[llvm-commits] [llvm] r94123 - in /llvm/trunk: include/llvm/Analysis/ lib/Transforms/Scalar/ test/CodeGen/ARM/ test/CodeGen/Thumb2/ test/CodeGen/X86/ test/Transforms/LoopStrengthReduce/
Dan Gohman
gohman at apple.com
Thu Jan 21 16:46:50 PST 2010
Author: djg
Date: Thu Jan 21 18:46:49 2010
New Revision: 94123
URL: http://llvm.org/viewvc/llvm-project?rev=94123&view=rev
Log:
Revert LoopStrengthReduce.cpp to pre-r94061 for now.
Removed:
llvm/trunk/test/CodeGen/X86/lsr-reuse.ll
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h
llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
llvm/trunk/test/CodeGen/ARM/arm-negative-stride.ll
llvm/trunk/test/CodeGen/ARM/lsr-code-insertion.ll
llvm/trunk/test/CodeGen/ARM/remat.ll
llvm/trunk/test/CodeGen/Thumb2/lsr-deficiency.ll
llvm/trunk/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
llvm/trunk/test/CodeGen/X86/2006-05-11-InstrSched.ll
llvm/trunk/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll
llvm/trunk/test/CodeGen/X86/iv-users-in-other-loops.ll
llvm/trunk/test/CodeGen/X86/loop-strength-reduce4.ll
llvm/trunk/test/CodeGen/X86/loop-strength-reduce8.ll
llvm/trunk/test/CodeGen/X86/masked-iv-safe.ll
llvm/trunk/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
llvm/trunk/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
llvm/trunk/test/Transforms/LoopStrengthReduce/count-to-zero.ll
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolutionExpander.h Thu Jan 21 18:46:49 2010
@@ -27,7 +27,10 @@
/// and destroy it when finished to allow the release of the associated
/// memory.
class SCEVExpander : public SCEVVisitor<SCEVExpander, Value*> {
+ public:
ScalarEvolution &SE;
+
+ private:
std::map<std::pair<const SCEV *, Instruction *>, AssertingVH<Value> >
InsertedExpressions;
std::set<Value*> InsertedValues;
Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Thu Jan 21 18:46:49 2010
@@ -17,45 +17,6 @@
// available on the target, and it performs a variety of other optimizations
// related to loop induction variables.
//
-// Terminology note: this code has a lot of handling for "post-increment" or
-// "post-inc" users. This is not talking about post-increment addressing modes;
-// it is instead talking about code like this:
-//
-// %i = phi [ 0, %entry ], [ %i.next, %latch ]
-// ...
-// %i.next = add %i, 1
-// %c = icmp eq %i.next, %n
-//
-// The SCEV for %i is {0,+,1}<%L>. The SCEV for %i.next is {1,+,1}<%L>, however
-// it's useful to think about these as the same register, with some uses using
-// the value of the register before the add and some using // it after. In this
-// example, the icmp is a post-increment user, since it uses %i.next, which is
-// the value of the induction variable after the increment. The other common
-// case of post-increment users is users outside the loop.
-//
-// TODO: More sophistication in the way Formulae are generated.
-//
-// TODO: Handle multiple loops at a time.
-//
-// TODO: test/CodeGen/X86/full-lsr.ll should get full lsr. The problem is
-// that {0,+,1}<%bb> is getting picked first because all 7 uses can
-// use it, and while it's a pretty good solution, it means that LSR
-// doesn't look further to find an even better solution.
-//
-// TODO: Should TargetLowering::AddrMode::BaseGV be changed to a ConstantExpr
-// instead of a GlobalValue?
-//
-// TODO: When truncation is free, truncate ICmp users' operands to make it a
-// smaller encoding (on x86 at least).
-//
-// TODO: When a negated register is used by an add (such as in a list of
-// multiple base registers, or as the increment expression in an addrec),
-// we may not actually need both reg and (-1 * reg) in registers; the
-// negation can be implemented by using a sub instead of an add. The
-// lack of support for taking this into consideration when making
-// register pressure decisions is partly worked around by the "Special"
-// use kind.
-//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loop-reduce"
@@ -65,1536 +26,1731 @@
#include "llvm/IntrinsicInst.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Analysis/IVUsers.h"
-#include "llvm/Analysis/Dominators.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
+#include "llvm/Transforms/Utils/AddrModeMatcher.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
-#include "llvm/ADT/SmallBitVector.h"
-#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLowering.h"
#include <algorithm>
using namespace llvm;
-namespace {
+STATISTIC(NumReduced , "Number of IV uses strength reduced");
+STATISTIC(NumInserted, "Number of PHIs inserted");
+STATISTIC(NumVariable, "Number of PHIs with variable strides");
+STATISTIC(NumEliminated, "Number of strides eliminated");
+STATISTIC(NumShadow, "Number of Shadow IVs optimized");
+STATISTIC(NumImmSunk, "Number of common expr immediates sunk into uses");
+STATISTIC(NumLoopCond, "Number of loop terminating conds optimized");
+STATISTIC(NumCountZero, "Number of count iv optimized to count toward zero");
+
+static cl::opt<bool> EnableFullLSRMode("enable-full-lsr",
+ cl::init(false),
+ cl::Hidden);
-// Constant strides come first which in turns are sorted by their absolute
-// values. If absolute values are the same, then positive strides comes first.
-// e.g.
-// 4, -1, X, 1, 2 ==> 1, -1, 2, 4, X
-struct StrideCompare {
- const ScalarEvolution &SE;
- explicit StrideCompare(const ScalarEvolution &se) : SE(se) {}
-
- bool operator()(const SCEV *const &LHS, const SCEV *const &RHS) const {
- const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS);
- const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS);
- if (LHSC && RHSC) {
- unsigned BitWidth = std::max(SE.getTypeSizeInBits(LHS->getType()),
- SE.getTypeSizeInBits(RHS->getType()));
- APInt LV = LHSC->getValue()->getValue();
- APInt RV = RHSC->getValue()->getValue();
- LV.sextOrTrunc(BitWidth);
- RV.sextOrTrunc(BitWidth);
- APInt ALV = LV.abs();
- APInt ARV = RV.abs();
- if (ALV == ARV) {
- if (LV != RV)
- return LV.sgt(RV);
- } else {
- return ALV.ult(ARV);
- }
+namespace {
- // If it's the same value but different type, sort by bit width so
- // that we emit larger induction variables before smaller
- // ones, letting the smaller be re-written in terms of larger ones.
- return SE.getTypeSizeInBits(RHS->getType()) <
- SE.getTypeSizeInBits(LHS->getType());
- }
- return LHSC && !RHSC;
- }
-};
+ struct BasedUser;
-/// RegSortData - This class holds data which is used to order reuse
-/// candidates.
-class RegSortData {
-public:
- /// Bits - This represents the set of LSRUses (by index) which reference a
- /// particular register.
- SmallBitVector Bits;
+ /// IVInfo - This structure keeps track of one IV expression inserted during
+ /// StrengthReduceStridedIVUsers. It contains the stride, the common base, as
+ /// well as the PHI node and increment value created for rewrite.
+ struct IVExpr {
+ const SCEV *Stride;
+ const SCEV *Base;
+ PHINode *PHI;
- /// MaxComplexity - This represents the greatest complexity (see the comments
- /// on Formula::getComplexity) seen with a particular register.
- uint32_t MaxComplexity;
+ IVExpr(const SCEV *const stride, const SCEV *const base, PHINode *phi)
+ : Stride(stride), Base(base), PHI(phi) {}
+ };
- /// Index - This holds an arbitrary value used as a last-resort tie breaker
- /// to ensure deterministic behavior.
- unsigned Index;
+ /// IVsOfOneStride - This structure keeps track of all IV expression inserted
+ /// during StrengthReduceStridedIVUsers for a particular stride of the IV.
+ struct IVsOfOneStride {
+ std::vector<IVExpr> IVs;
- RegSortData() {}
+ void addIV(const SCEV *const Stride, const SCEV *const Base, PHINode *PHI) {
+ IVs.push_back(IVExpr(Stride, Base, PHI));
+ }
+ };
- void print(raw_ostream &OS) const;
- void dump() const;
-};
+ class LoopStrengthReduce : public LoopPass {
+ IVUsers *IU;
+ ScalarEvolution *SE;
+ bool Changed;
+
+ /// IVsByStride - Keep track of all IVs that have been inserted for a
+ /// particular stride.
+ std::map<const SCEV *, IVsOfOneStride> IVsByStride;
+
+ /// DeadInsts - Keep track of instructions we may have made dead, so that
+ /// we can remove them after we are done working.
+ SmallVector<WeakVH, 16> DeadInsts;
+
+ /// TLI - Keep a pointer of a TargetLowering to consult for determining
+ /// transformation profitability.
+ const TargetLowering *TLI;
+
+ public:
+ static char ID; // Pass ID, replacement for typeid
+ explicit LoopStrengthReduce(const TargetLowering *tli = NULL) :
+ LoopPass(&ID), TLI(tli) {}
+
+ bool runOnLoop(Loop *L, LPPassManager &LPM);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ // We split critical edges, so we change the CFG. However, we do update
+ // many analyses if they are around.
+ AU.addPreservedID(LoopSimplifyID);
+ AU.addPreserved("loops");
+ AU.addPreserved("domfrontier");
+ AU.addPreserved("domtree");
+
+ AU.addRequiredID(LoopSimplifyID);
+ AU.addRequired<ScalarEvolution>();
+ AU.addPreserved<ScalarEvolution>();
+ AU.addRequired<IVUsers>();
+ AU.addPreserved<IVUsers>();
+ }
+
+ private:
+ void OptimizeIndvars(Loop *L);
+
+ /// OptimizeLoopTermCond - Change loop terminating condition to use the
+ /// postinc iv when possible.
+ void OptimizeLoopTermCond(Loop *L);
+
+ /// OptimizeShadowIV - If IV is used in a int-to-float cast
+ /// inside the loop then try to eliminate the cast opeation.
+ void OptimizeShadowIV(Loop *L);
+
+ /// OptimizeMax - Rewrite the loop's terminating condition
+ /// if it uses a max computation.
