (const SCEVUDivExpr *LC = dyn_cast<SCEVUDivExpr>(LHS)) {
- const SCEVUDivExpr *RC = cast<SCEVUDivExpr>(RHS);
- const SCEV *LL = LC->getLHS(), *LR = LC->getRHS(),
- *RL = RC->getLHS(), *RR = RC->getRHS();
- if (operator()(LL, RL))
- return true;
- if (operator()(RL, LL))
- return false;
- if (operator()(LR, RR))
- return true;
- if (operator()(RR, LR))
- return false;
- return false;
- }
-
- // Compare cast expressions by operand.
- if (const SCEVCastExpr *LC = dyn_cast<SCEVCastExpr>(LHS)) {
- const SCEVCastExpr *RC = cast<SCEVCastExpr>(RHS);
- return operator()(LC->getOperand(), RC->getOperand());
- }
-
- llvm_unreachable("Unknown SCEV kind!");
- return false;
- }
- };
-}
-
-/// GroupByComplexity - Given a list of SCEV objects, order them by their
-/// complexity, and group objects of the same complexity together by value.
-/// When this routine is finished, we know that any duplicates in the vector are
-/// consecutive and that complexity is monotonically increasing.
-///
-/// Note that we go take special precautions to ensure that we get deterministic
-/// results from this routine. In other words, we don't want the results of
-/// this to depend on where the addresses of various SCEV objects happened to
-/// land in memory.
-///
-static void GroupByComplexity(SmallVectorImpl<const SCEV *> &Ops,
- LoopInfo *LI) {
- if (Ops.size() < 2) return; // Noop
- if (Ops.size() == 2) {
- // This is the common case, which also happens to be trivially simple.
- // Special case it.
- if (SCEVComplexityCompare(LI)(Ops[1], Ops[0]))
- std::swap(Ops[0], Ops[1]);
- return;
- }
-
- // Do the rough sort by complexity.
- std::stable_sort(Ops.begin(), Ops.end(), SCEVComplexityCompare(LI));
-
- // Now that we are sorted by complexity, group elements of the same
- // complexity. Note that this is, at worst, N^2, but the vector is likely to
- // be extremely short in practice. Note that we take this approach because we
- // do not want to depend on the addresses of the objects we are grouping.
- for (unsigned i = 0, e = Ops.size(); i != e-2; ++i) {
- const SCEV *S = Ops[i];
- unsigned Complexity = S->getSCEVType();
-
- // If there are any objects of the same complexity and same value as this
- // one, group them.
- for (unsigned j = i+1; j != e && Ops[j]->getSCEVType() == Complexity; ++j) {
- if (Ops[j] == S) { // Found a duplicate.
- // Move it to immediately after i'th element.
- std::swap(Ops[i+1], Ops[j]);
- ++i; // no need to rescan it.
- if (i == e-2) return; // Done!
- }
- }
- }
-}
-
-
-
-//===----------------------------------------------------------------------===//
-// Simple SCEV method implementations
-//===----------------------------------------------------------------------===//
-
-/// BinomialCoefficient - Compute BC(It, K). The result has width W.
-/// Assume, K > 0.
-static const SCEV *BinomialCoefficient(const SCEV *It, unsigned K,
- ScalarEvolution &SE,
- const Type* ResultTy) {
- // Handle the simplest case efficiently.
- if (K == 1)
- return SE.getTruncateOrZeroExtend(It, ResultTy);
-
- // We are using the following formula for BC(It, K):
- //
- // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / K!
- //
- // Suppose, W is the bitwidth of the return value. We must be prepared for
- // overflow. Hence, we must assure that the result of our computation is
- // equal to the accurate one modulo 2^W. Unfortunately, division isn't
- // safe in modular arithmetic.
- //
- // However, this code doesn't use exactly that formula; the formula it uses
- // is something like the following, where T is the number of factors of 2 in
- // K! (i.e. trailing zeros in the binary representation of K!), and ^ is
- // exponentiation:
- //
- // BC(It, K) = (It * (It - 1) * ... * (It - K + 1)) / 2^T / (K! / 2^T)
- //
- // This formula is trivially equivalent to the previous formula. However,
- // this formula can be implemented much more efficiently. The trick is that
- // K! / 2^T is odd, and exact division by an odd number *is* safe in modular
- // arithmetic. To do exact division in modular arithmetic, all we have
- // to do is multiply by the inverse. Therefore, this step can be done at
- // width W.
- //
- // The next issue is how to safely do the division by 2^T. The way this
- // is done is by doing the multiplication step at a width of at least W + T
- // bits. This way, the bottom W+T bits of the product are accurate. Then,
- // when we perform the division by 2^T (which is equivalent to a right shift
- // by T), the bottom W bits are accurate. Extra bits are okay; they'll get
- // truncated out after the division by 2^T.
- //
- // In comparison to just directly using the first formula, this technique
- // is much more efficient; using the first formula requires W * K bits,
- // but this formula less than W + K bits. Also, the first formula requires
- // a division step, whereas this formula only requires multiplies and shifts.
- //
- // It doesn't matter whether the subtraction step is done in the calculation
- // width or the input iteration count's width; if the subtraction overflows,
- // the result must be zero anyway. We prefer here to do it in the width of
- // the induction variable because it helps a lot for certain cases; CodeGen
- // isn't smart enough to ignore the overflow, which leads to much less
- // efficient code if the width of the subtraction is wider than the native
- // register width.
- //
- // (It's possible to not widen at all by pulling out factors of 2 before
- // the multiplication; for example, K=2 can be calculated as
- // It/2*(It+(It*INT_MIN/INT_MIN)+-1). However, it requires
- // extra arithmetic, so it's not an obvious win, and it gets
- // much more complicated for K > 3.)
-
- // Protection from insane SCEVs; this bound is conservative,
- // but it probably doesn't matter.
- if (K > 1000)
- return SE.getCouldNotCompute();
-
- unsigned W = SE.getTypeSizeInBits(ResultTy);
-
- // Calculate K! / 2^T and T; we divide out the factors of two before
- // multiplying for calculating K! / 2^T to avoid overflow.
- // Other overflow doesn't matter because we only care about the bottom
- // W bits of the result.
- APInt OddFactorial(W, 1);
- unsigned T = 1;
- for (unsigned i = 3; i <= K; ++i) {
- APInt Mult(W, i);
- unsigned TwoFactors = Mult.countTrailingZeros();
- T += TwoFactors;
- Mult = Mult.lshr(TwoFactors);
- OddFactorial *= Mult;
- }
-
- // We need at least W + T bits for the multiplication step
- unsigned CalculationBits = W + T;
-
- // Calculate 2^T, at width T+W.
- APInt DivFactor = APInt(CalculationBits, 1).shl(T);
-
- // Calculate the multiplicative inverse of K! / 2^T;
- // this multiplication factor will perform the exact division by
- // K! / 2^T.
- APInt Mod = APInt::getSignedMinValue(W+1);
- APInt MultiplyFactor = OddFactorial.zext(W+1);
- MultiplyFactor = MultiplyFactor.multiplicativeInverse(Mod);
- MultiplyFactor = MultiplyFactor.trunc(W);
-
- // Calculate the product, at width T+W
- const IntegerType *CalculationTy = IntegerType::get(SE.getContext(),
- CalculationBits);
- const SCEV *Dividend = SE.getTruncateOrZeroExtend(It, CalculationTy);
- for (unsigned i = 1; i != K; ++i) {
- const SCEV *S = SE.getMinusSCEV(It, SE.getConstant(It->getType(), i));
- Dividend = SE.getMulExpr(Dividend,
- SE.getTruncateOrZeroExtend(S, CalculationTy));
- }
-
- // Divide by 2^T
- const SCEV *DivResult = SE.getUDivExpr(Dividend, SE.getConstant(DivFactor));
-
- // Truncate the result, and divide by K! / 2^T.
-
- return SE.getMulExpr(SE.getConstant(MultiplyFactor),
- SE.getTruncateOrZeroExtend(DivResult, ResultTy));
-}
-
-/// evaluateAtIteration - Return the value of this chain of recurrences at
-/// the specified iteration number. We can evaluate this recurrence by
-/// multiplying each element in the chain by the binomial coefficient
-/// corresponding to it. In other words, we can evaluate {A,+,B,+,C,+,D} as:
-///
-/// A*BC(It, 0) + B*BC(It, 1) + C*BC(It, 2) + D*BC(It, 3)
-///
-/// where BC(It, k) stands for binomial coefficient.
-///
-const SCEV *SCEVAddRecExpr::evaluateAtIteration(const SCEV *It,
- ScalarEvolution &SE) const {
- const SCEV *Result = getStart();
- for (unsigned i = 1, e = getNumOperands(); i != e; ++i) {
- // The computation is correct in the face of overflow provided that the
- // multiplication is performed _after_ the evaluation of the binomial
- // coefficient.
- const SCEV *Coeff = BinomialCoefficient(It, i, SE, getType());
- if (isa<SCEVCouldNotCompute>(Coeff))
- return Coeff;
-
- Result = SE.getAddExpr(Result, SE.getMulExpr(getOperand(i), Coeff));
- }
- return Result;
-}
-
-//===----------------------------------------------------------------------===//
-// SCEV Expression folder implementations
-//===----------------------------------------------------------------------===//
-
-const SCEV *ScalarEvolution::getTruncateExpr(const SCEV *Op,
- const Type *Ty) {
- assert(getTypeSizeInBits(Op->getType()) > getTypeSizeInBits(Ty) &&
- "This is not a truncating conversion!");
- assert(isSCEVable(Ty) &&
- "This is not a conversion to a SCEVable type!");
- Ty = getEffectiveSCEVType(Ty);
-
- FoldingSetNodeID ID;
- ID.AddInteger(scTruncate);
- ID.AddPointer(Op);
- ID.AddPointer(Ty);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
-
- // Fold if the operand is constant.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
- return getConstant(
- cast<ConstantInt>(ConstantExpr::getTrunc(SC->getValue(),
- getEffectiveSCEVType(Ty))));
-
- // trunc(trunc(x)) --> trunc(x)
- if (const SCEVTruncateExpr *ST = dyn_cast<SCEVTruncateExpr>(Op))
- return getTruncateExpr(ST->getOperand(), Ty);
-
- // trunc(sext(x)) --> sext(x) if widening or trunc(x) if narrowing
- if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
- return getTruncateOrSignExtend(SS->getOperand(), Ty);
-
- // trunc(zext(x)) --> zext(x) if widening or trunc(x) if narrowing
- if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
- return getTruncateOrZeroExtend(SZ->getOperand(), Ty);
-
- // If the input value is a chrec scev, truncate the chrec's operands.
- if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(Op)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
- Operands.push_back(getTruncateExpr(AddRec->getOperand(i), Ty));
- return getAddRecExpr(Operands, AddRec->getLoop());
- }
-
- // As a special case, fold trunc(undef) to undef. We don't want to
- // know too much about SCEVUnknowns, but this special case is handy
- // and harmless.
- if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
- if (isa<UndefValue>(U->getValue()))
- return getSCEV(UndefValue::get(Ty));
-
- // The cast wasn't folded; create an explicit cast node. We can reuse
- // the existing insert position since if we get here, we won't have
- // made any changes which would invalidate it.
- SCEV *S = new (SCEVAllocator) SCEVTruncateExpr(ID.Intern(SCEVAllocator),
- Op, Ty);
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-const SCEV *ScalarEvolution::getZeroExtendExpr(const SCEV *Op,
- const Type *Ty) {
- assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
- "This is not an extending conversion!");
- assert(isSCEVable(Ty) &&
- "This is not a conversion to a SCEVable type!");
- Ty = getEffectiveSCEVType(Ty);
-
- // Fold if the operand is constant.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
- return getConstant(
- cast<ConstantInt>(ConstantExpr::getZExt(SC->getValue(),
- getEffectiveSCEVType(Ty))));
-
- // zext(zext(x)) --> zext(x)
- if (const SCEVZeroExtendExpr *SZ = dyn_cast<SCEVZeroExtendExpr>(Op))
- return getZeroExtendExpr(SZ->getOperand(), Ty);
-
- // Before doing any expensive analysis, check to see if we've already
- // computed a SCEV for this Op and Ty.
- FoldingSetNodeID ID;
- ID.AddInteger(scZeroExtend);
- ID.AddPointer(Op);
- ID.AddPointer(Ty);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
-
- // If the input value is a chrec scev, and we can prove that the value
- // did not overflow the old, smaller, value, we can zero extend all of the
- // operands (often constants). This allows analysis of something like
- // this: for (unsigned char X = 0; X < 100; ++X) { int Y = X; }
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
- if (AR->isAffine()) {
- const SCEV *Start = AR->getStart();
- const SCEV *Step = AR->getStepRecurrence(*this);
- unsigned BitWidth = getTypeSizeInBits(AR->getType());
- const Loop *L = AR->getLoop();
-
- // If we have special knowledge that this addrec won't overflow,
- // we don't need to do any further analysis.
- if (AR->hasNoUnsignedWrap())
- return getAddRecExpr(getZeroExtendExpr(Start, Ty),
- getZeroExtendExpr(Step, Ty),
- L);
-
- // Check whether the backedge-taken count is SCEVCouldNotCompute.
- // Note that this serves two purposes: It filters out loops that are
- // simply not analyzable, and it covers the case where this code is
- // being called from within backedge-taken count analysis, such that
- // attempting to ask for the backedge-taken count would likely result
- // in infinite recursion. In the later case, the analysis code will
- // cope with a conservative value, and it will take care to purge
- // that value once it has finished.
- const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
- if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
- // Manually compute the final value for AR, checking for
- // overflow.
-
- // Check whether the backedge-taken count can be losslessly casted to
- // the addrec's type. The count is always unsigned.
- const SCEV *CastedMaxBECount =
- getTruncateOrZeroExtend(MaxBECount, Start->getType());
- const SCEV *RecastedMaxBECount =
- getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
- if (MaxBECount == RecastedMaxBECount) {
- const Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
- // Check whether Start+Step*MaxBECount has no unsigned overflow.
- const SCEV *ZMul = getMulExpr(CastedMaxBECount, Step);
- const SCEV *Add = getAddExpr(Start, ZMul);
- const SCEV *OperandExtendedAdd =
- getAddExpr(getZeroExtendExpr(Start, WideTy),
- getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
- getZeroExtendExpr(Step, WideTy)));
- if (getZeroExtendExpr(Add, WideTy) == OperandExtendedAdd)
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getZeroExtendExpr(Start, Ty),
- getZeroExtendExpr(Step, Ty),
- L);
-
- // Similar to above, only this time treat the step value as signed.
- // This covers loops that count down.
- const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
- Add = getAddExpr(Start, SMul);
- OperandExtendedAdd =
- getAddExpr(getZeroExtendExpr(Start, WideTy),
- getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
- getSignExtendExpr(Step, WideTy)));
- if (getZeroExtendExpr(Add, WideTy) == OperandExtendedAdd)
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getZeroExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
- }
-
- // If the backedge is guarded by a comparison with the pre-inc value
- // the addrec is safe. Also, if the entry is guarded by a comparison
- // with the start value and the backedge is guarded by a comparison
- // with the post-inc value, the addrec is safe.
- if (isKnownPositive(Step)) {
- const SCEV *N = getConstant(APInt::getMinValue(BitWidth) -
- getUnsignedRange(Step).getUnsignedMax());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT, AR, N) ||
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_ULT, Start, N) &&
- isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_ULT,
- AR->getPostIncExpr(*this), N)))
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getZeroExtendExpr(Start, Ty),
- getZeroExtendExpr(Step, Ty),
- L);
- } else if (isKnownNegative(Step)) {
- const SCEV *N = getConstant(APInt::getMaxValue(BitWidth) -
- getSignedRange(Step).getSignedMin());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT, AR, N) ||
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_UGT, Start, N) &&
- isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_UGT,
- AR->getPostIncExpr(*this), N)))
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getZeroExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
- }
- }
- }
-
- // The cast wasn't folded; create an explicit cast node.
- // Recompute the insert position, as it may have been invalidated.
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- SCEV *S = new (SCEVAllocator) SCEVZeroExtendExpr(ID.Intern(SCEVAllocator),
- Op, Ty);
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-const SCEV *ScalarEvolution::getSignExtendExpr(const SCEV *Op,
- const Type *Ty) {
- assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
- "This is not an extending conversion!");
- assert(isSCEVable(Ty) &&
- "This is not a conversion to a SCEVable type!");
- Ty = getEffectiveSCEVType(Ty);
-
- // Fold if the operand is constant.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
- return getConstant(
- cast<ConstantInt>(ConstantExpr::getSExt(SC->getValue(),
- getEffectiveSCEVType(Ty))));
-
- // sext(sext(x)) --> sext(x)
- if (const SCEVSignExtendExpr *SS = dyn_cast<SCEVSignExtendExpr>(Op))
- return getSignExtendExpr(SS->getOperand(), Ty);
-
- // Before doing any expensive analysis, check to see if we've already
- // computed a SCEV for this Op and Ty.
- FoldingSetNodeID ID;
- ID.AddInteger(scSignExtend);
- ID.AddPointer(Op);
- ID.AddPointer(Ty);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
-
- // If the input value is a chrec scev, and we can prove that the value
- // did not overflow the old, smaller, value, we can sign extend all of the
- // operands (often constants). This allows analysis of something like
- // this: for (signed char X = 0; X < 100; ++X) { int Y = X; }
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op))
- if (AR->isAffine()) {
- const SCEV *Start = AR->getStart();
- const SCEV *Step = AR->getStepRecurrence(*this);
- unsigned BitWidth = getTypeSizeInBits(AR->getType());
- const Loop *L = AR->getLoop();
-
- // If we have special knowledge that this addrec won't overflow,
- // we don't need to do any further analysis.
- if (AR->hasNoSignedWrap())
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
-
- // Check whether the backedge-taken count is SCEVCouldNotCompute.
- // Note that this serves two purposes: It filters out loops that are
- // simply not analyzable, and it covers the case where this code is
- // being called from within backedge-taken count analysis, such that
- // attempting to ask for the backedge-taken count would likely result
- // in infinite recursion. In the later case, the analysis code will
- // cope with a conservative value, and it will take care to purge
- // that value once it has finished.
- const SCEV *MaxBECount = getMaxBackedgeTakenCount(L);
- if (!isa<SCEVCouldNotCompute>(MaxBECount)) {
- // Manually compute the final value for AR, checking for
- // overflow.
-
- // Check whether the backedge-taken count can be losslessly casted to
- // the addrec's type. The count is always unsigned.
- const SCEV *CastedMaxBECount =
- getTruncateOrZeroExtend(MaxBECount, Start->getType());
- const SCEV *RecastedMaxBECount =
- getTruncateOrZeroExtend(CastedMaxBECount, MaxBECount->getType());
- if (MaxBECount == RecastedMaxBECount) {
- const Type *WideTy = IntegerType::get(getContext(), BitWidth * 2);
- // Check whether Start+Step*MaxBECount has no signed overflow.
- const SCEV *SMul = getMulExpr(CastedMaxBECount, Step);
- const SCEV *Add = getAddExpr(Start, SMul);
- const SCEV *OperandExtendedAdd =
- getAddExpr(getSignExtendExpr(Start, WideTy),
- getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
- getSignExtendExpr(Step, WideTy)));
- if (getSignExtendExpr(Add, WideTy) == OperandExtendedAdd)
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
-
- // Similar to above, only this time treat the step value as unsigned.
- // This covers loops that count up with an unsigned step.
- const SCEV *UMul = getMulExpr(CastedMaxBECount, Step);
- Add = getAddExpr(Start, UMul);
- OperandExtendedAdd =
- getAddExpr(getSignExtendExpr(Start, WideTy),
- getMulExpr(getZeroExtendExpr(CastedMaxBECount, WideTy),
- getZeroExtendExpr(Step, WideTy)));
- if (getSignExtendExpr(Add, WideTy) == OperandExtendedAdd)
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getZeroExtendExpr(Step, Ty),
- L);
- }
-
- // If the backedge is guarded by a comparison with the pre-inc value
- // the addrec is safe. Also, if the entry is guarded by a comparison
- // with the start value and the backedge is guarded by a comparison
- // with the post-inc value, the addrec is safe.
- if (isKnownPositive(Step)) {
- const SCEV *N = getConstant(APInt::getSignedMinValue(BitWidth) -
- getSignedRange(Step).getSignedMax());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SLT, AR, N) ||
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_SLT, Start, N) &&
- isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SLT,
- AR->getPostIncExpr(*this), N)))
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
- } else if (isKnownNegative(Step)) {
- const SCEV *N = getConstant(APInt::getSignedMaxValue(BitWidth) -
- getSignedRange(Step).getSignedMin());
- if (isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SGT, AR, N) ||
- (isLoopEntryGuardedByCond(L, ICmpInst::ICMP_SGT, Start, N) &&
- isLoopBackedgeGuardedByCond(L, ICmpInst::ICMP_SGT,
- AR->getPostIncExpr(*this), N)))
- // Return the expression with the addrec on the outside.
- return getAddRecExpr(getSignExtendExpr(Start, Ty),
- getSignExtendExpr(Step, Ty),
- L);
- }
- }
- }
-
- // The cast wasn't folded; create an explicit cast node.
- // Recompute the insert position, as it may have been invalidated.
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- SCEV *S = new (SCEVAllocator) SCEVSignExtendExpr(ID.Intern(SCEVAllocator),
- Op, Ty);
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-/// getAnyExtendExpr - Return a SCEV for the given operand extended with
-/// unspecified bits out to the given type.
-///
-const SCEV *ScalarEvolution::getAnyExtendExpr(const SCEV *Op,
- const Type *Ty) {
- assert(getTypeSizeInBits(Op->getType()) < getTypeSizeInBits(Ty) &&
- "This is not an extending conversion!");
- assert(isSCEVable(Ty) &&
- "This is not a conversion to a SCEVable type!");
- Ty = getEffectiveSCEVType(Ty);
-
- // Sign-extend negative constants.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Op))
- if (SC->getValue()->getValue().isNegative())
- return getSignExtendExpr(Op, Ty);
-
- // Peel off a truncate cast.
- if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Op)) {
- const SCEV *NewOp = T->getOperand();
- if (getTypeSizeInBits(NewOp->getType()) < getTypeSizeInBits(Ty))
- return getAnyExtendExpr(NewOp, Ty);
- return getTruncateOrNoop(NewOp, Ty);
- }
-
- // Next try a zext cast. If the cast is folded, use it.
- const SCEV *ZExt = getZeroExtendExpr(Op, Ty);
- if (!isa<SCEVZeroExtendExpr>(ZExt))
- return ZExt;
-
- // Next try a sext cast. If the cast is folded, use it.
- const SCEV *SExt = getSignExtendExpr(Op, Ty);
- if (!isa<SCEVSignExtendExpr>(SExt))
- return SExt;
-
- // Force the cast to be folded into the operands of an addrec.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Op)) {
- SmallVector<const SCEV *, 4> Ops;
- for (SCEVAddRecExpr::op_iterator I = AR->op_begin(), E = AR->op_end();
- I != E; ++I)
- Ops.push_back(getAnyExtendExpr(*I, Ty));
- return getAddRecExpr(Ops, AR->getLoop());
- }
-
- // As a special case, fold anyext(undef) to undef. We don't want to
- // know too much about SCEVUnknowns, but this special case is handy
- // and harmless.
- if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(Op))
- if (isa<UndefValue>(U->getValue()))
- return getSCEV(UndefValue::get(Ty));
-
- // If the expression is obviously signed, use the sext cast value.
- if (isa<SCEVSMaxExpr>(Op))
- return SExt;
-
- // Absent any other information, use the zext cast value.
- return ZExt;
-}
-
-/// CollectAddOperandsWithScales - Process the given Ops list, which is
-/// a list of operands to be added under the given scale, update the given
-/// map. This is a helper function for getAddRecExpr. As an example of
-/// what it does, given a sequence of operands that would form an add
-/// expression like this:
-///
-/// m + n + 13 + (A * (o + p + (B * q + m + 29))) + r + (-1 * r)
-///
-/// where A and B are constants, update the map with these values:
-///
-/// (m, 1+A*B), (n, 1), (o, A), (p, A), (q, A*B), (r, 0)
-///
-/// and add 13 + A*B*29 to AccumulatedConstant.
-/// This will allow getAddRecExpr to produce this:
-///
-/// 13+A*B*29 + n + (m * (1+A*B)) + ((o + p) * A) + (q * A*B)
-///
-/// This form often exposes folding opportunities that are hidden in
-/// the original operand list.
-///
-/// Return true iff it appears that any interesting folding opportunities
-/// may be exposed. This helps getAddRecExpr short-circuit extra work in
-/// the common case where no interesting opportunities are present, and
-/// is also used as a check to avoid infinite recursion.
-///
-static bool
-CollectAddOperandsWithScales(DenseMap<const SCEV *, APInt> &M,
- SmallVector<const SCEV *, 8> &NewOps,
- APInt &AccumulatedConstant,
- const SCEV *const *Ops, size_t NumOperands,
- const APInt &Scale,
- ScalarEvolution &SE) {
- bool Interesting = false;
-
- // Iterate over the add operands. They are sorted, with constants first.
- unsigned i = 0;
- while (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
- ++i;
- // Pull a buried constant out to the outside.
- if (Scale != 1 || AccumulatedConstant != 0 || C->getValue()->isZero())
- Interesting = true;
- AccumulatedConstant += Scale * C->getValue()->getValue();
- }
-
- // Next comes everything else. We're especially interested in multiplies
- // here, but they're in the middle, so just visit the rest with one loop.
- for (; i != NumOperands; ++i) {
- const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[i]);
- if (Mul && isa<SCEVConstant>(Mul->getOperand(0))) {
- APInt NewScale =
- Scale * cast<SCEVConstant>(Mul->getOperand(0))->getValue()->getValue();
- if (Mul->getNumOperands() == 2 && isa<SCEVAddExpr>(Mul->getOperand(1))) {
- // A multiplication of a constant with another add; recurse.
- const SCEVAddExpr *Add = cast<SCEVAddExpr>(Mul->getOperand(1));
- Interesting |=
- CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
- Add->op_begin(), Add->getNumOperands(),
- NewScale, SE);
- } else {
- // A multiplication of a constant with some other value. Update
- // the map.
- SmallVector<const SCEV *, 4> MulOps(Mul->op_begin()+1, Mul->op_end());
- const SCEV *Key = SE.getMulExpr(MulOps);
- std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
- M.insert(std::make_pair(Key, NewScale));
- if (Pair.second) {
- NewOps.push_back(Pair.first->first);
- } else {
- Pair.first->second += NewScale;
- // The map already had an entry for this value, which may indicate
- // a folding opportunity.
- Interesting = true;
- }
- }
- } else {
- // An ordinary operand. Update the map.
- std::pair<DenseMap<const SCEV *, APInt>::iterator, bool> Pair =
- M.insert(std::make_pair(Ops[i], Scale));
- if (Pair.second) {
- NewOps.push_back(Pair.first->first);
- } else {
- Pair.first->second += Scale;
- // The map already had an entry for this value, which may indicate
- // a folding opportunity.
- Interesting = true;
- }
- }
- }
-
- return Interesting;
-}
-
-namespace {
- struct APIntCompare {
- bool operator()(const APInt &LHS, const APInt &RHS) const {
- return LHS.ult(RHS);
- }
- };
-}
-
-/// getAddExpr - Get a canonical add expression, or something simpler if
-/// possible.
-const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
- bool HasNUW, bool HasNSW) {
- assert(!Ops.empty() && "Cannot get empty add!");
- if (Ops.size() == 1) return Ops[0];
-#ifndef NDEBUG
- const Type *ETy = getEffectiveSCEVType(Ops[0]->getType());
- for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) == ETy &&
- "SCEVAddExpr operand types don't match!");
-#endif
-
- // If HasNSW is true and all the operands are non-negative, infer HasNUW.
- if (!HasNUW && HasNSW) {
- bool All = true;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (!isKnownNonNegative(Ops[i])) {
- All = false;
- break;
- }
- if (All) HasNUW = true;
- }
-
- // Sort by complexity, this groups all similar expression types together.
- GroupByComplexity(Ops, LI);
-
- // If there are any constants, fold them together.
- unsigned Idx = 0;
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
- ++Idx;
- assert(Idx < Ops.size());
- while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
- // We found two constants, fold them together!
- Ops[0] = getConstant(LHSC->getValue()->getValue() +
- RHSC->getValue()->getValue());
- if (Ops.size() == 2) return Ops[0];
- Ops.erase(Ops.begin()+1); // Erase the folded element
- LHSC = cast<SCEVConstant>(Ops[0]);
- }
-
- // If we are left with a constant zero being added, strip it off.
- if (LHSC->getValue()->isZero()) {
- Ops.erase(Ops.begin());
- --Idx;
- }
-
- if (Ops.size() == 1) return Ops[0];
- }
-
- // Okay, check to see if the same value occurs in the operand list twice. If
- // so, merge them together into an multiply expression. Since we sorted the
- // list, these values are required to be adjacent.
- const Type *Ty = Ops[0]->getType();
- for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
- // Found a match, merge the two values into a multiply, and add any
- // remaining values to the result.
- const SCEV *Two = getConstant(Ty, 2);
- const SCEV *Mul = getMulExpr(Ops[i], Two);
- if (Ops.size() == 2)
- return Mul;
- Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
- Ops.push_back(Mul);
- return getAddExpr(Ops, HasNUW, HasNSW);
- }
-
- // Check for truncates. If all the operands are truncated from the same
- // type, see if factoring out the truncate would permit the result to be
- // folded. eg., trunc(x) + m*trunc(n) --> trunc(x + trunc(m)*n)
- // if the contents of the resulting outer trunc fold to something simple.
- for (; Idx < Ops.size() && isa<SCEVTruncateExpr>(Ops[Idx]); ++Idx) {
- const SCEVTruncateExpr *Trunc = cast<SCEVTruncateExpr>(Ops[Idx]);
- const Type *DstType = Trunc->getType();
- const Type *SrcType = Trunc->getOperand()->getType();
- SmallVector<const SCEV *, 8> LargeOps;
- bool Ok = true;
- // Check all the operands to see if they can be represented in the
- // source type of the truncate.
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(Ops[i])) {
- if (T->getOperand()->getType() != SrcType) {
- Ok = false;
- break;
- }
- LargeOps.push_back(T->getOperand());
- } else if (const SCEVConstant *C = dyn_cast<SCEVConstant>(Ops[i])) {
- LargeOps.push_back(getAnyExtendExpr(C, SrcType));
- } else if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(Ops[i])) {
- SmallVector<const SCEV *, 8> LargeMulOps;
- for (unsigned j = 0, f = M->getNumOperands(); j != f && Ok; ++j) {
- if (const SCEVTruncateExpr *T =
- dyn_cast<SCEVTruncateExpr>(M->getOperand(j))) {
- if (T->getOperand()->getType() != SrcType) {
- Ok = false;
- break;
- }
- LargeMulOps.push_back(T->getOperand());
- } else if (const SCEVConstant *C =
- dyn_cast<SCEVConstant>(M->getOperand(j))) {
- LargeMulOps.push_back(getAnyExtendExpr(C, SrcType));
- } else {
- Ok = false;
- break;
- }
- }
- if (Ok)
- LargeOps.push_back(getMulExpr(LargeMulOps));
- } else {
- Ok = false;
- break;
- }
- }
- if (Ok) {
- // Evaluate the expression in the larger type.
- const SCEV *Fold = getAddExpr(LargeOps, HasNUW, HasNSW);
- // If it folds to something simple, use it. Otherwise, don't.
- if (isa<SCEVConstant>(Fold) || isa<SCEVUnknown>(Fold))
- return getTruncateExpr(Fold, DstType);
- }
- }
-
- // Skip past any other cast SCEVs.
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddExpr)
- ++Idx;
-
- // If there are add operands they would be next.
- if (Idx < Ops.size()) {
- bool DeletedAdd = false;
- while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
- // If we have an add, expand the add operands onto the end of the operands
- // list.
- Ops.erase(Ops.begin()+Idx);
- Ops.append(Add->op_begin(), Add->op_end());
- DeletedAdd = true;
- }
-
- // If we deleted at least one add, we added operands to the end of the list,
- // and they are not necessarily sorted. Recurse to resort and resimplify
- // any operands we just acquired.
- if (DeletedAdd)
- return getAddExpr(Ops);
- }
-
- // Skip over the add expression until we get to a multiply.
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
- ++Idx;
-
- // Check to see if there are any folding opportunities present with
- // operands multiplied by constant values.
- if (Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx])) {
- uint64_t BitWidth = getTypeSizeInBits(Ty);
- DenseMap<const SCEV *, APInt> M;
- SmallVector<const SCEV *, 8> NewOps;
- APInt AccumulatedConstant(BitWidth, 0);
- if (CollectAddOperandsWithScales(M, NewOps, AccumulatedConstant,
- Ops.data(), Ops.size(),
- APInt(BitWidth, 1), *this)) {
- // Some interesting folding opportunity is present, so its worthwhile to
- // re-generate the operands list. Group the operands by constant scale,
- // to avoid multiplying by the same constant scale multiple times.
- std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare> MulOpLists;
- for (SmallVector<const SCEV *, 8>::iterator I = NewOps.begin(),
- E = NewOps.end(); I != E; ++I)
- MulOpLists[M.find(*I)->second].push_back(*I);
- // Re-generate the operands list.
- Ops.clear();
- if (AccumulatedConstant != 0)
- Ops.push_back(getConstant(AccumulatedConstant));
- for (std::map<APInt, SmallVector<const SCEV *, 4>, APIntCompare>::iterator
- I = MulOpLists.begin(), E = MulOpLists.end(); I != E; ++I)
- if (I->first != 0)
- Ops.push_back(getMulExpr(getConstant(I->first),
- getAddExpr(I->second)));
- if (Ops.empty())
- return getConstant(Ty, 0);
- if (Ops.size() == 1)
- return Ops[0];
- return getAddExpr(Ops);
- }
- }
-
- // If we are adding something to a multiply expression, make sure the
- // something is not already an operand of the multiply. If so, merge it into
- // the multiply.
- for (; Idx < Ops.size() && isa<SCEVMulExpr>(Ops[Idx]); ++Idx) {
- const SCEVMulExpr *Mul = cast<SCEVMulExpr>(Ops[Idx]);
- for (unsigned MulOp = 0, e = Mul->getNumOperands(); MulOp != e; ++MulOp) {
- const SCEV *MulOpSCEV = Mul->getOperand(MulOp);
- for (unsigned AddOp = 0, e = Ops.size(); AddOp != e; ++AddOp)
- if (MulOpSCEV == Ops[AddOp] && !isa<SCEVConstant>(Ops[AddOp])) {
- // Fold W + X + (X * Y * Z) --> W + (X * ((Y*Z)+1))
- const SCEV *InnerMul = Mul->getOperand(MulOp == 0);
- if (Mul->getNumOperands() != 2) {
- // If the multiply has more than two operands, we must get the
- // Y*Z term.
- SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(), Mul->op_end());
- MulOps.erase(MulOps.begin()+MulOp);
- InnerMul = getMulExpr(MulOps);
- }
- const SCEV *One = getConstant(Ty, 1);
- const SCEV *AddOne = getAddExpr(InnerMul, One);
- const SCEV *OuterMul = getMulExpr(AddOne, Ops[AddOp]);
- if (Ops.size() == 2) return OuterMul;
- if (AddOp < Idx) {
- Ops.erase(Ops.begin()+AddOp);
- Ops.erase(Ops.begin()+Idx-1);
- } else {
- Ops.erase(Ops.begin()+Idx);
- Ops.erase(Ops.begin()+AddOp-1);
- }
- Ops.push_back(OuterMul);
- return getAddExpr(Ops);
- }
-
- // Check this multiply against other multiplies being added together.
- for (unsigned OtherMulIdx = Idx+1;
- OtherMulIdx < Ops.size() && isa<SCEVMulExpr>(Ops[OtherMulIdx]);
- ++OtherMulIdx) {
- const SCEVMulExpr *OtherMul = cast<SCEVMulExpr>(Ops[OtherMulIdx]);
- // If MulOp occurs in OtherMul, we can fold the two multiplies
- // together.
- for (unsigned OMulOp = 0, e = OtherMul->getNumOperands();
- OMulOp != e; ++OMulOp)
- if (OtherMul->getOperand(OMulOp) == MulOpSCEV) {
- // Fold X + (A*B*C) + (A*D*E) --> X + (A*(B*C+D*E))
- const SCEV *InnerMul1 = Mul->getOperand(MulOp == 0);
- if (Mul->getNumOperands() != 2) {
- SmallVector<const SCEV *, 4> MulOps(Mul->op_begin(),
- Mul->op_end());
- MulOps.erase(MulOps.begin()+MulOp);
- InnerMul1 = getMulExpr(MulOps);
- }
- const SCEV *InnerMul2 = OtherMul->getOperand(OMulOp == 0);
- if (OtherMul->getNumOperands() != 2) {
- SmallVector<const SCEV *, 4> MulOps(OtherMul->op_begin(),
- OtherMul->op_end());
- MulOps.erase(MulOps.begin()+OMulOp);
- InnerMul2 = getMulExpr(MulOps);
- }
- const SCEV *InnerMulSum = getAddExpr(InnerMul1,InnerMul2);
- const SCEV *OuterMul = getMulExpr(MulOpSCEV, InnerMulSum);
- if (Ops.size() == 2) return OuterMul;
- Ops.erase(Ops.begin()+Idx);
- Ops.erase(Ops.begin()+OtherMulIdx-1);
- Ops.push_back(OuterMul);
- return getAddExpr(Ops);
- }
- }
- }
- }
-
- // If there are any add recurrences in the operands list, see if any other
- // added values are loop invariant. If so, we can fold them into the
- // recurrence.
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
- ++Idx;
-
- // Scan over all recurrences, trying to fold loop invariants into them.
- for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
- // Scan all of the other operands to this add and add them to the vector if
- // they are loop invariant w.r.t. the recurrence.
- SmallVector<const SCEV *, 8> LIOps;
- const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
- const Loop *AddRecLoop = AddRec->getLoop();
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (Ops[i]->isLoopInvariant(AddRecLoop)) {
- LIOps.push_back(Ops[i]);
- Ops.erase(Ops.begin()+i);
- --i; --e;
- }
-
- // If we found some loop invariants, fold them into the recurrence.
- if (!LIOps.empty()) {
- // NLI + LI + {Start,+,Step} --> NLI + {LI+Start,+,Step}
- LIOps.push_back(AddRec->getStart());
-
- SmallVector<const SCEV *, 4> AddRecOps(AddRec->op_begin(),
- AddRec->op_end());
- AddRecOps[0] = getAddExpr(LIOps);
-
- // Build the new addrec. Propagate the NUW and NSW flags if both the
- // outer add and the inner addrec are guaranteed to have no overflow.
- const SCEV *NewRec = getAddRecExpr(AddRecOps, AddRecLoop,
- HasNUW && AddRec->hasNoUnsignedWrap(),
- HasNSW && AddRec->hasNoSignedWrap());
-
- // If all of the other operands were loop invariant, we are done.
- if (Ops.size() == 1) return NewRec;
-
- // Otherwise, add the folded AddRec by the non-liv parts.
- for (unsigned i = 0;; ++i)
- if (Ops[i] == AddRec) {
- Ops[i] = NewRec;
- break;
- }
- return getAddExpr(Ops);
- }
-
- // Okay, if there weren't any loop invariants to be folded, check to see if
- // there are multiple AddRec's with the same loop induction variable being
- // added together. If so, we can fold them.
- for (unsigned OtherIdx = Idx+1;
- OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);++OtherIdx)
- if (OtherIdx != Idx) {
- const SCEVAddRecExpr *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
- if (AddRecLoop == OtherAddRec->getLoop()) {
- // Other + {A,+,B} + {C,+,D} --> Other + {A+C,+,B+D}
- SmallVector<const SCEV *, 4> NewOps(AddRec->op_begin(),
- AddRec->op_end());
- for (unsigned i = 0, e = OtherAddRec->getNumOperands(); i != e; ++i) {
- if (i >= NewOps.size()) {
- NewOps.append(OtherAddRec->op_begin()+i,
- OtherAddRec->op_end());
- break;
- }
- NewOps[i] = getAddExpr(NewOps[i], OtherAddRec->getOperand(i));
- }
- const SCEV *NewAddRec = getAddRecExpr(NewOps, AddRecLoop);
-
- if (Ops.size() == 2) return NewAddRec;
-
- Ops.erase(Ops.begin()+Idx);
- Ops.erase(Ops.begin()+OtherIdx-1);
- Ops.push_back(NewAddRec);
- return getAddExpr(Ops);
- }
- }
-
- // Otherwise couldn't fold anything into this recurrence. Move onto the
- // next one.
- }
-
- // Okay, it looks like we really DO need an add expr. Check to see if we
- // already have one, otherwise create a new one.
- FoldingSetNodeID ID;
- ID.AddInteger(scAddExpr);
- ID.AddInteger(Ops.size());
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- ID.AddPointer(Ops[i]);
- void *IP = 0;
- SCEVAddExpr *S =
- static_cast<SCEVAddExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
- if (!S) {
- const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
- std::uninitialized_copy(Ops.begin(), Ops.end(), O);
- S = new (SCEVAllocator) SCEVAddExpr(ID.Intern(SCEVAllocator),
- O, Ops.size());
- UniqueSCEVs.InsertNode(S, IP);
- }
- if (HasNUW) S->setHasNoUnsignedWrap(true);
- if (HasNSW) S->setHasNoSignedWrap(true);
- return S;
-}
-
-/// getMulExpr - Get a canonical multiply expression, or something simpler if
-/// possible.
-const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
- bool HasNUW, bool HasNSW) {
- assert(!Ops.empty() && "Cannot get empty mul!");
- if (Ops.size() == 1) return Ops[0];
-#ifndef NDEBUG
- for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
- "SCEVMulExpr operand types don't match!");
-#endif
-
- // If HasNSW is true and all the operands are non-negative, infer HasNUW.
- if (!HasNUW && HasNSW) {
- bool All = true;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (!isKnownNonNegative(Ops[i])) {
- All = false;
- break;
- }
- if (All) HasNUW = true;
- }
-
- // Sort by complexity, this groups all similar expression types together.
- GroupByComplexity(Ops, LI);
-
- // If there are any constants, fold them together.
- unsigned Idx = 0;
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
-
- // C1*(C2+V) -> C1*C2 + C1*V
- if (Ops.size() == 2)
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
- if (Add->getNumOperands() == 2 &&
- isa<SCEVConstant>(Add->getOperand(0)))
- return getAddExpr(getMulExpr(LHSC, Add->getOperand(0)),
- getMulExpr(LHSC, Add->getOperand(1)));
-
- ++Idx;
- while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
- // We found two constants, fold them together!
- ConstantInt *Fold = ConstantInt::get(getContext(),
- LHSC->getValue()->getValue() *
- RHSC->getValue()->getValue());
- Ops[0] = getConstant(Fold);
- Ops.erase(Ops.begin()+1); // Erase the folded element
- if (Ops.size() == 1) return Ops[0];
- LHSC = cast<SCEVConstant>(Ops[0]);
- }
-
- // If we are left with a constant one being multiplied, strip it off.
- if (cast<SCEVConstant>(Ops[0])->getValue()->equalsInt(1)) {
- Ops.erase(Ops.begin());
- --Idx;
- } else if (cast<SCEVConstant>(Ops[0])->getValue()->isZero()) {
- // If we have a multiply of zero, it will always be zero.
- return Ops[0];
- } else if (Ops[0]->isAllOnesValue()) {
- // If we have a mul by -1 of an add, try distributing the -1 among the
- // add operands.
- if (Ops.size() == 2)
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1])) {
- SmallVector<const SCEV *, 4> NewOps;
- bool AnyFolded = false;
- for (SCEVAddRecExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
- I != E; ++I) {
- const SCEV *Mul = getMulExpr(Ops[0], *I);
- if (!isa<SCEVMulExpr>(Mul)) AnyFolded = true;
- NewOps.push_back(Mul);
- }
- if (AnyFolded)
- return getAddExpr(NewOps);
- }
- }
-
- if (Ops.size() == 1)
- return Ops[0];
- }
-
- // Skip over the add expression until we get to a multiply.
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scMulExpr)
- ++Idx;
-
- // If there are mul operands inline them all into this expression.
- if (Idx < Ops.size()) {
- bool DeletedMul = false;
- while (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Ops[Idx])) {
- // If we have an mul, expand the mul operands onto the end of the operands
- // list.
- Ops.erase(Ops.begin()+Idx);
- Ops.append(Mul->op_begin(), Mul->op_end());
- DeletedMul = true;
- }
-
- // If we deleted at least one mul, we added operands to the end of the list,
- // and they are not necessarily sorted. Recurse to resort and resimplify
- // any operands we just acquired.
- if (DeletedMul)
- return getMulExpr(Ops);
- }
-
- // If there are any add recurrences in the operands list, see if any other
- // added values are loop invariant. If so, we can fold them into the
- // recurrence.
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scAddRecExpr)
- ++Idx;
-
- // Scan over all recurrences, trying to fold loop invariants into them.
- for (; Idx < Ops.size() && isa<SCEVAddRecExpr>(Ops[Idx]); ++Idx) {
- // Scan all of the other operands to this mul and add them to the vector if
- // they are loop invariant w.r.t. the recurrence.
- SmallVector<const SCEV *, 8> LIOps;
- const SCEVAddRecExpr *AddRec = cast<SCEVAddRecExpr>(Ops[Idx]);
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- if (Ops[i]->isLoopInvariant(AddRec->getLoop())) {
- LIOps.push_back(Ops[i]);
- Ops.erase(Ops.begin()+i);
- --i; --e;
- }
-
- // If we found some loop invariants, fold them into the recurrence.
- if (!LIOps.empty()) {
- // NLI * LI * {Start,+,Step} --> NLI * {LI*Start,+,LI*Step}
- SmallVector<const SCEV *, 4> NewOps;
- NewOps.reserve(AddRec->getNumOperands());
- const SCEV *Scale = getMulExpr(LIOps);
- for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i)
- NewOps.push_back(getMulExpr(Scale, AddRec->getOperand(i)));
-
- // Build the new addrec. Propagate the NUW and NSW flags if both the
- // outer mul and the inner addrec are guaranteed to have no overflow.
- const SCEV *NewRec = getAddRecExpr(NewOps, AddRec->getLoop(),
- HasNUW && AddRec->hasNoUnsignedWrap(),
- HasNSW && AddRec->hasNoSignedWrap());
-
- // If all of the other operands were loop invariant, we are done.
- if (Ops.size() == 1) return NewRec;
-
- // Otherwise, multiply the folded AddRec by the non-liv parts.
- for (unsigned i = 0;; ++i)
- if (Ops[i] == AddRec) {
- Ops[i] = NewRec;
- break;
- }
- return getMulExpr(Ops);
- }
-
- // Okay, if there weren't any loop invariants to be folded, check to see if
- // there are multiple AddRec's with the same loop induction variable being
- // multiplied together. If so, we can fold them.
- for (unsigned OtherIdx = Idx+1;
- OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);++OtherIdx)
- if (OtherIdx != Idx) {
- const SCEVAddRecExpr *OtherAddRec = cast<SCEVAddRecExpr>(Ops[OtherIdx]);
- if (AddRec->getLoop() == OtherAddRec->getLoop()) {
- // F * G --> {A,+,B} * {C,+,D} --> {A*C,+,F*D + G*B + B*D}
- const SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
- const SCEV *NewStart = getMulExpr(F->getStart(),
- G->getStart());
- const SCEV *B = F->getStepRecurrence(*this);
- const SCEV *D = G->getStepRecurrence(*this);
- const SCEV *NewStep = getAddExpr(getMulExpr(F, D),
- getMulExpr(G, B),
- getMulExpr(B, D));
- const SCEV *NewAddRec = getAddRecExpr(NewStart, NewStep,
- F->getLoop());
- if (Ops.size() == 2) return NewAddRec;
-
- Ops.erase(Ops.begin()+Idx);
- Ops.erase(Ops.begin()+OtherIdx-1);
- Ops.push_back(NewAddRec);
- return getMulExpr(Ops);
- }
- }
-
- // Otherwise couldn't fold anything into this recurrence. Move onto the
- // next one.
- }
-
- // Okay, it looks like we really DO need an mul expr. Check to see if we
- // already have one, otherwise create a new one.
- FoldingSetNodeID ID;
- ID.AddInteger(scMulExpr);
- ID.AddInteger(Ops.size());
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- ID.AddPointer(Ops[i]);
- void *IP = 0;
- SCEVMulExpr *S =
- static_cast<SCEVMulExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
- if (!S) {
- const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
- std::uninitialized_copy(Ops.begin(), Ops.end(), O);
- S = new (SCEVAllocator) SCEVMulExpr(ID.Intern(SCEVAllocator),
- O, Ops.size());
- UniqueSCEVs.InsertNode(S, IP);
- }
- if (HasNUW) S->setHasNoUnsignedWrap(true);
- if (HasNSW) S->setHasNoSignedWrap(true);
- return S;
-}
-
-/// getUDivExpr - Get a canonical unsigned division expression, or something
-/// simpler if possible.
-const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
- const SCEV *RHS) {
- assert(getEffectiveSCEVType(LHS->getType()) ==
- getEffectiveSCEVType(RHS->getType()) &&
- "SCEVUDivExpr operand types don't match!");
-
- if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
- if (RHSC->getValue()->equalsInt(1))
- return LHS; // X udiv 1 --> x
- // If the denominator is zero, the result of the udiv is undefined. Don't
- // try to analyze it, because the resolution chosen here may differ from
- // the resolution chosen in other parts of the compiler.
- if (!RHSC->getValue()->isZero()) {
- // Determine if the division can be folded into the operands of
- // its operands.
- // TODO: Generalize this to non-constants by using known-bits information.
- const Type *Ty = LHS->getType();
- unsigned LZ = RHSC->getValue()->getValue().countLeadingZeros();
- unsigned MaxShiftAmt = getTypeSizeInBits(Ty) - LZ;
- // For non-power-of-two values, effectively round the value up to the
- // nearest power of two.
- if (!RHSC->getValue()->getValue().isPowerOf2())
- ++MaxShiftAmt;
- const IntegerType *ExtTy =
- IntegerType::get(getContext(), getTypeSizeInBits(Ty) + MaxShiftAmt);
- // {X,+,N}/C --> {X/C,+,N/C} if safe and N/C can be folded.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
- if (const SCEVConstant *Step =
- dyn_cast<SCEVConstant>(AR->getStepRecurrence(*this)))
- if (!Step->getValue()->getValue()
- .urem(RHSC->getValue()->getValue()) &&
- getZeroExtendExpr(AR, ExtTy) ==
- getAddRecExpr(getZeroExtendExpr(AR->getStart(), ExtTy),
- getZeroExtendExpr(Step, ExtTy),
- AR->getLoop())) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = AR->getNumOperands(); i != e; ++i)
- Operands.push_back(getUDivExpr(AR->getOperand(i), RHS));
- return getAddRecExpr(Operands, AR->getLoop());
- }
- // (A*B)/C --> A*(B/C) if safe and B/C can be folded.
- if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(LHS)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i)
- Operands.push_back(getZeroExtendExpr(M->getOperand(i), ExtTy));
- if (getZeroExtendExpr(M, ExtTy) == getMulExpr(Operands))
- // Find an operand that's safely divisible.
- for (unsigned i = 0, e = M->getNumOperands(); i != e; ++i) {
- const SCEV *Op = M->getOperand(i);
- const SCEV *Div = getUDivExpr(Op, RHSC);
- if (!isa<SCEVUDivExpr>(Div) && getMulExpr(Div, RHSC) == Op) {
- Operands = SmallVector<const SCEV *, 4>(M->op_begin(),
- M->op_end());
- Operands[i] = Div;
- return getMulExpr(Operands);
- }
- }
- }
- // (A+B)/C --> (A/C + B/C) if safe and A/C and B/C can be folded.
- if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(LHS)) {
- SmallVector<const SCEV *, 4> Operands;
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i)
- Operands.push_back(getZeroExtendExpr(A->getOperand(i), ExtTy));
- if (getZeroExtendExpr(A, ExtTy) == getAddExpr(Operands)) {
- Operands.clear();
- for (unsigned i = 0, e = A->getNumOperands(); i != e; ++i) {
- const SCEV *Op = getUDivExpr(A->getOperand(i), RHS);
- if (isa<SCEVUDivExpr>(Op) ||
- getMulExpr(Op, RHS) != A->getOperand(i))
- break;
- Operands.push_back(Op);
- }
- if (Operands.size() == A->getNumOperands())
- return getAddExpr(Operands);
- }
- }
-
- // Fold if both operands are constant.
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
- Constant *LHSCV = LHSC->getValue();
- Constant *RHSCV = RHSC->getValue();
- return getConstant(cast<ConstantInt>(ConstantExpr::getUDiv(LHSCV,
- RHSCV)));
- }
- }
- }
-
- FoldingSetNodeID ID;
- ID.AddInteger(scUDivExpr);
- ID.AddPointer(LHS);
- ID.AddPointer(RHS);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- SCEV *S = new (SCEVAllocator) SCEVUDivExpr(ID.Intern(SCEVAllocator),
- LHS, RHS);
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-
-/// getAddRecExpr - Get an add recurrence expression for the specified loop.
-/// Simplify the expression as much as possible.
-const SCEV *ScalarEvolution::getAddRecExpr(const SCEV *Start,
- const SCEV *Step, const Loop *L,
- bool HasNUW, bool HasNSW) {
- SmallVector<const SCEV *, 4> Operands;
- Operands.push_back(Start);
- if (const SCEVAddRecExpr *StepChrec = dyn_cast<SCEVAddRecExpr>(Step))
- if (StepChrec->getLoop() == L) {
- Operands.append(StepChrec->op_begin(), StepChrec->op_end());
- return getAddRecExpr(Operands, L);
- }
-
- Operands.push_back(Step);
- return getAddRecExpr(Operands, L, HasNUW, HasNSW);
-}
-
-/// getAddRecExpr - Get an add recurrence expression for the specified loop.
-/// Simplify the expression as much as possible.
-const SCEV *
-ScalarEvolution::getAddRecExpr(SmallVectorImpl<const SCEV *> &Operands,
- const Loop *L,
- bool HasNUW, bool HasNSW) {
- if (Operands.size() == 1) return Operands[0];
-#ifndef NDEBUG
- for (unsigned i = 1, e = Operands.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Operands[i]->getType()) ==
- getEffectiveSCEVType(Operands[0]->getType()) &&
- "SCEVAddRecExpr operand types don't match!");
-#endif
-
- if (Operands.back()->isZero()) {
- Operands.pop_back();
- return getAddRecExpr(Operands, L, HasNUW, HasNSW); // {X,+,0} --> X
- }
-
- // It's tempting to want to call getMaxBackedgeTakenCount count here and
- // use that information to infer NUW and NSW flags. However, computing a
- // BE count requires calling getAddRecExpr, so we may not yet have a
- // meaningful BE count at this point (and if we don't, we'd be stuck
- // with a SCEVCouldNotCompute as the cached BE count).
-
- // If HasNSW is true and all the operands are non-negative, infer HasNUW.
- if (!HasNUW && HasNSW) {
- bool All = true;
- for (unsigned i = 0, e = Operands.size(); i != e; ++i)
- if (!isKnownNonNegative(Operands[i])) {
- All = false;
- break;
- }
- if (All) HasNUW = true;
- }
-
- // Canonicalize nested AddRecs in by nesting them in order of loop depth.
- if (const SCEVAddRecExpr *NestedAR = dyn_cast<SCEVAddRecExpr>(Operands[0])) {
- const Loop *NestedLoop = NestedAR->getLoop();
- if (L->contains(NestedLoop->getHeader()) ?
- (L->getLoopDepth() < NestedLoop->getLoopDepth()) :
- (!NestedLoop->contains(L->getHeader()) &&
- DT->dominates(L->getHeader(), NestedLoop->getHeader()))) {
- SmallVector<const SCEV *, 4> NestedOperands(NestedAR->op_begin(),
- NestedAR->op_end());
- Operands[0] = NestedAR->getStart();
- // AddRecs require their operands be loop-invariant with respect to their
- // loops. Don't perform this transformation if it would break this
- // requirement.
- bool AllInvariant = true;
- for (unsigned i = 0, e = Operands.size(); i != e; ++i)
- if (!Operands[i]->isLoopInvariant(L)) {
- AllInvariant = false;
- break;
- }
- if (AllInvariant) {
- NestedOperands[0] = getAddRecExpr(Operands, L);
- AllInvariant = true;
- for (unsigned i = 0, e = NestedOperands.size(); i != e; ++i)
- if (!NestedOperands[i]->isLoopInvariant(NestedLoop)) {
- AllInvariant = false;
- break;
- }
- if (AllInvariant)
- // Ok, both add recurrences are valid after the transformation.
- return getAddRecExpr(NestedOperands, NestedLoop, HasNUW, HasNSW);
- }
- // Reset Operands to its original state.
- Operands[0] = NestedAR;
- }
- }
-
- // Okay, it looks like we really DO need an addrec expr. Check to see if we
- // already have one, otherwise create a new one.
- FoldingSetNodeID ID;
- ID.AddInteger(scAddRecExpr);
- ID.AddInteger(Operands.size());
- for (unsigned i = 0, e = Operands.size(); i != e; ++i)
- ID.AddPointer(Operands[i]);
- ID.AddPointer(L);
- void *IP = 0;
- SCEVAddRecExpr *S =
- static_cast<SCEVAddRecExpr *>(UniqueSCEVs.FindNodeOrInsertPos(ID, IP));
- if (!S) {
- const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Operands.size());
- std::uninitialized_copy(Operands.begin(), Operands.end(), O);
- S = new (SCEVAllocator) SCEVAddRecExpr(ID.Intern(SCEVAllocator),
- O, Operands.size(), L);
- UniqueSCEVs.InsertNode(S, IP);
- }
- if (HasNUW) S->setHasNoUnsignedWrap(true);
- if (HasNSW) S->setHasNoSignedWrap(true);
- return S;
-}
-
-const SCEV *ScalarEvolution::getSMaxExpr(const SCEV *LHS,
- const SCEV *RHS) {
- SmallVector<const SCEV *, 2> Ops;
- Ops.push_back(LHS);
- Ops.push_back(RHS);
- return getSMaxExpr(Ops);
-}
-
-const SCEV *
-ScalarEvolution::getSMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
- assert(!Ops.empty() && "Cannot get empty smax!");
- if (Ops.size() == 1) return Ops[0];
-#ifndef NDEBUG
- for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
- "SCEVSMaxExpr operand types don't match!");
-#endif
-
- // Sort by complexity, this groups all similar expression types together.
- GroupByComplexity(Ops, LI);
-
- // If there are any constants, fold them together.
- unsigned Idx = 0;
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
- ++Idx;
- assert(Idx < Ops.size());
- while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
- // We found two constants, fold them together!
- ConstantInt *Fold = ConstantInt::get(getContext(),
- APIntOps::smax(LHSC->getValue()->getValue(),
- RHSC->getValue()->getValue()));
- Ops[0] = getConstant(Fold);
- Ops.erase(Ops.begin()+1); // Erase the folded element
- if (Ops.size() == 1) return Ops[0];
- LHSC = cast<SCEVConstant>(Ops[0]);
- }
-
- // If we are left with a constant minimum-int, strip it off.
- if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(true)) {
- Ops.erase(Ops.begin());
- --Idx;
- } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(true)) {
- // If we have an smax with a constant maximum-int, it will always be
- // maximum-int.
- return Ops[0];
- }
-
- if (Ops.size() == 1) return Ops[0];
- }
-
- // Find the first SMax
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scSMaxExpr)
- ++Idx;
-
- // Check to see if one of the operands is an SMax. If so, expand its operands
- // onto our operand list, and recurse to simplify.
- if (Idx < Ops.size()) {
- bool DeletedSMax = false;
- while (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(Ops[Idx])) {
- Ops.erase(Ops.begin()+Idx);
- Ops.append(SMax->op_begin(), SMax->op_end());
- DeletedSMax = true;
- }
-
- if (DeletedSMax)
- return getSMaxExpr(Ops);
- }
-
- // Okay, check to see if the same value occurs in the operand list twice. If
- // so, delete one. Since we sorted the list, these values are required to
- // be adjacent.
- for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- // X smax Y smax Y --> X smax Y
- // X smax Y --> X, if X is always greater than Y
- if (Ops[i] == Ops[i+1] ||
- isKnownPredicate(ICmpInst::ICMP_SGE, Ops[i], Ops[i+1])) {
- Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
- --i; --e;
- } else if (isKnownPredicate(ICmpInst::ICMP_SLE, Ops[i], Ops[i+1])) {
- Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
- --i; --e;
- }
-
- if (Ops.size() == 1) return Ops[0];
-
- assert(!Ops.empty() && "Reduced smax down to nothing!");
-
- // Okay, it looks like we really DO need an smax expr. Check to see if we
- // already have one, otherwise create a new one.
- FoldingSetNodeID ID;
- ID.AddInteger(scSMaxExpr);
- ID.AddInteger(Ops.size());
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- ID.AddPointer(Ops[i]);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
- std::uninitialized_copy(Ops.begin(), Ops.end(), O);
- SCEV *S = new (SCEVAllocator) SCEVSMaxExpr(ID.Intern(SCEVAllocator),
- O, Ops.size());
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-const SCEV *ScalarEvolution::getUMaxExpr(const SCEV *LHS,
- const SCEV *RHS) {
- SmallVector<const SCEV *, 2> Ops;
- Ops.push_back(LHS);
- Ops.push_back(RHS);
- return getUMaxExpr(Ops);
-}
-
-const SCEV *
-ScalarEvolution::getUMaxExpr(SmallVectorImpl<const SCEV *> &Ops) {
- assert(!Ops.empty() && "Cannot get empty umax!");
- if (Ops.size() == 1) return Ops[0];
-#ifndef NDEBUG
- for (unsigned i = 1, e = Ops.size(); i != e; ++i)
- assert(getEffectiveSCEVType(Ops[i]->getType()) ==
- getEffectiveSCEVType(Ops[0]->getType()) &&
- "SCEVUMaxExpr operand types don't match!");
-#endif
-
- // Sort by complexity, this groups all similar expression types together.
- GroupByComplexity(Ops, LI);
-
- // If there are any constants, fold them together.
- unsigned Idx = 0;
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
- ++Idx;
- assert(Idx < Ops.size());
- while (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(Ops[Idx])) {
- // We found two constants, fold them together!
- ConstantInt *Fold = ConstantInt::get(getContext(),
- APIntOps::umax(LHSC->getValue()->getValue(),
- RHSC->getValue()->getValue()));
- Ops[0] = getConstant(Fold);
- Ops.erase(Ops.begin()+1); // Erase the folded element
- if (Ops.size() == 1) return Ops[0];
- LHSC = cast<SCEVConstant>(Ops[0]);
- }
-
- // If we are left with a constant minimum-int, strip it off.
- if (cast<SCEVConstant>(Ops[0])->getValue()->isMinValue(false)) {
- Ops.erase(Ops.begin());
- --Idx;
- } else if (cast<SCEVConstant>(Ops[0])->getValue()->isMaxValue(false)) {
- // If we have an umax with a constant maximum-int, it will always be
- // maximum-int.
- return Ops[0];
- }
-
- if (Ops.size() == 1) return Ops[0];
- }
-
- // Find the first UMax
- while (Idx < Ops.size() && Ops[Idx]->getSCEVType() < scUMaxExpr)
- ++Idx;
-
- // Check to see if one of the operands is a UMax. If so, expand its operands
- // onto our operand list, and recurse to simplify.
- if (Idx < Ops.size()) {
- bool DeletedUMax = false;
- while (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(Ops[Idx])) {
- Ops.erase(Ops.begin()+Idx);
- Ops.append(UMax->op_begin(), UMax->op_end());
- DeletedUMax = true;
- }
-
- if (DeletedUMax)
- return getUMaxExpr(Ops);
- }
-
- // Okay, check to see if the same value occurs in the operand list twice. If
- // so, delete one. Since we sorted the list, these values are required to
- // be adjacent.
- for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
- // X umax Y umax Y --> X umax Y
- // X umax Y --> X, if X is always greater than Y
- if (Ops[i] == Ops[i+1] ||
- isKnownPredicate(ICmpInst::ICMP_UGE, Ops[i], Ops[i+1])) {
- Ops.erase(Ops.begin()+i+1, Ops.begin()+i+2);
- --i; --e;
- } else if (isKnownPredicate(ICmpInst::ICMP_ULE, Ops[i], Ops[i+1])) {
- Ops.erase(Ops.begin()+i, Ops.begin()+i+1);
- --i; --e;
- }
-
- if (Ops.size() == 1) return Ops[0];
-
- assert(!Ops.empty() && "Reduced umax down to nothing!");
-
- // Okay, it looks like we really DO need a umax expr. Check to see if we
- // already have one, otherwise create a new one.
- FoldingSetNodeID ID;
- ID.AddInteger(scUMaxExpr);
- ID.AddInteger(Ops.size());
- for (unsigned i = 0, e = Ops.size(); i != e; ++i)
- ID.AddPointer(Ops[i]);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- const SCEV **O = SCEVAllocator.Allocate<const SCEV *>(Ops.size());
- std::uninitialized_copy(Ops.begin(), Ops.end(), O);
- SCEV *S = new (SCEVAllocator) SCEVUMaxExpr(ID.Intern(SCEVAllocator),
- O, Ops.size());
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-const SCEV *ScalarEvolution::getSMinExpr(const SCEV *LHS,
- const SCEV *RHS) {
- // ~smax(~x, ~y) == smin(x, y).
- return getNotSCEV(getSMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
-}
-
-const SCEV *ScalarEvolution::getUMinExpr(const SCEV *LHS,
- const SCEV *RHS) {
- // ~umax(~x, ~y) == umin(x, y)
- return getNotSCEV(getUMaxExpr(getNotSCEV(LHS), getNotSCEV(RHS)));
-}
-
-const SCEV *ScalarEvolution::getSizeOfExpr(const Type *AllocTy) {
- // If we have TargetData, we can bypass creating a target-independent
- // constant expression and then folding it back into a ConstantInt.
- // This is just a compile-time optimization.
- if (TD)
- return getConstant(TD->getIntPtrType(getContext()),
- TD->getTypeAllocSize(AllocTy));
-
- Constant *C = ConstantExpr::getSizeOf(AllocTy);
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
- C = Folded;
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
- return getTruncateOrZeroExtend(getSCEV(C), Ty);
-}
-
-const SCEV *ScalarEvolution::getAlignOfExpr(const Type *AllocTy) {
- Constant *C = ConstantExpr::getAlignOf(AllocTy);
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
- C = Folded;
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(AllocTy));
- return getTruncateOrZeroExtend(getSCEV(C), Ty);
-}
-
-const SCEV *ScalarEvolution::getOffsetOfExpr(const StructType *STy,
- unsigned FieldNo) {
- // If we have TargetData, we can bypass creating a target-independent
- // constant expression and then folding it back into a ConstantInt.
- // This is just a compile-time optimization.
- if (TD)
- return getConstant(TD->getIntPtrType(getContext()),
- TD->getStructLayout(STy)->getElementOffset(FieldNo));
-
- Constant *C = ConstantExpr::getOffsetOf(STy, FieldNo);
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
- C = Folded;
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(STy));
- return getTruncateOrZeroExtend(getSCEV(C), Ty);
-}
-
-const SCEV *ScalarEvolution::getOffsetOfExpr(const Type *CTy,
- Constant *FieldNo) {
- Constant *C = ConstantExpr::getOffsetOf(CTy, FieldNo);
- if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
- if (Constant *Folded = ConstantFoldConstantExpression(CE, TD))
- C = Folded;
- const Type *Ty = getEffectiveSCEVType(PointerType::getUnqual(CTy));
- return getTruncateOrZeroExtend(getSCEV(C), Ty);
-}
-
-const SCEV *ScalarEvolution::getUnknown(Value *V) {
- // Don't attempt to do anything other than create a SCEVUnknown object
- // here. createSCEV only calls getUnknown after checking for all other
- // interesting possibilities, and any other code that calls getUnknown
- // is doing so in order to hide a value from SCEV canonicalization.
-
- FoldingSetNodeID ID;
- ID.AddInteger(scUnknown);
- ID.AddPointer(V);
- void *IP = 0;
- if (const SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) return S;
- SCEV *S = new (SCEVAllocator) SCEVUnknown(ID.Intern(SCEVAllocator), V);
- UniqueSCEVs.InsertNode(S, IP);
- return S;
-}
-
-//===----------------------------------------------------------------------===//
-// Basic SCEV Analysis and PHI Idiom Recognition Code
-//
-
-/// isSCEVable - Test if values of the given type are analyzable within
-/// the SCEV framework. This primarily includes integer types, and it
-/// can optionally include pointer types if the ScalarEvolution class
-/// has access to target-specific information.
-bool ScalarEvolution::isSCEVable(const Type *Ty) const {
- // Integers and pointers are always SCEVable.
- return Ty->isIntegerTy() || Ty->isPointerTy();
-}
-
-/// getTypeSizeInBits - Return the size in bits of the specified type,
-/// for which isSCEVable must return true.
-uint64_t ScalarEvolution::getTypeSizeInBits(const Type *Ty) const {
- assert(isSCEVable(Ty) && "Type is not SCEVable!");
-
- // If we have a TargetData, use it!
- if (TD)
- return TD->getTypeSizeInBits(Ty);
-
- // Integer types have fixed sizes.
- if (Ty->isIntegerTy())
- return Ty->getPrimitiveSizeInBits();
-
- // The only other support type is pointer. Without TargetData, conservatively
- // assume pointers are 64-bit.
- assert(Ty->isPointerTy() && "isSCEVable permitted a non-SCEVable type!");
- return 64;
-}
-
-/// getEffectiveSCEVType - Return a type with the same bitwidth as
-/// the given type and which represents how SCEV will treat the given
-/// type, for which isSCEVable must return true. For pointer types,
-/// this is the pointer-sized integer type.
-const Type *ScalarEvolution::getEffectiveSCEVType(const Type *Ty) const {
- assert(isSCEVable(Ty) && "Type is not SCEVable!");
-
- if (Ty->isIntegerTy())
- return Ty;
-
- // The only other support type is pointer.
- assert(Ty->isPointerTy() && "Unexpected non-pointer non-integer type!");
- if (TD) return TD->getIntPtrType(getContext());
-
- // Without TargetData, conservatively assume pointers are 64-bit.
- return Type::getInt64Ty(getContext());
-}
-
-const SCEV *ScalarEvolution::getCouldNotCompute() {
- return &CouldNotCompute;
-}
-
-/// getSCEV - Return an existing SCEV if it exists, otherwise analyze the
-/// expression and create a new one.
-const SCEV *ScalarEvolution::getSCEV(Value *V) {
- assert(isSCEVable(V->getType()) && "Value is not SCEVable!");
-
- std::map<SCEVCallbackVH, const SCEV *>::iterator I = Scalars.find(V);
- if (I != Scalars.end()) return I->second;
- const SCEV *S = createSCEV(V);
- Scalars.insert(std::make_pair(SCEVCallbackVH(V, this), S));
- return S;
-}
-
-/// getNegativeSCEV - Return a SCEV corresponding to -V = -1*V
-///
-const SCEV *ScalarEvolution::getNegativeSCEV(const SCEV *V) {
- if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
- return getConstant(
- cast<ConstantInt>(ConstantExpr::getNeg(VC->getValue())));
-
- const Type *Ty = V->getType();
- Ty = getEffectiveSCEVType(Ty);
- return getMulExpr(V,
- getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty))));
-}
-
-/// getNotSCEV - Return a SCEV corresponding to ~V = -1-V
-const SCEV *ScalarEvolution::getNotSCEV(const SCEV *V) {
- if (const SCEVConstant *VC = dyn_cast<SCEVConstant>(V))
- return getConstant(
- cast<ConstantInt>(ConstantExpr::getNot(VC->getValue())));
-
- const Type *Ty = V->getType();
- Ty = getEffectiveSCEVType(Ty);
- const SCEV *AllOnes =
- getConstant(cast<ConstantInt>(Constant::getAllOnesValue(Ty)));
- return getMinusSCEV(AllOnes, V);
-}
-
-/// getMinusSCEV - Return a SCEV corresponding to LHS - RHS.