+ ICmpInst *OptimizeMax(Loop *L, ICmpInst *Cond,
+ IVStrideUse* &CondUse);
+
+ /// OptimizeLoopCountIV - If, after all sharing of IVs, the IV used for
+ /// deciding when to exit the loop is used only for that purpose, try to
+ /// rearrange things so it counts down to a test against zero.
+ bool OptimizeLoopCountIV(Loop *L);
+ bool OptimizeLoopCountIVOfStride(const SCEV* &Stride,
+ IVStrideUse* &CondUse, Loop *L);
+
+ /// StrengthReduceIVUsersOfStride - Strength reduce all of the users of a
+ /// single stride of IV. All of the users may have different starting
+ /// values, and this may not be the only stride.
+ void StrengthReduceIVUsersOfStride(const SCEV *Stride,
+ IVUsersOfOneStride &Uses,
+ Loop *L);
+ void StrengthReduceIVUsers(Loop *L);
+
+ ICmpInst *ChangeCompareStride(Loop *L, ICmpInst *Cond,
+ IVStrideUse* &CondUse,
+ const SCEV* &CondStride,
+ bool PostPass = false);
+
+ bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse,
+ const SCEV* &CondStride);
+ bool RequiresTypeConversion(const Type *Ty, const Type *NewTy);
+ const SCEV *CheckForIVReuse(bool, bool, bool, const SCEV *,
+ IVExpr&, const Type*,
+ const std::vector<BasedUser>& UsersToProcess);
+ bool ValidScale(bool, int64_t,
+ const std::vector<BasedUser>& UsersToProcess);
+ bool ValidOffset(bool, int64_t, int64_t,
+ const std::vector<BasedUser>& UsersToProcess);
+ const SCEV *CollectIVUsers(const SCEV *Stride,
+ IVUsersOfOneStride &Uses,
+ Loop *L,
+ bool &AllUsesAreAddresses,
+ bool &AllUsesAreOutsideLoop,
+ std::vector<BasedUser> &UsersToProcess);
+ bool StrideMightBeShared(const SCEV *Stride, Loop *L, bool CheckPreInc);
+ bool ShouldUseFullStrengthReductionMode(
+ const std::vector<BasedUser> &UsersToProcess,
+ const Loop *L,
+ bool AllUsesAreAddresses,
+ const SCEV *Stride);
+ void PrepareToStrengthReduceFully(
+ std::vector<BasedUser> &UsersToProcess,
+ const SCEV *Stride,
+ const SCEV *CommonExprs,
+ const Loop *L,
+ SCEVExpander &PreheaderRewriter);
+ void PrepareToStrengthReduceFromSmallerStride(
+ std::vector<BasedUser> &UsersToProcess,
+ Value *CommonBaseV,
+ const IVExpr &ReuseIV,
+ Instruction *PreInsertPt);
+ void PrepareToStrengthReduceWithNewPhi(
+ std::vector<BasedUser> &UsersToProcess,
+ const SCEV *Stride,
+ const SCEV *CommonExprs,
+ Value *CommonBaseV,
+ Instruction *IVIncInsertPt,
+ const Loop *L,
+ SCEVExpander &PreheaderRewriter);
+ void DeleteTriviallyDeadInstructions();
+ };
}
-void RegSortData::print(raw_ostream &OS) const {
- OS << "[NumUses=" << Bits.count()
- << ", MaxComplexity=";
- OS.write_hex(MaxComplexity);
- OS << ", Index=" << Index << ']';
-}
+char LoopStrengthReduce::ID = 0;
+static RegisterPass<LoopStrengthReduce>
+X("loop-reduce", "Loop Strength Reduction");
-void RegSortData::dump() const {
- print(errs()); errs() << '\n';
+Pass *llvm::createLoopStrengthReducePass(const TargetLowering *TLI) {
+ return new LoopStrengthReduce(TLI);
}
-namespace {
+/// DeleteTriviallyDeadInstructions - If any of the instructions is the
+/// specified set are trivially dead, delete them and see if this makes any of
+/// their operands subsequently dead.
+void LoopStrengthReduce::DeleteTriviallyDeadInstructions() {
+ while (!DeadInsts.empty()) {
+ Instruction *I = dyn_cast_or_null<Instruction>(DeadInsts.pop_back_val());
-/// RegCount - This is a helper class to sort a given set of registers
-/// according to associated RegSortData values.
-class RegCount {
-public:
- const SCEV *Reg;
- RegSortData Sort;
-
- RegCount(const SCEV *R, const RegSortData &RSD)
- : Reg(R), Sort(RSD) {}
-
- // Sort by count. Returning true means the register is preferred.
- bool operator<(const RegCount &Other) const {
- // Sort by the number of unique uses of this register.
- unsigned A = Sort.Bits.count();
- unsigned B = Other.Sort.Bits.count();
- if (A != B) return A > B;
-
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) {
- const SCEVAddRecExpr *BR = dyn_cast<SCEVAddRecExpr>(Other.Reg);
- // AddRecs have higher priority than other things.
- if (!BR) return true;
-
- // Prefer affine values.
- if (AR->isAffine() != BR->isAffine())
- return AR->isAffine();
-
- const Loop *AL = AR->getLoop();
- const Loop *BL = BR->getLoop();
- if (AL != BL) {
- unsigned ADepth = AL->getLoopDepth();
- unsigned BDepth = BL->getLoopDepth();
- // Prefer a less deeply nested addrec.
- if (ADepth != BDepth)
- return ADepth < BDepth;
-
- // Different loops at the same depth; do something arbitrary.
- BasicBlock *AH = AL->getHeader();
- BasicBlock *BH = BL->getHeader();
- for (Function::iterator I = AH, E = AH->getParent()->end(); I != E; ++I)
- if (&*I == BH) return true;
- return false;
- }
-
- // Sort addrecs by stride.
- const SCEV *AStep = AR->getOperand(1);
- const SCEV *BStep = BR->getOperand(1);
- if (AStep != BStep) {
- if (const SCEVConstant *AC = dyn_cast<SCEVConstant>(AStep)) {
- const SCEVConstant *BC = dyn_cast<SCEVConstant>(BStep);
- if (!BC) return true;
- // Arbitrarily prefer wider registers.
- if (AC->getValue()->getValue().getBitWidth() !=
- BC->getValue()->getValue().getBitWidth())
- return AC->getValue()->getValue().getBitWidth() >
- BC->getValue()->getValue().getBitWidth();
- // Ignore the sign bit, assuming that striding by a negative value
- // is just as easy as by a positive value.
- // Prefer the addrec with the lesser absolute value stride, as it
- // will allow uses to have simpler addressing modes.
- return AC->getValue()->getValue().abs()
- .ult(BC->getValue()->getValue().abs());
- }
- }
+ if (I == 0 || !isInstructionTriviallyDead(I))
+ continue;
- // Then sort by the register which will permit the simplest uses.
- // This is a heuristic; currently we only track the most complex use as a
- // representative.
- if (Sort.MaxComplexity != Other.Sort.MaxComplexity)
- return Sort.MaxComplexity < Other.Sort.MaxComplexity;
-
- // Then sort them by their start values.
- const SCEV *AStart = AR->getStart();
- const SCEV *BStart = BR->getStart();
- if (AStart != BStart) {
- if (const SCEVConstant *AC = dyn_cast<SCEVConstant>(AStart)) {
- const SCEVConstant *BC = dyn_cast<SCEVConstant>(BStart);
- if (!BC) return true;
- // Arbitrarily prefer wider registers.
- if (AC->getValue()->getValue().getBitWidth() !=
- BC->getValue()->getValue().getBitWidth())
- return AC->getValue()->getValue().getBitWidth() >
- BC->getValue()->getValue().getBitWidth();
- // Prefer positive over negative if the absolute values are the same.
- if (AC->getValue()->getValue().abs() ==
- BC->getValue()->getValue().abs())
- return AC->getValue()->getValue().isStrictlyPositive();
- // Prefer the addrec with the lesser absolute value start.
- return AC->getValue()->getValue().abs()
- .ult(BC->getValue()->getValue().abs());
- }
+ for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI)
+ if (Instruction *U = dyn_cast<Instruction>(*OI)) {
+ *OI = 0;
+ if (U->use_empty())
+ DeadInsts.push_back(U);
}
- } else {
- // AddRecs have higher priority than other things.
- if (isa<SCEVAddRecExpr>(Other.Reg)) return false;
- // Sort by the register which will permit the simplest uses.
- // This is a heuristic; currently we only track the most complex use as a
- // representative.
- if (Sort.MaxComplexity != Other.Sort.MaxComplexity)
- return Sort.MaxComplexity < Other.Sort.MaxComplexity;
- }
-
- // Tie-breaker: the arbitrary index, to ensure a reliable ordering.
- return Sort.Index < Other.Sort.Index;
+ I->eraseFromParent();
+ Changed = true;
}
-
- void print(raw_ostream &OS) const;
- void dump() const;
-};
-
}
-void RegCount::print(raw_ostream &OS) const {
- OS << *Reg << ':';
- Sort.print(OS);
+/// isAddressUse - Returns true if the specified instruction is using the
+/// specified value as an address.
+static bool isAddressUse(Instruction *Inst, Value *OperandVal) {
+ bool isAddress = isa<LoadInst>(Inst);
+ if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
+ if (SI->getOperand(1) == OperandVal)
+ isAddress = true;
+ } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+ // Addressing modes can also be folded into prefetches and a variety
+ // of intrinsics.
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::prefetch:
+ case Intrinsic::x86_sse2_loadu_dq:
+ case Intrinsic::x86_sse2_loadu_pd:
+ case Intrinsic::x86_sse_loadu_ps:
+ case Intrinsic::x86_sse_storeu_ps:
+ case Intrinsic::x86_sse2_storeu_pd:
+ case Intrinsic::x86_sse2_storeu_dq:
+ case Intrinsic::x86_sse2_storel_dq:
+ if (II->getOperand(1) == OperandVal)
+ isAddress = true;
+ break;
+ }
+ }
+ return isAddress;
}
-void RegCount::dump() const {
- print(errs()); errs() << '\n';
+/// getAccessType - Return the type of the memory being accessed.
+static const Type *getAccessType(const Instruction *Inst) {
+ const Type *AccessTy = Inst->getType();
+ if (const StoreInst *SI = dyn_cast<StoreInst>(Inst))
+ AccessTy = SI->getOperand(0)->getType();
+ else if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
+ // Addressing modes can also be folded into prefetches and a variety
+ // of intrinsics.
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::x86_sse_storeu_ps:
+ case Intrinsic::x86_sse2_storeu_pd:
+ case Intrinsic::x86_sse2_storeu_dq:
+ case Intrinsic::x86_sse2_storel_dq:
+ AccessTy = II->getOperand(1)->getType();
+ break;
+ }
+ }
+ return AccessTy;
}
namespace {
-
-/// Formula - This class holds information that describes a formula for
-/// satisfying a use. It may include broken-out immediates and scaled registers.
-struct Formula {
- /// AM - This is used to represent complex addressing, as well as other kinds
- /// of interesting uses.
- TargetLowering::AddrMode AM;
-
- /// BaseRegs - The list of "base" registers for this use. When this is
- /// non-empty, AM.HasBaseReg should be set to true.
- SmallVector<const SCEV *, 2> BaseRegs;
-
- /// ScaledReg - The 'scaled' register for this use. This should be non-null
- /// when AM.Scale is not zero.
- const SCEV *ScaledReg;
-
- Formula() : ScaledReg(0) {}
-
- unsigned getNumRegs() const;
- uint32_t getComplexity() const;
- const Type *getType() const;
-
- void InitialMatch(const SCEV *S, Loop *L,
- ScalarEvolution &SE, DominatorTree &DT);
-
- /// referencesReg - Test if this formula references the given register.
- bool referencesReg(const SCEV *S) const {
- return S == ScaledReg ||
- std::find(BaseRegs.begin(), BaseRegs.end(), S) != BaseRegs.end();
- }
-
- bool operator==(const Formula &Other) const {
- return BaseRegs == Other.BaseRegs &&
- ScaledReg == Other.ScaledReg &&
- AM.Scale == Other.AM.Scale &&
- AM.BaseOffs == Other.AM.BaseOffs &&
- AM.BaseGV == Other.AM.BaseGV;
- }
-
- // This sorts at least partially based on host pointer values which are
- // not deterministic, so it is only usable for uniqification.
- bool operator<(const Formula &Other) const {
- if (BaseRegs != Other.BaseRegs)
- return BaseRegs < Other.BaseRegs;
- if (ScaledReg != Other.ScaledReg)
- return ScaledReg < Other.ScaledReg;
- if (AM.Scale != Other.AM.Scale)
- return AM.Scale < Other.AM.Scale;
- if (AM.BaseOffs != Other.AM.BaseOffs)
- return AM.BaseOffs < Other.AM.BaseOffs;
- if (AM.BaseGV != Other.AM.BaseGV)
- return AM.BaseGV < Other.AM.BaseGV;
- return false;
- }
-
- void print(raw_ostream &OS) const;
- void dump() const;
-};
-
+ /// BasedUser - For a particular base value, keep information about how we've
+ /// partitioned the expression so far.
+ struct BasedUser {
+ /// Base - The Base value for the PHI node that needs to be inserted for
+ /// this use. As the use is processed, information gets moved from this
+ /// field to the Imm field (below). BasedUser values are sorted by this
+ /// field.
+ const SCEV *Base;
+
+ /// Inst - The instruction using the induction variable.
+ Instruction *Inst;
+
+ /// OperandValToReplace - The operand value of Inst to replace with the
+ /// EmittedBase.
+ Value *OperandValToReplace;
+
+ /// Imm - The immediate value that should be added to the base immediately
+ /// before Inst, because it will be folded into the imm field of the
+ /// instruction. This is also sometimes used for loop-variant values that
+ /// must be added inside the loop.
+ const SCEV *Imm;
+
+ /// Phi - The induction variable that performs the striding that
+ /// should be used for this user.
+ PHINode *Phi;
+
+ // isUseOfPostIncrementedValue - True if this should use the
+ // post-incremented version of this IV, not the preincremented version.
+ // This can only be set in special cases, such as the terminating setcc
+ // instruction for a loop and uses outside the loop that are dominated by
+ // the loop.
+ bool isUseOfPostIncrementedValue;
+
+ BasedUser(IVStrideUse &IVSU, ScalarEvolution *se)
+ : Base(IVSU.getOffset()), Inst(IVSU.getUser()),
+ OperandValToReplace(IVSU.getOperandValToReplace()),
+ Imm(se->getIntegerSCEV(0, Base->getType())),
+ isUseOfPostIncrementedValue(IVSU.isUseOfPostIncrementedValue()) {}
+
+ // Once we rewrite the code to insert the new IVs we want, update the
+ // operands of Inst to use the new expression 'NewBase', with 'Imm' added
+ // to it.
+ void RewriteInstructionToUseNewBase(const SCEV *NewBase,
+ Instruction *InsertPt,
+ SCEVExpander &Rewriter, Loop *L, Pass *P,
+ SmallVectorImpl<WeakVH> &DeadInsts,
+ ScalarEvolution *SE);
+
+ Value *InsertCodeForBaseAtPosition(const SCEV *NewBase,
+ const Type *Ty,
+ SCEVExpander &Rewriter,
+ Instruction *IP,
+ ScalarEvolution *SE);
+ void dump() const;
+ };
}
-/// getNumRegs - Return the total number of register operands used by this
-/// formula. This does not include register uses implied by non-constant
-/// addrec strides.
-unsigned Formula::getNumRegs() const {
- return !!ScaledReg + BaseRegs.size();
-}
-
-/// getComplexity - Return an oversimplified value indicating the complexity
-/// of this formula. This is used as a tie-breaker in choosing register
-/// preferences.
-uint32_t Formula::getComplexity() const {
- // Encode the information in a uint32_t so that comparing with operator<
- // will be interesting.
- return
- // Most significant, the number of registers. This saturates because we
- // need the bits, and because beyond a few hundred it doesn't really matter.
- (std::min(getNumRegs(), (1u<<15)-1) << 17) |
- // Having multiple base regs is worse than having a base reg and a scale.
- ((BaseRegs.size() > 1) << 16) |
- // Scale absolute value.
- ((AM.Scale != 0 ? (Log2_64(abs64(AM.Scale)) + 1) : 0u) << 9) |
- // Scale sign, which is less significant than the absolute value.
- ((AM.Scale < 0) << 8) |
- // Offset absolute value.
- ((AM.BaseOffs != 0 ? (Log2_64(abs64(AM.BaseOffs)) + 1) : 0u) << 1) |
- // If a GV is present, treat it like a maximal offset.
- ((AM.BaseGV ? ((1u<<7)-1) : 0) << 1) |
- // Offset sign, which is less significant than the absolute offset.
- ((AM.BaseOffs < 0) << 0);
-}
-
-/// getType - Return the type of this formula, if it has one, or null
-/// otherwise. This type is meaningless except for the bit size.
-const Type *Formula::getType() const {
- return !BaseRegs.empty() ? BaseRegs.front()->getType() :
- ScaledReg ? ScaledReg->getType() :
- AM.BaseGV ? AM.BaseGV->getType() :
- 0;
+void BasedUser::dump() const {
+ dbgs() << " Base=" << *Base;
+ dbgs() << " Imm=" << *Imm;
+ dbgs() << " Inst: " << *Inst;
}
-namespace {
+Value *BasedUser::InsertCodeForBaseAtPosition(const SCEV *NewBase,
+ const Type *Ty,
+ SCEVExpander &Rewriter,
+ Instruction *IP,
+ ScalarEvolution *SE) {
+ Value *Base = Rewriter.expandCodeFor(NewBase, 0, IP);
-/// ComplexitySorter - A predicate which orders Formulae by the number of
-/// registers they contain.
-struct ComplexitySorter {
- bool operator()(const Formula &LHS, const Formula &RHS) const {
- unsigned L = LHS.getNumRegs();
- unsigned R = RHS.getNumRegs();
- if (L != R) return L < R;
-
- return LHS.getComplexity() < RHS.getComplexity();
- }
-};
+ // Wrap the base in a SCEVUnknown so that ScalarEvolution doesn't try to
+ // re-analyze it.
+ const SCEV *NewValSCEV = SE->getUnknown(Base);
+ // Always emit the immediate into the same block as the user.
+ NewValSCEV = SE->getAddExpr(NewValSCEV, Imm);
+
+ return Rewriter.expandCodeFor(NewValSCEV, Ty, IP);
}
-/// DoInitialMatch - Recurrsion helper for InitialMatch.
-static void DoInitialMatch(const SCEV *S, Loop *L,
- SmallVectorImpl<const SCEV *> &Good,
- SmallVectorImpl<const SCEV *> &Bad,
- ScalarEvolution &SE, DominatorTree &DT) {
- // Collect expressions which properly dominate the loop header.
- if (S->properlyDominates(L->getHeader(), &DT)) {
- Good.push_back(S);
- return;
- }
- // Look at add operands.
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
- for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
- I != E; ++I)
- DoInitialMatch(*I, L, Good, Bad, SE, DT);
+// Once we rewrite the code to insert the new IVs we want, update the
+// operands of Inst to use the new expression 'NewBase', with 'Imm' added
+// to it. NewBasePt is the last instruction which contributes to the
+// value of NewBase in the case that it's a diffferent instruction from
+// the PHI that NewBase is computed from, or null otherwise.
+//
+void BasedUser::RewriteInstructionToUseNewBase(const SCEV *NewBase,
+ Instruction *NewBasePt,
+ SCEVExpander &Rewriter, Loop *L, Pass *P,
+ SmallVectorImpl<WeakVH> &DeadInsts,
+ ScalarEvolution *SE) {
+ if (!isa<PHINode>(Inst)) {
+ // By default, insert code at the user instruction.
+ BasicBlock::iterator InsertPt = Inst;
+
+ // However, if the Operand is itself an instruction, the (potentially
+ // complex) inserted code may be shared by many users. Because of this, we
+ // want to emit code for the computation of the operand right before its old
+ // computation. This is usually safe, because we obviously used to use the
+ // computation when it was computed in its current block. However, in some
+ // cases (e.g. use of a post-incremented induction variable) the NewBase
+ // value will be pinned to live somewhere after the original computation.