-///
-const SCEV *ScalarEvolution::getMinusSCEV(const SCEV *LHS,
- const SCEV *RHS) {
- // X - Y --> X + -Y
- return getAddExpr(LHS, getNegativeSCEV(RHS));
-}
-
-/// getTruncateOrZeroExtend - Return a SCEV corresponding to a conversion of the
-/// input value to the specified type. If the type must be extended, it is zero
-/// extended.
-const SCEV *
-ScalarEvolution::getTruncateOrZeroExtend(const SCEV *V,
- const Type *Ty) {
- const Type *SrcTy = V->getType();
- assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot truncate or zero extend with non-integer arguments!");
- if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
- return V; // No conversion
- if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
- return getTruncateExpr(V, Ty);
- return getZeroExtendExpr(V, Ty);
-}
-
-/// getTruncateOrSignExtend - Return a SCEV corresponding to a conversion of the
-/// input value to the specified type. If the type must be extended, it is sign
-/// extended.
-const SCEV *
-ScalarEvolution::getTruncateOrSignExtend(const SCEV *V,
- const Type *Ty) {
- const Type *SrcTy = V->getType();
- assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot truncate or zero extend with non-integer arguments!");
- if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
- return V; // No conversion
- if (getTypeSizeInBits(SrcTy) > getTypeSizeInBits(Ty))
- return getTruncateExpr(V, Ty);
- return getSignExtendExpr(V, Ty);
-}
-
-/// getNoopOrZeroExtend - Return a SCEV corresponding to a conversion of the
-/// input value to the specified type. If the type must be extended, it is zero
-/// extended. The conversion must not be narrowing.
-const SCEV *
-ScalarEvolution::getNoopOrZeroExtend(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
- assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot noop or zero extend with non-integer arguments!");
- assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
- "getNoopOrZeroExtend cannot truncate!");
- if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
- return V; // No conversion
- return getZeroExtendExpr(V, Ty);
-}
-
-/// getNoopOrSignExtend - Return a SCEV corresponding to a conversion of the
-/// input value to the specified type. If the type must be extended, it is sign
-/// extended. The conversion must not be narrowing.
-const SCEV *
-ScalarEvolution::getNoopOrSignExtend(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
- assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot noop or sign extend with non-integer arguments!");
- assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
- "getNoopOrSignExtend cannot truncate!");
- if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
- return V; // No conversion
- return getSignExtendExpr(V, Ty);
-}
-
-/// getNoopOrAnyExtend - Return a SCEV corresponding to a conversion of
-/// the input value to the specified type. If the type must be extended,
-/// it is extended with unspecified bits. The conversion must not be
-/// narrowing.
-const SCEV *
-ScalarEvolution::getNoopOrAnyExtend(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
- assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot noop or any extend with non-integer arguments!");
- assert(getTypeSizeInBits(SrcTy) <= getTypeSizeInBits(Ty) &&
- "getNoopOrAnyExtend cannot truncate!");
- if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
- return V; // No conversion
- return getAnyExtendExpr(V, Ty);
-}
-
-/// getTruncateOrNoop - Return a SCEV corresponding to a conversion of the
-/// input value to the specified type. The conversion must not be widening.
-const SCEV *
-ScalarEvolution::getTruncateOrNoop(const SCEV *V, const Type *Ty) {
- const Type *SrcTy = V->getType();
- assert((SrcTy->isIntegerTy() || SrcTy->isPointerTy()) &&
- (Ty->isIntegerTy() || Ty->isPointerTy()) &&
- "Cannot truncate or noop with non-integer arguments!");
- assert(getTypeSizeInBits(SrcTy) >= getTypeSizeInBits(Ty) &&
- "getTruncateOrNoop cannot extend!");
- if (getTypeSizeInBits(SrcTy) == getTypeSizeInBits(Ty))
- return V; // No conversion
- return getTruncateExpr(V, Ty);
-}
-
-/// getUMaxFromMismatchedTypes - Promote the operands to the wider of
-/// the types using zero-extension, and then perform a umax operation
-/// with them.
-const SCEV *ScalarEvolution::getUMaxFromMismatchedTypes(const SCEV *LHS,
- const SCEV *RHS) {
- const SCEV *PromotedLHS = LHS;
- const SCEV *PromotedRHS = RHS;
-
- if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
- PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
- else
- PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
-
- return getUMaxExpr(PromotedLHS, PromotedRHS);
-}
-
-/// getUMinFromMismatchedTypes - Promote the operands to the wider of
-/// the types using zero-extension, and then perform a umin operation
-/// with them.
-const SCEV *ScalarEvolution::getUMinFromMismatchedTypes(const SCEV *LHS,
- const SCEV *RHS) {
- const SCEV *PromotedLHS = LHS;
- const SCEV *PromotedRHS = RHS;
-
- if (getTypeSizeInBits(LHS->getType()) > getTypeSizeInBits(RHS->getType()))
- PromotedRHS = getZeroExtendExpr(RHS, LHS->getType());
- else
- PromotedLHS = getNoopOrZeroExtend(LHS, RHS->getType());
-
- return getUMinExpr(PromotedLHS, PromotedRHS);
-}
-
-/// PushDefUseChildren - Push users of the given Instruction
-/// onto the given Worklist.
-static void
-PushDefUseChildren(Instruction *I,
- SmallVectorImpl<Instruction *> &Worklist) {
- // Push the def-use children onto the Worklist stack.
- for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
- UI != UE; ++UI)
- Worklist.push_back(cast<Instruction>(*UI));
-}
-
-/// ForgetSymbolicValue - This looks up computed SCEV values for all
-/// instructions that depend on the given instruction and removes them from
-/// the Scalars map if they reference SymName. This is used during PHI
-/// resolution.
-void
-ScalarEvolution::ForgetSymbolicName(Instruction *PN, const SCEV *SymName) {
- SmallVector<Instruction *, 16> Worklist;
- PushDefUseChildren(PN, Worklist);
-
- SmallPtrSet<Instruction *, 8> Visited;
- Visited.insert(PN);
- while (!Worklist.empty()) {
- Instruction *I = Worklist.pop_back_val();
- if (!Visited.insert(I)) continue;
-
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- // Short-circuit the def-use traversal if the symbolic name
- // ceases to appear in expressions.
- if (It->second != SymName && !It->second->hasOperand(SymName))
- continue;
-
- // SCEVUnknown for a PHI either means that it has an unrecognized
- // structure, it's a PHI that's in the progress of being computed
- // by createNodeForPHI, or it's a single-value PHI. In the first case,
- // additional loop trip count information isn't going to change anything.
- // In the second case, createNodeForPHI will perform the necessary
- // updates on its own when it gets to that point. In the third, we do
- // want to forget the SCEVUnknown.
- if (!isa<PHINode>(I) ||
- !isa<SCEVUnknown>(It->second) ||
- (I != PN && It->second == SymName)) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
- }
- }
-
- PushDefUseChildren(I, Worklist);
- }
-}
-
-/// createNodeForPHI - PHI nodes have two cases. Either the PHI node exists in
-/// a loop header, making it a potential recurrence, or it doesn't.
-///
-const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) {
- if (const Loop *L = LI->getLoopFor(PN->getParent()))
- if (L->getHeader() == PN->getParent()) {
- // The loop may have multiple entrances or multiple exits; we can analyze
- // this phi as an addrec if it has a unique entry value and a unique
- // backedge value.
- Value *BEValueV = 0, *StartValueV = 0;
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
- Value *V = PN->getIncomingValue(i);
- if (L->contains(PN->getIncomingBlock(i))) {
- if (!BEValueV) {
- BEValueV = V;
- } else if (BEValueV != V) {
- BEValueV = 0;
- break;
- }
- } else if (!StartValueV) {
- StartValueV = V;
- } else if (StartValueV != V) {
- StartValueV = 0;
- break;
- }
- }
- if (BEValueV && StartValueV) {
- // While we are analyzing this PHI node, handle its value symbolically.
- const SCEV *SymbolicName = getUnknown(PN);
- assert(Scalars.find(PN) == Scalars.end() &&
- "PHI node already processed?");
- Scalars.insert(std::make_pair(SCEVCallbackVH(PN, this), SymbolicName));
-
- // Using this symbolic name for the PHI, analyze the value coming around
- // the back-edge.
- const SCEV *BEValue = getSCEV(BEValueV);
-
- // NOTE: If BEValue is loop invariant, we know that the PHI node just
- // has a special value for the first iteration of the loop.
-
- // If the value coming around the backedge is an add with the symbolic
- // value we just inserted, then we found a simple induction variable!
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BEValue)) {
- // If there is a single occurrence of the symbolic value, replace it
- // with a recurrence.
- unsigned FoundIndex = Add->getNumOperands();
- for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
- if (Add->getOperand(i) == SymbolicName)
- if (FoundIndex == e) {
- FoundIndex = i;
- break;
- }
-
- if (FoundIndex != Add->getNumOperands()) {
- // Create an add with everything but the specified operand.
- SmallVector<const SCEV *, 8> Ops;
- for (unsigned i = 0, e = Add->getNumOperands(); i != e; ++i)
- if (i != FoundIndex)
- Ops.push_back(Add->getOperand(i));
- const SCEV *Accum = getAddExpr(Ops);
-
- // This is not a valid addrec if the step amount is varying each
- // loop iteration, but is not itself an addrec in this loop.
- if (Accum->isLoopInvariant(L) ||
- (isa<SCEVAddRecExpr>(Accum) &&
- cast<SCEVAddRecExpr>(Accum)->getLoop() == L)) {
- bool HasNUW = false;
- bool HasNSW = false;
-
- // If the increment doesn't overflow, then neither the addrec nor
- // the post-increment will overflow.
- if (const AddOperator *OBO = dyn_cast<AddOperator>(BEValueV)) {
- if (OBO->hasNoUnsignedWrap())
- HasNUW = true;
- if (OBO->hasNoSignedWrap())
- HasNSW = true;
- }
-
- const SCEV *StartVal = getSCEV(StartValueV);
- const SCEV *PHISCEV =
- getAddRecExpr(StartVal, Accum, L, HasNUW, HasNSW);
-
- // Since the no-wrap flags are on the increment, they apply to the
- // post-incremented value as well.
- if (Accum->isLoopInvariant(L))
- (void)getAddRecExpr(getAddExpr(StartVal, Accum),
- Accum, L, HasNUW, HasNSW);
-
- // Okay, for the entire analysis of this edge we assumed the PHI
- // to be symbolic. We now need to go back and purge all of the
- // entries for the scalars that use the symbolic expression.
- ForgetSymbolicName(PN, SymbolicName);
- Scalars[SCEVCallbackVH(PN, this)] = PHISCEV;
- return PHISCEV;
- }
- }
- } else if (const SCEVAddRecExpr *AddRec =
- dyn_cast<SCEVAddRecExpr>(BEValue)) {
- // Otherwise, this could be a loop like this:
- // i = 0; for (j = 1; ..; ++j) { .... i = j; }
- // In this case, j = {1,+,1} and BEValue is j.
- // Because the other in-value of i (0) fits the evolution of BEValue
- // i really is an addrec evolution.
- if (AddRec->getLoop() == L && AddRec->isAffine()) {
- const SCEV *StartVal = getSCEV(StartValueV);
-
- // If StartVal = j.start - j.stride, we can use StartVal as the
- // initial step of the addrec evolution.
- if (StartVal == getMinusSCEV(AddRec->getOperand(0),
- AddRec->getOperand(1))) {
- const SCEV *PHISCEV =
- getAddRecExpr(StartVal, AddRec->getOperand(1), L);
-
- // Okay, for the entire analysis of this edge we assumed the PHI
- // to be symbolic. We now need to go back and purge all of the
- // entries for the scalars that use the symbolic expression.
- ForgetSymbolicName(PN, SymbolicName);
- Scalars[SCEVCallbackVH(PN, this)] = PHISCEV;
- return PHISCEV;
- }
- }
- }
- }
- }
-
- // If the PHI has a single incoming value, follow that value, unless the
- // PHI's incoming blocks are in a different loop, in which case doing so
- // risks breaking LCSSA form. Instcombine would normally zap these, but
- // it doesn't have DominatorTree information, so it may miss cases.
- if (Value *V = PN->hasConstantValue(DT)) {
- bool AllSameLoop = true;
- Loop *PNLoop = LI->getLoopFor(PN->getParent());
- for (size_t i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (LI->getLoopFor(PN->getIncomingBlock(i)) != PNLoop) {
- AllSameLoop = false;
- break;
- }
- if (AllSameLoop)
- return getSCEV(V);
- }
-
- // If it's not a loop phi, we can't handle it yet.
- return getUnknown(PN);
-}
-
-/// createNodeForGEP - Expand GEP instructions into add and multiply
-/// operations. This allows them to be analyzed by regular SCEV code.
-///
-const SCEV *ScalarEvolution::createNodeForGEP(GEPOperator *GEP) {
-
- // Don't blindly transfer the inbounds flag from the GEP instruction to the
- // Add expression, because the Instruction may be guarded by control flow
- // and the no-overflow bits may not be valid for the expression in any
- // context.
-
- const Type *IntPtrTy = getEffectiveSCEVType(GEP->getType());
- Value *Base = GEP->getOperand(0);
- // Don't attempt to analyze GEPs over unsized objects.
- if (!cast<PointerType>(Base->getType())->getElementType()->isSized())
- return getUnknown(GEP);
- const SCEV *TotalOffset = getConstant(IntPtrTy, 0);
- gep_type_iterator GTI = gep_type_begin(GEP);
- for (GetElementPtrInst::op_iterator I = next(GEP->op_begin()),
- E = GEP->op_end();
- I != E; ++I) {
- Value *Index = *I;
- // Compute the (potentially symbolic) offset in bytes for this index.
- if (const StructType *STy = dyn_cast<StructType>(*GTI++)) {
- // For a struct, add the member offset.
- unsigned FieldNo = cast<ConstantInt>(Index)->getZExtValue();
- const SCEV *FieldOffset = getOffsetOfExpr(STy, FieldNo);
-
- // Add the field offset to the running total offset.
- TotalOffset = getAddExpr(TotalOffset, FieldOffset);
- } else {
- // For an array, add the element offset, explicitly scaled.
- const SCEV *ElementSize = getSizeOfExpr(*GTI);
- const SCEV *IndexS = getSCEV(Index);
- // Getelementptr indices are signed.
- IndexS = getTruncateOrSignExtend(IndexS, IntPtrTy);
-
- // Multiply the index by the element size to compute the element offset.
- const SCEV *LocalOffset = getMulExpr(IndexS, ElementSize);
-
- // Add the element offset to the running total offset.
- TotalOffset = getAddExpr(TotalOffset, LocalOffset);
- }
- }
-
- // Get the SCEV for the GEP base.
- const SCEV *BaseS = getSCEV(Base);
-
- // Add the total offset from all the GEP indices to the base.
- return getAddExpr(BaseS, TotalOffset);
-}
-
-/// GetMinTrailingZeros - Determine the minimum number of zero bits that S is
-/// guaranteed to end in (at every loop iteration). It is, at the same time,
-/// the minimum number of times S is divisible by 2. For example, given {4,+,8}
-/// it returns 2. If S is guaranteed to be 0, it returns the bitwidth of S.
-uint32_t
-ScalarEvolution::GetMinTrailingZeros(const SCEV *S) {
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
- return C->getValue()->getValue().countTrailingZeros();
-
- if (const SCEVTruncateExpr *T = dyn_cast<SCEVTruncateExpr>(S))
- return std::min(GetMinTrailingZeros(T->getOperand()),
- (uint32_t)getTypeSizeInBits(T->getType()));
-
- if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
- uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
- return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
- getTypeSizeInBits(E->getType()) : OpRes;
- }
-
- if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
- uint32_t OpRes = GetMinTrailingZeros(E->getOperand());
- return OpRes == getTypeSizeInBits(E->getOperand()->getType()) ?
- getTypeSizeInBits(E->getType()) : OpRes;
- }
-
- if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {
- // The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
- for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
- return MinOpRes;
- }
-
- if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S)) {
- // The result is the sum of all operands results.
- uint32_t SumOpRes = GetMinTrailingZeros(M->getOperand(0));
- uint32_t BitWidth = getTypeSizeInBits(M->getType());
- for (unsigned i = 1, e = M->getNumOperands();
- SumOpRes != BitWidth && i != e; ++i)
- SumOpRes = std::min(SumOpRes + GetMinTrailingZeros(M->getOperand(i)),
- BitWidth);
- return SumOpRes;
- }
-
- if (const SCEVAddRecExpr *A = dyn_cast<SCEVAddRecExpr>(S)) {
- // The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(A->getOperand(0));
- for (unsigned i = 1, e = A->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(A->getOperand(i)));
- return MinOpRes;
- }
-
- if (const SCEVSMaxExpr *M = dyn_cast<SCEVSMaxExpr>(S)) {
- // The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
- for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
- return MinOpRes;
- }
-
- if (const SCEVUMaxExpr *M = dyn_cast<SCEVUMaxExpr>(S)) {
- // The result is the min of all operands results.
- uint32_t MinOpRes = GetMinTrailingZeros(M->getOperand(0));
- for (unsigned i = 1, e = M->getNumOperands(); MinOpRes && i != e; ++i)
- MinOpRes = std::min(MinOpRes, GetMinTrailingZeros(M->getOperand(i)));
- return MinOpRes;
- }
-
- if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
- // For a SCEVUnknown, ask ValueTracking.
- unsigned BitWidth = getTypeSizeInBits(U->getType());
- APInt Mask = APInt::getAllOnesValue(BitWidth);
- APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
- ComputeMaskedBits(U->getValue(), Mask, Zeros, Ones);
- return Zeros.countTrailingOnes();
- }
-
- // SCEVUDivExpr
- return 0;
-}
-
-/// getUnsignedRange - Determine the unsigned range for a particular SCEV.
-///
-ConstantRange
-ScalarEvolution::getUnsignedRange(const SCEV *S) {
-
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
- return ConstantRange(C->getValue()->getValue());
-
- unsigned BitWidth = getTypeSizeInBits(S->getType());
- ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
-
- // If the value has known zeros, the maximum unsigned value will have those
- // known zeros as well.
- uint32_t TZ = GetMinTrailingZeros(S);
- if (TZ != 0)
- ConservativeResult =
- ConstantRange(APInt::getMinValue(BitWidth),
- APInt::getMaxValue(BitWidth).lshr(TZ).shl(TZ) + 1);
-
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
- ConstantRange X = getUnsignedRange(Add->getOperand(0));
- for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
- X = X.add(getUnsignedRange(Add->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
- ConstantRange X = getUnsignedRange(Mul->getOperand(0));
- for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
- X = X.multiply(getUnsignedRange(Mul->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
- ConstantRange X = getUnsignedRange(SMax->getOperand(0));
- for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
- X = X.smax(getUnsignedRange(SMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
- ConstantRange X = getUnsignedRange(UMax->getOperand(0));
- for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
- X = X.umax(getUnsignedRange(UMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
- ConstantRange X = getUnsignedRange(UDiv->getLHS());
- ConstantRange Y = getUnsignedRange(UDiv->getRHS());
- return ConservativeResult.intersectWith(X.udiv(Y));
- }
-
- if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
- ConstantRange X = getUnsignedRange(ZExt->getOperand());
- return ConservativeResult.intersectWith(X.zeroExtend(BitWidth));
- }
-
- if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
- ConstantRange X = getUnsignedRange(SExt->getOperand());
- return ConservativeResult.intersectWith(X.signExtend(BitWidth));
- }
-
- if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
- ConstantRange X = getUnsignedRange(Trunc->getOperand());
- return ConservativeResult.intersectWith(X.truncate(BitWidth));
- }
-
- if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
- // If there's no unsigned wrap, the value will never be less than its
- // initial value.
- if (AddRec->hasNoUnsignedWrap())
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(AddRec->getStart()))
- if (!C->getValue()->isZero())
- ConservativeResult =
- ConservativeResult.intersectWith(
- ConstantRange(C->getValue()->getValue(), APInt(BitWidth, 0)));
-
- // TODO: non-affine addrec
- if (AddRec->isAffine()) {
- const Type *Ty = AddRec->getType();
- const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
- if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
- getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
- MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty);
-
- const SCEV *Start = AddRec->getStart();
- const SCEV *Step = AddRec->getStepRecurrence(*this);
-
- ConstantRange StartRange = getUnsignedRange(Start);
- ConstantRange StepRange = getSignedRange(Step);
- ConstantRange MaxBECountRange = getUnsignedRange(MaxBECount);
- ConstantRange EndRange =
- StartRange.add(MaxBECountRange.multiply(StepRange));
-
- // Check for overflow. This must be done with ConstantRange arithmetic
- // because we could be called from within the ScalarEvolution overflow
- // checking code.
- ConstantRange ExtStartRange = StartRange.zextOrTrunc(BitWidth*2+1);
- ConstantRange ExtStepRange = StepRange.sextOrTrunc(BitWidth*2+1);
- ConstantRange ExtMaxBECountRange =
- MaxBECountRange.zextOrTrunc(BitWidth*2+1);
- ConstantRange ExtEndRange = EndRange.zextOrTrunc(BitWidth*2+1);
- if (ExtStartRange.add(ExtMaxBECountRange.multiply(ExtStepRange)) !=
- ExtEndRange)
- return ConservativeResult;
-
- APInt Min = APIntOps::umin(StartRange.getUnsignedMin(),
- EndRange.getUnsignedMin());
- APInt Max = APIntOps::umax(StartRange.getUnsignedMax(),
- EndRange.getUnsignedMax());
- if (Min.isMinValue() && Max.isMaxValue())
- return ConservativeResult;
- return ConservativeResult.intersectWith(ConstantRange(Min, Max+1));
- }
- }
-
- return ConservativeResult;
- }
-
- if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
- // For a SCEVUnknown, ask ValueTracking.
- APInt Mask = APInt::getAllOnesValue(BitWidth);
- APInt Zeros(BitWidth, 0), Ones(BitWidth, 0);
- ComputeMaskedBits(U->getValue(), Mask, Zeros, Ones, TD);
- if (Ones == ~Zeros + 1)
- return ConservativeResult;
- return ConservativeResult.intersectWith(ConstantRange(Ones, ~Zeros + 1));
- }
-
- return ConservativeResult;
-}
-
-/// getSignedRange - Determine the signed range for a particular SCEV.
-///
-ConstantRange
-ScalarEvolution::getSignedRange(const SCEV *S) {
-
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S))
- return ConstantRange(C->getValue()->getValue());
-
- unsigned BitWidth = getTypeSizeInBits(S->getType());
- ConstantRange ConservativeResult(BitWidth, /*isFullSet=*/true);
-
- // If the value has known zeros, the maximum signed value will have those
- // known zeros as well.
- uint32_t TZ = GetMinTrailingZeros(S);
- if (TZ != 0)
- ConservativeResult =
- ConstantRange(APInt::getSignedMinValue(BitWidth),
- APInt::getSignedMaxValue(BitWidth).ashr(TZ).shl(TZ) + 1);
-
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
- ConstantRange X = getSignedRange(Add->getOperand(0));
- for (unsigned i = 1, e = Add->getNumOperands(); i != e; ++i)
- X = X.add(getSignedRange(Add->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
- ConstantRange X = getSignedRange(Mul->getOperand(0));
- for (unsigned i = 1, e = Mul->getNumOperands(); i != e; ++i)
- X = X.multiply(getSignedRange(Mul->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVSMaxExpr *SMax = dyn_cast<SCEVSMaxExpr>(S)) {
- ConstantRange X = getSignedRange(SMax->getOperand(0));
- for (unsigned i = 1, e = SMax->getNumOperands(); i != e; ++i)
- X = X.smax(getSignedRange(SMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVUMaxExpr *UMax = dyn_cast<SCEVUMaxExpr>(S)) {
- ConstantRange X = getSignedRange(UMax->getOperand(0));
- for (unsigned i = 1, e = UMax->getNumOperands(); i != e; ++i)
- X = X.umax(getSignedRange(UMax->getOperand(i)));
- return ConservativeResult.intersectWith(X);
- }
-
- if (const SCEVUDivExpr *UDiv = dyn_cast<SCEVUDivExpr>(S)) {
- ConstantRange X = getSignedRange(UDiv->getLHS());
- ConstantRange Y = getSignedRange(UDiv->getRHS());
- return ConservativeResult.intersectWith(X.udiv(Y));
- }
-
- if (const SCEVZeroExtendExpr *ZExt = dyn_cast<SCEVZeroExtendExpr>(S)) {
- ConstantRange X = getSignedRange(ZExt->getOperand());
- return ConservativeResult.intersectWith(X.zeroExtend(BitWidth));
- }
-
- if (const SCEVSignExtendExpr *SExt = dyn_cast<SCEVSignExtendExpr>(S)) {
- ConstantRange X = getSignedRange(SExt->getOperand());
- return ConservativeResult.intersectWith(X.signExtend(BitWidth));
- }
-
- if (const SCEVTruncateExpr *Trunc = dyn_cast<SCEVTruncateExpr>(S)) {
- ConstantRange X = getSignedRange(Trunc->getOperand());
- return ConservativeResult.intersectWith(X.truncate(BitWidth));
- }
-
- if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(S)) {
- // If there's no signed wrap, and all the operands have the same sign or
- // zero, the value won't ever change sign.
- if (AddRec->hasNoSignedWrap()) {
- bool AllNonNeg = true;
- bool AllNonPos = true;
- for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
- if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
- if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
- }
- if (AllNonNeg)
- ConservativeResult = ConservativeResult.intersectWith(
- ConstantRange(APInt(BitWidth, 0),
- APInt::getSignedMinValue(BitWidth)));
- else if (AllNonPos)
- ConservativeResult = ConservativeResult.intersectWith(
- ConstantRange(APInt::getSignedMinValue(BitWidth),
- APInt(BitWidth, 1)));
- }
-
- // TODO: non-affine addrec
- if (AddRec->isAffine()) {
- const Type *Ty = AddRec->getType();
- const SCEV *MaxBECount = getMaxBackedgeTakenCount(AddRec->getLoop());
- if (!isa<SCEVCouldNotCompute>(MaxBECount) &&
- getTypeSizeInBits(MaxBECount->getType()) <= BitWidth) {
- MaxBECount = getNoopOrZeroExtend(MaxBECount, Ty);
-
- const SCEV *Start = AddRec->getStart();
- const SCEV *Step = AddRec->getStepRecurrence(*this);
-
- ConstantRange StartRange = getSignedRange(Start);
- ConstantRange StepRange = getSignedRange(Step);
- ConstantRange MaxBECountRange = getUnsignedRange(MaxBECount);
- ConstantRange EndRange =
- StartRange.add(MaxBECountRange.multiply(StepRange));
-
- // Check for overflow. This must be done with ConstantRange arithmetic
- // because we could be called from within the ScalarEvolution overflow
- // checking code.
- ConstantRange ExtStartRange = StartRange.sextOrTrunc(BitWidth*2+1);
- ConstantRange ExtStepRange = StepRange.sextOrTrunc(BitWidth*2+1);
- ConstantRange ExtMaxBECountRange =
- MaxBECountRange.zextOrTrunc(BitWidth*2+1);
- ConstantRange ExtEndRange = EndRange.sextOrTrunc(BitWidth*2+1);
- if (ExtStartRange.add(ExtMaxBECountRange.multiply(ExtStepRange)) !=
- ExtEndRange)
- return ConservativeResult;
-
- APInt Min = APIntOps::smin(StartRange.getSignedMin(),
- EndRange.getSignedMin());
- APInt Max = APIntOps::smax(StartRange.getSignedMax(),
- EndRange.getSignedMax());
- if (Min.isMinSignedValue() && Max.isMaxSignedValue())
- return ConservativeResult;
- return ConservativeResult.intersectWith(ConstantRange(Min, Max+1));
- }
- }
-
- return ConservativeResult;
- }
-
- if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
- // For a SCEVUnknown, ask ValueTracking.
- if (!U->getValue()->getType()->isIntegerTy() && !TD)
- return ConservativeResult;
- unsigned NS = ComputeNumSignBits(U->getValue(), TD);
- if (NS == 1)
- return ConservativeResult;
- return ConservativeResult.intersectWith(
- ConstantRange(APInt::getSignedMinValue(BitWidth).ashr(NS - 1),
- APInt::getSignedMaxValue(BitWidth).ashr(NS - 1)+1));
- }
-
- return ConservativeResult;
-}
-
-/// createSCEV - We know that there is no SCEV for the specified value.
-/// Analyze the expression.
-///
-const SCEV *ScalarEvolution::createSCEV(Value *V) {
- if (!isSCEVable(V->getType()))
- return getUnknown(V);
-
- unsigned Opcode = Instruction::UserOp1;
- if (Instruction *I = dyn_cast<Instruction>(V)) {
- Opcode = I->getOpcode();
-
- // Don't attempt to analyze instructions in blocks that aren't
- // reachable. Such instructions don't matter, and they aren't required
- // to obey basic rules for definitions dominating uses which this
- // analysis depends on.
- if (!DT->isReachableFromEntry(I->getParent()))
- return getUnknown(V);
- } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
- Opcode = CE->getOpcode();
- else if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
- return getConstant(CI);
- else if (isa<ConstantPointerNull>(V))
- return getConstant(V->getType(), 0);
- else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V))
- return GA->mayBeOverridden() ? getUnknown(V) : getSCEV(GA->getAliasee());
- else
- return getUnknown(V);
-
- Operator *U = cast<Operator>(V);
- switch (Opcode) {
- case Instruction::Add:
- return getAddExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
- case Instruction::Mul:
- return getMulExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
- case Instruction::UDiv:
- return getUDivExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
- case Instruction::Sub:
- return getMinusSCEV(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
- case Instruction::And:
- // For an expression like x&255 that merely masks off the high bits,
- // use zext(trunc(x)) as the SCEV expression.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
- if (CI->isNullValue())
- return getSCEV(U->getOperand(1));
- if (CI->isAllOnesValue())
- return getSCEV(U->getOperand(0));
- const APInt &A = CI->getValue();
-
- // Instcombine's ShrinkDemandedConstant may strip bits out of
- // constants, obscuring what would otherwise be a low-bits mask.
- // Use ComputeMaskedBits to compute what ShrinkDemandedConstant
- // knew about to reconstruct a low-bits mask value.
- unsigned LZ = A.countLeadingZeros();
- unsigned BitWidth = A.getBitWidth();
- APInt AllOnes = APInt::getAllOnesValue(BitWidth);
- APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
- ComputeMaskedBits(U->getOperand(0), AllOnes, KnownZero, KnownOne, TD);
-
- APInt EffectiveMask = APInt::getLowBitsSet(BitWidth, BitWidth - LZ);
-
- if (LZ != 0 && !((~A & ~KnownZero) & EffectiveMask))
- return
- getZeroExtendExpr(getTruncateExpr(getSCEV(U->getOperand(0)),
- IntegerType::get(getContext(), BitWidth - LZ)),
- U->getType());
- }
- break;
-
- case Instruction::Or:
- // If the RHS of the Or is a constant, we may have something like:
- // X*4+1 which got turned into X*4|1. Handle this as an Add so loop
- // optimizations will transparently handle this case.
- //
- // In order for this transformation to be safe, the LHS must be of the
- // form X*(2^n) and the Or constant must be less than 2^n.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
- const SCEV *LHS = getSCEV(U->getOperand(0));
- const APInt &CIVal = CI->getValue();
- if (GetMinTrailingZeros(LHS) >=
- (CIVal.getBitWidth() - CIVal.countLeadingZeros())) {
- // Build a plain add SCEV.
- const SCEV *S = getAddExpr(LHS, getSCEV(CI));
- // If the LHS of the add was an addrec and it has no-wrap flags,
- // transfer the no-wrap flags, since an or won't introduce a wrap.
- if (const SCEVAddRecExpr *NewAR = dyn_cast<SCEVAddRecExpr>(S)) {
- const SCEVAddRecExpr *OldAR = cast<SCEVAddRecExpr>(LHS);
- if (OldAR->hasNoUnsignedWrap())
- const_cast<SCEVAddRecExpr *>(NewAR)->setHasNoUnsignedWrap(true);
- if (OldAR->hasNoSignedWrap())
- const_cast<SCEVAddRecExpr *>(NewAR)->setHasNoSignedWrap(true);
- }
- return S;
- }
- }
- break;
- case Instruction::Xor:
- if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
- // If the RHS of the xor is a signbit, then this is just an add.
- // Instcombine turns add of signbit into xor as a strength reduction step.
- if (CI->getValue().isSignBit())
- return getAddExpr(getSCEV(U->getOperand(0)),
- getSCEV(U->getOperand(1)));
-
- // If the RHS of xor is -1, then this is a not operation.
- if (CI->isAllOnesValue())
- return getNotSCEV(getSCEV(U->getOperand(0)));
-
- // Model xor(and(x, C), C) as and(~x, C), if C is a low-bits mask.
- // This is a variant of the check for xor with -1, and it handles
- // the case where instcombine has trimmed non-demanded bits out
- // of an xor with -1.
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(U->getOperand(0)))
- if (ConstantInt *LCI = dyn_cast<ConstantInt>(BO->getOperand(1)))
- if (BO->getOpcode() == Instruction::And &&
- LCI->getValue() == CI->getValue())
- if (const SCEVZeroExtendExpr *Z =
- dyn_cast<SCEVZeroExtendExpr>(getSCEV(U->getOperand(0)))) {
- const Type *UTy = U->getType();
- const SCEV *Z0 = Z->getOperand();
- const Type *Z0Ty = Z0->getType();
- unsigned Z0TySize = getTypeSizeInBits(Z0Ty);
-
- // If C is a low-bits mask, the zero extend is serving to
- // mask off the high bits. Complement the operand and
- // re-apply the zext.
- if (APIntOps::isMask(Z0TySize, CI->getValue()))
- return getZeroExtendExpr(getNotSCEV(Z0), UTy);
-
- // If C is a single bit, it may be in the sign-bit position
- // before the zero-extend. In this case, represent the xor
- // using an add, which is equivalent, and re-apply the zext.
- APInt Trunc = APInt(CI->getValue()).trunc(Z0TySize);
- if (APInt(Trunc).zext(getTypeSizeInBits(UTy)) == CI->getValue() &&
- Trunc.isSignBit())
- return getZeroExtendExpr(getAddExpr(Z0, getConstant(Trunc)),
- UTy);
- }
- }
- break;
-
- case Instruction::Shl:
- // Turn shift left of a constant amount into a multiply.
- if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
- uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth();
-
- // If the shift count is not less than the bitwidth, the result of
- // the shift is undefined. Don't try to analyze it, because the
- // resolution chosen here may differ from the resolution chosen in
- // other parts of the compiler.
- if (SA->getValue().uge(BitWidth))
- break;
-
- Constant *X = ConstantInt::get(getContext(),
- APInt(BitWidth, 1).shl(SA->getZExtValue()));
- return getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X));
- }
- break;
-
- case Instruction::LShr:
- // Turn logical shift right of a constant into a unsigned divide.
- if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
- uint32_t BitWidth = cast<IntegerType>(U->getType())->getBitWidth();
-
- // If the shift count is not less than the bitwidth, the result of
- // the shift is undefined. Don't try to analyze it, because the
- // resolution chosen here may differ from the resolution chosen in
- // other parts of the compiler.