+ // In this case, we have to back off.
+ //
+ // If this is a use outside the loop (which means after, since it is based
+ // on a loop indvar) we use the post-incremented value, so that we don't
+ // artificially make the preinc value live out the bottom of the loop.
+ if (!isUseOfPostIncrementedValue && L->contains(Inst)) {
+ if (NewBasePt && isa<PHINode>(OperandValToReplace)) {
+ InsertPt = NewBasePt;
+ ++InsertPt;
+ } else if (Instruction *OpInst
+ = dyn_cast<Instruction>(OperandValToReplace)) {
+ InsertPt = OpInst;
+ while (isa<PHINode>(InsertPt)) ++InsertPt;
+ }
+ }
+ Value *NewVal = InsertCodeForBaseAtPosition(NewBase,
+ OperandValToReplace->getType(),
+ Rewriter, InsertPt, SE);
+ // Replace the use of the operand Value with the new Phi we just created.
+ Inst->replaceUsesOfWith(OperandValToReplace, NewVal);
+
+ DEBUG(dbgs() << " Replacing with ");
+ DEBUG(WriteAsOperand(dbgs(), NewVal, /*PrintType=*/false));
+ DEBUG(dbgs() << ", which has value " << *NewBase << " plus IMM "
+ << *Imm << "\n");
return;
}
- // Look at addrec operands.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
- if (!AR->getStart()->isZero()) {
- DoInitialMatch(AR->getStart(), L, Good, Bad, SE, DT);
- DoInitialMatch(SE.getAddRecExpr(SE.getIntegerSCEV(0, AR->getType()),
- AR->getStepRecurrence(SE),
- AR->getLoop()),
- L, Good, Bad, SE, DT);
- return;
- }
- }
-
- // Handle a multiplication by -1 (negation) if it didn't fold.
- if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S))
- if (Mul->getOperand(0)->isAllOnesValue()) {
- SmallVector<const SCEV *, 4> Ops(Mul->op_begin()+1, Mul->op_end());
- const SCEV *NewMul = SE.getMulExpr(Ops);
-
- SmallVector<const SCEV *, 4> MyGood;
- SmallVector<const SCEV *, 4> MyBad;
- DoInitialMatch(NewMul, L, MyGood, MyBad, SE, DT);
- const SCEV *NegOne = SE.getSCEV(ConstantInt::getAllOnesValue(
- SE.getEffectiveSCEVType(NewMul->getType())));
- for (SmallVectorImpl<const SCEV *>::const_iterator I = MyGood.begin(),
- E = MyGood.end(); I != E; ++I)
- Good.push_back(SE.getMulExpr(NegOne, *I));
- for (SmallVectorImpl<const SCEV *>::const_iterator I = MyBad.begin(),
- E = MyBad.end(); I != E; ++I)
- Bad.push_back(SE.getMulExpr(NegOne, *I));
- return;
- }
-
- // Ok, we can't do anything interesting. Just stuff the whole thing into a
- // register and hope for the best.
- Bad.push_back(S);
-}
-
-/// InitialMatch - Incorporate loop-variant parts of S into this Formula,
-/// attempting to keep all loop-invariant and loop-computable values in a
-/// single base register.
-void Formula::InitialMatch(const SCEV *S, Loop *L,
- ScalarEvolution &SE, DominatorTree &DT) {
- SmallVector<const SCEV *, 4> Good;
- SmallVector<const SCEV *, 4> Bad;
- DoInitialMatch(S, L, Good, Bad, SE, DT);
- if (!Good.empty()) {
- BaseRegs.push_back(SE.getAddExpr(Good));
- AM.HasBaseReg = true;
- }
- if (!Bad.empty()) {
- BaseRegs.push_back(SE.getAddExpr(Bad));
- AM.HasBaseReg = true;
- }
-}
-
-void Formula::print(raw_ostream &OS) const {
- bool First = true;
- if (AM.BaseGV) {
- if (!First) OS << " + "; else First = false;
- WriteAsOperand(OS, AM.BaseGV, /*PrintType=*/false);
- }
- if (AM.BaseOffs != 0) {
- if (!First) OS << " + "; else First = false;
- OS << AM.BaseOffs;
- }
- for (SmallVectorImpl<const SCEV *>::const_iterator I = BaseRegs.begin(),
- E = BaseRegs.end(); I != E; ++I) {
- if (!First) OS << " + "; else First = false;
- OS << "reg(";
- OS << **I;
- OS << ")";
- }
- if (AM.Scale != 0) {
- if (!First) OS << " + "; else First = false;
- OS << AM.Scale << "*reg(";
- if (ScaledReg)
- OS << *ScaledReg;
- else
- OS << "<unknown>";
- OS << ")";
- }
-}
+ // PHI nodes are more complex. We have to insert one copy of the NewBase+Imm
+ // expression into each operand block that uses it. Note that PHI nodes can
+ // have multiple entries for the same predecessor. We use a map to make sure
+ // that a PHI node only has a single Value* for each predecessor (which also
+ // prevents us from inserting duplicate code in some blocks).
+ DenseMap<BasicBlock*, Value*> InsertedCode;
+ PHINode *PN = cast<PHINode>(Inst);
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ if (PN->getIncomingValue(i) == OperandValToReplace) {
+ // If the original expression is outside the loop, put the replacement
+ // code in the same place as the original expression,
+ // which need not be an immediate predecessor of this PHI. This way we
+ // need only one copy of it even if it is referenced multiple times in
+ // the PHI. We don't do this when the original expression is inside the
+ // loop because multiple copies sometimes do useful sinking of code in
+ // that case(?).
+ Instruction *OldLoc = dyn_cast<Instruction>(OperandValToReplace);
+ BasicBlock *PHIPred = PN->getIncomingBlock(i);
+ if (L->contains(OldLoc)) {
+ // If this is a critical edge, split the edge so that we do not insert
+ // the code on all predecessor/successor paths. We do this unless this
+ // is the canonical backedge for this loop, as this can make some
+ // inserted code be in an illegal position.
+ if (e != 1 && PHIPred->getTerminator()->getNumSuccessors() > 1 &&
+ !isa<IndirectBrInst>(PHIPred->getTerminator()) &&
+ (PN->getParent() != L->getHeader() || !L->contains(PHIPred))) {
+
+ // First step, split the critical edge.
+ BasicBlock *NewBB = SplitCriticalEdge(PHIPred, PN->getParent(),
+ P, false);
-void Formula::dump() const {
- print(errs()); errs() << '\n';
-}
+ // Next step: move the basic block. In particular, if the PHI node
+ // is outside of the loop, and PredTI is in the loop, we want to
+ // move the block to be immediately before the PHI block, not
+ // immediately after PredTI.
+ if (L->contains(PHIPred) && !L->contains(PN))
+ NewBB->moveBefore(PN->getParent());
-/// getSDiv - Return an expression for LHS /s RHS, if it can be determined,
-/// or null otherwise. If IgnoreSignificantBits is true, expressions like
-/// (X * Y) /s Y are simplified to Y, ignoring that the multiplication may
-/// overflow, which is useful when the result will be used in a context where
-/// the most significant bits are ignored.
-static const SCEV *getSDiv(const SCEV *LHS, const SCEV *RHS,
- ScalarEvolution &SE,
- bool IgnoreSignificantBits = false) {
- // Handle the trivial case, which works for any SCEV type.
- if (LHS == RHS)
- return SE.getIntegerSCEV(1, LHS->getType());
-
- // Handle x /s -1 as x * -1, to give ScalarEvolution a chance to do some
- // folding.
- if (RHS->isAllOnesValue())
- return SE.getMulExpr(LHS, RHS);
-
- // Check for a division of a constant by a constant.
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(LHS)) {
- const SCEVConstant *RC = dyn_cast<SCEVConstant>(RHS);
- if (!RC)
- return 0;
- if (C->getValue()->getValue().srem(RC->getValue()->getValue()) != 0)
- return 0;
- return SE.getConstant(C->getValue()->getValue()
- .sdiv(RC->getValue()->getValue()));
- }
-
- // Distribute the sdiv over addrec operands.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(LHS)) {
- const SCEV *Start = getSDiv(AR->getStart(), RHS, SE,
- IgnoreSignificantBits);
- if (!Start) return 0;
- const SCEV *Step = getSDiv(AR->getStepRecurrence(SE), RHS, SE,
- IgnoreSignificantBits);
- if (!Step) return 0;
- return SE.getAddRecExpr(Start, Step, AR->getLoop());
- }
-
- // Distribute the sdiv over add operands.
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(LHS)) {
- SmallVector<const SCEV *, 8> Ops;
- for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
- I != E; ++I) {
- const SCEV *Op = getSDiv(*I, RHS, SE,
- IgnoreSignificantBits);
- if (!Op) return 0;
- Ops.push_back(Op);
- }
- return SE.getAddExpr(Ops);
- }
-
- // Check for a multiply operand that we can pull RHS out of.
- if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(LHS))
- if (IgnoreSignificantBits || Mul->hasNoSignedWrap()) {
- SmallVector<const SCEV *, 4> Ops;
- bool Found = false;
- for (SCEVMulExpr::op_iterator I = Mul->op_begin(), E = Mul->op_end();
- I != E; ++I) {
- if (!Found)
- if (const SCEV *Q = getSDiv(*I, RHS, SE, IgnoreSignificantBits)) {
- Ops.push_back(Q);
- Found = true;
- continue;
- }
- Ops.push_back(*I);
+ // Splitting the edge can reduce the number of PHI entries we have.
+ e = PN->getNumIncomingValues();
+ PHIPred = NewBB;
+ i = PN->getBasicBlockIndex(PHIPred);
+ }
}
- return Found ? SE.getMulExpr(Ops) : 0;
+ Value *&Code = InsertedCode[PHIPred];
+ if (!Code) {
+ // Insert the code into the end of the predecessor block.
+ Instruction *InsertPt = (L->contains(OldLoc)) ?