- if (SA->getValue().uge(BitWidth))
- break;
-
- Constant *X = ConstantInt::get(getContext(),
- APInt(BitWidth, 1).shl(SA->getZExtValue()));
- return getUDivExpr(getSCEV(U->getOperand(0)), getSCEV(X));
- }
- break;
-
- case Instruction::AShr:
- // For a two-shift sext-inreg, use sext(trunc(x)) as the SCEV expression.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1)))
- if (Operator *L = dyn_cast<Operator>(U->getOperand(0)))
- if (L->getOpcode() == Instruction::Shl &&
- L->getOperand(1) == U->getOperand(1)) {
- uint64_t BitWidth = getTypeSizeInBits(U->getType());
-
- // If the shift count is not less than the bitwidth, the result of
- // the shift is undefined. Don't try to analyze it, because the
- // resolution chosen here may differ from the resolution chosen in
- // other parts of the compiler.
- if (CI->getValue().uge(BitWidth))
- break;
-
- uint64_t Amt = BitWidth - CI->getZExtValue();
- if (Amt == BitWidth)
- return getSCEV(L->getOperand(0)); // shift by zero --> noop
- return
- getSignExtendExpr(getTruncateExpr(getSCEV(L->getOperand(0)),
- IntegerType::get(getContext(),
- Amt)),
- U->getType());
- }
- break;
-
- case Instruction::Trunc:
- return getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
-
- case Instruction::ZExt:
- return getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
-
- case Instruction::SExt:
- return getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
-
- case Instruction::BitCast:
- // BitCasts are no-op casts so we just eliminate the cast.
- if (isSCEVable(U->getType()) && isSCEVable(U->getOperand(0)->getType()))
- return getSCEV(U->getOperand(0));
- break;
-
- // It's tempting to handle inttoptr and ptrtoint as no-ops, however this can
- // lead to pointer expressions which cannot safely be expanded to GEPs,
- // because ScalarEvolution doesn't respect the GEP aliasing rules when
- // simplifying integer expressions.
-
- case Instruction::GetElementPtr:
- return createNodeForGEP(cast<GEPOperator>(U));
-
- case Instruction::PHI:
- return createNodeForPHI(cast<PHINode>(U));
-
- case Instruction::Select:
- // This could be a smax or umax that was lowered earlier.
- // Try to recover it.
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(U->getOperand(0))) {
- Value *LHS = ICI->getOperand(0);
- Value *RHS = ICI->getOperand(1);
- switch (ICI->getPredicate()) {
- case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE:
- std::swap(LHS, RHS);
- // fall through
- case ICmpInst::ICMP_SGT:
- case ICmpInst::ICMP_SGE:
- // a >s b ? a+x : b+x -> smax(a, b)+x
- // a >s b ? b+x : a+x -> smin(a, b)+x
- if (LHS->getType() == U->getType()) {
- const SCEV *LS = getSCEV(LHS);
- const SCEV *RS = getSCEV(RHS);
- const SCEV *LA = getSCEV(U->getOperand(1));
- const SCEV *RA = getSCEV(U->getOperand(2));
- const SCEV *LDiff = getMinusSCEV(LA, LS);
- const SCEV *RDiff = getMinusSCEV(RA, RS);
- if (LDiff == RDiff)
- return getAddExpr(getSMaxExpr(LS, RS), LDiff);
- LDiff = getMinusSCEV(LA, RS);
- RDiff = getMinusSCEV(RA, LS);
- if (LDiff == RDiff)
- return getAddExpr(getSMinExpr(LS, RS), LDiff);
- }
- break;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_ULE:
- std::swap(LHS, RHS);
- // fall through
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_UGE:
- // a >u b ? a+x : b+x -> umax(a, b)+x
- // a >u b ? b+x : a+x -> umin(a, b)+x
- if (LHS->getType() == U->getType()) {
- const SCEV *LS = getSCEV(LHS);
- const SCEV *RS = getSCEV(RHS);
- const SCEV *LA = getSCEV(U->getOperand(1));
- const SCEV *RA = getSCEV(U->getOperand(2));
- const SCEV *LDiff = getMinusSCEV(LA, LS);
- const SCEV *RDiff = getMinusSCEV(RA, RS);
- if (LDiff == RDiff)
- return getAddExpr(getUMaxExpr(LS, RS), LDiff);
- LDiff = getMinusSCEV(LA, RS);
- RDiff = getMinusSCEV(RA, LS);
- if (LDiff == RDiff)
- return getAddExpr(getUMinExpr(LS, RS), LDiff);
- }
- break;
- case ICmpInst::ICMP_NE:
- // n != 0 ? n+x : 1+x -> umax(n, 1)+x
- if (LHS->getType() == U->getType() &&
- isa<ConstantInt>(RHS) &&
- cast<ConstantInt>(RHS)->isZero()) {
- const SCEV *One = getConstant(LHS->getType(), 1);
- const SCEV *LS = getSCEV(LHS);
- const SCEV *LA = getSCEV(U->getOperand(1));
- const SCEV *RA = getSCEV(U->getOperand(2));
- const SCEV *LDiff = getMinusSCEV(LA, LS);
- const SCEV *RDiff = getMinusSCEV(RA, One);
- if (LDiff == RDiff)
- return getAddExpr(getUMaxExpr(LS, One), LDiff);
- }
- break;
- case ICmpInst::ICMP_EQ:
- // n == 0 ? 1+x : n+x -> umax(n, 1)+x
- if (LHS->getType() == U->getType() &&
- isa<ConstantInt>(RHS) &&
- cast<ConstantInt>(RHS)->isZero()) {
- const SCEV *One = getConstant(LHS->getType(), 1);
- const SCEV *LS = getSCEV(LHS);
- const SCEV *LA = getSCEV(U->getOperand(1));
- const SCEV *RA = getSCEV(U->getOperand(2));
- const SCEV *LDiff = getMinusSCEV(LA, One);
- const SCEV *RDiff = getMinusSCEV(RA, LS);
- if (LDiff == RDiff)
- return getAddExpr(getUMaxExpr(LS, One), LDiff);
- }
- break;
- default:
- break;
- }
- }
-
- default: // We cannot analyze this expression.
- break;
- }
-
- return getUnknown(V);
-}
-
-
-
-//===----------------------------------------------------------------------===//
-// Iteration Count Computation Code
-//
-
-/// getBackedgeTakenCount - If the specified loop has a predictable
-/// backedge-taken count, return it, otherwise return a SCEVCouldNotCompute
-/// object. The backedge-taken count is the number of times the loop header
-/// will be branched to from within the loop. This is one less than the
-/// trip count of the loop, since it doesn't count the first iteration,
-/// when the header is branched to from outside the loop.
-///
-/// Note that it is not valid to call this method on a loop without a
-/// loop-invariant backedge-taken count (see
-/// hasLoopInvariantBackedgeTakenCount).
-///
-const SCEV *ScalarEvolution::getBackedgeTakenCount(const Loop *L) {
- return getBackedgeTakenInfo(L).Exact;
-}
-
-/// getMaxBackedgeTakenCount - Similar to getBackedgeTakenCount, except
-/// return the least SCEV value that is known never to be less than the
-/// actual backedge taken count.
-const SCEV *ScalarEvolution::getMaxBackedgeTakenCount(const Loop *L) {
- return getBackedgeTakenInfo(L).Max;
-}
-
-/// PushLoopPHIs - Push PHI nodes in the header of the given loop
-/// onto the given Worklist.
-static void
-PushLoopPHIs(const Loop *L, SmallVectorImpl<Instruction *> &Worklist) {
- BasicBlock *Header = L->getHeader();
-
- // Push all Loop-header PHIs onto the Worklist stack.
- for (BasicBlock::iterator I = Header->begin();
- PHINode *PN = dyn_cast<PHINode>(I); ++I)
- Worklist.push_back(PN);
-}
-
-const ScalarEvolution::BackedgeTakenInfo &
-ScalarEvolution::getBackedgeTakenInfo(const Loop *L) {
- // Initially insert a CouldNotCompute for this loop. If the insertion
- // succeeds, proceed to actually compute a backedge-taken count and
- // update the value. The temporary CouldNotCompute value tells SCEV
- // code elsewhere that it shouldn't attempt to request a new
- // backedge-taken count, which could result in infinite recursion.
- std::pair<std::map<const Loop *, BackedgeTakenInfo>::iterator, bool> Pair =
- BackedgeTakenCounts.insert(std::make_pair(L, getCouldNotCompute()));
- if (Pair.second) {
- BackedgeTakenInfo BECount = ComputeBackedgeTakenCount(L);
- if (BECount.Exact != getCouldNotCompute()) {
- assert(BECount.Exact->isLoopInvariant(L) &&
- BECount.Max->isLoopInvariant(L) &&
- "Computed backedge-taken count isn't loop invariant for loop!");
- ++NumTripCountsComputed;
-
- // Update the value in the map.
- Pair.first->second = BECount;
- } else {
- if (BECount.Max != getCouldNotCompute())
- // Update the value in the map.
- Pair.first->second = BECount;
- if (isa<PHINode>(L->getHeader()->begin()))
- // Only count loops that have phi nodes as not being computable.
- ++NumTripCountsNotComputed;
- }
-
- // Now that we know more about the trip count for this loop, forget any
- // existing SCEV values for PHI nodes in this loop since they are only
- // conservative estimates made without the benefit of trip count
- // information. This is similar to the code in forgetLoop, except that
- // it handles SCEVUnknown PHI nodes specially.
- if (BECount.hasAnyInfo()) {
- SmallVector<Instruction *, 16> Worklist;
- PushLoopPHIs(L, Worklist);
-
- SmallPtrSet<Instruction *, 8> Visited;
- while (!Worklist.empty()) {
- Instruction *I = Worklist.pop_back_val();
- if (!Visited.insert(I)) continue;
-
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- // SCEVUnknown for a PHI either means that it has an unrecognized
- // structure, or it's a PHI that's in the progress of being computed
- // by createNodeForPHI. In the former case, additional loop trip
- // count information isn't going to change anything. In the later
- // case, createNodeForPHI will perform the necessary updates on its
- // own when it gets to that point.
- if (!isa<PHINode>(I) || !isa<SCEVUnknown>(It->second)) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
- }
- if (PHINode *PN = dyn_cast<PHINode>(I))
- ConstantEvolutionLoopExitValue.erase(PN);
- }
-
- PushDefUseChildren(I, Worklist);
- }
- }
- }
- return Pair.first->second;
-}
-
-/// forgetLoop - This method should be called by the client when it has
-/// changed a loop in a way that may effect ScalarEvolution's ability to
-/// compute a trip count, or if the loop is deleted.
-void ScalarEvolution::forgetLoop(const Loop *L) {
- // Drop any stored trip count value.
- BackedgeTakenCounts.erase(L);
-
- // Drop information about expressions based on loop-header PHIs.
- SmallVector<Instruction *, 16> Worklist;
- PushLoopPHIs(L, Worklist);
-
- SmallPtrSet<Instruction *, 8> Visited;
- while (!Worklist.empty()) {
- Instruction *I = Worklist.pop_back_val();
- if (!Visited.insert(I)) continue;
-
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
- if (PHINode *PN = dyn_cast<PHINode>(I))
- ConstantEvolutionLoopExitValue.erase(PN);
- }
-
- PushDefUseChildren(I, Worklist);
- }
-}
-
-/// forgetValue - This method should be called by the client when it has
-/// changed a value in a way that may effect its value, or which may
-/// disconnect it from a def-use chain linking it to a loop.
-void ScalarEvolution::forgetValue(Value *V) {
- Instruction *I = dyn_cast<Instruction>(V);
- if (!I) return;
-
- // Drop information about expressions based on loop-header PHIs.
- SmallVector<Instruction *, 16> Worklist;
- Worklist.push_back(I);
-
- SmallPtrSet<Instruction *, 8> Visited;
- while (!Worklist.empty()) {
- I = Worklist.pop_back_val();
- if (!Visited.insert(I)) continue;
-
- std::map<SCEVCallbackVH, const SCEV *>::iterator It =
- Scalars.find(static_cast<Value *>(I));
- if (It != Scalars.end()) {
- ValuesAtScopes.erase(It->second);
- Scalars.erase(It);
- if (PHINode *PN = dyn_cast<PHINode>(I))
- ConstantEvolutionLoopExitValue.erase(PN);
- }
-
- // If there's a SCEVUnknown tying this value into the SCEV
- // space, remove it from the folding set map. The SCEVUnknown
- // object and any other SCEV objects which reference it
- // (transitively) remain allocated, effectively leaked until
- // the underlying BumpPtrAllocator is freed.
- //
- // This permits SCEV pointers to be used as keys in maps
- // such as the ValuesAtScopes map.
- FoldingSetNodeID ID;
- ID.AddInteger(scUnknown);
- ID.AddPointer(I);
- void *IP;
- if (SCEV *S = UniqueSCEVs.FindNodeOrInsertPos(ID, IP)) {
- UniqueSCEVs.RemoveNode(S);
-
- // This isn't necessary, but we might as well remove the
- // value from the ValuesAtScopes map too.
- ValuesAtScopes.erase(S);
- }
-
- PushDefUseChildren(I, Worklist);
- }
-}
-
-/// ComputeBackedgeTakenCount - Compute the number of times the backedge
-/// of the specified loop will execute.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCount(const Loop *L) {
- SmallVector<BasicBlock *, 8> ExitingBlocks;
- L->getExitingBlocks(ExitingBlocks);
-
- // Examine all exits and pick the most conservative values.
- const SCEV *BECount = getCouldNotCompute();
- const SCEV *MaxBECount = getCouldNotCompute();
- bool CouldNotComputeBECount = false;
- for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
- BackedgeTakenInfo NewBTI =
- ComputeBackedgeTakenCountFromExit(L, ExitingBlocks[i]);
-
- if (NewBTI.Exact == getCouldNotCompute()) {
- // We couldn't compute an exact value for this exit, so
- // we won't be able to compute an exact value for the loop.
- CouldNotComputeBECount = true;
- BECount = getCouldNotCompute();
- } else if (!CouldNotComputeBECount) {
- if (BECount == getCouldNotCompute())
- BECount = NewBTI.Exact;
- else
- BECount = getUMinFromMismatchedTypes(BECount, NewBTI.Exact);
- }
- if (MaxBECount == getCouldNotCompute())
- MaxBECount = NewBTI.Max;
- else if (NewBTI.Max != getCouldNotCompute())
- MaxBECount = getUMinFromMismatchedTypes(MaxBECount, NewBTI.Max);
- }
-
- return BackedgeTakenInfo(BECount, MaxBECount);
-}
-
-/// ComputeBackedgeTakenCountFromExit - Compute the number of times the backedge
-/// of the specified loop will execute if it exits via the specified block.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExit(const Loop *L,
- BasicBlock *ExitingBlock) {
-
- // Okay, we've chosen an exiting block. See what condition causes us to
- // exit at this block.
- //
- // FIXME: we should be able to handle switch instructions (with a single exit)
- BranchInst *ExitBr = dyn_cast<BranchInst>(ExitingBlock->getTerminator());
- if (ExitBr == 0) return getCouldNotCompute();
- assert(ExitBr->isConditional() && "If unconditional, it can't be in loop!");
-
- // At this point, we know we have a conditional branch that determines whether
- // the loop is exited. However, we don't know if the branch is executed each
- // time through the loop. If not, then the execution count of the branch will
- // not be equal to the trip count of the loop.
- //
- // Currently we check for this by checking to see if the Exit branch goes to
- // the loop header. If so, we know it will always execute the same number of
- // times as the loop. We also handle the case where the exit block *is* the
- // loop header. This is common for un-rotated loops.
- //
- // If both of those tests fail, walk up the unique predecessor chain to the
- // header, stopping if there is an edge that doesn't exit the loop. If the
- // header is reached, the execution count of the branch will be equal to the
- // trip count of the loop.
- //
- // More extensive analysis could be done to handle more cases here.
- //
- if (ExitBr->getSuccessor(0) != L->getHeader() &&
- ExitBr->getSuccessor(1) != L->getHeader() &&
- ExitBr->getParent() != L->getHeader()) {
- // The simple checks failed, try climbing the unique predecessor chain
- // up to the header.
- bool Ok = false;
- for (BasicBlock *BB = ExitBr->getParent(); BB; ) {
- BasicBlock *Pred = BB->getUniquePredecessor();
- if (!Pred)
- return getCouldNotCompute();
- TerminatorInst *PredTerm = Pred->getTerminator();
- for (unsigned i = 0, e = PredTerm->getNumSuccessors(); i != e; ++i) {
- BasicBlock *PredSucc = PredTerm->getSuccessor(i);
- if (PredSucc == BB)
- continue;
- // If the predecessor has a successor that isn't BB and isn't
- // outside the loop, assume the worst.
- if (L->contains(PredSucc))
- return getCouldNotCompute();
- }
- if (Pred == L->getHeader()) {
- Ok = true;
- break;
- }
- BB = Pred;
- }
- if (!Ok)
- return getCouldNotCompute();
- }
-
- // Proceed to the next level to examine the exit condition expression.
- return ComputeBackedgeTakenCountFromExitCond(L, ExitBr->getCondition(),
- ExitBr->getSuccessor(0),
- ExitBr->getSuccessor(1));
-}
-
-/// ComputeBackedgeTakenCountFromExitCond - Compute the number of times the
-/// backedge of the specified loop will execute if its exit condition
-/// were a conditional branch of ExitCond, TBB, and FBB.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExitCond(const Loop *L,
- Value *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB) {
- // Check if the controlling expression for this loop is an And or Or.
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(ExitCond)) {
- if (BO->getOpcode() == Instruction::And) {
- // Recurse on the operands of the and.
- BackedgeTakenInfo BTI0 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(0), TBB, FBB);
- BackedgeTakenInfo BTI1 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(1), TBB, FBB);
- const SCEV *BECount = getCouldNotCompute();
- const SCEV *MaxBECount = getCouldNotCompute();
- if (L->contains(TBB)) {
- // Both conditions must be true for the loop to continue executing.
- // Choose the less conservative count.
- if (BTI0.Exact == getCouldNotCompute() ||
- BTI1.Exact == getCouldNotCompute())
- BECount = getCouldNotCompute();
- else
- BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max == getCouldNotCompute())
- MaxBECount = BTI1.Max;
- else if (BTI1.Max == getCouldNotCompute())
- MaxBECount = BTI0.Max;
- else
- MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
- } else {
- // Both conditions must be true for the loop to exit.
- assert(L->contains(FBB) && "Loop block has no successor in loop!");
- if (BTI0.Exact != getCouldNotCompute() &&
- BTI1.Exact != getCouldNotCompute())
- BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max != getCouldNotCompute() &&
- BTI1.Max != getCouldNotCompute())
- MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max);
- }
-
- return BackedgeTakenInfo(BECount, MaxBECount);
- }
- if (BO->getOpcode() == Instruction::Or) {
- // Recurse on the operands of the or.
- BackedgeTakenInfo BTI0 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(0), TBB, FBB);
- BackedgeTakenInfo BTI1 =
- ComputeBackedgeTakenCountFromExitCond(L, BO->getOperand(1), TBB, FBB);
- const SCEV *BECount = getCouldNotCompute();
- const SCEV *MaxBECount = getCouldNotCompute();
- if (L->contains(FBB)) {
- // Both conditions must be false for the loop to continue executing.
- // Choose the less conservative count.
- if (BTI0.Exact == getCouldNotCompute() ||
- BTI1.Exact == getCouldNotCompute())
- BECount = getCouldNotCompute();
- else
- BECount = getUMinFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max == getCouldNotCompute())
- MaxBECount = BTI1.Max;
- else if (BTI1.Max == getCouldNotCompute())
- MaxBECount = BTI0.Max;
- else
- MaxBECount = getUMinFromMismatchedTypes(BTI0.Max, BTI1.Max);
- } else {
- // Both conditions must be false for the loop to exit.
- assert(L->contains(TBB) && "Loop block has no successor in loop!");
- if (BTI0.Exact != getCouldNotCompute() &&
- BTI1.Exact != getCouldNotCompute())
- BECount = getUMaxFromMismatchedTypes(BTI0.Exact, BTI1.Exact);
- if (BTI0.Max != getCouldNotCompute() &&
- BTI1.Max != getCouldNotCompute())
- MaxBECount = getUMaxFromMismatchedTypes(BTI0.Max, BTI1.Max);
- }
-
- return BackedgeTakenInfo(BECount, MaxBECount);
- }
- }
-
- // With an icmp, it may be feasible to compute an exact backedge-taken count.
- // Proceed to the next level to examine the icmp.
- if (ICmpInst *ExitCondICmp = dyn_cast<ICmpInst>(ExitCond))
- return ComputeBackedgeTakenCountFromExitCondICmp(L, ExitCondICmp, TBB, FBB);
-
- // Check for a constant condition. These are normally stripped out by
- // SimplifyCFG, but ScalarEvolution may be used by a pass which wishes to
- // preserve the CFG and is temporarily leaving constant conditions
- // in place.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(ExitCond)) {
- if (L->contains(FBB) == !CI->getZExtValue())
- // The backedge is always taken.
- return getCouldNotCompute();
- else
- // The backedge is never taken.
- return getConstant(CI->getType(), 0);
- }
-
- // If it's not an integer or pointer comparison then compute it the hard way.
- return ComputeBackedgeTakenCountExhaustively(L, ExitCond, !L->contains(TBB));
-}
-
-/// ComputeBackedgeTakenCountFromExitCondICmp - Compute the number of times the
-/// backedge of the specified loop will execute if its exit condition
-/// were a conditional branch of the ICmpInst ExitCond, TBB, and FBB.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeBackedgeTakenCountFromExitCondICmp(const Loop *L,
- ICmpInst *ExitCond,
- BasicBlock *TBB,
- BasicBlock *FBB) {
-
- // If the condition was exit on true, convert the condition to exit on false
- ICmpInst::Predicate Cond;
- if (!L->contains(FBB))
- Cond = ExitCond->getPredicate();
- else
- Cond = ExitCond->getInversePredicate();
-
- // Handle common loops like: for (X = "string"; *X; ++X)
- if (LoadInst *LI = dyn_cast<LoadInst>(ExitCond->getOperand(0)))
- if (Constant *RHS = dyn_cast<Constant>(ExitCond->getOperand(1))) {
- BackedgeTakenInfo ItCnt =
- ComputeLoadConstantCompareBackedgeTakenCount(LI, RHS, L, Cond);
- if (ItCnt.hasAnyInfo())
- return ItCnt;
- }
-
- const SCEV *LHS = getSCEV(ExitCond->getOperand(0));
- const SCEV *RHS = getSCEV(ExitCond->getOperand(1));
-
- // Try to evaluate any dependencies out of the loop.
- LHS = getSCEVAtScope(LHS, L);
- RHS = getSCEVAtScope(RHS, L);
-
- // At this point, we would like to compute how many iterations of the
- // loop the predicate will return true for these inputs.
- if (LHS->isLoopInvariant(L) && !RHS->isLoopInvariant(L)) {
- // If there is a loop-invariant, force it into the RHS.
- std::swap(LHS, RHS);
- Cond = ICmpInst::getSwappedPredicate(Cond);
- }
-
- // Simplify the operands before analyzing them.
- (void)SimplifyICmpOperands(Cond, LHS, RHS);
-
- // If we have a comparison of a chrec against a constant, try to use value
- // ranges to answer this query.
- if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS))
- if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS))
- if (AddRec->getLoop() == L) {
- // Form the constant range.
- ConstantRange CompRange(
- ICmpInst::makeConstantRange(Cond, RHSC->getValue()->getValue()));
-
- const SCEV *Ret = AddRec->getNumIterationsInRange(CompRange, *this);
- if (!isa<SCEVCouldNotCompute>(Ret)) return Ret;
- }
-
- switch (Cond) {
- case ICmpInst::ICMP_NE: { // while (X != Y)
- // Convert to: while (X-Y != 0)
- BackedgeTakenInfo BTI = HowFarToZero(getMinusSCEV(LHS, RHS), L);
- if (BTI.hasAnyInfo()) return BTI;
- break;
- }
- case ICmpInst::ICMP_EQ: { // while (X == Y)
- // Convert to: while (X-Y == 0)
- BackedgeTakenInfo BTI = HowFarToNonZero(getMinusSCEV(LHS, RHS), L);
- if (BTI.hasAnyInfo()) return BTI;
- break;
- }
- case ICmpInst::ICMP_SLT: {
- BackedgeTakenInfo BTI = HowManyLessThans(LHS, RHS, L, true);
- if (BTI.hasAnyInfo()) return BTI;
- break;
- }
- case ICmpInst::ICMP_SGT: {
- BackedgeTakenInfo BTI = HowManyLessThans(getNotSCEV(LHS),
- getNotSCEV(RHS), L, true);
- if (BTI.hasAnyInfo()) return BTI;
- break;
- }
- case ICmpInst::ICMP_ULT: {
- BackedgeTakenInfo BTI = HowManyLessThans(LHS, RHS, L, false);
- if (BTI.hasAnyInfo()) return BTI;
- break;
- }
- case ICmpInst::ICMP_UGT: {
- BackedgeTakenInfo BTI = HowManyLessThans(getNotSCEV(LHS),
- getNotSCEV(RHS), L, false);
- if (BTI.hasAnyInfo()) return BTI;
- break;
- }
- default:
-#if 0
- dbgs() << "ComputeBackedgeTakenCount ";
- if (ExitCond->getOperand(0)->getType()->isUnsigned())
- dbgs() << "[unsigned] ";
- dbgs() << *LHS << " "
- << Instruction::getOpcodeName(Instruction::ICmp)
- << " " << *RHS << "\n";
-#endif
- break;
- }
- return
- ComputeBackedgeTakenCountExhaustively(L, ExitCond, !L->contains(TBB));
-}
-
-static ConstantInt *
-EvaluateConstantChrecAtConstant(const SCEVAddRecExpr *AddRec, ConstantInt *C,
- ScalarEvolution &SE) {
- const SCEV *InVal = SE.getConstant(C);
- const SCEV *Val = AddRec->evaluateAtIteration(InVal, SE);
- assert(isa<SCEVConstant>(Val) &&
- "Evaluation of SCEV at constant didn't fold correctly?");
- return cast<SCEVConstant>(Val)->getValue();
-}
-
-/// GetAddressedElementFromGlobal - Given a global variable with an initializer
-/// and a GEP expression (missing the pointer index) indexing into it, return
-/// the addressed element of the initializer or null if the index expression is
-/// invalid.
-static Constant *
-GetAddressedElementFromGlobal(GlobalVariable *GV,
- const std::vector<ConstantInt*> &Indices) {
- Constant *Init = GV->getInitializer();
- for (unsigned i = 0, e = Indices.size(); i != e; ++i) {
- uint64_t Idx = Indices[i]->getZExtValue();
- if (ConstantStruct *CS = dyn_cast<ConstantStruct>(Init)) {
- assert(Idx < CS->getNumOperands() && "Bad struct index!");
- Init = cast<Constant>(CS->getOperand(Idx));
- } else if (ConstantArray *CA = dyn_cast<ConstantArray>(Init)) {
- if (Idx >= CA->getNumOperands()) return 0; // Bogus program
- Init = cast<Constant>(CA->getOperand(Idx));
- } else if (isa<ConstantAggregateZero>(Init)) {
- if (const StructType *STy = dyn_cast<StructType>(Init->getType())) {
- assert(Idx < STy->getNumElements() && "Bad struct index!");
- Init = Constant::getNullValue(STy->getElementType(Idx));
- } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Init->getType())) {
- if (Idx >= ATy->getNumElements()) return 0; // Bogus program
- Init = Constant::getNullValue(ATy->getElementType());
- } else {
- llvm_unreachable("Unknown constant aggregate type!");
- }
- return 0;
- } else {
- return 0; // Unknown initializer type
- }
- }
- return Init;
-}
-
-/// ComputeLoadConstantCompareBackedgeTakenCount - Given an exit condition of
-/// 'icmp op load X, cst', try to see if we can compute the backedge
-/// execution count.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::ComputeLoadConstantCompareBackedgeTakenCount(
- LoadInst *LI,
- Constant *RHS,
- const Loop *L,
- ICmpInst::Predicate predicate) {
- if (LI->isVolatile()) return getCouldNotCompute();
-
- // Check to see if the loaded pointer is a getelementptr of a global.
- // TODO: Use SCEV instead of manually grubbing with GEPs.
- GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LI->getOperand(0));
- if (!GEP) return getCouldNotCompute();
-
- // Make sure that it is really a constant global we are gepping, with an
- // initializer, and make sure the first IDX is really 0.
- GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
- if (!GV || !GV->isConstant() || !GV->hasDefinitiveInitializer() ||
- GEP->getNumOperands() < 3 || !isa<Constant>(GEP->getOperand(1)) ||
- !cast<Constant>(GEP->getOperand(1))->isNullValue())
- return getCouldNotCompute();
-
- // Okay, we allow one non-constant index into the GEP instruction.
- Value *VarIdx = 0;
- std::vector<ConstantInt*> Indexes;
- unsigned VarIdxNum = 0;
- for (unsigned i = 2, e = GEP->getNumOperands(); i != e; ++i)
- if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(i))) {
- Indexes.push_back(CI);
- } else if (!isa<ConstantInt>(GEP->getOperand(i))) {
- if (VarIdx) return getCouldNotCompute(); // Multiple non-constant idx's.
- VarIdx = GEP->getOperand(i);
- VarIdxNum = i-2;
- Indexes.push_back(0);
- }
-
- // Okay, we know we have a (load (gep GV, 0, X)) comparison with a constant.
- // Check to see if X is a loop variant variable value now.
- const SCEV *Idx = getSCEV(VarIdx);
- Idx = getSCEVAtScope(Idx, L);
-
- // We can only recognize very limited forms of loop index expressions, in
- // particular, only affine AddRec's like {C1,+,C2}.
- const SCEVAddRecExpr *IdxExpr = dyn_cast<SCEVAddRecExpr>(Idx);
- if (!IdxExpr || !IdxExpr->isAffine() || IdxExpr->isLoopInvariant(L) ||
- !isa<SCEVConstant>(IdxExpr->getOperand(0)) ||
- !isa<SCEVConstant>(IdxExpr->getOperand(1)))
- return getCouldNotCompute();
-
- unsigned MaxSteps = MaxBruteForceIterations;
- for (unsigned IterationNum = 0; IterationNum != MaxSteps; ++IterationNum) {
- ConstantInt *ItCst = ConstantInt::get(
- cast<IntegerType>(IdxExpr->getType()), IterationNum);
- ConstantInt *Val = EvaluateConstantChrecAtConstant(IdxExpr, ItCst, *this);
-
- // Form the GEP offset.
- Indexes[VarIdxNum] = Val;
-
- Constant *Result = GetAddressedElementFromGlobal(GV, Indexes);
- if (Result == 0) break; // Cannot compute!
-
- // Evaluate the condition for this iteration.
- Result = ConstantExpr::getICmp(predicate, Result, RHS);
- if (!isa<ConstantInt>(Result)) break; // Couldn't decide for sure
- if (cast<ConstantInt>(Result)->getValue().isMinValue()) {
-#if 0
- dbgs() << "\n***\n*** Computed loop count " << *ItCst
- << "\n*** From global " << *GV << "*** BB: " << *L->getHeader()
- << "***\n";
-#endif
- ++NumArrayLenItCounts;
- return getConstant(ItCst); // Found terminating iteration!
- }
- }
- return getCouldNotCompute();
-}
-
-
-/// CanConstantFold - Return true if we can constant fold an instruction of the
-/// specified type, assuming that all operands were constants.
-static bool CanConstantFold(const Instruction *I) {
- if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
- isa<SelectInst>(I) || isa<CastInst>(I) || isa<GetElementPtrInst>(I))
- return true;
-
- if (const CallInst *CI = dyn_cast<CallInst>(I))
- if (const Function *F = CI->getCalledFunction())
- return canConstantFoldCallTo(F);
- return false;
-}
-
-/// getConstantEvolvingPHI - Given an LLVM value and a loop, return a PHI node
-/// in the loop that V is derived from. We allow arbitrary operations along the
-/// way, but the operands of an operation must either be constants or a value
-/// derived from a constant PHI. If this expression does not fit with these
-/// constraints, return null.
-static PHINode *getConstantEvolvingPHI(Value *V, const Loop *L) {
- // If this is not an instruction, or if this is an instruction outside of the
- // loop, it can't be derived from a loop PHI.
- Instruction *I = dyn_cast<Instruction>(V);
- if (I == 0 || !L->contains(I)) return 0;
-
- if (PHINode *PN = dyn_cast<PHINode>(I)) {
- if (L->getHeader() == I->getParent())
- return PN;
- else
- // We don't currently keep track of the control flow needed to evaluate
- // PHIs, so we cannot handle PHIs inside of loops.
- return 0;
- }
-
- // If we won't be able to constant fold this expression even if the operands
- // are constants, return early.
- if (!CanConstantFold(I)) return 0;
-
- // Otherwise, we can evaluate this instruction if all of its operands are
- // constant or derived from a PHI node themselves.
- PHINode *PHI = 0;
- for (unsigned Op = 0, e = I->getNumOperands(); Op != e; ++Op)
- if (!isa<Constant>(I->getOperand(Op))) {
- PHINode *P = getConstantEvolvingPHI(I->getOperand(Op), L);
- if (P == 0) return 0; // Not evolving from PHI
- if (PHI == 0)
- PHI = P;
- else if (PHI != P)
- return 0; // Evolving from multiple different PHIs.
- }
-
- // This is a expression evolving from a constant PHI!
- return PHI;
-}
-
-/// EvaluateExpression - Given an expression that passes the
-/// getConstantEvolvingPHI predicate, evaluate its value assuming the PHI node
-/// in the loop has the value PHIVal. If we can't fold this expression for some
-/// reason, return null.
-static Constant *EvaluateExpression(Value *V, Constant *PHIVal,
- const TargetData *TD) {
- if (isa<PHINode>(V)) return PHIVal;
- if (Constant *C = dyn_cast<Constant>(V)) return C;
- Instruction *I = cast<Instruction>(V);
-
- std::vector<Constant*> Operands(I->getNumOperands());
-
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
- Operands[i] = EvaluateExpression(I->getOperand(i), PHIVal, TD);
- if (Operands[i] == 0) return 0;
- }
-
- if (const CmpInst *CI = dyn_cast<CmpInst>(I))
- return ConstantFoldCompareInstOperands(CI->getPredicate(), Operands[0],
- Operands[1], TD);
- return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
- &Operands[0], Operands.size(), TD);
-}
-
-/// getConstantEvolutionLoopExitValue - If we know that the specified Phi is
-/// in the header of its containing loop, we know the loop executes a
-/// constant number of times, and the PHI node is just a recurrence
-/// involving constants, fold it.
-Constant *
-ScalarEvolution::getConstantEvolutionLoopExitValue(PHINode *PN,
- const APInt &BEs,
- const Loop *L) {
- std::map<PHINode*, Constant*>::iterator I =
- ConstantEvolutionLoopExitValue.find(PN);
- if (I != ConstantEvolutionLoopExitValue.end())
- return I->second;
-
- if (BEs.ugt(MaxBruteForceIterations))
- return ConstantEvolutionLoopExitValue[PN] = 0; // Not going to evaluate it.
-
- Constant *&RetVal = ConstantEvolutionLoopExitValue[PN];
-
- // Since the loop is canonicalized, the PHI node must have two entries. One
- // entry must be a constant (coming in from outside of the loop), and the
- // second must be derived from the same PHI.
- bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1));
- Constant *StartCST =
- dyn_cast<Constant>(PN->getIncomingValue(!SecondIsBackedge));
- if (StartCST == 0)
- return RetVal = 0; // Must be a constant.
-
- Value *BEValue = PN->getIncomingValue(SecondIsBackedge);
- if (getConstantEvolvingPHI(BEValue, L) != PN &&
- !isa<Constant>(BEValue))
- return RetVal = 0; // Not derived from same PHI.
-
- // Execute the loop symbolically to determine the exit value.
- if (BEs.getActiveBits() >= 32)
- return RetVal = 0; // More than 2^32-1 iterations?? Not doing it!
-
- unsigned NumIterations = BEs.getZExtValue(); // must be in range
- unsigned IterationNum = 0;
- for (Constant *PHIVal = StartCST; ; ++IterationNum) {
- if (IterationNum == NumIterations)
- return RetVal = PHIVal; // Got exit value!