+ PHIPred->getTerminator() :
+ OldLoc->getParent()->getTerminator();
+ Code = InsertCodeForBaseAtPosition(NewBase, PN->getType(),
+ Rewriter, InsertPt, SE);
+
+ DEBUG(dbgs() << " Changing PHI use to ");
+ DEBUG(WriteAsOperand(dbgs(), Code, /*PrintType=*/false));
+ DEBUG(dbgs() << ", which has value " << *NewBase << " plus IMM "
+ << *Imm << "\n");
+ }
+
+ // Replace the use of the operand Value with the new Phi we just created.
+ PN->setIncomingValue(i, Code);
+ Rewriter.clear();
}
+ }
- // Otherwise we don't know.
- return 0;
+ // PHI node might have become a constant value after SplitCriticalEdge.
+ DeadInsts.push_back(Inst);
}
-namespace {
-/// LSRUse - This class holds the state that LSR keeps for each use in
-/// IVUsers, as well as uses invented by LSR itself. It includes information
-/// about what kinds of things can be folded into the user, information
-/// about the user itself, and information about how the use may be satisfied.
-/// TODO: Represent multiple users of the same expression in common?
-class LSRUse {
- SmallSet<Formula, 8> FormulaeUniquifier;
-
-public:
- /// KindType - An enum for a kind of use, indicating what types of
- /// scaled and immediate operands it might support.
- enum KindType {
- Basic, ///< A normal use, with no folding.
- Special, ///< A special case of basic, allowing -1 scales.
- Address, ///< An address use; folding according to TargetLowering
- ICmpZero ///< An equality icmp with both operands folded into one.
- // TODO: Add a generic icmp too?
- };
+/// fitsInAddressMode - Return true if V can be subsumed within an addressing
+/// mode, and does not need to be put in a register first.
+static bool fitsInAddressMode(const SCEV *V, const Type *AccessTy,
+ const TargetLowering *TLI, bool HasBaseReg) {
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(V)) {
+ int64_t VC = SC->getValue()->getSExtValue();
+ if (TLI) {
+ TargetLowering::AddrMode AM;
+ AM.BaseOffs = VC;
+ AM.HasBaseReg = HasBaseReg;
+ return TLI->isLegalAddressingMode(AM, AccessTy);
+ } else {
+ // Defaults to PPC. PPC allows a sign-extended 16-bit immediate field.
+ return (VC > -(1 << 16) && VC < (1 << 16)-1);
+ }
+ }
- KindType Kind;
- const Type *AccessTy;
- Instruction *UserInst;
- Value *OperandValToReplace;
-
- /// PostIncLoop - If this user is to use the post-incremented value of an
- /// induction variable, this variable is non-null and holds the loop
- /// associated with the induction variable.
- const Loop *PostIncLoop;
-
- /// Formulae - A list of ways to build a value that can satisfy this user.
- /// After the list is populated, one of these is selected heuristically and
- /// used to formulate a replacement for OperandValToReplace in UserInst.
- SmallVector<Formula, 12> Formulae;
-
- LSRUse() : Kind(Basic), AccessTy(0),
- UserInst(0), OperandValToReplace(0), PostIncLoop(0) {}
-
- void InsertInitialFormula(const SCEV *S, Loop *L,
- ScalarEvolution &SE, DominatorTree &DT);
- void InsertSupplementalFormula(const SCEV *S);
-
- bool InsertFormula(const Formula &F);
-
- void Rewrite(Loop *L, Instruction *IVIncInsertPos,
- SCEVExpander &Rewriter,
- SmallVectorImpl<WeakVH> &DeadInsts,
- ScalarEvolution &SE, DominatorTree &DT,
- Pass *P) const;
-
- void print(raw_ostream &OS) const;
- void dump() const;
-
-private:
- Value *Expand(BasicBlock::iterator IP, Loop *L, Instruction *IVIncInsertPos,
- SCEVExpander &Rewriter,
- SmallVectorImpl<WeakVH> &DeadInsts,
- ScalarEvolution &SE, DominatorTree &DT) const;
-};
+ if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(V))
+ if (GlobalValue *GV = dyn_cast<GlobalValue>(SU->getValue())) {
+ if (TLI) {
+ TargetLowering::AddrMode AM;
+ AM.BaseGV = GV;
+ AM.HasBaseReg = HasBaseReg;
+ return TLI->isLegalAddressingMode(AM, AccessTy);
+ } else {
+ // Default: assume global addresses are not legal.
+ }
+ }
+ return false;
}
-/// ExtractImmediate - If S involves the addition of a constant integer value,
-/// return that integer value, and mutate S to point to a new SCEV with that
-/// value excluded.
-static int64_t ExtractImmediate(const SCEV *&S, ScalarEvolution &SE) {
- if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
- if (C->getValue()->getValue().getMinSignedBits() <= 64) {
- S = SE.getIntegerSCEV(0, C->getType());
- return C->getValue()->getSExtValue();
- }
- } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
- SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
- int64_t Result = ExtractImmediate(NewOps.front(), SE);
- S = SE.getAddExpr(NewOps);
- return Result;
- } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
- SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
- int64_t Result = ExtractImmediate(NewOps.front(), SE);
- S = SE.getAddRecExpr(NewOps, AR->getLoop());
- return Result;
- }
- return 0;
-}
+/// MoveLoopVariantsToImmediateField - Move any subexpressions from Val that are
+/// loop varying to the Imm operand.
+static void MoveLoopVariantsToImmediateField(const SCEV *&Val, const SCEV *&Imm,
+ Loop *L, ScalarEvolution *SE) {
+ if (Val->isLoopInvariant(L)) return; // Nothing to do.
+
+ if (const SCEVAddExpr *SAE = dyn_cast<SCEVAddExpr>(Val)) {
+ SmallVector<const SCEV *, 4> NewOps;
+ NewOps.reserve(SAE->getNumOperands());
+
+ for (unsigned i = 0; i != SAE->getNumOperands(); ++i)
+ if (!SAE->getOperand(i)->isLoopInvariant(L)) {
+ // If this is a loop-variant expression, it must stay in the immediate
+ // field of the expression.
+ Imm = SE->getAddExpr(Imm, SAE->getOperand(i));
+ } else {
+ NewOps.push_back(SAE->getOperand(i));
+ }
-/// ExtractSymbol - If S involves the addition of a GlobalValue address,
-/// return that symbol, and mutate S to point to a new SCEV with that
-/// value excluded.
-static GlobalValue *ExtractSymbol(const SCEV *&S, ScalarEvolution &SE) {
- if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
- if (GlobalValue *GV = dyn_cast<GlobalValue>(U->getValue())) {
- S = SE.getIntegerSCEV(0, GV->getType());
- return GV;
- }
- } else if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
- SmallVector<const SCEV *, 8> NewOps(Add->op_begin(), Add->op_end());
- GlobalValue *Result = ExtractSymbol(NewOps.back(), SE);
- S = SE.getAddExpr(NewOps);
- return Result;
- } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
- SmallVector<const SCEV *, 8> NewOps(AR->op_begin(), AR->op_end());
- GlobalValue *Result = ExtractSymbol(NewOps.front(), SE);
- S = SE.getAddRecExpr(NewOps, AR->getLoop());
- return Result;
+ if (NewOps.empty())
+ Val = SE->getIntegerSCEV(0, Val->getType());
+ else
+ Val = SE->getAddExpr(NewOps);
+ } else if (const SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Val)) {
+ // Try to pull immediates out of the start value of nested addrec's.
+ const SCEV *Start = SARE->getStart();
+ MoveLoopVariantsToImmediateField(Start, Imm, L, SE);
+
+ SmallVector<const SCEV *, 4> Ops(SARE->op_begin(), SARE->op_end());
+ Ops[0] = Start;
+ Val = SE->getAddRecExpr(Ops, SARE->getLoop());
+ } else {
+ // Otherwise, all of Val is variant, move the whole thing over.
+ Imm = SE->getAddExpr(Imm, Val);
+ Val = SE->getIntegerSCEV(0, Val->getType());
}
- return 0;
}
-/// isLegalUse - Test whether the use described by AM is "legal", meaning
-/// it can be completely folded into the user instruction at isel time.
-/// This includes address-mode folding and special icmp tricks.
-static bool isLegalUse(const TargetLowering::AddrMode &AM,
- LSRUse::KindType Kind, const Type *AccessTy,
- const TargetLowering *TLI) {
- switch (Kind) {
- case LSRUse::Address:
- // If we have low-level target information, ask the target if it can
- // completely fold this address.
- if (TLI) return TLI->isLegalAddressingMode(AM, AccessTy);
-
- // Otherwise, just guess that reg+reg addressing is legal.
- return !AM.BaseGV && AM.BaseOffs == 0 && AM.Scale <= 1;
-
- case LSRUse::ICmpZero:
- // There's not even a target hook for querying whether it would be legal
- // to fold a GV into an ICmp.
- if (AM.BaseGV)
- return false;
-
- // ICmp only has two operands; don't allow more than two non-trivial parts.
- if (AM.Scale != 0 && AM.HasBaseReg && AM.BaseOffs != 0)
- return false;
-
- // ICmp only supports no scale or a -1 scale, as we can "fold" a -1 scale
- // by putting the scaled register in the other operand of the icmp.
- if (AM.Scale != 0 && AM.Scale != -1)
- return false;
- // If we have low-level target information, ask the target if it can
- // fold an integer immediate on an icmp.
- if (AM.BaseOffs != 0) {
- if (TLI) return TLI->isLegalICmpImmediate(-AM.BaseOffs);
- return false;
+/// MoveImmediateValues - Look at Val, and pull out any additions of constants
+/// that can fit into the immediate field of instructions in the target.
+/// Accumulate these immediate values into the Imm value.
+static void MoveImmediateValues(const TargetLowering *TLI,
+ const Type *AccessTy,
+ const SCEV *&Val, const SCEV *&Imm,
+ bool isAddress, Loop *L,
+ ScalarEvolution *SE) {
+ if (const SCEVAddExpr *SAE = dyn_cast<SCEVAddExpr>(Val)) {
+ SmallVector<const SCEV *, 4> NewOps;
+ NewOps.reserve(SAE->getNumOperands());
+
+ for (unsigned i = 0; i != SAE->getNumOperands(); ++i) {
+ const SCEV *NewOp = SAE->getOperand(i);
+ MoveImmediateValues(TLI, AccessTy, NewOp, Imm, isAddress, L, SE);
+
+ if (!NewOp->isLoopInvariant(L)) {
+ // If this is a loop-variant expression, it must stay in the immediate
+ // field of the expression.