-
- // Compute the value of the PHI node for the next iteration.
- Constant *NextPHI = EvaluateExpression(BEValue, PHIVal, TD);
- if (NextPHI == PHIVal)
- return RetVal = NextPHI; // Stopped evolving!
- if (NextPHI == 0)
- return 0; // Couldn't evaluate!
- PHIVal = NextPHI;
- }
-}
-
-/// ComputeBackedgeTakenCountExhaustively - If the loop is known to execute a
-/// constant number of times (the condition evolves only from constants),
-/// try to evaluate a few iterations of the loop until we get the exit
-/// condition gets a value of ExitWhen (true or false). If we cannot
-/// evaluate the trip count of the loop, return getCouldNotCompute().
-const SCEV *
-ScalarEvolution::ComputeBackedgeTakenCountExhaustively(const Loop *L,
- Value *Cond,
- bool ExitWhen) {
- PHINode *PN = getConstantEvolvingPHI(Cond, L);
- if (PN == 0) return getCouldNotCompute();
-
- // If the loop is canonicalized, the PHI will have exactly two entries.
- // That's the only form we support here.
- if (PN->getNumIncomingValues() != 2) return getCouldNotCompute();
-
- // One entry must be a constant (coming in from outside of the loop), and the
- // second must be derived from the same PHI.
- bool SecondIsBackedge = L->contains(PN->getIncomingBlock(1));
- Constant *StartCST =
- dyn_cast<Constant>(PN->getIncomingValue(!SecondIsBackedge));
- if (StartCST == 0) return getCouldNotCompute(); // Must be a constant.
-
- Value *BEValue = PN->getIncomingValue(SecondIsBackedge);
- if (getConstantEvolvingPHI(BEValue, L) != PN &&
- !isa<Constant>(BEValue))
- return getCouldNotCompute(); // Not derived from same PHI.
-
- // Okay, we find a PHI node that defines the trip count of this loop. Execute
- // the loop symbolically to determine when the condition gets a value of
- // "ExitWhen".
- unsigned IterationNum = 0;
- unsigned MaxIterations = MaxBruteForceIterations; // Limit analysis.
- for (Constant *PHIVal = StartCST;
- IterationNum != MaxIterations; ++IterationNum) {
- ConstantInt *CondVal =
- dyn_cast_or_null<ConstantInt>(EvaluateExpression(Cond, PHIVal, TD));
-
- // Couldn't symbolically evaluate.
- if (!CondVal) return getCouldNotCompute();
-
- if (CondVal->getValue() == uint64_t(ExitWhen)) {
- ++NumBruteForceTripCountsComputed;
- return getConstant(Type::getInt32Ty(getContext()), IterationNum);
- }
-
- // Compute the value of the PHI node for the next iteration.
- Constant *NextPHI = EvaluateExpression(BEValue, PHIVal, TD);
- if (NextPHI == 0 || NextPHI == PHIVal)
- return getCouldNotCompute();// Couldn't evaluate or not making progress...
- PHIVal = NextPHI;
- }
-
- // Too many iterations were needed to evaluate.
- return getCouldNotCompute();
-}
-
-/// getSCEVAtScope - Return a SCEV expression for the specified value
-/// at the specified scope in the program. The L value specifies a loop
-/// nest to evaluate the expression at, where null is the top-level or a
-/// specified loop is immediately inside of the loop.
-///
-/// This method can be used to compute the exit value for a variable defined
-/// in a loop by querying what the value will hold in the parent loop.
-///
-/// In the case that a relevant loop exit value cannot be computed, the
-/// original value V is returned.
-const SCEV *ScalarEvolution::getSCEVAtScope(const SCEV *V, const Loop *L) {
- // Check to see if we've folded this expression at this loop before.
- std::map<const Loop *, const SCEV *> &Values = ValuesAtScopes[V];
- std::pair<std::map<const Loop *, const SCEV *>::iterator, bool> Pair =
- Values.insert(std::make_pair(L, static_cast<const SCEV *>(0)));
- if (!Pair.second)
- return Pair.first->second ? Pair.first->second : V;
-
- // Otherwise compute it.
- const SCEV *C = computeSCEVAtScope(V, L);
- ValuesAtScopes[V][L] = C;
- return C;
-}
-
-const SCEV *ScalarEvolution::computeSCEVAtScope(const SCEV *V, const Loop *L) {
- if (isa<SCEVConstant>(V)) return V;
-
- // If this instruction is evolved from a constant-evolving PHI, compute the
- // exit value from the loop without using SCEVs.
- if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V)) {
- if (Instruction *I = dyn_cast<Instruction>(SU->getValue())) {
- const Loop *LI = (*this->LI)[I->getParent()];
- if (LI && LI->getParentLoop() == L) // Looking for loop exit value.
- if (PHINode *PN = dyn_cast<PHINode>(I))
- if (PN->getParent() == LI->getHeader()) {
- // Okay, there is no closed form solution for the PHI node. Check
- // to see if the loop that contains it has a known backedge-taken
- // count. If so, we may be able to force computation of the exit
- // value.
- const SCEV *BackedgeTakenCount = getBackedgeTakenCount(LI);
- if (const SCEVConstant *BTCC =
- dyn_cast<SCEVConstant>(BackedgeTakenCount)) {
- // Okay, we know how many times the containing loop executes. If
- // this is a constant evolving PHI node, get the final value at
- // the specified iteration number.
- Constant *RV = getConstantEvolutionLoopExitValue(PN,
- BTCC->getValue()->getValue(),
- LI);
- if (RV) return getSCEV(RV);
- }
- }
-
- // Okay, this is an expression that we cannot symbolically evaluate
- // into a SCEV. Check to see if it's possible to symbolically evaluate
- // the arguments into constants, and if so, try to constant propagate the
- // result. This is particularly useful for computing loop exit values.
- if (CanConstantFold(I)) {
- SmallVector<Constant *, 4> Operands;
- bool MadeImprovement = false;
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
- Value *Op = I->getOperand(i);
- if (Constant *C = dyn_cast<Constant>(Op)) {
- Operands.push_back(C);
- continue;
- }
-
- // If any of the operands is non-constant and if they are
- // non-integer and non-pointer, don't even try to analyze them
- // with scev techniques.
- if (!isSCEVable(Op->getType()))
- return V;
-
- const SCEV *OrigV = getSCEV(Op);
- const SCEV *OpV = getSCEVAtScope(OrigV, L);
- MadeImprovement |= OrigV != OpV;
-
- Constant *C = 0;
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(OpV))
- C = SC->getValue();
- if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(OpV))
- C = dyn_cast<Constant>(SU->getValue());
- if (!C) return V;
- if (C->getType() != Op->getType())
- C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
- Op->getType(),
- false),
- C, Op->getType());
- Operands.push_back(C);
- }
-
- // Check to see if getSCEVAtScope actually made an improvement.
- if (MadeImprovement) {
- Constant *C = 0;
- if (const CmpInst *CI = dyn_cast<CmpInst>(I))
- C = ConstantFoldCompareInstOperands(CI->getPredicate(),
- Operands[0], Operands[1], TD);
- else
- C = ConstantFoldInstOperands(I->getOpcode(), I->getType(),
- &Operands[0], Operands.size(), TD);
- if (!C) return V;
- return getSCEV(C);
- }
- }
- }
-
- // This is some other type of SCEVUnknown, just return it.
- return V;
- }
-
- if (const SCEVCommutativeExpr *Comm = dyn_cast<SCEVCommutativeExpr>(V)) {
- // Avoid performing the look-up in the common case where the specified
- // expression has no loop-variant portions.
- for (unsigned i = 0, e = Comm->getNumOperands(); i != e; ++i) {
- const SCEV *OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
- if (OpAtScope != Comm->getOperand(i)) {
- // Okay, at least one of these operands is loop variant but might be
- // foldable. Build a new instance of the folded commutative expression.
- SmallVector<const SCEV *, 8> NewOps(Comm->op_begin(),
- Comm->op_begin()+i);
- NewOps.push_back(OpAtScope);
-
- for (++i; i != e; ++i) {
- OpAtScope = getSCEVAtScope(Comm->getOperand(i), L);
- NewOps.push_back(OpAtScope);
- }
- if (isa<SCEVAddExpr>(Comm))
- return getAddExpr(NewOps);
- if (isa<SCEVMulExpr>(Comm))
- return getMulExpr(NewOps);
- if (isa<SCEVSMaxExpr>(Comm))
- return getSMaxExpr(NewOps);
- if (isa<SCEVUMaxExpr>(Comm))
- return getUMaxExpr(NewOps);
- llvm_unreachable("Unknown commutative SCEV type!");
- }
- }
- // If we got here, all operands are loop invariant.
- return Comm;
- }
-
- if (const SCEVUDivExpr *Div = dyn_cast<SCEVUDivExpr>(V)) {
- const SCEV *LHS = getSCEVAtScope(Div->getLHS(), L);
- const SCEV *RHS = getSCEVAtScope(Div->getRHS(), L);
- if (LHS == Div->getLHS() && RHS == Div->getRHS())
- return Div; // must be loop invariant
- return getUDivExpr(LHS, RHS);
- }
-
- // If this is a loop recurrence for a loop that does not contain L, then we
- // are dealing with the final value computed by the loop.
- if (const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V)) {
- // First, attempt to evaluate each operand.
- // Avoid performing the look-up in the common case where the specified
- // expression has no loop-variant portions.
- for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
- const SCEV *OpAtScope = getSCEVAtScope(AddRec->getOperand(i), L);
- if (OpAtScope == AddRec->getOperand(i))
- continue;
-
- // Okay, at least one of these operands is loop variant but might be
- // foldable. Build a new instance of the folded commutative expression.
- SmallVector<const SCEV *, 8> NewOps(AddRec->op_begin(),
- AddRec->op_begin()+i);
- NewOps.push_back(OpAtScope);
- for (++i; i != e; ++i)
- NewOps.push_back(getSCEVAtScope(AddRec->getOperand(i), L));
-
- AddRec = cast<SCEVAddRecExpr>(getAddRecExpr(NewOps, AddRec->getLoop()));
- break;
- }
-
- // If the scope is outside the addrec's loop, evaluate it by using the
- // loop exit value of the addrec.
- if (!AddRec->getLoop()->contains(L)) {
- // To evaluate this recurrence, we need to know how many times the AddRec
- // loop iterates. Compute this now.
- const SCEV *BackedgeTakenCount = getBackedgeTakenCount(AddRec->getLoop());
- if (BackedgeTakenCount == getCouldNotCompute()) return AddRec;
-
- // Then, evaluate the AddRec.
- return AddRec->evaluateAtIteration(BackedgeTakenCount, *this);
- }
-
- return AddRec;
- }
-
- if (const SCEVZeroExtendExpr *Cast = dyn_cast<SCEVZeroExtendExpr>(V)) {
- const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
- if (Op == Cast->getOperand())
- return Cast; // must be loop invariant
- return getZeroExtendExpr(Op, Cast->getType());
- }
-
- if (const SCEVSignExtendExpr *Cast = dyn_cast<SCEVSignExtendExpr>(V)) {
- const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
- if (Op == Cast->getOperand())
- return Cast; // must be loop invariant
- return getSignExtendExpr(Op, Cast->getType());
- }
-
- if (const SCEVTruncateExpr *Cast = dyn_cast<SCEVTruncateExpr>(V)) {
- const SCEV *Op = getSCEVAtScope(Cast->getOperand(), L);
- if (Op == Cast->getOperand())
- return Cast; // must be loop invariant
- return getTruncateExpr(Op, Cast->getType());
- }
-
- llvm_unreachable("Unknown SCEV type!");
- return 0;
-}
-
-/// getSCEVAtScope - This is a convenience function which does
-/// getSCEVAtScope(getSCEV(V), L).
-const SCEV *ScalarEvolution::getSCEVAtScope(Value *V, const Loop *L) {
- return getSCEVAtScope(getSCEV(V), L);
-}
-
-/// SolveLinEquationWithOverflow - Finds the minimum unsigned root of the
-/// following equation:
-///
-/// A * X = B (mod N)
-///
-/// where N = 2^BW and BW is the common bit width of A and B. The signedness of
-/// A and B isn't important.
-///
-/// If the equation does not have a solution, SCEVCouldNotCompute is returned.
-static const SCEV *SolveLinEquationWithOverflow(const APInt &A, const APInt &B,
- ScalarEvolution &SE) {
- uint32_t BW = A.getBitWidth();
- assert(BW == B.getBitWidth() && "Bit widths must be the same.");
- assert(A != 0 && "A must be non-zero.");
-
- // 1. D = gcd(A, N)
- //
- // The gcd of A and N may have only one prime factor: 2. The number of
- // trailing zeros in A is its multiplicity
- uint32_t Mult2 = A.countTrailingZeros();
- // D = 2^Mult2
-
- // 2. Check if B is divisible by D.
- //
- // B is divisible by D if and only if the multiplicity of prime factor 2 for B
- // is not less than multiplicity of this prime factor for D.
- if (B.countTrailingZeros() < Mult2)
- return SE.getCouldNotCompute();
-
- // 3. Compute I: the multiplicative inverse of (A / D) in arithmetic
- // modulo (N / D).
- //
- // (N / D) may need BW+1 bits in its representation. Hence, we'll use this
- // bit width during computations.
- APInt AD = A.lshr(Mult2).zext(BW + 1); // AD = A / D
- APInt Mod(BW + 1, 0);
- Mod.set(BW - Mult2); // Mod = N / D
- APInt I = AD.multiplicativeInverse(Mod);
-
- // 4. Compute the minimum unsigned root of the equation:
- // I * (B / D) mod (N / D)
- APInt Result = (I * B.lshr(Mult2).zext(BW + 1)).urem(Mod);
-
- // The result is guaranteed to be less than 2^BW so we may truncate it to BW
- // bits.
- return SE.getConstant(Result.trunc(BW));
-}
-
-/// SolveQuadraticEquation - Find the roots of the quadratic equation for the
-/// given quadratic chrec {L,+,M,+,N}. This returns either the two roots (which
-/// might be the same) or two SCEVCouldNotCompute objects.
-///
-static std::pair<const SCEV *,const SCEV *>
-SolveQuadraticEquation(const SCEVAddRecExpr *AddRec, ScalarEvolution &SE) {
- assert(AddRec->getNumOperands() == 3 && "This is not a quadratic chrec!");
- const SCEVConstant *LC = dyn_cast<SCEVConstant>(AddRec->getOperand(0));
- const SCEVConstant *MC = dyn_cast<SCEVConstant>(AddRec->getOperand(1));
- const SCEVConstant *NC = dyn_cast<SCEVConstant>(AddRec->getOperand(2));
-
- // We currently can only solve this if the coefficients are constants.
- if (!LC || !MC || !NC) {
- const SCEV *CNC = SE.getCouldNotCompute();
- return std::make_pair(CNC, CNC);
- }
-
- uint32_t BitWidth = LC->getValue()->getValue().getBitWidth();
- const APInt &L = LC->getValue()->getValue();
- const APInt &M = MC->getValue()->getValue();
- const APInt &N = NC->getValue()->getValue();
- APInt Two(BitWidth, 2);
- APInt Four(BitWidth, 4);
-
- {
- using namespace APIntOps;
- const APInt& C = L;
- // Convert from chrec coefficients to polynomial coefficients AX^2+BX+C
- // The B coefficient is M-N/2
- APInt B(M);
- B -= sdiv(N,Two);
-
- // The A coefficient is N/2
- APInt A(N.sdiv(Two));
-
- // Compute the B^2-4ac term.
- APInt SqrtTerm(B);
- SqrtTerm *= B;
- SqrtTerm -= Four * (A * C);
-
- // Compute sqrt(B^2-4ac). This is guaranteed to be the nearest
- // integer value or else APInt::sqrt() will assert.
- APInt SqrtVal(SqrtTerm.sqrt());
-
- // Compute the two solutions for the quadratic formula.
- // The divisions must be performed as signed divisions.
- APInt NegB(-B);
- APInt TwoA( A << 1 );
- if (TwoA.isMinValue()) {
- const SCEV *CNC = SE.getCouldNotCompute();
- return std::make_pair(CNC, CNC);
- }
-
- LLVMContext &Context = SE.getContext();
-
- ConstantInt *Solution1 =
- ConstantInt::get(Context, (NegB + SqrtVal).sdiv(TwoA));
- ConstantInt *Solution2 =
- ConstantInt::get(Context, (NegB - SqrtVal).sdiv(TwoA));
-
- return std::make_pair(SE.getConstant(Solution1),
- SE.getConstant(Solution2));
- } // end APIntOps namespace
-}
-
-/// HowFarToZero - Return the number of times a backedge comparing the specified
-/// value to zero will execute. If not computable, return CouldNotCompute.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::HowFarToZero(const SCEV *V, const Loop *L) {
- // If the value is a constant
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
- // If the value is already zero, the branch will execute zero times.
- if (C->getValue()->isZero()) return C;
- return getCouldNotCompute(); // Otherwise it will loop infinitely.
- }
-
- const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(V);
- if (!AddRec || AddRec->getLoop() != L)
- return getCouldNotCompute();
-
- if (AddRec->isAffine()) {
- // If this is an affine expression, the execution count of this branch is
- // the minimum unsigned root of the following equation:
- //
- // Start + Step*N = 0 (mod 2^BW)
- //
- // equivalent to:
- //
- // Step*N = -Start (mod 2^BW)
- //
- // where BW is the common bit width of Start and Step.
-
- // Get the initial value for the loop.
- const SCEV *Start = getSCEVAtScope(AddRec->getStart(),
- L->getParentLoop());
- const SCEV *Step = getSCEVAtScope(AddRec->getOperand(1),
- L->getParentLoop());
-
- if (const SCEVConstant *StepC = dyn_cast<SCEVConstant>(Step)) {
- // For now we handle only constant steps.
-
- // First, handle unitary steps.
- if (StepC->getValue()->equalsInt(1)) // 1*N = -Start (mod 2^BW), so:
- return getNegativeSCEV(Start); // N = -Start (as unsigned)
- if (StepC->getValue()->isAllOnesValue()) // -1*N = -Start (mod 2^BW), so:
- return Start; // N = Start (as unsigned)
-
- // Then, try to solve the above equation provided that Start is constant.
- if (const SCEVConstant *StartC = dyn_cast<SCEVConstant>(Start))
- return SolveLinEquationWithOverflow(StepC->getValue()->getValue(),
- -StartC->getValue()->getValue(),
- *this);
- }
- } else if (AddRec->isQuadratic() && AddRec->getType()->isIntegerTy()) {
- // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of
- // the quadratic equation to solve it.
- std::pair<const SCEV *,const SCEV *> Roots = SolveQuadraticEquation(AddRec,
- *this);
- const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
- const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
- if (R1) {
-#if 0
- dbgs() << "HFTZ: " << *V << " - sol#1: " << *R1
- << " sol#2: " << *R2 << "\n";
-#endif
- // Pick the smallest positive root value.
- if (ConstantInt *CB =
- dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT,
- R1->getValue(), R2->getValue()))) {
- if (CB->getZExtValue() == false)
- std::swap(R1, R2); // R1 is the minimum root now.
-
- // We can only use this value if the chrec ends up with an exact zero
- // value at this index. When solving for "X*X != 5", for example, we
- // should not accept a root of 2.
- const SCEV *Val = AddRec->evaluateAtIteration(R1, *this);
- if (Val->isZero())
- return R1; // We found a quadratic root!
- }
- }
- }
-
- return getCouldNotCompute();
-}
-
-/// HowFarToNonZero - Return the number of times a backedge checking the
-/// specified value for nonzero will execute. If not computable, return
-/// CouldNotCompute
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::HowFarToNonZero(const SCEV *V, const Loop *L) {
- // Loops that look like: while (X == 0) are very strange indeed. We don't
- // handle them yet except for the trivial case. This could be expanded in the
- // future as needed.
-
- // If the value is a constant, check to see if it is known to be non-zero
- // already. If so, the backedge will execute zero times.
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(V)) {
- if (!C->getValue()->isNullValue())
- return getConstant(C->getType(), 0);
- return getCouldNotCompute(); // Otherwise it will loop infinitely.
- }
-
- // We could implement others, but I really doubt anyone writes loops like
- // this, and if they did, they would already be constant folded.
- return getCouldNotCompute();
-}
-
-/// getPredecessorWithUniqueSuccessorForBB - Return a predecessor of BB
-/// (which may not be an immediate predecessor) which has exactly one
-/// successor from which BB is reachable, or null if no such block is
-/// found.
-///
-std::pair<BasicBlock *, BasicBlock *>
-ScalarEvolution::getPredecessorWithUniqueSuccessorForBB(BasicBlock *BB) {
- // If the block has a unique predecessor, then there is no path from the
- // predecessor to the block that does not go through the direct edge
- // from the predecessor to the block.
- if (BasicBlock *Pred = BB->getSinglePredecessor())
- return std::make_pair(Pred, BB);
-
- // A loop's header is defined to be a block that dominates the loop.
- // If the header has a unique predecessor outside the loop, it must be
- // a block that has exactly one successor that can reach the loop.
- if (Loop *L = LI->getLoopFor(BB))
- return std::make_pair(L->getLoopPredecessor(), L->getHeader());
-
- return std::pair<BasicBlock *, BasicBlock *>();
-}
-
-/// HasSameValue - SCEV structural equivalence is usually sufficient for
-/// testing whether two expressions are equal, however for the purposes of
-/// looking for a condition guarding a loop, it can be useful to be a little
-/// more general, since a front-end may have replicated the controlling
-/// expression.
-///
-static bool HasSameValue(const SCEV *A, const SCEV *B) {
- // Quick check to see if they are the same SCEV.
- if (A == B) return true;
-
- // Otherwise, if they're both SCEVUnknown, it's possible that they hold
- // two different instructions with the same value. Check for this case.
- if (const SCEVUnknown *AU = dyn_cast<SCEVUnknown>(A))
- if (const SCEVUnknown *BU = dyn_cast<SCEVUnknown>(B))
- if (const Instruction *AI = dyn_cast<Instruction>(AU->getValue()))
- if (const Instruction *BI = dyn_cast<Instruction>(BU->getValue()))
- if (AI->isIdenticalTo(BI) && !AI->mayReadFromMemory())
- return true;
-
- // Otherwise assume they may have a different value.
- return false;
-}
-
-/// SimplifyICmpOperands - Simplify LHS and RHS in a comparison with
-/// predicate Pred. Return true iff any changes were made.
-///
-bool ScalarEvolution::SimplifyICmpOperands(ICmpInst::Predicate &Pred,
- const SCEV *&LHS, const SCEV *&RHS) {
- bool Changed = false;
-
- // Canonicalize a constant to the right side.
- if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS)) {
- // Check for both operands constant.
- if (const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS)) {
- if (ConstantExpr::getICmp(Pred,
- LHSC->getValue(),
- RHSC->getValue())->isNullValue())
- goto trivially_false;
- else
- goto trivially_true;
- }
- // Otherwise swap the operands to put the constant on the right.
- std::swap(LHS, RHS);
- Pred = ICmpInst::getSwappedPredicate(Pred);
- Changed = true;
- }
-
- // If we're comparing an addrec with a value which is loop-invariant in the
- // addrec's loop, put the addrec on the left. Also make a dominance check,
- // as both operands could be addrecs loop-invariant in each other's loop.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS)) {
- const Loop *L = AR->getLoop();
- if (LHS->isLoopInvariant(L) && LHS->properlyDominates(L->getHeader(), DT)) {
- std::swap(LHS, RHS);
- Pred = ICmpInst::getSwappedPredicate(Pred);
- Changed = true;
- }
- }
-
- // If there's a constant operand, canonicalize comparisons with boundary
- // cases, and canonicalize *-or-equal comparisons to regular comparisons.
- if (const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS)) {
- const APInt &RA = RC->getValue()->getValue();
- switch (Pred) {
- default: llvm_unreachable("Unexpected ICmpInst::Predicate value!");
- case ICmpInst::ICMP_EQ:
- case ICmpInst::ICMP_NE:
- break;
- case ICmpInst::ICMP_UGE:
- if ((RA - 1).isMinValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA - 1);
- Changed = true;
- break;
- }
- if (RA.isMaxValue()) {
- Pred = ICmpInst::ICMP_EQ;
- Changed = true;
- break;
- }
- if (RA.isMinValue()) goto trivially_true;
-
- Pred = ICmpInst::ICMP_UGT;
- RHS = getConstant(RA - 1);
- Changed = true;
- break;
- case ICmpInst::ICMP_ULE:
- if ((RA + 1).isMaxValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA + 1);
- Changed = true;
- break;
- }
- if (RA.isMinValue()) {
- Pred = ICmpInst::ICMP_EQ;
- Changed = true;
- break;
- }
- if (RA.isMaxValue()) goto trivially_true;
-
- Pred = ICmpInst::ICMP_ULT;
- RHS = getConstant(RA + 1);
- Changed = true;
- break;
- case ICmpInst::ICMP_SGE:
- if ((RA - 1).isMinSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA - 1);
- Changed = true;
- break;
- }
- if (RA.isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- Changed = true;
- break;
- }
- if (RA.isMinSignedValue()) goto trivially_true;
-
- Pred = ICmpInst::ICMP_SGT;
- RHS = getConstant(RA - 1);
- Changed = true;
- break;
- case ICmpInst::ICMP_SLE:
- if ((RA + 1).isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- RHS = getConstant(RA + 1);
- Changed = true;
- break;
- }
- if (RA.isMinSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- Changed = true;
- break;
- }
- if (RA.isMaxSignedValue()) goto trivially_true;
-
- Pred = ICmpInst::ICMP_SLT;
- RHS = getConstant(RA + 1);
- Changed = true;
- break;
- case ICmpInst::ICMP_UGT:
- if (RA.isMinValue()) {
- Pred = ICmpInst::ICMP_NE;
- Changed = true;
- break;
- }
- if ((RA + 1).isMaxValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA + 1);
- Changed = true;
- break;
- }
- if (RA.isMaxValue()) goto trivially_false;
- break;
- case ICmpInst::ICMP_ULT:
- if (RA.isMaxValue()) {
- Pred = ICmpInst::ICMP_NE;
- Changed = true;
- break;
- }
- if ((RA - 1).isMinValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA - 1);
- Changed = true;
- break;
- }
- if (RA.isMinValue()) goto trivially_false;
- break;
- case ICmpInst::ICMP_SGT:
- if (RA.isMinSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- Changed = true;
- break;
- }
- if ((RA + 1).isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA + 1);
- Changed = true;
- break;
- }
- if (RA.isMaxSignedValue()) goto trivially_false;
- break;
- case ICmpInst::ICMP_SLT:
- if (RA.isMaxSignedValue()) {
- Pred = ICmpInst::ICMP_NE;
- Changed = true;
- break;
- }
- if ((RA - 1).isMinSignedValue()) {
- Pred = ICmpInst::ICMP_EQ;
- RHS = getConstant(RA - 1);
- Changed = true;
- break;
- }
- if (RA.isMinSignedValue()) goto trivially_false;
- break;
- }
- }
-
- // Check for obvious equality.
- if (HasSameValue(LHS, RHS)) {
- if (ICmpInst::isTrueWhenEqual(Pred))
- goto trivially_true;
- if (ICmpInst::isFalseWhenEqual(Pred))
- goto trivially_false;
- }
-
- // If possible, canonicalize GE/LE comparisons to GT/LT comparisons, by
- // adding or subtracting 1 from one of the operands.
- switch (Pred) {
- case ICmpInst::ICMP_SLE:
- if (!getSignedRange(RHS).getSignedMax().isMaxSignedValue()) {
- RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
- /*HasNUW=*/false, /*HasNSW=*/true);
- Pred = ICmpInst::ICMP_SLT;
- Changed = true;
- } else if (!getSignedRange(LHS).getSignedMin().isMinSignedValue()) {
- LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
- /*HasNUW=*/false, /*HasNSW=*/true);
- Pred = ICmpInst::ICMP_SLT;
- Changed = true;
- }
- break;
- case ICmpInst::ICMP_SGE:
- if (!getSignedRange(RHS).getSignedMin().isMinSignedValue()) {
- RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
- /*HasNUW=*/false, /*HasNSW=*/true);
- Pred = ICmpInst::ICMP_SGT;
- Changed = true;
- } else if (!getSignedRange(LHS).getSignedMax().isMaxSignedValue()) {
- LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
- /*HasNUW=*/false, /*HasNSW=*/true);
- Pred = ICmpInst::ICMP_SGT;
- Changed = true;
- }
- break;
- case ICmpInst::ICMP_ULE:
- if (!getUnsignedRange(RHS).getUnsignedMax().isMaxValue()) {
- RHS = getAddExpr(getConstant(RHS->getType(), 1, true), RHS,
- /*HasNUW=*/true, /*HasNSW=*/false);
- Pred = ICmpInst::ICMP_ULT;
- Changed = true;
- } else if (!getUnsignedRange(LHS).getUnsignedMin().isMinValue()) {
- LHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), LHS,
- /*HasNUW=*/true, /*HasNSW=*/false);
- Pred = ICmpInst::ICMP_ULT;
- Changed = true;
- }
- break;
- case ICmpInst::ICMP_UGE:
- if (!getUnsignedRange(RHS).getUnsignedMin().isMinValue()) {
- RHS = getAddExpr(getConstant(RHS->getType(), (uint64_t)-1, true), RHS,
- /*HasNUW=*/true, /*HasNSW=*/false);
- Pred = ICmpInst::ICMP_UGT;
- Changed = true;
- } else if (!getUnsignedRange(LHS).getUnsignedMax().isMaxValue()) {
- LHS = getAddExpr(getConstant(RHS->getType(), 1, true), LHS,
- /*HasNUW=*/true, /*HasNSW=*/false);
- Pred = ICmpInst::ICMP_UGT;
- Changed = true;
- }
- break;
- default:
- break;
- }
-
- // TODO: More simplifications are possible here.
-
- return Changed;
-
-trivially_true:
- // Return 0 == 0.
- LHS = RHS = getConstant(Type::getInt1Ty(getContext()), 0);
- Pred = ICmpInst::ICMP_EQ;
- return true;
-
-trivially_false:
- // Return 0 != 0.
- LHS = RHS = getConstant(Type::getInt1Ty(getContext()), 0);
- Pred = ICmpInst::ICMP_NE;
- return true;
-}
-
-bool ScalarEvolution::isKnownNegative(const SCEV *S) {
- return getSignedRange(S).getSignedMax().isNegative();
-}
-
-bool ScalarEvolution::isKnownPositive(const SCEV *S) {
- return getSignedRange(S).getSignedMin().isStrictlyPositive();
-}
-
-bool ScalarEvolution::isKnownNonNegative(const SCEV *S) {
- return !getSignedRange(S).getSignedMin().isNegative();
-}
-
-bool ScalarEvolution::isKnownNonPositive(const SCEV *S) {
- return !getSignedRange(S).getSignedMax().isStrictlyPositive();
-}
-
-bool ScalarEvolution::isKnownNonZero(const SCEV *S) {
- return isKnownNegative(S) || isKnownPositive(S);
-}
-
-bool ScalarEvolution::isKnownPredicate(ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS) {
- // Canonicalize the inputs first.
- (void)SimplifyICmpOperands(Pred, LHS, RHS);
-
- // If LHS or RHS is an addrec, check to see if the condition is true in
- // every iteration of the loop.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS))
- if (isLoopEntryGuardedByCond(
- AR->getLoop(), Pred, AR->getStart(), RHS) &&
- isLoopBackedgeGuardedByCond(
- AR->getLoop(), Pred, AR->getPostIncExpr(*this), RHS))
- return true;
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(RHS))
- if (isLoopEntryGuardedByCond(
- AR->getLoop(), Pred, LHS, AR->getStart()) &&
- isLoopBackedgeGuardedByCond(
- AR->getLoop(), Pred, LHS, AR->getPostIncExpr(*this)))
- return true;
-
- // Otherwise see what can be done with known constant ranges.
- return isKnownPredicateWithRanges(Pred, LHS, RHS);
-}
-
-bool
-ScalarEvolution::isKnownPredicateWithRanges(ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS) {
- if (HasSameValue(LHS, RHS))
- return ICmpInst::isTrueWhenEqual(Pred);
-
- // This code is split out from isKnownPredicate because it is called from
- // within isLoopEntryGuardedByCond.
- switch (Pred) {
- default:
- llvm_unreachable("Unexpected ICmpInst::Predicate value!");
- break;
- case ICmpInst::ICMP_SGT:
- Pred = ICmpInst::ICMP_SLT;
- std::swap(LHS, RHS);
- case ICmpInst::ICMP_SLT: {
- ConstantRange LHSRange = getSignedRange(LHS);
- ConstantRange RHSRange = getSignedRange(RHS);
- if (LHSRange.getSignedMax().slt(RHSRange.getSignedMin()))
- return true;
- if (LHSRange.getSignedMin().sge(RHSRange.getSignedMax()))
- return false;
- break;
- }
- case ICmpInst::ICMP_SGE:
- Pred = ICmpInst::ICMP_SLE;
- std::swap(LHS, RHS);
- case ICmpInst::ICMP_SLE: {
- ConstantRange LHSRange = getSignedRange(LHS);
- ConstantRange RHSRange = getSignedRange(RHS);
- if (LHSRange.getSignedMax().sle(RHSRange.getSignedMin()))
- return true;
- if (LHSRange.getSignedMin().sgt(RHSRange.getSignedMax()))
- return false;
- break;
- }
- case ICmpInst::ICMP_UGT:
- Pred = ICmpInst::ICMP_ULT;
- std::swap(LHS, RHS);
- case ICmpInst::ICMP_ULT: {
- ConstantRange LHSRange = getUnsignedRange(LHS);
- ConstantRange RHSRange = getUnsignedRange(RHS);
- if (LHSRange.getUnsignedMax().ult(RHSRange.getUnsignedMin()))
- return true;
- if (LHSRange.getUnsignedMin().uge(RHSRange.getUnsignedMax()))
- return false;
- break;
- }
- case ICmpInst::ICMP_UGE:
- Pred = ICmpInst::ICMP_ULE;
- std::swap(LHS, RHS);
- case ICmpInst::ICMP_ULE: {
- ConstantRange LHSRange = getUnsignedRange(LHS);
- ConstantRange RHSRange = getUnsignedRange(RHS);
- if (LHSRange.getUnsignedMax().ule(RHSRange.getUnsignedMin()))
- return true;
- if (LHSRange.getUnsignedMin().ugt(RHSRange.getUnsignedMax()))
- return false;
- break;
- }
- case ICmpInst::ICMP_NE: {
- if (getUnsignedRange(LHS).intersectWith(getUnsignedRange(RHS)).isEmptySet())
- return true;
- if (getSignedRange(LHS).intersectWith(getSignedRange(RHS)).isEmptySet())
- return true;
-
- const SCEV *Diff = getMinusSCEV(LHS, RHS);
- if (isKnownNonZero(Diff))
- return true;
- break;
- }
- case ICmpInst::ICMP_EQ:
- // The check at the top of the function catches the case where
- // the values are known to be equal.
- break;
- }
- return false;
-}
-
-/// isLoopBackedgeGuardedByCond - Test whether the backedge of the loop is
-/// protected by a conditional between LHS and RHS. This is used to
-/// to eliminate casts.
-bool
-ScalarEvolution::isLoopBackedgeGuardedByCond(const Loop *L,
- ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS) {
- // Interpret a null as meaning no loop, where there is obviously no guard
- // (interprocedural conditions notwithstanding).
- if (!L) return true;
-
- BasicBlock *Latch = L->getLoopLatch();
- if (!Latch)
- return false;
-
- BranchInst *LoopContinuePredicate =
- dyn_cast<BranchInst>(Latch->getTerminator());
- if (!LoopContinuePredicate ||
- LoopContinuePredicate->isUnconditional())
- return false;
-
- return isImpliedCond(LoopContinuePredicate->getCondition(), Pred, LHS, RHS,
- LoopContinuePredicate->getSuccessor(0) != L->getHeader());
-}
-
-/// isLoopEntryGuardedByCond - Test whether entry to the loop is protected
-/// by a conditional between LHS and RHS. This is used to help avoid max
-/// expressions in loop trip counts, and to eliminate casts.
-bool
-ScalarEvolution::isLoopEntryGuardedByCond(const Loop *L,
- ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS) {
- // Interpret a null as meaning no loop, where there is obviously no guard
- // (interprocedural conditions notwithstanding).
- if (!L) return false;
-
- // Starting at the loop predecessor, climb up the predecessor chain, as long
- // as there are predecessors that can be found that have unique successors
- // leading to the original header.
- for (std::pair<BasicBlock *, BasicBlock *>
- Pair(L->getLoopPredecessor(), L->getHeader());
- Pair.first;
- Pair = getPredecessorWithUniqueSuccessorForBB(Pair.first)) {
-
- BranchInst *LoopEntryPredicate =
- dyn_cast<BranchInst>(Pair.first->getTerminator());
- if (!LoopEntryPredicate ||
- LoopEntryPredicate->isUnconditional())
- continue;
-
- if (isImpliedCond(LoopEntryPredicate->getCondition(), Pred, LHS, RHS,
- LoopEntryPredicate->getSuccessor(0) != Pair.second))
- return true;
- }
-
- return false;
-}
-
-/// isImpliedCond - Test whether the condition described by Pred, LHS,
-/// and RHS is true whenever the given Cond value evaluates to true.
-bool ScalarEvolution::isImpliedCond(Value *CondValue,
- ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS,
- bool Inverse) {
- // Recursively handle And and Or conditions.
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(CondValue)) {
- if (BO->getOpcode() == Instruction::And) {
- if (!Inverse)
- return isImpliedCond(BO->getOperand(0), Pred, LHS, RHS, Inverse) ||
- isImpliedCond(BO->getOperand(1), Pred, LHS, RHS, Inverse);
- } else if (BO->getOpcode() == Instruction::Or) {
- if (Inverse)
- return isImpliedCond(BO->getOperand(0), Pred, LHS, RHS, Inverse) ||
- isImpliedCond(BO->getOperand(1), Pred, LHS, RHS, Inverse);
- }
- }
-
- ICmpInst *ICI = dyn_cast<ICmpInst>(CondValue);
- if (!ICI) return false;
-
- // Bail if the ICmp's operands' types are wider than the needed type
- // before attempting to call getSCEV on them. This avoids infinite
- // recursion, since the analysis of widening casts can require loop
- // exit condition information for overflow checking, which would
- // lead back here.
- if (getTypeSizeInBits(LHS->getType()) <
- getTypeSizeInBits(ICI->getOperand(0)->getType()))
- return false;
-
- // Now that we found a conditional branch that dominates the loop, check to
- // see if it is the comparison we are looking for.
- ICmpInst::Predicate FoundPred;
- if (Inverse)
- FoundPred = ICI->getInversePredicate();
- else
- FoundPred = ICI->getPredicate();
-
- const SCEV *FoundLHS = getSCEV(ICI->getOperand(0));
- const SCEV *FoundRHS = getSCEV(ICI->getOperand(1));
-
- // Balance the types. The case where FoundLHS' type is wider than
- // LHS' type is checked for above.
- if (getTypeSizeInBits(LHS->getType()) >
- getTypeSizeInBits(FoundLHS->getType())) {
- if (CmpInst::isSigned(Pred)) {
- FoundLHS = getSignExtendExpr(FoundLHS, LHS->getType());
- FoundRHS = getSignExtendExpr(FoundRHS, LHS->getType());
- } else {
- FoundLHS = getZeroExtendExpr(FoundLHS, LHS->getType());
- FoundRHS = getZeroExtendExpr(FoundRHS, LHS->getType());
- }
- }
-
- // Canonicalize the query to match the way instcombine will have
- // canonicalized the comparison.
- if (SimplifyICmpOperands(Pred, LHS, RHS))
- if (LHS == RHS)
- return CmpInst::isTrueWhenEqual(Pred);
- if (SimplifyICmpOperands(FoundPred, FoundLHS, FoundRHS))
- if (FoundLHS == FoundRHS)
- return CmpInst::isFalseWhenEqual(Pred);
-
- // Check to see if we can make the LHS or RHS match.
- if (LHS == FoundRHS || RHS == FoundLHS) {
- if (isa<SCEVConstant>(RHS)) {
- std::swap(FoundLHS, FoundRHS);
- FoundPred = ICmpInst::getSwappedPredicate(FoundPred);
- } else {
- std::swap(LHS, RHS);
- Pred = ICmpInst::getSwappedPredicate(Pred);
- }
- }
-
- // Check whether the found predicate is the same as the desired predicate.
- if (FoundPred == Pred)
- return isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS);
-
- // Check whether swapping the found predicate makes it the same as the
- // desired predicate.
- if (ICmpInst::getSwappedPredicate(FoundPred) == Pred) {
- if (isa<SCEVConstant>(RHS))
- return isImpliedCondOperands(Pred, LHS, RHS, FoundRHS, FoundLHS);
- else
- return isImpliedCondOperands(ICmpInst::getSwappedPredicate(Pred),
- RHS, LHS, FoundLHS, FoundRHS);
- }
-
- // Check whether the actual condition is beyond sufficient.
- if (FoundPred == ICmpInst::ICMP_EQ)
- if (ICmpInst::isTrueWhenEqual(Pred))
- if (isImpliedCondOperands(Pred, LHS, RHS, FoundLHS, FoundRHS))
- return true;
- if (Pred == ICmpInst::ICMP_NE)
- if (!ICmpInst::isTrueWhenEqual(FoundPred))
- if (isImpliedCondOperands(FoundPred, LHS, RHS, FoundLHS, FoundRHS))
- return true;
-
- // Otherwise assume the worst.
- return false;
-}
-
-/// isImpliedCondOperands - Test whether the condition described by Pred,
-/// LHS, and RHS is true whenever the condition described by Pred, FoundLHS,
-/// and FoundRHS is true.
-bool ScalarEvolution::isImpliedCondOperands(ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS,
- const SCEV *FoundLHS,
- const SCEV *FoundRHS) {
- return isImpliedCondOperandsHelper(Pred, LHS, RHS,
- FoundLHS, FoundRHS) ||
- // ~x < ~y --> x > y
- isImpliedCondOperandsHelper(Pred, LHS, RHS,
- getNotSCEV(FoundRHS),
- getNotSCEV(FoundLHS));
-}
-
-/// isImpliedCondOperandsHelper - Test whether the condition described by
-/// Pred, LHS, and RHS is true whenever the condition described by Pred,
-/// FoundLHS, and FoundRHS is true.
-bool
-ScalarEvolution::isImpliedCondOperandsHelper(ICmpInst::Predicate Pred,
- const SCEV *LHS, const SCEV *RHS,
- const SCEV *FoundLHS,
- const SCEV *FoundRHS) {
- switch (Pred) {
- default: llvm_unreachable("Unexpected ICmpInst::Predicate value!");
- case ICmpInst::ICMP_EQ:
- case ICmpInst::ICMP_NE:
- if (HasSameValue(LHS, FoundLHS) && HasSameValue(RHS, FoundRHS))
- return true;
- break;
- case ICmpInst::ICMP_SLT:
- case ICmpInst::ICMP_SLE:
- if (isKnownPredicateWithRanges(ICmpInst::ICMP_SLE, LHS, FoundLHS) &&
- isKnownPredicateWithRanges(ICmpInst::ICMP_SGE, RHS, FoundRHS))
- return true;
- break;
- case ICmpInst::ICMP_SGT:
- case ICmpInst::ICMP_SGE:
- if (isKnownPredicateWithRanges(ICmpInst::ICMP_SGE, LHS, FoundLHS) &&
- isKnownPredicateWithRanges(ICmpInst::ICMP_SLE, RHS, FoundRHS))
- return true;
- break;
- case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_ULE:
- if (isKnownPredicateWithRanges(ICmpInst::ICMP_ULE, LHS, FoundLHS) &&
- isKnownPredicateWithRanges(ICmpInst::ICMP_UGE, RHS, FoundRHS))
- return true;
- break;
- case ICmpInst::ICMP_UGT:
- case ICmpInst::ICMP_UGE:
- if (isKnownPredicateWithRanges(ICmpInst::ICMP_UGE, LHS, FoundLHS) &&
- isKnownPredicateWithRanges(ICmpInst::ICMP_ULE, RHS, FoundRHS))
- return true;
- break;
- }
-
- return false;
-}
-
-/// getBECount - Subtract the end and start values and divide by the step,
-/// rounding up, to get the number of times the backedge is executed. Return
-/// CouldNotCompute if an intermediate computation overflows.
-const SCEV *ScalarEvolution::getBECount(const SCEV *Start,
- const SCEV *End,
- const SCEV *Step,
- bool NoWrap) {
- assert(!isKnownNegative(Step) &&
- "This code doesn't handle negative strides yet!");
-
- const Type *Ty = Start->getType();
- const SCEV *NegOne = getConstant(Ty, (uint64_t)-1);
- const SCEV *Diff = getMinusSCEV(End, Start);
- const SCEV *RoundUp = getAddExpr(Step, NegOne);
-
- // Add an adjustment to the difference between End and Start so that
- // the division will effectively round up.
- const SCEV *Add = getAddExpr(Diff, RoundUp);
-
- if (!NoWrap) {
- // Check Add for unsigned overflow.
- // TODO: More sophisticated things could be done here.
- const Type *WideTy = IntegerType::get(getContext(),
- getTypeSizeInBits(Ty) + 1);
- const SCEV *EDiff = getZeroExtendExpr(Diff, WideTy);
- const SCEV *ERoundUp = getZeroExtendExpr(RoundUp, WideTy);
- const SCEV *OperandExtendedAdd = getAddExpr(EDiff, ERoundUp);
- if (getZeroExtendExpr(Add, WideTy) != OperandExtendedAdd)
- return getCouldNotCompute();
- }
-
- return getUDivExpr(Add, Step);
-}
-
-/// HowManyLessThans - Return the number of times a backedge containing the
-/// specified less-than comparison will execute. If not computable, return
-/// CouldNotCompute.
-ScalarEvolution::BackedgeTakenInfo
-ScalarEvolution::HowManyLessThans(const SCEV *LHS, const SCEV *RHS,
- const Loop *L, bool isSigned) {
- // Only handle: "ADDREC < LoopInvariant".
- if (!RHS->isLoopInvariant(L)) return getCouldNotCompute();
-
- const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(LHS);
- if (!AddRec || AddRec->getLoop() != L)
- return getCouldNotCompute();
-
- // Check to see if we have a flag which makes analysis easy.
- bool NoWrap = isSigned ? AddRec->hasNoSignedWrap() :
- AddRec->hasNoUnsignedWrap();
-
- if (AddRec->isAffine()) {
- unsigned BitWidth = getTypeSizeInBits(AddRec->getType());
- const SCEV *Step = AddRec->getStepRecurrence(*this);
-
- if (Step->isZero())
- return getCouldNotCompute();
- if (Step->isOne()) {
- // With unit stride, the iteration never steps past the limit value.
- } else if (isKnownPositive(Step)) {
- // Test whether a positive iteration can step past the limit
- // value and past the maximum value for its type in a single step.
- // Note that it's not sufficient to check NoWrap here, because even
- // though the value after a wrap is undefined, it's not undefined
- // behavior, so if wrap does occur, the loop could either terminate or
- // loop infinitely, but in either case, the loop is guaranteed to
- // iterate at least until the iteration where the wrapping occurs.
- const SCEV *One = getConstant(Step->getType(), 1);
- if (isSigned) {
- APInt Max = APInt::getSignedMaxValue(BitWidth);
- if ((Max - getSignedRange(getMinusSCEV(Step, One)).getSignedMax())
- .slt(getSignedRange(RHS).getSignedMax()))
- return getCouldNotCompute();
- } else {
- APInt Max = APInt::getMaxValue(BitWidth);
- if ((Max - getUnsignedRange(getMinusSCEV(Step, One)).getUnsignedMax())
- .ult(getUnsignedRange(RHS).getUnsignedMax()))
- return getCouldNotCompute();
- }
- } else
- // TODO: Handle negative strides here and below.
- return getCouldNotCompute();
-
- // We know the LHS is of the form {n,+,s} and the RHS is some loop-invariant
- // m. So, we count the number of iterations in which {n,+,s} < m is true.
- // Note that we cannot simply return max(m-n,0)/s because it's not safe to
- // treat m-n as signed nor unsigned due to overflow possibility.
-
- // First, we get the value of the LHS in the first iteration: n
- const SCEV *Start = AddRec->getOperand(0);
-
- // Determine the minimum constant start value.
- const SCEV *MinStart = getConstant(isSigned ?
- getSignedRange(Start).getSignedMin() :
- getUnsignedRange(Start).getUnsignedMin());
-
- // If we know that the condition is true in order to enter the loop,
- // then we know that it will run exactly (m-n)/s times. Otherwise, we
- // only know that it will execute (max(m,n)-n)/s times. In both cases,
- // the division must round up.
- const SCEV *End = RHS;
- if (!isLoopEntryGuardedByCond(L,
- isSigned ? ICmpInst::ICMP_SLT :
- ICmpInst::ICMP_ULT,
- getMinusSCEV(Start, Step), RHS))
- End = isSigned ? getSMaxExpr(RHS, Start)
- : getUMaxExpr(RHS, Start);
-
- // Determine the maximum constant end value.
- const SCEV *MaxEnd = getConstant(isSigned ?
- getSignedRange(End).getSignedMax() :
- getUnsignedRange(End).getUnsignedMax());
-
- // If MaxEnd is within a step of the maximum integer value in its type,
- // adjust it down to the minimum value which would produce the same effect.
- // This allows the subsequent ceiling division of (N+(step-1))/step to
- // compute the correct value.
- const SCEV *StepMinusOne = getMinusSCEV(Step,
- getConstant(Step->getType(), 1));
- MaxEnd = isSigned ?
- getSMinExpr(MaxEnd,
- getMinusSCEV(getConstant(APInt::getSignedMaxValue(BitWidth)),
- StepMinusOne)) :
- getUMinExpr(MaxEnd,
- getMinusSCEV(getConstant(APInt::getMaxValue(BitWidth)),
- StepMinusOne));
-
- // Finally, we subtract these two values and divide, rounding up, to get
- // the number of times the backedge is executed.
- const SCEV *BECount = getBECount(Start, End, Step, NoWrap);
-
- // The maximum backedge count is similar, except using the minimum start
- // value and the maximum end value.
- const SCEV *MaxBECount = getBECount(MinStart, MaxEnd, Step, NoWrap);
-
- return BackedgeTakenInfo(BECount, MaxBECount);
- }
-
- return getCouldNotCompute();
-}
-
-/// getNumIterationsInRange - Return the number of iterations of this loop that
-/// produce values in the specified constant range. Another way of looking at
-/// this is that it returns the first iteration number where the value is not in
-/// the condition, thus computing the exit count. If the iteration count can't
-/// be computed, an instance of SCEVCouldNotCompute is returned.
-const SCEV *SCEVAddRecExpr::getNumIterationsInRange(ConstantRange Range,
- ScalarEvolution &SE) const {
- if (Range.isFullSet()) // Infinite loop.
- return SE.getCouldNotCompute();
-
- // If the start is a non-zero constant, shift the range to simplify things.
- if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(getStart()))
- if (!SC->getValue()->isZero()) {
- SmallVector<const SCEV *, 4> Operands(op_begin(), op_end());
- Operands[0] = SE.getConstant(SC->getType(), 0);
- const SCEV *Shifted = SE.getAddRecExpr(Operands, getLoop());
- if (const SCEVAddRecExpr *ShiftedAddRec =
- dyn_cast<SCEVAddRecExpr>(Shifted))
- return ShiftedAddRec->getNumIterationsInRange(
- Range.subtract(SC->getValue()->getValue()), SE);
- // This is strange and shouldn't happen.
- return SE.getCouldNotCompute();
- }
-
- // The only time we can solve this is when we have all constant indices.
- // Otherwise, we cannot determine the overflow conditions.
- for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
- if (!isa<SCEVConstant>(getOperand(i)))
- return SE.getCouldNotCompute();
-
-
- // Okay at this point we know that all elements of the chrec are constants and
- // that the start element is zero.
-
- // First check to see if the range contains zero. If not, the first
- // iteration exits.
- unsigned BitWidth = SE.getTypeSizeInBits(getType());
- if (!Range.contains(APInt(BitWidth, 0)))
- return SE.getConstant(getType(), 0);
-
- if (isAffine()) {
- // If this is an affine expression then we have this situation:
- // Solve {0,+,A} in Range === Ax in Range
-
- // We know that zero is in the range. If A is positive then we know that
- // the upper value of the range must be the first possible exit value.
- // If A is negative then the lower of the range is the last possible loop
- // value. Also note that we already checked for a full range.
- APInt One(BitWidth,1);
- APInt A = cast<SCEVConstant>(getOperand(1))->getValue()->getValue();
- APInt End = A.sge(One) ? (Range.getUpper() - One) : Range.getLower();
-
- // The exit value should be (End+A)/A.
- APInt ExitVal = (End + A).udiv(A);
- ConstantInt *ExitValue = ConstantInt::get(SE.getContext(), ExitVal);
-
- // Evaluate at the exit value. If we really did fall out of the valid
- // range, then we computed our trip count, otherwise wrap around or other
- // things must have happened.
- ConstantInt *Val = EvaluateConstantChrecAtConstant(this, ExitValue, SE);
- if (Range.contains(Val->getValue()))
- return SE.getCouldNotCompute(); // Something strange happened
-
- // Ensure that the previous value is in the range. This is a sanity check.
- assert(Range.contains(
- EvaluateConstantChrecAtConstant(this,
- ConstantInt::get(SE.getContext(), ExitVal - One), SE)->getValue()) &&
- "Linear scev computation is off in a bad way!");
- return SE.getConstant(ExitValue);
- } else if (isQuadratic()) {
- // If this is a quadratic (3-term) AddRec {L,+,M,+,N}, find the roots of the
- // quadratic equation to solve it. To do this, we must frame our problem in
- // terms of figuring out when zero is crossed, instead of when
- // Range.getUpper() is crossed.
- SmallVector<const SCEV *, 4> NewOps(op_begin(), op_end());
- NewOps[0] = SE.getNegativeSCEV(SE.getConstant(Range.getUpper()));
- const SCEV *NewAddRec = SE.getAddRecExpr(NewOps, getLoop());
-
- // Next, solve the constructed addrec
- std::pair<const SCEV *,const SCEV *> Roots =
- SolveQuadraticEquation(cast<SCEVAddRecExpr>(NewAddRec), SE);
- const SCEVConstant *R1 = dyn_cast<SCEVConstant>(Roots.first);
- const SCEVConstant *R2 = dyn_cast<SCEVConstant>(Roots.second);
- if (R1) {
- // Pick the smallest positive root value.
- if (ConstantInt *CB =
- dyn_cast<ConstantInt>(ConstantExpr::getICmp(ICmpInst::ICMP_ULT,
- R1->getValue(), R2->getValue()))) {
- if (CB->getZExtValue() == false)
- std::swap(R1, R2); // R1 is the minimum root now.
-
- // Make sure the root is not off by one. The returned iteration should
- // not be in the range, but the previous one should be. When solving
- // for "X*X < 5", for example, we should not return a root of 2.
- ConstantInt *R1Val = EvaluateConstantChrecAtConstant(this,
- R1->getValue(),
- SE);
- if (Range.contains(R1Val->getValue())) {
- // The next iteration must be out of the range...
- ConstantInt *NextVal =
- ConstantInt::get(SE.getContext(), R1->getValue()->getValue()+1);
-
- R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
- if (!Range.contains(R1Val->getValue()))
- return SE.getConstant(NextVal);
- return SE.getCouldNotCompute(); // Something strange happened
- }
-
- // If R1 was not in the range, then it is a good return value. Make
- // sure that R1-1 WAS in the range though, just in case.
- ConstantInt *NextVal =
- ConstantInt::get(SE.getContext(), R1->getValue()->getValue()-1);
- R1Val = EvaluateConstantChrecAtConstant(this, NextVal, SE);
- if (Range.contains(R1Val->getValue()))
- return R1;
- return SE.getCouldNotCompute(); // Something strange happened
- }
- }
- }
-
- return SE.getCouldNotCompute();
-}
-
-
-
-//===----------------------------------------------------------------------===//
-// SCEVCallbackVH Class Implementation
-//===----------------------------------------------------------------------===//
-
-void ScalarEvolution::SCEVCallbackVH::deleted() {
- assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!");
- if (PHINode *PN = dyn_cast<PHINode>(getValPtr()))
- SE->ConstantEvolutionLoopExitValue.erase(PN);
- SE->Scalars.erase(getValPtr());
- // this now dangles!
-}
-
-void ScalarEvolution::SCEVCallbackVH::allUsesReplacedWith(Value *) {
- assert(SE && "SCEVCallbackVH called with a null ScalarEvolution!");
-
- // Forget all the expressions associated with users of the old value,
- // so that future queries will recompute the expressions using the new
- // value.
- SmallVector<User *, 16> Worklist;
- SmallPtrSet<User *, 8> Visited;
- Value *Old = getValPtr();
- for (Value::use_iterator UI = Old->use_begin(), UE = Old->use_end();
- UI != UE; ++UI)
- Worklist.push_back(*UI);
- while (!Worklist.empty()) {
- User *U = Worklist.pop_back_val();
- // Deleting the Old value will cause this to dangle. Postpone
- // that until everything else is done.
- if (U == Old)
- continue;
- if (!Visited.insert(U))
- continue;
- if (PHINode *PN = dyn_cast<PHINode>(U))
- SE->ConstantEvolutionLoopExitValue.erase(PN);
- SE->Scalars.erase(U);
- for (Value::use_iterator UI = U->use_begin(), UE = U->use_end();
- UI != UE; ++UI)
- Worklist.push_back(*UI);
- }
- // Delete the Old value.
- if (PHINode *PN = dyn_cast<PHINode>(Old))
- SE->ConstantEvolutionLoopExitValue.erase(PN);
- SE->Scalars.erase(Old);
- // this now dangles!
-}
-
-ScalarEvolution::SCEVCallbackVH::SCEVCallbackVH(Value *V, ScalarEvolution *se)
- : CallbackVH(V), SE(se) {}
-
-//===----------------------------------------------------------------------===//
-// ScalarEvolution Class Implementation
-//===----------------------------------------------------------------------===//
-
-ScalarEvolution::ScalarEvolution()
- : FunctionPass(&ID) {
-}
-
-bool ScalarEvolution::runOnFunction(Function &F) {
- this->F = &F;
- LI = &getAnalysis<LoopInfo>();
- TD = getAnalysisIfAvailable<TargetData>();
- DT = &getAnalysis<DominatorTree>();
- return false;
-}
-
-void ScalarEvolution::releaseMemory() {
- Scalars.clear();
- BackedgeTakenCounts.clear();
- ConstantEvolutionLoopExitValue.clear();
- ValuesAtScopes.clear();
- UniqueSCEVs.clear();
- SCEVAllocator.Reset();
-}
-
-void ScalarEvolution::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesAll();
- AU.addRequiredTransitive<LoopInfo>();
- AU.addRequiredTransitive<DominatorTree>();
-}
-
-bool ScalarEvolution::hasLoopInvariantBackedgeTakenCount(const Loop *L) {
- return !isa<SCEVCouldNotCompute>(getBackedgeTakenCount(L));
-}
-
-static void PrintLoopInfo(raw_ostream &OS, ScalarEvolution *SE,
- const Loop *L) {
- // Print all inner loops first
- for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
- PrintLoopInfo(OS, SE, *I);
-
- OS << "Loop ";
- WriteAsOperand(OS, L->getHeader(), /*PrintType=*/false);
- OS << ": ";
-
- SmallVector<BasicBlock *, 8> ExitBlocks;
- L->getExitBlocks(ExitBlocks);
- if (ExitBlocks.size() != 1)
- OS << "<multiple exits> ";
-
- if (SE->hasLoopInvariantBackedgeTakenCount(L)) {
- OS << "backedge-taken count is " << *SE->getBackedgeTakenCount(L);
- } else {
- OS << "Unpredictable backedge-taken count. ";
- }
-
- OS << "\n"
- "Loop ";
- WriteAsOperand(OS, L->getHeader(), /*PrintType=*/false);
- OS << ": ";
-
- if (!isa<SCEVCouldNotCompute>(SE->getMaxBackedgeTakenCount(L))) {
- OS << "max backedge-taken count is " << *SE->getMaxBackedgeTakenCount(L);
- } else {
- OS << "Unpredictable max backedge-taken count. ";
- }
-
- OS << "\n";
-}
-
-void ScalarEvolution::print(raw_ostream &OS, const Module *) const {
- // ScalarEvolution's implementation of the print method is to print
- // out SCEV values of all instructions that are interesting. Doing
- // this potentially causes it to create new SCEV objects though,
- // which technically conflicts with the const qualifier. This isn't
- // observable from outside the class though, so casting away the
- // const isn't dangerous.
- ScalarEvolution &SE = *const_cast<ScalarEvolution *>(this);
-
- OS << "Classifying expressions for: ";
- WriteAsOperand(OS, F, /*PrintType=*/false);
- OS << "\n";
- for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I)
- if (isSCEVable(I->getType()) && !isa<CmpInst>(*I)) {
- OS << *I << '\n';
- OS << " --> ";
- const SCEV *SV = SE.getSCEV(&*I);
- SV->print(OS);
-
- const Loop *L = LI->getLoopFor((*I).getParent());
-
- const SCEV *AtUse = SE.getSCEVAtScope(SV, L);
- if (AtUse != SV) {
- OS << " --> ";
- AtUse->print(OS);
- }
-
- if (L) {
- OS << "\t\t" "Exits: ";
- const SCEV *ExitValue = SE.getSCEVAtScope(SV, L->getParentLoop());
- if (!ExitValue->isLoopInvariant(L)) {
- OS << "<<Unknown>>";
- } else {
- OS << *ExitValue;
- }
- }
-
- OS << "\n";
- }
-
- OS << "Determining loop execution counts for: ";
- WriteAsOperand(OS, F, /*PrintType=*/false);
- OS << "\n";
- for (LoopInfo::iterator I = LI->begin(), E = LI->end(); I != E; ++I)
- PrintLoopInfo(OS, &SE, *I);
-}
-
Removed: llvm/branches/Apple/williamson/lib/Transforms/Scalar/GVN.cpp.orig
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/Apple/williamson/lib/Transforms/Scalar/GVN.cpp.orig?rev=109615&view=auto
==============================================================================
--- llvm/branches/Apple/williamson/lib/Transforms/Scalar/GVN.cpp.orig (original)
+++ llvm/branches/Apple/williamson/lib/Transforms/Scalar/GVN.cpp.orig (removed)
@@ -1,2316 +0,0 @@
-//===- GVN.cpp - Eliminate redundant values and loads ---------------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This pass performs global value numbering to eliminate fully redundant
-// instructions. It also performs simple dead load elimination.
-//
-// Note that this pass does the value numbering itself; it does not use the
-// ValueNumbering analysis passes.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "gvn"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/GlobalVariable.h"
-#include "llvm/Function.h"
-#include "llvm/IntrinsicInst.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Operator.h"
-#include "llvm/Value.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/PostOrderIterator.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/Loads.h"
-#include "llvm/Analysis/MemoryBuiltins.h"
-#include "llvm/Analysis/MemoryDependenceAnalysis.h"
-#include "llvm/Analysis/PHITransAddr.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/IRBuilder.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Target/TargetData.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/Transforms/Utils/SSAUpdater.h"
-using namespace llvm;
-
-STATISTIC(NumGVNInstr, "Number of instructions deleted");
-STATISTIC(NumGVNLoad, "Number of loads deleted");
-STATISTIC(NumGVNPRE, "Number of instructions PRE'd");
-STATISTIC(NumGVNBlocks, "Number of blocks merged");
-STATISTIC(NumPRELoad, "Number of loads PRE'd");
-
-static cl::opt<bool> EnablePRE("enable-pre",
- cl::init(true), cl::Hidden);
-static cl::opt<bool> EnableLoadPRE("enable-load-pre", cl::init(true));
-static cl::opt<bool> EnableFullLoadPRE("enable-full-load-pre", cl::init(false));
-
-//===----------------------------------------------------------------------===//
-// ValueTable Class
-//===----------------------------------------------------------------------===//
-
-/// This class holds the mapping between values and value numbers. It is used
-/// as an efficient mechanism to determine the expression-wise equivalence of
-/// two values.
-namespace {
- struct Expression {
- enum ExpressionOpcode {
- ADD = Instruction::Add,
- FADD = Instruction::FAdd,
- SUB = Instruction::Sub,
- FSUB = Instruction::FSub,
- MUL = Instruction::Mul,
- FMUL = Instruction::FMul,
- UDIV = Instruction::UDiv,
- SDIV = Instruction::SDiv,
- FDIV = Instruction::FDiv,
- UREM = Instruction::URem,
- SREM = Instruction::SRem,
- FREM = Instruction::FRem,
- SHL = Instruction::Shl,
- LSHR = Instruction::LShr,
- ASHR = Instruction::AShr,
- AND = Instruction::And,
- OR = Instruction::Or,
- XOR = Instruction::Xor,
- TRUNC = Instruction::Trunc,
- ZEXT = Instruction::ZExt,
- SEXT = Instruction::SExt,
- FPTOUI = Instruction::FPToUI,
- FPTOSI = Instruction::FPToSI,
- UITOFP = Instruction::UIToFP,
- SITOFP = Instruction::SIToFP,
- FPTRUNC = Instruction::FPTrunc,
- FPEXT = Instruction::FPExt,
- PTRTOINT = Instruction::PtrToInt,
- INTTOPTR = Instruction::IntToPtr,
- BITCAST = Instruction::BitCast,
- ICMPEQ, ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
- ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
- FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
- FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
- FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
- SHUFFLE, SELECT, GEP, CALL, CONSTANT,
- INSERTVALUE, EXTRACTVALUE, EMPTY, TOMBSTONE };
-
- ExpressionOpcode opcode;
- const Type* type;
- SmallVector<uint32_t, 4> varargs;
- Value *function;
-
- Expression() { }
- Expression(ExpressionOpcode o) : opcode(o) { }
-
- bool operator==(const Expression &other) const {
- if (opcode != other.opcode)
- return false;
- else if (opcode == EMPTY || opcode == TOMBSTONE)
- return true;
- else if (type != other.type)
- return false;
- else if (function != other.function)
- return false;
- else {
- if (varargs.size() != other.varargs.size())
- return false;
-
- for (size_t i = 0; i < varargs.size(); ++i)
- if (varargs[i] != other.varargs[i])
- return false;
-
- return true;
- }
- }
-
- bool operator!=(const Expression &other) const {
- return !(*this == other);
- }
- };
-
- class ValueTable {
- private:
- DenseMap<Value*, uint32_t> valueNumbering;
- DenseMap<Expression, uint32_t> expressionNumbering;
- AliasAnalysis* AA;
- MemoryDependenceAnalysis* MD;
- DominatorTree* DT;
-
- uint32_t nextValueNumber;
-
- Expression::ExpressionOpcode getOpcode(CmpInst* C);
- Expression create_expression(BinaryOperator* BO);
- Expression create_expression(CmpInst* C);
- Expression create_expression(ShuffleVectorInst* V);
- Expression create_expression(ExtractElementInst* C);
- Expression create_expression(InsertElementInst* V);
- Expression create_expression(SelectInst* V);
- Expression create_expression(CastInst* C);
- Expression create_expression(GetElementPtrInst* G);
- Expression create_expression(CallInst* C);
- Expression create_expression(Constant* C);
- Expression create_expression(ExtractValueInst* C);
- Expression create_expression(InsertValueInst* C);
-
- uint32_t lookup_or_add_call(CallInst* C);
- public:
- ValueTable() : nextValueNumber(1) { }
- uint32_t lookup_or_add(Value *V);
- uint32_t lookup(Value *V) const;
- void add(Value *V, uint32_t num);
- void clear();
- void erase(Value *v);
- unsigned size();
- void setAliasAnalysis(AliasAnalysis* A) { AA = A; }
- AliasAnalysis *getAliasAnalysis() const { return AA; }
- void setMemDep(MemoryDependenceAnalysis* M) { MD = M; }
- void setDomTree(DominatorTree* D) { DT = D; }
- uint32_t getNextUnusedValueNumber() { return nextValueNumber; }
- void verifyRemoved(const Value *) const;
- };
-}
-
-namespace llvm {
-template <> struct DenseMapInfo<Expression> {
- static inline Expression getEmptyKey() {
- return Expression(Expression::EMPTY);
- }
-
- static inline Expression getTombstoneKey() {
- return Expression(Expression::TOMBSTONE);
- }
-
- static unsigned getHashValue(const Expression e) {
- unsigned hash = e.opcode;
-
- hash = ((unsigned)((uintptr_t)e.type >> 4) ^
- (unsigned)((uintptr_t)e.type >> 9));
-
- for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
- E = e.varargs.end(); I != E; ++I)
- hash = *I + hash * 37;
-
- hash = ((unsigned)((uintptr_t)e.function >> 4) ^
- (unsigned)((uintptr_t)e.function >> 9)) +
- hash * 37;
-
- return hash;
- }
- static bool isEqual(const Expression &LHS, const Expression &RHS) {
- return LHS == RHS;
- }
-};
-
-template <>
-struct isPodLike<Expression> { static const bool value = true; };
-
-}
-
-//===----------------------------------------------------------------------===//
-// ValueTable Internal Functions
-//===----------------------------------------------------------------------===//
-
-Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
- if (isa<ICmpInst>(C)) {
- switch (C->getPredicate()) {
- default: // THIS SHOULD NEVER HAPPEN
- llvm_unreachable("Comparison with unknown predicate?");
- case ICmpInst::ICMP_EQ: return Expression::ICMPEQ;
- case ICmpInst::ICMP_NE: return Expression::ICMPNE;
- case ICmpInst::ICMP_UGT: return Expression::ICMPUGT;
- case ICmpInst::ICMP_UGE: return Expression::ICMPUGE;
- case ICmpInst::ICMP_ULT: return Expression::ICMPULT;
- case ICmpInst::ICMP_ULE: return Expression::ICMPULE;
- case ICmpInst::ICMP_SGT: return Expression::ICMPSGT;
- case ICmpInst::ICMP_SGE: return Expression::ICMPSGE;
- case ICmpInst::ICMP_SLT: return Expression::ICMPSLT;
- case ICmpInst::ICMP_SLE: return Expression::ICMPSLE;
- }
- } else {
- switch (C->getPredicate()) {
- default: // THIS SHOULD NEVER HAPPEN
- llvm_unreachable("Comparison with unknown predicate?");
- case FCmpInst::FCMP_OEQ: return Expression::FCMPOEQ;
- case FCmpInst::FCMP_OGT: return Expression::FCMPOGT;
- case FCmpInst::FCMP_OGE: return Expression::FCMPOGE;
- case FCmpInst::FCMP_OLT: return Expression::FCMPOLT;
- case FCmpInst::FCMP_OLE: return Expression::FCMPOLE;
- case FCmpInst::FCMP_ONE: return Expression::FCMPONE;
- case FCmpInst::FCMP_ORD: return Expression::FCMPORD;
- case FCmpInst::FCMP_UNO: return Expression::FCMPUNO;
- case FCmpInst::FCMP_UEQ: return Expression::FCMPUEQ;
- case FCmpInst::FCMP_UGT: return Expression::FCMPUGT;
- case FCmpInst::FCMP_UGE: return Expression::FCMPUGE;
- case FCmpInst::FCMP_ULT: return Expression::FCMPULT;
- case FCmpInst::FCMP_ULE: return Expression::FCMPULE;
- case FCmpInst::FCMP_UNE: return Expression::FCMPUNE;
- }
- }
-}
-
-Expression ValueTable::create_expression(CallInst* C) {
- Expression e;
-
- e.type = C->getType();
- e.function = C->getCalledFunction();
- e.opcode = Expression::CALL;
-
- CallSite CS(C);
- for (CallInst::op_iterator I = CS.arg_begin(), E = CS.arg_end();
- I != E; ++I)
- e.varargs.push_back(lookup_or_add(*I));
-
- return e;
-}
-
-Expression ValueTable::create_expression(BinaryOperator* BO) {
- Expression e;
- e.varargs.push_back(lookup_or_add(BO->getOperand(0)));
- e.varargs.push_back(lookup_or_add(BO->getOperand(1)));
- e.function = 0;
- e.type = BO->getType();
- e.opcode = static_cast<Expression::ExpressionOpcode>(BO->getOpcode());
-
- return e;
-}
-
-Expression ValueTable::create_expression(CmpInst* C) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(C->getOperand(0)));
- e.varargs.push_back(lookup_or_add(C->getOperand(1)));
- e.function = 0;
- e.type = C->getType();
- e.opcode = getOpcode(C);
-
- return e;
-}
-
-Expression ValueTable::create_expression(CastInst* C) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(C->getOperand(0)));
- e.function = 0;
- e.type = C->getType();
- e.opcode = static_cast<Expression::ExpressionOpcode>(C->getOpcode());
-
- return e;
-}
-
-Expression ValueTable::create_expression(ShuffleVectorInst* S) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(S->getOperand(0)));
- e.varargs.push_back(lookup_or_add(S->getOperand(1)));
- e.varargs.push_back(lookup_or_add(S->getOperand(2)));
- e.function = 0;
- e.type = S->getType();
- e.opcode = Expression::SHUFFLE;
-
- return e;
-}
-
-Expression ValueTable::create_expression(ExtractElementInst* E) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(E->getOperand(0)));
- e.varargs.push_back(lookup_or_add(E->getOperand(1)));
- e.function = 0;
- e.type = E->getType();
- e.opcode = Expression::EXTRACT;
-
- return e;
-}
-
-Expression ValueTable::create_expression(InsertElementInst* I) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(I->getOperand(0)));
- e.varargs.push_back(lookup_or_add(I->getOperand(1)));
- e.varargs.push_back(lookup_or_add(I->getOperand(2)));
- e.function = 0;
- e.type = I->getType();
- e.opcode = Expression::INSERT;
-
- return e;
-}
-
-Expression ValueTable::create_expression(SelectInst* I) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(I->getCondition()));
- e.varargs.push_back(lookup_or_add(I->getTrueValue()));
- e.varargs.push_back(lookup_or_add(I->getFalseValue()));
- e.function = 0;
- e.type = I->getType();
- e.opcode = Expression::SELECT;
-
- return e;
-}
-
-Expression ValueTable::create_expression(GetElementPtrInst* G) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(G->getPointerOperand()));
- e.function = 0;
- e.type = G->getType();
- e.opcode = Expression::GEP;
-
- for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
- I != E; ++I)
- e.varargs.push_back(lookup_or_add(*I));
-
- return e;
-}
-
-Expression ValueTable::create_expression(ExtractValueInst* E) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
- for (ExtractValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
- II != IE; ++II)
- e.varargs.push_back(*II);
- e.function = 0;
- e.type = E->getType();
- e.opcode = Expression::EXTRACTVALUE;
-
- return e;
-}
-
-Expression ValueTable::create_expression(InsertValueInst* E) {
- Expression e;
-
- e.varargs.push_back(lookup_or_add(E->getAggregateOperand()));
- e.varargs.push_back(lookup_or_add(E->getInsertedValueOperand()));
- for (InsertValueInst::idx_iterator II = E->idx_begin(), IE = E->idx_end();
- II != IE; ++II)
- e.varargs.push_back(*II);
- e.function = 0;
- e.type = E->getType();
- e.opcode = Expression::INSERTVALUE;
-
- return e;
-}
-
-//===----------------------------------------------------------------------===//
-// ValueTable External Functions
-//===----------------------------------------------------------------------===//
-
-/// add - Insert a value into the table with a specified value number.