+ Imm = SE->getAddExpr(Imm, NewOp);
+ } else {
+ NewOps.push_back(NewOp);
+ }
}
- return true;
+ if (NewOps.empty())
+ Val = SE->getIntegerSCEV(0, Val->getType());
+ else
+ Val = SE->getAddExpr(NewOps);
+ return;
+ } else if (const SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Val)) {
+ // Try to pull immediates out of the start value of nested addrec's.
+ const SCEV *Start = SARE->getStart();
+ MoveImmediateValues(TLI, AccessTy, Start, Imm, isAddress, L, SE);
+
+ if (Start != SARE->getStart()) {
+ SmallVector<const SCEV *, 4> Ops(SARE->op_begin(), SARE->op_end());
+ Ops[0] = Start;
+ Val = SE->getAddRecExpr(Ops, SARE->getLoop());
+ }
+ return;
+ } else if (const SCEVMulExpr *SME = dyn_cast<SCEVMulExpr>(Val)) {
+ // Transform "8 * (4 + v)" -> "32 + 8*V" if "32" fits in the immed field.
+ if (isAddress &&
+ fitsInAddressMode(SME->getOperand(0), AccessTy, TLI, false) &&
+ SME->getNumOperands() == 2 && SME->isLoopInvariant(L)) {
+
+ const SCEV *SubImm = SE->getIntegerSCEV(0, Val->getType());
+ const SCEV *NewOp = SME->getOperand(1);
+ MoveImmediateValues(TLI, AccessTy, NewOp, SubImm, isAddress, L, SE);
+
+ // If we extracted something out of the subexpressions, see if we can
+ // simplify this!
+ if (NewOp != SME->getOperand(1)) {
+ // Scale SubImm up by "8". If the result is a target constant, we are
+ // good.
+ SubImm = SE->getMulExpr(SubImm, SME->getOperand(0));
+ if (fitsInAddressMode(SubImm, AccessTy, TLI, false)) {
+ // Accumulate the immediate.
+ Imm = SE->getAddExpr(Imm, SubImm);
+
+ // Update what is left of 'Val'.
+ Val = SE->getMulExpr(SME->getOperand(0), NewOp);
+ return;
+ }
+ }
+ }
+ }
- case LSRUse::Basic:
- // Only handle single-register values.
- return !AM.BaseGV && AM.Scale == 0 && AM.BaseOffs == 0;
-
- case LSRUse::Special:
- // Only handle -1 scales, or no scale.
- return AM.Scale == 0 || AM.Scale == -1;
+ // Loop-variant expressions must stay in the immediate field of the
+ // expression.
+ if ((isAddress && fitsInAddressMode(Val, AccessTy, TLI, false)) ||
+ !Val->isLoopInvariant(L)) {
+ Imm = SE->getAddExpr(Imm, Val);
+ Val = SE->getIntegerSCEV(0, Val->getType());
+ return;
}
- return false;
+ // Otherwise, no immediates to move.
}
-static bool isAlwaysFoldable(const SCEV *S,
- bool HasBaseReg,
- LSRUse::KindType Kind, const Type *AccessTy,
- const TargetLowering *TLI,
- ScalarEvolution &SE) {
- // Fast-path: zero is always foldable.
- if (S->isZero()) return true;
-
- // Conservatively, create an address with an immediate and a
- // base and a scale.
- TargetLowering::AddrMode AM;
- AM.BaseOffs = ExtractImmediate(S, SE);
- AM.BaseGV = ExtractSymbol(S, SE);
- AM.HasBaseReg = HasBaseReg;
- AM.Scale = Kind == LSRUse::ICmpZero ? -1 : 1;
-
- // If there's anything else involved, it's not foldable.
- if (!S->isZero()) return false;
-
- return isLegalUse(AM, Kind, AccessTy, TLI);
-}
-
-/// InsertFormula - If the given formula has not yet been inserted, add it
-/// to the list, and return true. Return false otherwise.
-bool LSRUse::InsertFormula(const Formula &F) {
- Formula Copy = F;
-
- // Sort the base regs, to avoid adding the same solution twice with
- // the base regs in different orders. This uses host pointer values, but
- // it doesn't matter since it's only used for uniquifying.
- std::sort(Copy.BaseRegs.begin(), Copy.BaseRegs.end());
-
- DEBUG(for (SmallVectorImpl<const SCEV *>::const_iterator I =
- F.BaseRegs.begin(), E = F.BaseRegs.end(); I != E; ++I)
- assert(!(*I)->isZero() && "Zero allocated in a base register!");
- assert((!F.ScaledReg || !F.ScaledReg->isZero()) &&
- "Zero allocated in a scaled register!"));
+static void MoveImmediateValues(const TargetLowering *TLI,
+ Instruction *User,
+ const SCEV *&Val, const SCEV *&Imm,
+ bool isAddress, Loop *L,
+ ScalarEvolution *SE) {
+ const Type *AccessTy = getAccessType(User);
+ MoveImmediateValues(TLI, AccessTy, Val, Imm, isAddress, L, SE);
+}
+
+/// SeparateSubExprs - Decompose Expr into all of the subexpressions that are
+/// added together. This is used to reassociate common addition subexprs
+/// together for maximal sharing when rewriting bases.
+static void SeparateSubExprs(SmallVector<const SCEV *, 16> &SubExprs,
+ const SCEV *Expr,
+ ScalarEvolution *SE) {
+ if (const SCEVAddExpr *AE = dyn_cast<SCEVAddExpr>(Expr)) {
+ for (unsigned j = 0, e = AE->getNumOperands(); j != e; ++j)
+ SeparateSubExprs(SubExprs, AE->getOperand(j), SE);
+ } else if (const SCEVAddRecExpr *SARE = dyn_cast<SCEVAddRecExpr>(Expr)) {
+ const SCEV *Zero = SE->getIntegerSCEV(0, Expr->getType());
+ if (SARE->getOperand(0) == Zero) {
+ SubExprs.push_back(Expr);
+ } else {
+ // Compute the addrec with zero as its base.
+ SmallVector<const SCEV *, 4> Ops(SARE->op_begin(), SARE->op_end());
+ Ops[0] = Zero; // Start with zero base.
+ SubExprs.push_back(SE->getAddRecExpr(Ops, SARE->getLoop()));
+
+
+ SeparateSubExprs(SubExprs, SARE->getOperand(0), SE);
+ }
+ } else if (!Expr->isZero()) {
+ // Do not add zero.
+ SubExprs.push_back(Expr);
+ }
+}
- if (FormulaeUniquifier.insert(Copy)) {
- Formulae.push_back(F);
- return true;
+// This is logically local to the following function, but C++ says we have
+// to make it file scope.
+struct SubExprUseData { unsigned Count; bool notAllUsesAreFree; };
+
+/// RemoveCommonExpressionsFromUseBases - Look through all of the Bases of all
+/// the Uses, removing any common subexpressions, except that if all such
+/// subexpressions can be folded into an addressing mode for all uses inside
+/// the loop (this case is referred to as "free" in comments herein) we do
+/// not remove anything. This looks for things like (a+b+c) and
+/// (a+c+d) and computes the common (a+c) subexpression. The common expression
+/// is *removed* from the Bases and returned.
+static const SCEV *
+RemoveCommonExpressionsFromUseBases(std::vector<BasedUser> &Uses,
+ ScalarEvolution *SE, Loop *L,
+ const TargetLowering *TLI) {
+ unsigned NumUses = Uses.size();
+
+ // Only one use? This is a very common case, so we handle it specially and
+ // cheaply.
+ const SCEV *Zero = SE->getIntegerSCEV(0, Uses[0].Base->getType());
+ const SCEV *Result = Zero;
+ const SCEV *FreeResult = Zero;
+ if (NumUses == 1) {
+ // If the use is inside the loop, use its base, regardless of what it is:
+ // it is clearly shared across all the IV's. If the use is outside the loop
+ // (which means after it) we don't want to factor anything *into* the loop,
+ // so just use 0 as the base.
+ if (L->contains(Uses[0].Inst))
+ std::swap(Result, Uses[0].Base);
+ return Result;
}
- return false;
-}
+ // To find common subexpressions, count how many of Uses use each expression.
+ // If any subexpressions are used Uses.size() times, they are common.
+ // Also track whether all uses of each expression can be moved into an
+ // an addressing mode "for free"; such expressions are left within the loop.
+ // struct SubExprUseData { unsigned Count; bool notAllUsesAreFree; };
+ std::map<const SCEV *, SubExprUseData> SubExpressionUseData;
+
+ // UniqueSubExprs - Keep track of all of the subexpressions we see in the
+ // order we see them.
+ SmallVector<const SCEV *, 16> UniqueSubExprs;
+
+ SmallVector<const SCEV *, 16> SubExprs;
+ unsigned NumUsesInsideLoop = 0;
+ for (unsigned i = 0; i != NumUses; ++i) {
+ // If the user is outside the loop, just ignore it for base computation.
+ // Since the user is outside the loop, it must be *after* the loop (if it
+ // were before, it could not be based on the loop IV). We don't want users
+ // after the loop to affect base computation of values *inside* the loop,
+ // because we can always add their offsets to the result IV after the loop
+ // is done, ensuring we get good code inside the loop.
+ if (!L->contains(Uses[i].Inst))
+ continue;
+ NumUsesInsideLoop++;
-void
-LSRUse::InsertInitialFormula(const SCEV *S, Loop *L,
- ScalarEvolution &SE, DominatorTree &DT) {
- Formula F;
- F.InitialMatch(S, L, SE, DT);
- bool Inserted = InsertFormula(F);
- assert(Inserted && "Initial formula already exists!"); (void)Inserted;
-}
+ // If the base is zero (which is common), return zero now, there are no
+ // CSEs we can find.
+ if (Uses[i].Base == Zero) return Zero;
+
+ // If this use is as an address we may be able to put CSEs in the addressing
+ // mode rather than hoisting them.