-void ValueTable::add(Value *V, uint32_t num) {
- valueNumbering.insert(std::make_pair(V, num));
-}
-
-uint32_t ValueTable::lookup_or_add_call(CallInst* C) {
- if (AA->doesNotAccessMemory(C)) {
- Expression exp = create_expression(C);
- uint32_t& e = expressionNumbering[exp];
- if (!e) e = nextValueNumber++;
- valueNumbering[C] = e;
- return e;
- } else if (AA->onlyReadsMemory(C)) {
- Expression exp = create_expression(C);
- uint32_t& e = expressionNumbering[exp];
- if (!e) {
- e = nextValueNumber++;
- valueNumbering[C] = e;
- return e;
- }
- if (!MD) {
- e = nextValueNumber++;
- valueNumbering[C] = e;
- return e;
- }
-
- MemDepResult local_dep = MD->getDependency(C);
-
- if (!local_dep.isDef() && !local_dep.isNonLocal()) {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
-
- if (local_dep.isDef()) {
- CallInst* local_cdep = cast<CallInst>(local_dep.getInst());
-
- if (local_cdep->getNumArgOperands() != C->getNumArgOperands()) {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
-
- for (unsigned i = 0, e = C->getNumArgOperands(); i < e; ++i) {
- uint32_t c_vn = lookup_or_add(C->getArgOperand(i));
- uint32_t cd_vn = lookup_or_add(local_cdep->getArgOperand(i));
- if (c_vn != cd_vn) {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
- }
-
- uint32_t v = lookup_or_add(local_cdep);
- valueNumbering[C] = v;
- return v;
- }
-
- // Non-local case.
- const MemoryDependenceAnalysis::NonLocalDepInfo &deps =
- MD->getNonLocalCallDependency(CallSite(C));
- // FIXME: call/call dependencies for readonly calls should return def, not
- // clobber! Move the checking logic to MemDep!
- CallInst* cdep = 0;
-
- // Check to see if we have a single dominating call instruction that is
- // identical to C.
- for (unsigned i = 0, e = deps.size(); i != e; ++i) {
- const NonLocalDepEntry *I = &deps[i];
- // Ignore non-local dependencies.
- if (I->getResult().isNonLocal())
- continue;
-
- // We don't handle non-depedencies. If we already have a call, reject
- // instruction dependencies.
- if (I->getResult().isClobber() || cdep != 0) {
- cdep = 0;
- break;
- }
-
- CallInst *NonLocalDepCall = dyn_cast<CallInst>(I->getResult().getInst());
- // FIXME: All duplicated with non-local case.
- if (NonLocalDepCall && DT->properlyDominates(I->getBB(), C->getParent())){
- cdep = NonLocalDepCall;
- continue;
- }
-
- cdep = 0;
- break;
- }
-
- if (!cdep) {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
-
- if (cdep->getNumArgOperands() != C->getNumArgOperands()) {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
- for (unsigned i = 0, e = C->getNumArgOperands(); i < e; ++i) {
- uint32_t c_vn = lookup_or_add(C->getArgOperand(i));
- uint32_t cd_vn = lookup_or_add(cdep->getArgOperand(i));
- if (c_vn != cd_vn) {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
- }
-
- uint32_t v = lookup_or_add(cdep);
- valueNumbering[C] = v;
- return v;
-
- } else {
- valueNumbering[C] = nextValueNumber;
- return nextValueNumber++;
- }
-}
-
-/// lookup_or_add - Returns the value number for the specified value, assigning
-/// it a new number if it did not have one before.
-uint32_t ValueTable::lookup_or_add(Value *V) {
- DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
- if (VI != valueNumbering.end())
- return VI->second;
-
- if (!isa<Instruction>(V)) {
- valueNumbering[V] = nextValueNumber;
- return nextValueNumber++;
- }
-
- Instruction* I = cast<Instruction>(V);
- Expression exp;
- switch (I->getOpcode()) {
- case Instruction::Call:
- return lookup_or_add_call(cast<CallInst>(I));
- case Instruction::Add:
- case Instruction::FAdd:
- case Instruction::Sub:
- case Instruction::FSub:
- case Instruction::Mul:
- case Instruction::FMul:
- case Instruction::UDiv:
- case Instruction::SDiv:
- case Instruction::FDiv:
- case Instruction::URem:
- case Instruction::SRem:
- case Instruction::FRem:
- case Instruction::Shl:
- case Instruction::LShr:
- case Instruction::AShr:
- case Instruction::And:
- case Instruction::Or :
- case Instruction::Xor:
- exp = create_expression(cast<BinaryOperator>(I));
- break;
- case Instruction::ICmp:
- case Instruction::FCmp:
- exp = create_expression(cast<CmpInst>(I));
- break;
- case Instruction::Trunc:
- case Instruction::ZExt:
- case Instruction::SExt:
- case Instruction::FPToUI:
- case Instruction::FPToSI:
- case Instruction::UIToFP:
- case Instruction::SIToFP:
- case Instruction::FPTrunc:
- case Instruction::FPExt:
- case Instruction::PtrToInt:
- case Instruction::IntToPtr:
- case Instruction::BitCast:
- exp = create_expression(cast<CastInst>(I));
- break;
- case Instruction::Select:
- exp = create_expression(cast<SelectInst>(I));
- break;
- case Instruction::ExtractElement:
- exp = create_expression(cast<ExtractElementInst>(I));
- break;
- case Instruction::InsertElement:
- exp = create_expression(cast<InsertElementInst>(I));
- break;
- case Instruction::ShuffleVector:
- exp = create_expression(cast<ShuffleVectorInst>(I));
- break;
- case Instruction::ExtractValue:
- exp = create_expression(cast<ExtractValueInst>(I));
- break;
- case Instruction::InsertValue:
- exp = create_expression(cast<InsertValueInst>(I));
- break;
- case Instruction::GetElementPtr:
- exp = create_expression(cast<GetElementPtrInst>(I));
- break;
- default:
- valueNumbering[V] = nextValueNumber;
- return nextValueNumber++;
- }
-
- uint32_t& e = expressionNumbering[exp];
- if (!e) e = nextValueNumber++;
- valueNumbering[V] = e;
- return e;
-}
-
-/// lookup - Returns the value number of the specified value. Fails if
-/// the value has not yet been numbered.
-uint32_t ValueTable::lookup(Value *V) const {
- DenseMap<Value*, uint32_t>::const_iterator VI = valueNumbering.find(V);
- assert(VI != valueNumbering.end() && "Value not numbered?");
- return VI->second;
-}
-
-/// clear - Remove all entries from the ValueTable
-void ValueTable::clear() {
- valueNumbering.clear();
- expressionNumbering.clear();
- nextValueNumber = 1;
-}
-
-/// erase - Remove a value from the value numbering
-void ValueTable::erase(Value *V) {
- valueNumbering.erase(V);
-}
-
-/// verifyRemoved - Verify that the value is removed from all internal data
-/// structures.
-void ValueTable::verifyRemoved(const Value *V) const {
- for (DenseMap<Value*, uint32_t>::const_iterator
- I = valueNumbering.begin(), E = valueNumbering.end(); I != E; ++I) {
- assert(I->first != V && "Inst still occurs in value numbering map!");
- }
-}
-
-//===----------------------------------------------------------------------===//
-// GVN Pass
-//===----------------------------------------------------------------------===//
-
-namespace {
- struct ValueNumberScope {
- ValueNumberScope* parent;
- DenseMap<uint32_t, Value*> table;
-
- ValueNumberScope(ValueNumberScope* p) : parent(p) { }
- };
-}
-
-namespace {
-
- class GVN : public FunctionPass {
- bool runOnFunction(Function &F);
- public:
- static char ID; // Pass identification, replacement for typeid
- explicit GVN(bool noloads = false)
- : FunctionPass(&ID), NoLoads(noloads), MD(0) { }
-
- private:
- bool NoLoads;
- MemoryDependenceAnalysis *MD;
- DominatorTree *DT;
-
- ValueTable VN;
- DenseMap<BasicBlock*, ValueNumberScope*> localAvail;
-
- // List of critical edges to be split between iterations.
- SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
-
- // This transformation requires dominator postdominator info
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequired<DominatorTree>();
- if (!NoLoads)
- AU.addRequired<MemoryDependenceAnalysis>();
- AU.addRequired<AliasAnalysis>();
-
- AU.addPreserved<DominatorTree>();
- AU.addPreserved<AliasAnalysis>();
- }
-
- // Helper fuctions
- // FIXME: eliminate or document these better
- bool processLoad(LoadInst* L,
- SmallVectorImpl<Instruction*> &toErase);
- bool processInstruction(Instruction *I,
- SmallVectorImpl<Instruction*> &toErase);
- bool processNonLocalLoad(LoadInst* L,
- SmallVectorImpl<Instruction*> &toErase);
- bool processBlock(BasicBlock *BB);
- void dump(DenseMap<uint32_t, Value*>& d);
- bool iterateOnFunction(Function &F);
- Value *CollapsePhi(PHINode* p);
- bool performPRE(Function& F);
- Value *lookupNumber(BasicBlock *BB, uint32_t num);
- void cleanupGlobalSets();
- void verifyRemoved(const Instruction *I) const;
- bool splitCriticalEdges();
- };
-
- char GVN::ID = 0;
-}
-
-// createGVNPass - The public interface to this file...
-FunctionPass *llvm::createGVNPass(bool NoLoads) {
- return new GVN(NoLoads);
-}
-
-static RegisterPass<GVN> X("gvn",
- "Global Value Numbering");
-
-void GVN::dump(DenseMap<uint32_t, Value*>& d) {
- errs() << "{\n";
- for (DenseMap<uint32_t, Value*>::iterator I = d.begin(),
- E = d.end(); I != E; ++I) {
- errs() << I->first << "\n";
- I->second->dump();
- }
- errs() << "}\n";
-}
-
-static bool isSafeReplacement(PHINode* p, Instruction *inst) {
- if (!isa<PHINode>(inst))
- return true;
-
- for (Instruction::use_iterator UI = p->use_begin(), E = p->use_end();
- UI != E; ++UI)
- if (PHINode* use_phi = dyn_cast<PHINode>(UI))
- if (use_phi->getParent() == inst->getParent())
- return false;
-
- return true;
-}
-
-Value *GVN::CollapsePhi(PHINode *PN) {
- Value *ConstVal = PN->hasConstantValue(DT);
- if (!ConstVal) return 0;
-
- Instruction *Inst = dyn_cast<Instruction>(ConstVal);
- if (!Inst)
- return ConstVal;
-
- if (DT->dominates(Inst, PN))
- if (isSafeReplacement(PN, Inst))
- return Inst;
- return 0;
-}
-
-/// IsValueFullyAvailableInBlock - Return true if we can prove that the value
-/// we're analyzing is fully available in the specified block. As we go, keep
-/// track of which blocks we know are fully alive in FullyAvailableBlocks. This
-/// map is actually a tri-state map with the following values:
-/// 0) we know the block *is not* fully available.
-/// 1) we know the block *is* fully available.
-/// 2) we do not know whether the block is fully available or not, but we are
-/// currently speculating that it will be.
-/// 3) we are speculating for this block and have used that to speculate for
-/// other blocks.
-static bool IsValueFullyAvailableInBlock(BasicBlock *BB,
- DenseMap<BasicBlock*, char> &FullyAvailableBlocks) {
- // Optimistically assume that the block is fully available and check to see
- // if we already know about this block in one lookup.
- std::pair<DenseMap<BasicBlock*, char>::iterator, char> IV =
- FullyAvailableBlocks.insert(std::make_pair(BB, 2));
-
- // If the entry already existed for this block, return the precomputed value.
- if (!IV.second) {
- // If this is a speculative "available" value, mark it as being used for
- // speculation of other blocks.
- if (IV.first->second == 2)
- IV.first->second = 3;
- return IV.first->second != 0;
- }
-
- // Otherwise, see if it is fully available in all predecessors.
- pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
-
- // If this block has no predecessors, it isn't live-in here.
- if (PI == PE)
- goto SpeculationFailure;
-
- for (; PI != PE; ++PI)
- // If the value isn't fully available in one of our predecessors, then it
- // isn't fully available in this block either. Undo our previous
- // optimistic assumption and bail out.
- if (!IsValueFullyAvailableInBlock(*PI, FullyAvailableBlocks))
- goto SpeculationFailure;
-
- return true;
-
-// SpeculationFailure - If we get here, we found out that this is not, after
-// all, a fully-available block. We have a problem if we speculated on this and
-// used the speculation to mark other blocks as available.
-SpeculationFailure:
- char &BBVal = FullyAvailableBlocks[BB];
-
- // If we didn't speculate on this, just return with it set to false.
- if (BBVal == 2) {
- BBVal = 0;
- return false;
- }
-
- // If we did speculate on this value, we could have blocks set to 1 that are
- // incorrect. Walk the (transitive) successors of this block and mark them as
- // 0 if set to one.
- SmallVector<BasicBlock*, 32> BBWorklist;
- BBWorklist.push_back(BB);
-
- do {
- BasicBlock *Entry = BBWorklist.pop_back_val();
- // Note that this sets blocks to 0 (unavailable) if they happen to not
- // already be in FullyAvailableBlocks. This is safe.
- char &EntryVal = FullyAvailableBlocks[Entry];
- if (EntryVal == 0) continue; // Already unavailable.
-
- // Mark as unavailable.
- EntryVal = 0;
-
- for (succ_iterator I = succ_begin(Entry), E = succ_end(Entry); I != E; ++I)
- BBWorklist.push_back(*I);
- } while (!BBWorklist.empty());
-
- return false;
-}
-
-
-/// CanCoerceMustAliasedValueToLoad - Return true if
-/// CoerceAvailableValueToLoadType will succeed.
-static bool CanCoerceMustAliasedValueToLoad(Value *StoredVal,
- const Type *LoadTy,
- const TargetData &TD) {
- // If the loaded or stored value is an first class array or struct, don't try
- // to transform them. We need to be able to bitcast to integer.
- if (LoadTy->isStructTy() || LoadTy->isArrayTy() ||
- StoredVal->getType()->isStructTy() ||
- StoredVal->getType()->isArrayTy())
- return false;
-
- // The store has to be at least as big as the load.
- if (TD.getTypeSizeInBits(StoredVal->getType()) <
- TD.getTypeSizeInBits(LoadTy))
- return false;
-
- return true;
-}
-
-
-/// CoerceAvailableValueToLoadType - If we saw a store of a value to memory, and
-/// then a load from a must-aliased pointer of a different type, try to coerce
-/// the stored value. LoadedTy is the type of the load we want to replace and
-/// InsertPt is the place to insert new instructions.
-///
-/// If we can't do it, return null.
-static Value *CoerceAvailableValueToLoadType(Value *StoredVal,
- const Type *LoadedTy,
- Instruction *InsertPt,
- const TargetData &TD) {
- if (!CanCoerceMustAliasedValueToLoad(StoredVal, LoadedTy, TD))
- return 0;
-
- const Type *StoredValTy = StoredVal->getType();
-
- uint64_t StoreSize = TD.getTypeStoreSizeInBits(StoredValTy);
- uint64_t LoadSize = TD.getTypeSizeInBits(LoadedTy);
-
- // If the store and reload are the same size, we can always reuse it.
- if (StoreSize == LoadSize) {
- if (StoredValTy->isPointerTy() && LoadedTy->isPointerTy()) {
- // Pointer to Pointer -> use bitcast.
- return new BitCastInst(StoredVal, LoadedTy, "", InsertPt);
- }
-
- // Convert source pointers to integers, which can be bitcast.
- if (StoredValTy->isPointerTy()) {
- StoredValTy = TD.getIntPtrType(StoredValTy->getContext());
- StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
- }
-
- const Type *TypeToCastTo = LoadedTy;
- if (TypeToCastTo->isPointerTy())
- TypeToCastTo = TD.getIntPtrType(StoredValTy->getContext());
-
- if (StoredValTy != TypeToCastTo)
- StoredVal = new BitCastInst(StoredVal, TypeToCastTo, "", InsertPt);
-
- // Cast to pointer if the load needs a pointer type.
- if (LoadedTy->isPointerTy())
- StoredVal = new IntToPtrInst(StoredVal, LoadedTy, "", InsertPt);
-
- return StoredVal;
- }
-
- // If the loaded value is smaller than the available value, then we can
- // extract out a piece from it. If the available value is too small, then we
- // can't do anything.
- assert(StoreSize >= LoadSize && "CanCoerceMustAliasedValueToLoad fail");
-
- // Convert source pointers to integers, which can be manipulated.
- if (StoredValTy->isPointerTy()) {
- StoredValTy = TD.getIntPtrType(StoredValTy->getContext());
- StoredVal = new PtrToIntInst(StoredVal, StoredValTy, "", InsertPt);
- }
-
- // Convert vectors and fp to integer, which can be manipulated.
- if (!StoredValTy->isIntegerTy()) {
- StoredValTy = IntegerType::get(StoredValTy->getContext(), StoreSize);
- StoredVal = new BitCastInst(StoredVal, StoredValTy, "", InsertPt);
- }
-
- // If this is a big-endian system, we need to shift the value down to the low
- // bits so that a truncate will work.
- if (TD.isBigEndian()) {
- Constant *Val = ConstantInt::get(StoredVal->getType(), StoreSize-LoadSize);
- StoredVal = BinaryOperator::CreateLShr(StoredVal, Val, "tmp", InsertPt);
- }
-
- // Truncate the integer to the right size now.
- const Type *NewIntTy = IntegerType::get(StoredValTy->getContext(), LoadSize);
- StoredVal = new TruncInst(StoredVal, NewIntTy, "trunc", InsertPt);
-
- if (LoadedTy == NewIntTy)
- return StoredVal;
-
- // If the result is a pointer, inttoptr.
- if (LoadedTy->isPointerTy())
- return new IntToPtrInst(StoredVal, LoadedTy, "inttoptr", InsertPt);
-
- // Otherwise, bitcast.
- return new BitCastInst(StoredVal, LoadedTy, "bitcast", InsertPt);
-}
-
-/// GetBaseWithConstantOffset - Analyze the specified pointer to see if it can
-/// be expressed as a base pointer plus a constant offset. Return the base and
-/// offset to the caller.
-static Value *GetBaseWithConstantOffset(Value *Ptr, int64_t &Offset,
- const TargetData &TD) {
- Operator *PtrOp = dyn_cast<Operator>(Ptr);
- if (PtrOp == 0) return Ptr;
-
- // Just look through bitcasts.
- if (PtrOp->getOpcode() == Instruction::BitCast)
- return GetBaseWithConstantOffset(PtrOp->getOperand(0), Offset, TD);
-
- // If this is a GEP with constant indices, we can look through it.
- GEPOperator *GEP = dyn_cast<GEPOperator>(PtrOp);
- if (GEP == 0 || !GEP->hasAllConstantIndices()) return Ptr;
-
- gep_type_iterator GTI = gep_type_begin(GEP);
- for (User::op_iterator I = GEP->idx_begin(), E = GEP->idx_end(); I != E;
- ++I, ++GTI) {
- ConstantInt *OpC = cast<ConstantInt>(*I);
- if (OpC->isZero()) continue;
-
- // Handle a struct and array indices which add their offset to the pointer.
- if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
- Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
- } else {
- uint64_t Size = TD.getTypeAllocSize(GTI.getIndexedType());
- Offset += OpC->getSExtValue()*Size;
- }
- }
-
- // Re-sign extend from the pointer size if needed to get overflow edge cases
- // right.
- unsigned PtrSize = TD.getPointerSizeInBits();
- if (PtrSize < 64)
- Offset = (Offset << (64-PtrSize)) >> (64-PtrSize);
-
- return GetBaseWithConstantOffset(GEP->getPointerOperand(), Offset, TD);
-}
-
-
-/// AnalyzeLoadFromClobberingWrite - This function is called when we have a
-/// memdep query of a load that ends up being a clobbering memory write (store,
-/// memset, memcpy, memmove). This means that the write *may* provide bits used
-/// by the load but we can't be sure because the pointers don't mustalias.
-///
-/// Check this case to see if there is anything more we can do before we give
-/// up. This returns -1 if we have to give up, or a byte number in the stored
-/// value of the piece that feeds the load.
-static int AnalyzeLoadFromClobberingWrite(const Type *LoadTy, Value *LoadPtr,
- Value *WritePtr,
- uint64_t WriteSizeInBits,
- const TargetData &TD) {
- // If the loaded or stored value is an first class array or struct, don't try
- // to transform them. We need to be able to bitcast to integer.
- if (LoadTy->isStructTy() || LoadTy->isArrayTy())
- return -1;
-
- int64_t StoreOffset = 0, LoadOffset = 0;
- Value *StoreBase = GetBaseWithConstantOffset(WritePtr, StoreOffset, TD);
- Value *LoadBase =
- GetBaseWithConstantOffset(LoadPtr, LoadOffset, TD);
- if (StoreBase != LoadBase)
- return -1;
-
- // If the load and store are to the exact same address, they should have been
- // a must alias. AA must have gotten confused.
- // FIXME: Study to see if/when this happens. One case is forwarding a memset
- // to a load from the base of the memset.
-#if 0
- if (LoadOffset == StoreOffset) {
- dbgs() << "STORE/LOAD DEP WITH COMMON POINTER MISSED:\n"
- << "Base = " << *StoreBase << "\n"
- << "Store Ptr = " << *WritePtr << "\n"
- << "Store Offs = " << StoreOffset << "\n"
- << "Load Ptr = " << *LoadPtr << "\n";
- abort();
- }
-#endif
-
- // If the load and store don't overlap at all, the store doesn't provide
- // anything to the load. In this case, they really don't alias at all, AA
- // must have gotten confused.
- // FIXME: Investigate cases where this bails out, e.g. rdar://7238614. Then
- // remove this check, as it is duplicated with what we have below.
- uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy);
-
- if ((WriteSizeInBits & 7) | (LoadSize & 7))
- return -1;
- uint64_t StoreSize = WriteSizeInBits >> 3; // Convert to bytes.
- LoadSize >>= 3;
-
-
- bool isAAFailure = false;
- if (StoreOffset < LoadOffset)
- isAAFailure = StoreOffset+int64_t(StoreSize) <= LoadOffset;
- else
- isAAFailure = LoadOffset+int64_t(LoadSize) <= StoreOffset;
-
- if (isAAFailure) {
-#if 0
- dbgs() << "STORE LOAD DEP WITH COMMON BASE:\n"
- << "Base = " << *StoreBase << "\n"
- << "Store Ptr = " << *WritePtr << "\n"
- << "Store Offs = " << StoreOffset << "\n"
- << "Load Ptr = " << *LoadPtr << "\n";
- abort();
-#endif
- return -1;
- }
-
- // If the Load isn't completely contained within the stored bits, we don't
- // have all the bits to feed it. We could do something crazy in the future
- // (issue a smaller load then merge the bits in) but this seems unlikely to be
- // valuable.
- if (StoreOffset > LoadOffset ||
- StoreOffset+StoreSize < LoadOffset+LoadSize)
- return -1;
-
- // Okay, we can do this transformation. Return the number of bytes into the
- // store that the load is.
- return LoadOffset-StoreOffset;
-}
-
-/// AnalyzeLoadFromClobberingStore - This function is called when we have a
-/// memdep query of a load that ends up being a clobbering store.
-static int AnalyzeLoadFromClobberingStore(const Type *LoadTy, Value *LoadPtr,
- StoreInst *DepSI,
- const TargetData &TD) {
- // Cannot handle reading from store of first-class aggregate yet.
- if (DepSI->getOperand(0)->getType()->isStructTy() ||
- DepSI->getOperand(0)->getType()->isArrayTy())
- return -1;
-
- Value *StorePtr = DepSI->getPointerOperand();
- uint64_t StoreSize = TD.getTypeSizeInBits(DepSI->getOperand(0)->getType());
- return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr,
- StorePtr, StoreSize, TD);
-}
-
-static int AnalyzeLoadFromClobberingMemInst(const Type *LoadTy, Value *LoadPtr,
- MemIntrinsic *MI,
- const TargetData &TD) {
- // If the mem operation is a non-constant size, we can't handle it.
- ConstantInt *SizeCst = dyn_cast<ConstantInt>(MI->getLength());
- if (SizeCst == 0) return -1;
- uint64_t MemSizeInBits = SizeCst->getZExtValue()*8;
-
- // If this is memset, we just need to see if the offset is valid in the size
- // of the memset..
- if (MI->getIntrinsicID() == Intrinsic::memset)
- return AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr, MI->getDest(),
- MemSizeInBits, TD);
-
- // If we have a memcpy/memmove, the only case we can handle is if this is a
- // copy from constant memory. In that case, we can read directly from the
- // constant memory.
- MemTransferInst *MTI = cast<MemTransferInst>(MI);
-
- Constant *Src = dyn_cast<Constant>(MTI->getSource());
- if (Src == 0) return -1;
-
- GlobalVariable *GV = dyn_cast<GlobalVariable>(Src->getUnderlyingObject());
- if (GV == 0 || !GV->isConstant()) return -1;
-
- // See if the access is within the bounds of the transfer.
- int Offset = AnalyzeLoadFromClobberingWrite(LoadTy, LoadPtr,
- MI->getDest(), MemSizeInBits, TD);
- if (Offset == -1)
- return Offset;
-
- // Otherwise, see if we can constant fold a load from the constant with the
- // offset applied as appropriate.
- Src = ConstantExpr::getBitCast(Src,
- llvm::Type::getInt8PtrTy(Src->getContext()));
- Constant *OffsetCst =
- ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
- Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
- Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
- if (ConstantFoldLoadFromConstPtr(Src, &TD))
- return Offset;
- return -1;
-}
-
-
-/// GetStoreValueForLoad - This function is called when we have a
-/// memdep query of a load that ends up being a clobbering store. This means
-/// that the store *may* provide bits used by the load but we can't be sure
-/// because the pointers don't mustalias. Check this case to see if there is
-/// anything more we can do before we give up.
-static Value *GetStoreValueForLoad(Value *SrcVal, unsigned Offset,
- const Type *LoadTy,
- Instruction *InsertPt, const TargetData &TD){
- LLVMContext &Ctx = SrcVal->getType()->getContext();
-
- uint64_t StoreSize = (TD.getTypeSizeInBits(SrcVal->getType()) + 7) / 8;
- uint64_t LoadSize = (TD.getTypeSizeInBits(LoadTy) + 7) / 8;
-
- IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
-
- // Compute which bits of the stored value are being used by the load. Convert
- // to an integer type to start with.
- if (SrcVal->getType()->isPointerTy())
- SrcVal = Builder.CreatePtrToInt(SrcVal, TD.getIntPtrType(Ctx), "tmp");
- if (!SrcVal->getType()->isIntegerTy())
- SrcVal = Builder.CreateBitCast(SrcVal, IntegerType::get(Ctx, StoreSize*8),
- "tmp");
-
- // Shift the bits to the least significant depending on endianness.
- unsigned ShiftAmt;
- if (TD.isLittleEndian())
- ShiftAmt = Offset*8;
- else
- ShiftAmt = (StoreSize-LoadSize-Offset)*8;
-
- if (ShiftAmt)
- SrcVal = Builder.CreateLShr(SrcVal, ShiftAmt, "tmp");
-
- if (LoadSize != StoreSize)
- SrcVal = Builder.CreateTrunc(SrcVal, IntegerType::get(Ctx, LoadSize*8),
- "tmp");
-
- return CoerceAvailableValueToLoadType(SrcVal, LoadTy, InsertPt, TD);
-}
-
-/// GetMemInstValueForLoad - This function is called when we have a
-/// memdep query of a load that ends up being a clobbering mem intrinsic.
-static Value *GetMemInstValueForLoad(MemIntrinsic *SrcInst, unsigned Offset,
- const Type *LoadTy, Instruction *InsertPt,
- const TargetData &TD){
- LLVMContext &Ctx = LoadTy->getContext();
- uint64_t LoadSize = TD.getTypeSizeInBits(LoadTy)/8;
-
- IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
-
- // We know that this method is only called when the mem transfer fully
- // provides the bits for the load.
- if (MemSetInst *MSI = dyn_cast<MemSetInst>(SrcInst)) {
- // memset(P, 'x', 1234) -> splat('x'), even if x is a variable, and
- // independently of what the offset is.
- Value *Val = MSI->getValue();
- if (LoadSize != 1)
- Val = Builder.CreateZExt(Val, IntegerType::get(Ctx, LoadSize*8));
-
- Value *OneElt = Val;
-
- // Splat the value out to the right number of bits.
- for (unsigned NumBytesSet = 1; NumBytesSet != LoadSize; ) {
- // If we can double the number of bytes set, do it.
- if (NumBytesSet*2 <= LoadSize) {
- Value *ShVal = Builder.CreateShl(Val, NumBytesSet*8);
- Val = Builder.CreateOr(Val, ShVal);
- NumBytesSet <<= 1;
- continue;
- }
-
- // Otherwise insert one byte at a time.
- Value *ShVal = Builder.CreateShl(Val, 1*8);
- Val = Builder.CreateOr(OneElt, ShVal);
- ++NumBytesSet;
- }
-
- return CoerceAvailableValueToLoadType(Val, LoadTy, InsertPt, TD);
- }
-
- // Otherwise, this is a memcpy/memmove from a constant global.
- MemTransferInst *MTI = cast<MemTransferInst>(SrcInst);
- Constant *Src = cast<Constant>(MTI->getSource());
-
- // Otherwise, see if we can constant fold a load from the constant with the
- // offset applied as appropriate.
- Src = ConstantExpr::getBitCast(Src,
- llvm::Type::getInt8PtrTy(Src->getContext()));
- Constant *OffsetCst =
- ConstantInt::get(Type::getInt64Ty(Src->getContext()), (unsigned)Offset);
- Src = ConstantExpr::getGetElementPtr(Src, &OffsetCst, 1);
- Src = ConstantExpr::getBitCast(Src, PointerType::getUnqual(LoadTy));
- return ConstantFoldLoadFromConstPtr(Src, &TD);
-}
-
-namespace {
-
-struct AvailableValueInBlock {
- /// BB - The basic block in question.
- BasicBlock *BB;
- enum ValType {
- SimpleVal, // A simple offsetted value that is accessed.
- MemIntrin // A memory intrinsic which is loaded from.
- };
-
- /// V - The value that is live out of the block.
- PointerIntPair<Value *, 1, ValType> Val;
-
- /// Offset - The byte offset in Val that is interesting for the load query.
- unsigned Offset;
-
- static AvailableValueInBlock get(BasicBlock *BB, Value *V,
- unsigned Offset = 0) {
- AvailableValueInBlock Res;
- Res.BB = BB;
- Res.Val.setPointer(V);
- Res.Val.setInt(SimpleVal);
- Res.Offset = Offset;
- return Res;
- }
-
- static AvailableValueInBlock getMI(BasicBlock *BB, MemIntrinsic *MI,
- unsigned Offset = 0) {
- AvailableValueInBlock Res;
- Res.BB = BB;
- Res.Val.setPointer(MI);
- Res.Val.setInt(MemIntrin);
- Res.Offset = Offset;
- return Res;
- }
-
- bool isSimpleValue() const { return Val.getInt() == SimpleVal; }
- Value *getSimpleValue() const {
- assert(isSimpleValue() && "Wrong accessor");
- return Val.getPointer();
- }
-
- MemIntrinsic *getMemIntrinValue() const {
- assert(!isSimpleValue() && "Wrong accessor");
- return cast<MemIntrinsic>(Val.getPointer());
- }
-
- /// MaterializeAdjustedValue - Emit code into this block to adjust the value
- /// defined here to the specified type. This handles various coercion cases.
- Value *MaterializeAdjustedValue(const Type *LoadTy,
- const TargetData *TD) const {
- Value *Res;
- if (isSimpleValue()) {
- Res = getSimpleValue();
- if (Res->getType() != LoadTy) {
- assert(TD && "Need target data to handle type mismatch case");
- Res = GetStoreValueForLoad(Res, Offset, LoadTy, BB->getTerminator(),
- *TD);
-
- DEBUG(errs() << "GVN COERCED NONLOCAL VAL:\nOffset: " << Offset << " "
- << *getSimpleValue() << '\n'
- << *Res << '\n' << "\n\n\n");
- }
- } else {
- Res = GetMemInstValueForLoad(getMemIntrinValue(), Offset,
- LoadTy, BB->getTerminator(), *TD);
- DEBUG(errs() << "GVN COERCED NONLOCAL MEM INTRIN:\nOffset: " << Offset
- << " " << *getMemIntrinValue() << '\n'
- << *Res << '\n' << "\n\n\n");
- }
- return Res;
- }
-};
-
-}
-
-/// ConstructSSAForLoadSet - Given a set of loads specified by ValuesPerBlock,
-/// construct SSA form, allowing us to eliminate LI. This returns the value
-/// that should be used at LI's definition site.
-static Value *ConstructSSAForLoadSet(LoadInst *LI,
- SmallVectorImpl<AvailableValueInBlock> &ValuesPerBlock,
- const TargetData *TD,
- const DominatorTree &DT,
- AliasAnalysis *AA) {
- // Check for the fully redundant, dominating load case. In this case, we can
- // just use the dominating value directly.
- if (ValuesPerBlock.size() == 1 &&
- DT.properlyDominates(ValuesPerBlock[0].BB, LI->getParent()))
- return ValuesPerBlock[0].MaterializeAdjustedValue(LI->getType(), TD);
-
- // Otherwise, we have to construct SSA form.
- SmallVector<PHINode*, 8> NewPHIs;
- SSAUpdater SSAUpdate(&NewPHIs);
- SSAUpdate.Initialize(LI);
-
- const Type *LoadTy = LI->getType();
-
- for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
- const AvailableValueInBlock &AV = ValuesPerBlock[i];
- BasicBlock *BB = AV.BB;
-
- if (SSAUpdate.HasValueForBlock(BB))
- continue;
-
- SSAUpdate.AddAvailableValue(BB, AV.MaterializeAdjustedValue(LoadTy, TD));
- }
-
- // Perform PHI construction.
- Value *V = SSAUpdate.GetValueInMiddleOfBlock(LI->getParent());
-
- // If new PHI nodes were created, notify alias analysis.
- if (V->getType()->isPointerTy())
- for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i)
- AA->copyValue(LI, NewPHIs[i]);
-
- return V;
-}
-
-static bool isLifetimeStart(const Instruction *Inst) {
- if (const IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst))
- return II->getIntrinsicID() == Intrinsic::lifetime_start;
- return false;
-}
-
-/// processNonLocalLoad - Attempt to eliminate a load whose dependencies are
-/// non-local by performing PHI construction.
-bool GVN::processNonLocalLoad(LoadInst *LI,
- SmallVectorImpl<Instruction*> &toErase) {
- // Find the non-local dependencies of the load.
- SmallVector<NonLocalDepResult, 64> Deps;
- MD->getNonLocalPointerDependency(LI->getOperand(0), true, LI->getParent(),
- Deps);
- //DEBUG(dbgs() << "INVESTIGATING NONLOCAL LOAD: "
- // << Deps.size() << *LI << '\n');
-
- // If we had to process more than one hundred blocks to find the
- // dependencies, this load isn't worth worrying about. Optimizing
- // it will be too expensive.
- if (Deps.size() > 100)
- return false;
-
- // If we had a phi translation failure, we'll have a single entry which is a
- // clobber in the current block. Reject this early.
- if (Deps.size() == 1 && Deps[0].getResult().isClobber()) {
- DEBUG(
- dbgs() << "GVN: non-local load ";
- WriteAsOperand(dbgs(), LI);
- dbgs() << " is clobbered by " << *Deps[0].getResult().getInst() << '\n';
- );
- return false;
- }
-
- // Filter out useless results (non-locals, etc). Keep track of the blocks
- // where we have a value available in repl, also keep track of whether we see
- // dependencies that produce an unknown value for the load (such as a call
- // that could potentially clobber the load).
- SmallVector<AvailableValueInBlock, 16> ValuesPerBlock;
- SmallVector<BasicBlock*, 16> UnavailableBlocks;
-
- const TargetData *TD = 0;
-
- for (unsigned i = 0, e = Deps.size(); i != e; ++i) {
- BasicBlock *DepBB = Deps[i].getBB();
- MemDepResult DepInfo = Deps[i].getResult();
-
- if (DepInfo.isClobber()) {
- // The address being loaded in this non-local block may not be the same as
- // the pointer operand of the load if PHI translation occurs. Make sure
- // to consider the right address.
- Value *Address = Deps[i].getAddress();
-
- // If the dependence is to a store that writes to a superset of the bits
- // read by the load, we can extract the bits we need for the load from the
- // stored value.
- if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInfo.getInst())) {
- if (TD == 0)
- TD = getAnalysisIfAvailable<TargetData>();
- if (TD && Address) {
- int Offset = AnalyzeLoadFromClobberingStore(LI->getType(), Address,
- DepSI, *TD);
- if (Offset != -1) {
- ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
- DepSI->getOperand(0),
- Offset));
- continue;
- }
- }
- }
-
- // If the clobbering value is a memset/memcpy/memmove, see if we can
- // forward a value on from it.
- if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(DepInfo.getInst())) {
- if (TD == 0)
- TD = getAnalysisIfAvailable<TargetData>();
- if (TD && Address) {
- int Offset = AnalyzeLoadFromClobberingMemInst(LI->getType(), Address,
- DepMI, *TD);
- if (Offset != -1) {
- ValuesPerBlock.push_back(AvailableValueInBlock::getMI(DepBB, DepMI,
- Offset));
- continue;
- }
- }
- }
-
- UnavailableBlocks.push_back(DepBB);
- continue;
- }
-
- Instruction *DepInst = DepInfo.getInst();
-
- // Loading the allocation -> undef.
- if (isa<AllocaInst>(DepInst) || isMalloc(DepInst) ||
- // Loading immediately after lifetime begin -> undef.
- isLifetimeStart(DepInst)) {
- ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
- UndefValue::get(LI->getType())));
- continue;
- }
-
- if (StoreInst *S = dyn_cast<StoreInst>(DepInst)) {
- // Reject loads and stores that are to the same address but are of
- // different types if we have to.
- if (S->getOperand(0)->getType() != LI->getType()) {
- if (TD == 0)
- TD = getAnalysisIfAvailable<TargetData>();
-
- // If the stored value is larger or equal to the loaded value, we can
- // reuse it.
- if (TD == 0 || !CanCoerceMustAliasedValueToLoad(S->getOperand(0),
- LI->getType(), *TD)) {
- UnavailableBlocks.push_back(DepBB);
- continue;
- }
- }
-
- ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB,
- S->getOperand(0)));
- continue;
- }
-
- if (LoadInst *LD = dyn_cast<LoadInst>(DepInst)) {
- // If the types mismatch and we can't handle it, reject reuse of the load.
- if (LD->getType() != LI->getType()) {
- if (TD == 0)
- TD = getAnalysisIfAvailable<TargetData>();
-
- // If the stored value is larger or equal to the loaded value, we can
- // reuse it.
- if (TD == 0 || !CanCoerceMustAliasedValueToLoad(LD, LI->getType(),*TD)){
- UnavailableBlocks.push_back(DepBB);
- continue;
- }
- }
- ValuesPerBlock.push_back(AvailableValueInBlock::get(DepBB, LD));
- continue;
- }
-
- UnavailableBlocks.push_back(DepBB);
- continue;
- }
-
- // If we have no predecessors that produce a known value for this load, exit
- // early.
- if (ValuesPerBlock.empty()) return false;
-
- // If all of the instructions we depend on produce a known value for this
- // load, then it is fully redundant and we can use PHI insertion to compute
- // its value. Insert PHIs and remove the fully redundant value now.
- if (UnavailableBlocks.empty()) {
- DEBUG(dbgs() << "GVN REMOVING NONLOCAL LOAD: " << *LI << '\n');
-
- // Perform PHI construction.
- Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT,
- VN.getAliasAnalysis());
- LI->replaceAllUsesWith(V);
-
- if (isa<PHINode>(V))
- V->takeName(LI);
- if (V->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(V);
- VN.erase(LI);
- toErase.push_back(LI);
- ++NumGVNLoad;
- return true;
- }
-
- if (!EnablePRE || !EnableLoadPRE)
- return false;
-
- // Okay, we have *some* definitions of the value. This means that the value
- // is available in some of our (transitive) predecessors. Lets think about
- // doing PRE of this load. This will involve inserting a new load into the
- // predecessor when it's not available. We could do this in general, but
- // prefer to not increase code size. As such, we only do this when we know
- // that we only have to insert *one* load (which means we're basically moving
- // the load, not inserting a new one).
-
- SmallPtrSet<BasicBlock *, 4> Blockers;
- for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
- Blockers.insert(UnavailableBlocks[i]);
-
- // Lets find first basic block with more than one predecessor. Walk backwards
- // through predecessors if needed.
- BasicBlock *LoadBB = LI->getParent();
- BasicBlock *TmpBB = LoadBB;
-
- bool isSinglePred = false;
- bool allSingleSucc = true;
- while (TmpBB->getSinglePredecessor()) {
- isSinglePred = true;
- TmpBB = TmpBB->getSinglePredecessor();
- if (TmpBB == LoadBB) // Infinite (unreachable) loop.
- return false;
- if (Blockers.count(TmpBB))
- return false;
- if (TmpBB->getTerminator()->getNumSuccessors() != 1)
- allSingleSucc = false;
- }
-
- assert(TmpBB);
- LoadBB = TmpBB;
-
- // If we have a repl set with LI itself in it, this means we have a loop where
- // at least one of the values is LI. Since this means that we won't be able
- // to eliminate LI even if we insert uses in the other predecessors, we will
- // end up increasing code size. Reject this by scanning for LI.
- for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
- if (ValuesPerBlock[i].isSimpleValue() &&
- ValuesPerBlock[i].getSimpleValue() == LI) {
- // Skip cases where LI is the only definition, even for EnableFullLoadPRE.
- if (!EnableFullLoadPRE || e == 1)
- return false;
- }
- }
-
- // FIXME: It is extremely unclear what this loop is doing, other than
- // artificially restricting loadpre.
- if (isSinglePred) {
- bool isHot = false;
- for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i) {
- const AvailableValueInBlock &AV = ValuesPerBlock[i];
- if (AV.isSimpleValue())
- // "Hot" Instruction is in some loop (because it dominates its dep.
- // instruction).
- if (Instruction *I = dyn_cast<Instruction>(AV.getSimpleValue()))
- if (DT->dominates(LI, I)) {
- isHot = true;
- break;
- }
- }
-
- // We are interested only in "hot" instructions. We don't want to do any
- // mis-optimizations here.
- if (!isHot)
- return false;
- }
-
- // Check to see how many predecessors have the loaded value fully
- // available.
- DenseMap<BasicBlock*, Value*> PredLoads;
- DenseMap<BasicBlock*, char> FullyAvailableBlocks;
- for (unsigned i = 0, e = ValuesPerBlock.size(); i != e; ++i)
- FullyAvailableBlocks[ValuesPerBlock[i].BB] = true;
- for (unsigned i = 0, e = UnavailableBlocks.size(); i != e; ++i)
- FullyAvailableBlocks[UnavailableBlocks[i]] = false;
-
- SmallVector<std::pair<TerminatorInst*, unsigned>, 4> NeedToSplit;
- for (pred_iterator PI = pred_begin(LoadBB), E = pred_end(LoadBB);
- PI != E; ++PI) {
- BasicBlock *Pred = *PI;
- if (IsValueFullyAvailableInBlock(Pred, FullyAvailableBlocks)) {
- continue;
- }
- PredLoads[Pred] = 0;
-
- if (Pred->getTerminator()->getNumSuccessors() != 1) {
- if (isa<IndirectBrInst>(Pred->getTerminator())) {
- DEBUG(dbgs() << "COULD NOT PRE LOAD BECAUSE OF INDBR CRITICAL EDGE '"
- << Pred->getName() << "': " << *LI << '\n');
- return false;
- }
- unsigned SuccNum = GetSuccessorNumber(Pred, LoadBB);
- NeedToSplit.push_back(std::make_pair(Pred->getTerminator(), SuccNum));
- }
- }
- if (!NeedToSplit.empty()) {
- toSplit.append(NeedToSplit.begin(), NeedToSplit.end());
- return false;
- }
-
- // Decide whether PRE is profitable for this load.
- unsigned NumUnavailablePreds = PredLoads.size();
- assert(NumUnavailablePreds != 0 &&
- "Fully available value should be eliminated above!");
- if (!EnableFullLoadPRE) {
- // If this load is unavailable in multiple predecessors, reject it.
- // FIXME: If we could restructure the CFG, we could make a common pred with
- // all the preds that don't have an available LI and insert a new load into
- // that one block.
- if (NumUnavailablePreds != 1)
- return false;
- }
-
- // Check if the load can safely be moved to all the unavailable predecessors.
- bool CanDoPRE = true;
- SmallVector<Instruction*, 8> NewInsts;
- for (DenseMap<BasicBlock*, Value*>::iterator I = PredLoads.begin(),
- E = PredLoads.end(); I != E; ++I) {
- BasicBlock *UnavailablePred = I->first;
-
- // Do PHI translation to get its value in the predecessor if necessary. The
- // returned pointer (if non-null) is guaranteed to dominate UnavailablePred.
-
- // If all preds have a single successor, then we know it is safe to insert
- // the load on the pred (?!?), so we can insert code to materialize the
- // pointer if it is not available.
- PHITransAddr Address(LI->getOperand(0), TD);
- Value *LoadPtr = 0;
- if (allSingleSucc) {
- LoadPtr = Address.PHITranslateWithInsertion(LoadBB, UnavailablePred,
- *DT, NewInsts);
- } else {
- Address.PHITranslateValue(LoadBB, UnavailablePred, DT);
- LoadPtr = Address.getAddr();
- }
-
- // If we couldn't find or insert a computation of this phi translated value,
- // we fail PRE.
- if (LoadPtr == 0) {
- DEBUG(dbgs() << "COULDN'T INSERT PHI TRANSLATED VALUE OF: "
- << *LI->getOperand(0) << "\n");
- CanDoPRE = false;
- break;
- }
-
- // Make sure it is valid to move this load here. We have to watch out for:
- // @1 = getelementptr (i8* p, ...
- // test p and branch if == 0
- // load @1
- // It is valid to have the getelementptr before the test, even if p can be 0,
- // as getelementptr only does address arithmetic.
- // If we are not pushing the value through any multiple-successor blocks
- // we do not have this case. Otherwise, check that the load is safe to
- // put anywhere; this can be improved, but should be conservatively safe.
- if (!allSingleSucc &&
- // FIXME: REEVALUTE THIS.
- !isSafeToLoadUnconditionally(LoadPtr,
- UnavailablePred->getTerminator(),
- LI->getAlignment(), TD)) {
- CanDoPRE = false;
- break;
- }
-
- I->second = LoadPtr;
- }
-
- if (!CanDoPRE) {
- while (!NewInsts.empty())
- NewInsts.pop_back_val()->eraseFromParent();
- return false;
- }
-
- // Okay, we can eliminate this load by inserting a reload in the predecessor
- // and using PHI construction to get the value in the other predecessors, do
- // it.
- DEBUG(dbgs() << "GVN REMOVING PRE LOAD: " << *LI << '\n');
- DEBUG(if (!NewInsts.empty())
- dbgs() << "INSERTED " << NewInsts.size() << " INSTS: "
- << *NewInsts.back() << '\n');
-
- // Assign value numbers to the new instructions.
- for (unsigned i = 0, e = NewInsts.size(); i != e; ++i) {
- // FIXME: We really _ought_ to insert these value numbers into their
- // parent's availability map. However, in doing so, we risk getting into
- // ordering issues. If a block hasn't been processed yet, we would be
- // marking a value as AVAIL-IN, which isn't what we intend.
- VN.lookup_or_add(NewInsts[i]);
- }
-
- for (DenseMap<BasicBlock*, Value*>::iterator I = PredLoads.begin(),
- E = PredLoads.end(); I != E; ++I) {
- BasicBlock *UnavailablePred = I->first;
- Value *LoadPtr = I->second;
-
- Value *NewLoad = new LoadInst(LoadPtr, LI->getName()+".pre", false,
- LI->getAlignment(),
- UnavailablePred->getTerminator());
-
- // Add the newly created load.
- ValuesPerBlock.push_back(AvailableValueInBlock::get(UnavailablePred,
- NewLoad));
- MD->invalidateCachedPointerInfo(LoadPtr);
- DEBUG(dbgs() << "GVN INSERTED " << *NewLoad << '\n');
- }
-
- // Perform PHI construction.
- Value *V = ConstructSSAForLoadSet(LI, ValuesPerBlock, TD, *DT,
- VN.getAliasAnalysis());
- LI->replaceAllUsesWith(V);
- if (isa<PHINode>(V))
- V->takeName(LI);
- if (V->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(V);
- VN.erase(LI);
- toErase.push_back(LI);
- ++NumPRELoad;
- return true;
-}
-
-/// processLoad - Attempt to eliminate a load, first by eliminating it
-/// locally, and then attempting non-local elimination if that fails.
-bool GVN::processLoad(LoadInst *L, SmallVectorImpl<Instruction*> &toErase) {
- if (!MD)
- return false;
-
- if (L->isVolatile())
- return false;
-
- // ... to a pointer that has been loaded from before...
- MemDepResult Dep = MD->getDependency(L);
-
- // If the value isn't available, don't do anything!
- if (Dep.isClobber()) {
- // Check to see if we have something like this:
- // store i32 123, i32* %P
- // %A = bitcast i32* %P to i8*
- // %B = gep i8* %A, i32 1
- // %C = load i8* %B
- //
- // We could do that by recognizing if the clobber instructions are obviously
- // a common base + constant offset, and if the previous store (or memset)
- // completely covers this load. This sort of thing can happen in bitfield
- // access code.
- Value *AvailVal = 0;
- if (StoreInst *DepSI = dyn_cast<StoreInst>(Dep.getInst()))
- if (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
- int Offset = AnalyzeLoadFromClobberingStore(L->getType(),
- L->getPointerOperand(),
- DepSI, *TD);
- if (Offset != -1)
- AvailVal = GetStoreValueForLoad(DepSI->getOperand(0), Offset,
- L->getType(), L, *TD);
- }
-
- // If the clobbering value is a memset/memcpy/memmove, see if we can forward
- // a value on from it.
- if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(Dep.getInst())) {
- if (const TargetData *TD = getAnalysisIfAvailable<TargetData>()) {
- int Offset = AnalyzeLoadFromClobberingMemInst(L->getType(),
- L->getPointerOperand(),
- DepMI, *TD);
- if (Offset != -1)
- AvailVal = GetMemInstValueForLoad(DepMI, Offset, L->getType(), L,*TD);
- }
- }
-
- if (AvailVal) {
- DEBUG(dbgs() << "GVN COERCED INST:\n" << *Dep.getInst() << '\n'
- << *AvailVal << '\n' << *L << "\n\n\n");
-
- // Replace the load!
- L->replaceAllUsesWith(AvailVal);
- if (AvailVal->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(AvailVal);
- VN.erase(L);
- toErase.push_back(L);
- ++NumGVNLoad;
- return true;
- }
-
- DEBUG(
- // fast print dep, using operator<< on instruction would be too slow
- dbgs() << "GVN: load ";
- WriteAsOperand(dbgs(), L);
- Instruction *I = Dep.getInst();
- dbgs() << " is clobbered by " << *I << '\n';
- );
- return false;
- }
-
- // If it is defined in another block, try harder.
- if (Dep.isNonLocal())
- return processNonLocalLoad(L, toErase);
-
- Instruction *DepInst = Dep.getInst();
- if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInst)) {
- Value *StoredVal = DepSI->getOperand(0);
-
- // The store and load are to a must-aliased pointer, but they may not
- // actually have the same type. See if we know how to reuse the stored
- // value (depending on its type).
- const TargetData *TD = 0;
- if (StoredVal->getType() != L->getType()) {
- if ((TD = getAnalysisIfAvailable<TargetData>())) {
- StoredVal = CoerceAvailableValueToLoadType(StoredVal, L->getType(),
- L, *TD);
- if (StoredVal == 0)
- return false;
-
- DEBUG(dbgs() << "GVN COERCED STORE:\n" << *DepSI << '\n' << *StoredVal
- << '\n' << *L << "\n\n\n");
- }
- else
- return false;
- }
-
- // Remove it!
- L->replaceAllUsesWith(StoredVal);
- if (StoredVal->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(StoredVal);
- VN.erase(L);
- toErase.push_back(L);
- ++NumGVNLoad;
- return true;
- }
-
- if (LoadInst *DepLI = dyn_cast<LoadInst>(DepInst)) {
- Value *AvailableVal = DepLI;
-
- // The loads are of a must-aliased pointer, but they may not actually have
- // the same type. See if we know how to reuse the previously loaded value
- // (depending on its type).
- const TargetData *TD = 0;
- if (DepLI->getType() != L->getType()) {
- if ((TD = getAnalysisIfAvailable<TargetData>())) {
- AvailableVal = CoerceAvailableValueToLoadType(DepLI, L->getType(), L,*TD);
- if (AvailableVal == 0)
- return false;
-
- DEBUG(dbgs() << "GVN COERCED LOAD:\n" << *DepLI << "\n" << *AvailableVal
- << "\n" << *L << "\n\n\n");
- }
- else
- return false;
- }
-
- // Remove it!
- L->replaceAllUsesWith(AvailableVal);
- if (DepLI->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(DepLI);
- VN.erase(L);
- toErase.push_back(L);
- ++NumGVNLoad;
- return true;
- }
-
- // If this load really doesn't depend on anything, then we must be loading an
- // undef value. This can happen when loading for a fresh allocation with no
- // intervening stores, for example.
- if (isa<AllocaInst>(DepInst) || isMalloc(DepInst)) {
- L->replaceAllUsesWith(UndefValue::get(L->getType()));
- VN.erase(L);
- toErase.push_back(L);
- ++NumGVNLoad;
- return true;
- }
-
- // If this load occurs either right after a lifetime begin,
- // then the loaded value is undefined.
- if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(DepInst)) {
- if (II->getIntrinsicID() == Intrinsic::lifetime_start) {
- L->replaceAllUsesWith(UndefValue::get(L->getType()));
- VN.erase(L);
- toErase.push_back(L);
- ++NumGVNLoad;
- return true;
- }
- }
-
- return false;
-}
-
-Value *GVN::lookupNumber(BasicBlock *BB, uint32_t num) {
- DenseMap<BasicBlock*, ValueNumberScope*>::iterator I = localAvail.find(BB);
- if (I == localAvail.end())
- return 0;
-
- ValueNumberScope *Locals = I->second;
- while (Locals) {
- DenseMap<uint32_t, Value*>::iterator I = Locals->table.find(num);
- if (I != Locals->table.end())
- return I->second;
- Locals = Locals->parent;
- }
-
- return 0;
-}
-
-
-/// processInstruction - When calculating availability, handle an instruction
-/// by inserting it into the appropriate sets
-bool GVN::processInstruction(Instruction *I,
- SmallVectorImpl<Instruction*> &toErase) {
- // Ignore dbg info intrinsics.
- if (isa<DbgInfoIntrinsic>(I))
- return false;
-
- if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
- bool Changed = processLoad(LI, toErase);
-
- if (!Changed) {
- unsigned Num = VN.lookup_or_add(LI);
- localAvail[I->getParent()]->table.insert(std::make_pair(Num, LI));
- }
-
- return Changed;
- }
-
- uint32_t NextNum = VN.getNextUnusedValueNumber();
- unsigned Num = VN.lookup_or_add(I);
-
- if (BranchInst *BI = dyn_cast<BranchInst>(I)) {
- localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
-
- if (!BI->isConditional() || isa<Constant>(BI->getCondition()))
- return false;
-
- Value *BranchCond = BI->getCondition();
- uint32_t CondVN = VN.lookup_or_add(BranchCond);
-
- BasicBlock *TrueSucc = BI->getSuccessor(0);
- BasicBlock *FalseSucc = BI->getSuccessor(1);
-
- if (TrueSucc->getSinglePredecessor())
- localAvail[TrueSucc]->table[CondVN] =
- ConstantInt::getTrue(TrueSucc->getContext());
- if (FalseSucc->getSinglePredecessor())
- localAvail[FalseSucc]->table[CondVN] =
- ConstantInt::getFalse(TrueSucc->getContext());
-
- return false;
-
- // Allocations are always uniquely numbered, so we can save time and memory
- // by fast failing them.
- } else if (isa<AllocaInst>(I) || isa<TerminatorInst>(I)) {
- localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
- return false;
- }
-
- // Collapse PHI nodes
- if (PHINode* p = dyn_cast<PHINode>(I)) {
- Value *constVal = CollapsePhi(p);
-
- if (constVal) {
- p->replaceAllUsesWith(constVal);
- if (MD && constVal->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(constVal);
- VN.erase(p);
-
- toErase.push_back(p);
- } else {
- localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
- }
-
- // If the number we were assigned was a brand new VN, then we don't
- // need to do a lookup to see if the number already exists
- // somewhere in the domtree: it can't!
- } else if (Num == NextNum) {
- localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
-
- // Perform fast-path value-number based elimination of values inherited from
- // dominators.
- } else if (Value *repl = lookupNumber(I->getParent(), Num)) {
- // Remove it!
- VN.erase(I);
- I->replaceAllUsesWith(repl);
- if (MD && repl->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(repl);
- toErase.push_back(I);
- return true;
-
- } else {
- localAvail[I->getParent()]->table.insert(std::make_pair(Num, I));
- }
-
- return false;
-}
-
-/// runOnFunction - This is the main transformation entry point for a function.
-bool GVN::runOnFunction(Function& F) {
- if (!NoLoads)
- MD = &getAnalysis<MemoryDependenceAnalysis>();
- DT = &getAnalysis<DominatorTree>();
- VN.setAliasAnalysis(&getAnalysis<AliasAnalysis>());
- VN.setMemDep(MD);
- VN.setDomTree(DT);
-
- bool Changed = false;
- bool ShouldContinue = true;
-
- // Merge unconditional branches, allowing PRE to catch more
- // optimization opportunities.
- for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ) {
- BasicBlock *BB = FI;
- ++FI;
- bool removedBlock = MergeBlockIntoPredecessor(BB, this);
- if (removedBlock) ++NumGVNBlocks;
-
- Changed |= removedBlock;
- }
-
- unsigned Iteration = 0;
-
- while (ShouldContinue) {
- DEBUG(dbgs() << "GVN iteration: " << Iteration << "\n");
- ShouldContinue = iterateOnFunction(F);
- if (splitCriticalEdges())
- ShouldContinue = true;
- Changed |= ShouldContinue;
- ++Iteration;
- }
-
- if (EnablePRE) {
- bool PREChanged = true;
- while (PREChanged) {
- PREChanged = performPRE(F);
- Changed |= PREChanged;
- }
- }
- // FIXME: Should perform GVN again after PRE does something. PRE can move
- // computations into blocks where they become fully redundant. Note that
- // we can't do this until PRE's critical edge splitting updates memdep.
- // Actually, when this happens, we should just fully integrate PRE into GVN.
-
- cleanupGlobalSets();
-
- return Changed;
-}
-
-
-bool GVN::processBlock(BasicBlock *BB) {
- // FIXME: Kill off toErase by doing erasing eagerly in a helper function (and
- // incrementing BI before processing an instruction).
- SmallVector<Instruction*, 8> toErase;
- bool ChangedFunction = false;
-
- for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
- BI != BE;) {
- ChangedFunction |= processInstruction(BI, toErase);
- if (toErase.empty()) {
- ++BI;
- continue;
- }
-
- // If we need some instructions deleted, do it now.
- NumGVNInstr += toErase.size();
-
- // Avoid iterator invalidation.
- bool AtStart = BI == BB->begin();
- if (!AtStart)
- --BI;
-
- for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
- E = toErase.end(); I != E; ++I) {
- DEBUG(dbgs() << "GVN removed: " << **I << '\n');
- if (MD) MD->removeInstruction(*I);
- (*I)->eraseFromParent();
- DEBUG(verifyRemoved(*I));
- }
- toErase.clear();
-
- if (AtStart)
- BI = BB->begin();
- else
- ++BI;
- }
-
- return ChangedFunction;
-}
-
-/// performPRE - Perform a purely local form of PRE that looks for diamond
-/// control flow patterns and attempts to perform simple PRE at the join point.
-bool GVN::performPRE(Function &F) {
- bool Changed = false;
- DenseMap<BasicBlock*, Value*> predMap;
- for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
- DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
- BasicBlock *CurrentBlock = *DI;
-
- // Nothing to PRE in the entry block.
- if (CurrentBlock == &F.getEntryBlock()) continue;
-
- for (BasicBlock::iterator BI = CurrentBlock->begin(),
- BE = CurrentBlock->end(); BI != BE; ) {
- Instruction *CurInst = BI++;
-
- if (isa<AllocaInst>(CurInst) ||
- isa<TerminatorInst>(CurInst) || isa<PHINode>(CurInst) ||
- CurInst->getType()->isVoidTy() ||
- CurInst->mayReadFromMemory() || CurInst->mayHaveSideEffects() ||
- isa<DbgInfoIntrinsic>(CurInst))
- continue;
-
- uint32_t ValNo = VN.lookup(CurInst);
-
- // Look for the predecessors for PRE opportunities. We're
- // only trying to solve the basic diamond case, where
- // a value is computed in the successor and one predecessor,
- // but not the other. We also explicitly disallow cases
- // where the successor is its own predecessor, because they're
- // more complicated to get right.
- unsigned NumWith = 0;
- unsigned NumWithout = 0;
- BasicBlock *PREPred = 0;
- predMap.clear();
-
- for (pred_iterator PI = pred_begin(CurrentBlock),
- PE = pred_end(CurrentBlock); PI != PE; ++PI) {
- BasicBlock *P = *PI;
- // We're not interested in PRE where the block is its
- // own predecessor, or in blocks with predecessors
- // that are not reachable.
- if (P == CurrentBlock) {
- NumWithout = 2;
- break;
- } else if (!localAvail.count(P)) {
- NumWithout = 2;
- break;
- }
-
- DenseMap<uint32_t, Value*>::iterator predV =
- localAvail[P]->table.find(ValNo);
- if (predV == localAvail[P]->table.end()) {
- PREPred = P;
- ++NumWithout;
- } else if (predV->second == CurInst) {
- NumWithout = 2;
- } else {
- predMap[P] = predV->second;
- ++NumWith;
- }
- }
-
- // Don't do PRE when it might increase code size, i.e. when
- // we would need to insert instructions in more than one pred.
- if (NumWithout != 1 || NumWith == 0)
- continue;
-
- // Don't do PRE across indirect branch.
- if (isa<IndirectBrInst>(PREPred->getTerminator()))
- continue;
-
- // We can't do PRE safely on a critical edge, so instead we schedule
- // the edge to be split and perform the PRE the next time we iterate
- // on the function.
- unsigned SuccNum = GetSuccessorNumber(PREPred, CurrentBlock);
- if (isCriticalEdge(PREPred->getTerminator(), SuccNum)) {
- toSplit.push_back(std::make_pair(PREPred->getTerminator(), SuccNum));
- continue;
- }
-
- // Instantiate the expression in the predecessor that lacked it.
- // Because we are going top-down through the block, all value numbers
- // will be available in the predecessor by the time we need them. Any
- // that weren't originally present will have been instantiated earlier
- // in this loop.
- Instruction *PREInstr = CurInst->clone();
- bool success = true;
- for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
- Value *Op = PREInstr->getOperand(i);
- if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
- continue;
-
- if (Value *V = lookupNumber(PREPred, VN.lookup(Op))) {
- PREInstr->setOperand(i, V);
- } else {
- success = false;
- break;
- }
- }
-
- // Fail out if we encounter an operand that is not available in
- // the PRE predecessor. This is typically because of loads which
- // are not value numbered precisely.
- if (!success) {
- delete PREInstr;
- DEBUG(verifyRemoved(PREInstr));
- continue;
- }
-
- PREInstr->insertBefore(PREPred->getTerminator());
- PREInstr->setName(CurInst->getName() + ".pre");
- predMap[PREPred] = PREInstr;
- VN.add(PREInstr, ValNo);
- ++NumGVNPRE;
-
- // Update the availability map to include the new instruction.
- localAvail[PREPred]->table.insert(std::make_pair(ValNo, PREInstr));
-
- // Create a PHI to make the value available in this block.
- PHINode* Phi = PHINode::Create(CurInst->getType(),
- CurInst->getName() + ".pre-phi",
- CurrentBlock->begin());
- for (pred_iterator PI = pred_begin(CurrentBlock),
- PE = pred_end(CurrentBlock); PI != PE; ++PI) {
- BasicBlock *P = *PI;
- Phi->addIncoming(predMap[P], P);
- }
-
- VN.add(Phi, ValNo);
- localAvail[CurrentBlock]->table[ValNo] = Phi;
-
- CurInst->replaceAllUsesWith(Phi);
- if (MD && Phi->getType()->isPointerTy())
- MD->invalidateCachedPointerInfo(Phi);
- VN.erase(CurInst);
-
- DEBUG(dbgs() << "GVN PRE removed: " << *CurInst << '\n');
- if (MD) MD->removeInstruction(CurInst);
- CurInst->eraseFromParent();
- DEBUG(verifyRemoved(CurInst));
- Changed = true;
- }
- }
-
- if (splitCriticalEdges())
- Changed = true;
-
- return Changed;
-}
-
-/// splitCriticalEdges - Split critical edges found during the previous
-/// iteration that may enable further optimization.
-bool GVN::splitCriticalEdges() {
- if (toSplit.empty())
- return false;
- do {
- std::pair<TerminatorInst*, unsigned> Edge = toSplit.pop_back_val();
- SplitCriticalEdge(Edge.first, Edge.second, this);
- } while (!toSplit.empty());
- if (MD) MD->invalidateCachedPredecessors();
- return true;
-}
-
-/// iterateOnFunction - Executes one iteration of GVN
-bool GVN::iterateOnFunction(Function &F) {
- cleanupGlobalSets();
-
- for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
- DE = df_end(DT->getRootNode()); DI != DE; ++DI) {
- if (DI->getIDom())
- localAvail[DI->getBlock()] =
- new ValueNumberScope(localAvail[DI->getIDom()->getBlock()]);
- else
- localAvail[DI->getBlock()] = new ValueNumberScope(0);
- }
-
- // Top-down walk of the dominator tree
- bool Changed = false;
-#if 0
- // Needed for value numbering with phi construction to work.
- ReversePostOrderTraversal<Function*> RPOT(&F);
- for (ReversePostOrderTraversal<Function*>::rpo_iterator RI = RPOT.begin(),
- RE = RPOT.end(); RI != RE; ++RI)
- Changed |= processBlock(*RI);
-#else
- for (df_iterator<DomTreeNode*> DI = df_begin(DT->getRootNode()),
- DE = df_end(DT->getRootNode()); DI != DE; ++DI)
- Changed |= processBlock(DI->getBlock());
-#endif
-
- return Changed;
-}
-
-void GVN::cleanupGlobalSets() {
- VN.clear();
-
- for (DenseMap<BasicBlock*, ValueNumberScope*>::iterator
- I = localAvail.begin(), E = localAvail.end(); I != E; ++I)
- delete I->second;
- localAvail.clear();
-}
-
-/// verifyRemoved - Verify that the specified instruction does not occur in our
-/// internal data structures.
-void GVN::verifyRemoved(const Instruction *Inst) const {
- VN.verifyRemoved(Inst);
-
- // Walk through the value number scope to make sure the instruction isn't
- // ferreted away in it.
- for (DenseMap<BasicBlock*, ValueNumberScope*>::const_iterator
- I = localAvail.begin(), E = localAvail.end(); I != E; ++I) {
- const ValueNumberScope *VNS = I->second;
-
- while (VNS) {
- for (DenseMap<uint32_t, Value*>::const_iterator
- II = VNS->table.begin(), IE = VNS->table.end(); II != IE; ++II) {
- assert(II->second != Inst && "Inst still in value numbering scope!");
- }
-
- VNS = VNS->parent;
- }
- }
-}
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