+ bool isAddrUse = isAddressUse(Uses[i].Inst, Uses[i].OperandValToReplace);
+ // We may need the AccessTy below, but only when isAddrUse, so compute it
+ // only in that case.
+ const Type *AccessTy = 0;
+ if (isAddrUse)
+ AccessTy = getAccessType(Uses[i].Inst);
+
+ // Split the expression into subexprs.
+ SeparateSubExprs(SubExprs, Uses[i].Base, SE);
+ // Add one to SubExpressionUseData.Count for each subexpr present, and
+ // if the subexpr is not a valid immediate within an addressing mode use,
+ // set SubExpressionUseData.notAllUsesAreFree. We definitely want to
+ // hoist these out of the loop (if they are common to all uses).
+ for (unsigned j = 0, e = SubExprs.size(); j != e; ++j) {
+ if (++SubExpressionUseData[SubExprs[j]].Count == 1)
+ UniqueSubExprs.push_back(SubExprs[j]);
+ if (!isAddrUse || !fitsInAddressMode(SubExprs[j], AccessTy, TLI, false))
+ SubExpressionUseData[SubExprs[j]].notAllUsesAreFree = true;
+ }
+ SubExprs.clear();
+ }
+
+ // Now that we know how many times each is used, build Result. Iterate over
+ // UniqueSubexprs so that we have a stable ordering.
+ for (unsigned i = 0, e = UniqueSubExprs.size(); i != e; ++i) {
+ std::map<const SCEV *, SubExprUseData>::iterator I =
+ SubExpressionUseData.find(UniqueSubExprs[i]);
+ assert(I != SubExpressionUseData.end() && "Entry not found?");
+ if (I->second.Count == NumUsesInsideLoop) { // Found CSE!
+ if (I->second.notAllUsesAreFree)
+ Result = SE->getAddExpr(Result, I->first);
+ else
+ FreeResult = SE->getAddExpr(FreeResult, I->first);
+ } else
+ // Remove non-cse's from SubExpressionUseData.
+ SubExpressionUseData.erase(I);
+ }
-void
-LSRUse::InsertSupplementalFormula(const SCEV *S) {
- Formula F;
- F.BaseRegs.push_back(S);
- F.AM.HasBaseReg = true;
- bool Inserted = InsertFormula(F);
- assert(Inserted && "Supplemental formula already exists!"); (void)Inserted;
-}
-
-/// getImmediateDominator - A handy utility for the specific DominatorTree
-/// query that we need here.
-///
-static BasicBlock *getImmediateDominator(BasicBlock *BB, DominatorTree &DT) {
- DomTreeNode *Node = DT.getNode(BB);
- if (!Node) return 0;
- Node = Node->getIDom();
- if (!Node) return 0;
- return Node->getBlock();
-}
-
-Value *LSRUse::Expand(BasicBlock::iterator IP,
- Loop *L, Instruction *IVIncInsertPos,
- SCEVExpander &Rewriter,
- SmallVectorImpl<WeakVH> &DeadInsts,
- ScalarEvolution &SE, DominatorTree &DT) const {
- // Then, collect some instructions which we will remain dominated by when
- // expanding the replacement. These must be dominated by any operands that
- // will be required in the expansion.
- SmallVector<Instruction *, 4> Inputs;
- if (Instruction *I = dyn_cast<Instruction>(OperandValToReplace))
- Inputs.push_back(I);
- if (Kind == ICmpZero)
- if (Instruction *I =
- dyn_cast<Instruction>(cast<ICmpInst>(UserInst)->getOperand(1)))
- Inputs.push_back(I);
- if (PostIncLoop && !L->contains(UserInst))
- Inputs.push_back(L->getLoopLatch()->getTerminator());
-
- // Then, climb up the immediate dominator tree as far as we can go while
- // still being dominated by the input positions.
- for (;;) {
- bool AllDominate = true;
- Instruction *BetterPos = 0;
- BasicBlock *IDom = getImmediateDominator(IP->getParent(), DT);
- if (!IDom) break;
- Instruction *Tentative = IDom->getTerminator();
- for (SmallVectorImpl<Instruction *>::const_iterator I = Inputs.begin(),
- E = Inputs.end(); I != E; ++I) {
- Instruction *Inst = *I;
- if (Inst == Tentative || !DT.dominates(Inst, Tentative)) {
- AllDominate = false;
+ if (FreeResult != Zero) {
+ // We have some subexpressions that can be subsumed into addressing
+ // modes in every use inside the loop. However, it's possible that
+ // there are so many of them that the combined FreeResult cannot
+ // be subsumed, or that the target cannot handle both a FreeResult
+ // and a Result in the same instruction (for example because it would
+ // require too many registers). Check this.
+ for (unsigned i=0; i<NumUses; ++i) {
+ if (!L->contains(Uses[i].Inst))
+ continue;
+ // We know this is an addressing mode use; if there are any uses that
+ // are not, FreeResult would be Zero.
+ const Type *AccessTy = getAccessType(Uses[i].Inst);
+ if (!fitsInAddressMode(FreeResult, AccessTy, TLI, Result!=Zero)) {
+ // FIXME: could split up FreeResult into pieces here, some hoisted
+ // and some not. There is no obvious advantage to this.
+ Result = SE->getAddExpr(Result, FreeResult);
+ FreeResult = Zero;
break;
}
- if (IDom == Inst->getParent() &&
- (!BetterPos || DT.dominates(BetterPos, Inst)))
- BetterPos = next(BasicBlock::iterator(Inst));
}
- if (!AllDominate)
- break;
- if (BetterPos)
- IP = BetterPos;
- else
- IP = Tentative;
}
- while (isa<PHINode>(IP)) ++IP;
- // The first formula in the list is the winner.
- const Formula &F = Formulae.front();
+ // If we found no CSE's, return now.
+ if (Result == Zero) return Result;
- // Inform the Rewriter if we have a post-increment use, so that it can
- // perform an advantageous expansion.
- Rewriter.setPostInc(PostIncLoop);
-
- // This is the type that the user actually needs.
- const Type *OpTy = OperandValToReplace->getType();
- // This will be the type that we'll initially expand to.
- const Type *Ty = F.getType();
- if (!Ty)
- // No type known; just expand directly to the ultimate type.
- Ty = OpTy;
- else if (SE.getEffectiveSCEVType(Ty) == SE.getEffectiveSCEVType(OpTy))
- // Expand directly to the ultimate type if it's the right size.
- Ty = OpTy;
- // This is the type to do integer arithmetic in.
- const Type *IntTy = SE.getEffectiveSCEVType(Ty);
-
- // Build up a list of operands to add together to form the full base.
- SmallVector<const SCEV *, 8> Ops;
-
- // Expand the BaseRegs portion.
- for (SmallVectorImpl<const SCEV *>::const_iterator I = F.BaseRegs.begin(),
- E = F.BaseRegs.end(); I != E; ++I) {
- const SCEV *Reg = *I;
- assert(!Reg->isZero() && "Zero allocated in a base register!");
-
- // If we're expanding for a post-inc user for the add-rec's loop, make the
- // post-inc adjustment.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg))
- if (AR->getLoop() == PostIncLoop) {
- Reg = SE.getAddExpr(Reg, AR->getStepRecurrence(SE));
- // If the user is inside the loop, insert the code after the increment
- // so that it is dominated by its operand.
- if (L->contains(UserInst))
- IP = IVIncInsertPos;
- }
-
- Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, 0, IP)));
- }
-
- // Expand the ScaledReg portion.
- Value *ICmpScaledV = 0;
- if (F.AM.Scale != 0) {
- const SCEV *ScaledS = F.ScaledReg;
-
- // If we're expanding for a post-inc user for the add-rec's loop, make the
- // post-inc adjustment.
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(ScaledS))
- if (AR->getLoop() == PostIncLoop)
- ScaledS = SE.getAddExpr(ScaledS, AR->getStepRecurrence(SE));
-
- if (Kind == ICmpZero) {
- // An interesting way of "folding" with an icmp is to use a negated
- // scale, which we'll implement by inserting it into the other operand
- // of the icmp.
- assert(F.AM.Scale == -1 &&
- "The only scale supported by ICmpZero uses is -1!");
- ICmpScaledV = Rewriter.expandCodeFor(ScaledS, 0, IP);
- } else {
- // Otherwise just expand the scaled register and an explicit scale,
- // which is expected to be matched as part of the address.
- ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, 0, IP));
- const Type *ScaledTy = SE.getEffectiveSCEVType(ScaledS->getType());
- ScaledS = SE.getMulExpr(ScaledS,
- SE.getSCEV(ConstantInt::get(ScaledTy,
- F.AM.Scale)));
- Ops.push_back(ScaledS);
+ // If we still have a FreeResult, remove its subexpressions from
+ // SubExpressionUseData. This means they will remain in the use Bases.
+ if (FreeResult != Zero) {
+ SeparateSubExprs(SubExprs, FreeResult, SE);
+ for (unsigned j = 0, e = SubExprs.size(); j != e; ++j) {
+ std::map<const SCEV *, SubExprUseData>::iterator I =
+ SubExpressionUseData.find(SubExprs[j]);
+ SubExpressionUseData.erase(I);
+ }
+ SubExprs.clear();
+ }
+
+ // Otherwise, remove all of the CSE's we found from each of the base values.
+ for (unsigned i = 0; i != NumUses; ++i) {
+ // Uses outside the loop don't necessarily include the common base, but
+ // the final IV value coming into those uses does. Instead of trying to
+ // remove the pieces of the common base, which might not be there,
+ // subtract off the base to compensate for this.
+ if (!L->contains(Uses[i].Inst)) {
+ Uses[i].Base = SE->getMinusSCEV(Uses[i].Base, Result);
+ continue;
}
- }
- // Expand the immediate portions.
- if (F.AM.BaseGV)
- Ops.push_back(SE.getSCEV(F.AM.BaseGV));
- if (F.AM.BaseOffs != 0) {
- if (Kind == ICmpZero) {
- // The other interesting way of "folding" with an ICmpZero is to use a
- // negated immediate.
- if (!ICmpScaledV)
- ICmpScaledV = ConstantInt::get(IntTy, -F.AM.BaseOffs);
- else {
- Ops.push_back(SE.getUnknown(ICmpScaledV));
- ICmpScaledV = ConstantInt::get(IntTy, F.AM.BaseOffs);
+ // Split the expression into subexprs.
+ SeparateSubExprs(SubExprs, Uses[i].Base, SE);
+
+ // Remove any common subexpressions.
+ for (unsigned j = 0, e = SubExprs.size(); j != e; ++j)
+ if (SubExpressionUseData.count(SubExprs[j])) {
+ SubExprs.erase(SubExprs.begin()+j);
+ --j; --e;
}
- } else {
- // Just add the immediate values. These again are expected to be matched
- // as part of the address.
- Ops.push_back(SE.getSCEV(ConstantInt::get(IntTy, F.AM.BaseOffs)));
- }
+
+ // Finally, add the non-shared expressions together.
+ if (SubExprs.empty())
+ Uses[i].Base = Zero;
+ else
+ Uses[i].Base = SE->getAddExpr(SubExprs);
+ SubExprs.clear();
}
- // Emit instructions summing all the operands.
- const SCEV *FullS = Ops.empty() ?
- SE.getIntegerSCEV(0, IntTy) :
- SE.getAddExpr(Ops);
- Value *FullV = Rewriter.expandCodeFor(FullS, Ty, IP);
-
- // We're done expanding now, so reset the rewriter.
- Rewriter.setPostInc(0);
-
- // An ICmpZero Formula represents an ICmp which we're handling as a
- // comparison against zero. Now that we've expanded an expression for that
- // form, update the ICmp's other operand.
- if (Kind == ICmpZero) {
- ICmpInst *CI = cast<ICmpInst>(UserInst);
- DeadInsts.push_back(CI->getOperand(1));
- assert(!F.AM.BaseGV && "ICmp does not support folding a global value and "
- "a scale at the same time!");
- if (F.AM.Scale == -1) {
- if (ICmpScaledV->getType() != OpTy) {
- Instruction *Cast =
- CastInst::Create(CastInst::getCastOpcode(ICmpScaledV, false,
- OpTy, false),
- ICmpScaledV, OpTy, "tmp", CI);
- ICmpScaledV = Cast;
- }
- CI->setOperand(1, ICmpScaledV);
- } else {
- assert(F.AM.Scale == 0 &&
- "ICmp does not support folding a global value and "
- "a scale at the same time!");
- Constant *C = ConstantInt::getSigned(SE.getEffectiveSCEVType(OpTy),
- -(uint64_t)F.AM.BaseOffs);
- if (C->getType() != OpTy)
- C = ConstantExpr::getCast(CastInst::getCastOpcode(C, false,
- OpTy, false),
- C, OpTy);
-
- CI->setOperand(1, C);
- }
+ return Result;
+}
+
+/// ValidScale - Check whether the given Scale is valid for all loads and
+/// stores in UsersToProcess.
+///
+bool LoopStrengthReduce::ValidScale(bool HasBaseReg, int64_t Scale,
+ const std::vector<BasedUser>& UsersToProcess) {
+ if (!TLI)
+ return true;
+
+ for (unsigned i = 0, e = UsersToProcess.size(); i!=e; ++i) {
+ // If this is a load or other access, pass the type of the access in.
+ const Type *AccessTy =
+ Type::getVoidTy(UsersToProcess[i].Inst->getContext());
+ if (isAddressUse(UsersToProcess[i].Inst,
+ UsersToProcess[i].OperandValToReplace))
+ AccessTy = getAccessType(UsersToProcess[i].Inst);
+ else if (isa<PHINode>(UsersToProcess[i].Inst))
+ continue;
+
+ TargetLowering::AddrMode AM;
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(UsersToProcess[i].Imm))
+ AM.BaseOffs = SC->getValue()->getSExtValue();
+ AM.HasBaseReg = HasBaseReg || !UsersToProcess[i].Base->isZero();
+ AM.Scale = Scale;
+
+ // If load[imm+r*scale] is illegal, bail out.
+ if (!TLI->isLegalAddressingMode(AM, AccessTy))
+ return false;
}
+ return true;
+}
- return FullV;
-}
-
-/// Rewrite - Emit instructions for the leading candidate expression for this
-/// LSRUse (this is called "expanding"), and update the UserInst to reference
-/// the newly expanded value.
-void LSRUse::Rewrite(Loop *L, Instruction *IVIncInsertPos,
- SCEVExpander &Rewriter,
- SmallVectorImpl<WeakVH> &DeadInsts,
- ScalarEvolution &SE, DominatorTree &DT,
- Pass *P) const {
- const Type *OpTy = OperandValToReplace->getType();
-
- // First, find an insertion point that dominates UserInst. For PHI nodes,
- // find the nearest block which dominates all the relevant uses.
- if (PHINode *PN = dyn_cast<PHINode>(UserInst)) {
- DenseMap<BasicBlock *, Value *> Inserted;
- for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
- if (PN->getIncomingValue(i) == OperandValToReplace) {
- BasicBlock *BB = PN->getIncomingBlock(i);
+/// ValidOffset - Check whether the given Offset is valid for all loads and
+/// stores in UsersToProcess.
+///
+bool LoopStrengthReduce::ValidOffset(bool HasBaseReg,
+ int64_t Offset,
+ int64_t Scale,
+ const std::vector<BasedUser>& UsersToProcess) {
+ if (!TLI)
+ return true;
- // If this is a critical edge, split the edge so that we do not insert
- // the code on all predecessor/successor paths. We do this unless this
- // is the canonical backedge for this loop, which complicates post-inc
- // users.
- if (e != 1 && BB->getTerminator()->getNumSuccessors() > 1 &&
- !isa<IndirectBrInst>(BB->getTerminator()) &&
- (PN->getParent() != L->getHeader() || !L->contains(BB))) {
- // Split the critical edge.
- BasicBlock *NewBB = SplitCriticalEdge(BB, PN->getParent(), P);
+ for (unsigned i=0, e = UsersToProcess.size(); i!=e; ++i) {
+ // If this is a load or other access, pass the type of the access in.
+ const Type *AccessTy =
+ Type::getVoidTy(UsersToProcess[i].Inst->getContext());
+ if (isAddressUse(UsersToProcess[i].Inst,
+ UsersToProcess[i].OperandValToReplace))
+ AccessTy = getAccessType(UsersToProcess[i].Inst);
+ else if (isa<PHINode>(UsersToProcess[i].Inst))
+ continue;
- // If PN is outside of the loop and BB is in the loop, we want to
- // move the block to be immediately before the PHI block, not
- // immediately after BB.
- if (L->contains(BB) && !L->contains(PN))
- NewBB->moveBefore(PN->getParent());
+ TargetLowering::AddrMode AM;
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(UsersToProcess[i].Imm))
+ AM.BaseOffs = SC->getValue()->getSExtValue();
+ AM.BaseOffs = (uint64_t)AM.BaseOffs + (uint64_t)Offset;
+ AM.HasBaseReg = HasBaseReg || !UsersToProcess[i].Base->isZero();
+ AM.Scale = Scale;
- // Splitting the edge can reduce the number of PHI entries we have.
- e = PN->getNumIncomingValues();
- BB = NewBB;
- i = PN->getBasicBlockIndex(BB);
- }
+ // If load[imm+r*scale] is illegal, bail out.
+ if (!TLI->isLegalAddressingMode(AM, AccessTy))
+ return false;
+ }
+ return true;
+}
- std::pair<DenseMap<BasicBlock *, Value *>::iterator, bool> Pair =
- Inserted.insert(std::make_pair(BB, static_cast<Value *>(0)));
- if (!Pair.second)
- PN->setIncomingValue(i, Pair.first->second);
- else {
- Value *FullV = Expand(BB->getTerminator(), L, IVIncInsertPos,
- Rewriter, DeadInsts, SE, DT);
-
- // If this is reuse-by-noop-cast, insert the noop cast.
- if (FullV->getType() != OpTy)
- FullV =
- CastInst::Create(CastInst::getCastOpcode(FullV, false,
- OpTy, false),
- FullV, OperandValToReplace->getType(),
- "tmp", BB->getTerminator());
+/// RequiresTypeConversion - Returns true if converting Ty1 to Ty2 is not
+/// a nop.
+bool LoopStrengthReduce::RequiresTypeConversion(const Type *Ty1,
+ const Type *Ty2) {
+ if (Ty1 == Ty2)
+ return false;
+ Ty1 = SE->getEffectiveSCEVType(Ty1);
+ Ty2 = SE->getEffectiveSCEVType(Ty2);
+ if (Ty1 == Ty2)
+ return false;
+ if (Ty1->canLosslesslyBitCastTo(Ty2))
+ return false;
+ if (TLI && TLI->isTruncateFree(Ty1, Ty2))
+ return false;
+ return true;
+}
- PN->setIncomingValue(i, FullV);
- Pair.first->second = FullV;
+/// CheckForIVReuse - Returns the multiple if the stride is the multiple
+/// of a previous stride and it is a legal value for the target addressing
+/// mode scale component and optional base reg. This allows the users of
+/// this stride to be rewritten as prev iv * factor. It returns 0 if no
+/// reuse is possible. Factors can be negative on same targets, e.g. ARM.
+///
+/// If all uses are outside the loop, we don't require that all multiplies
+/// be folded into the addressing mode, nor even that the factor be constant;
+/// a multiply (executed once) outside the loop is better than another IV
+/// within. Well, usually.
+const SCEV *LoopStrengthReduce::CheckForIVReuse(bool HasBaseReg,
+ bool AllUsesAreAddresses,
+ bool AllUsesAreOutsideLoop,
+ const SCEV *Stride,
+ IVExpr &IV, const Type *Ty,
+ const std::vector<BasedUser>& UsersToProcess) {
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Stride)) {
+ int64_t SInt = SC->getValue()->getSExtValue();
+ for (unsigned NewStride = 0, e = IU->StrideOrder.size();
+ NewStride != e; ++NewStride) {
+ std::map<const SCEV *, IVsOfOneStride>::iterator SI =
+ IVsByStride.find(IU->StrideOrder[NewStride]);
+ if (SI == IVsByStride.end() || !isa<SCEVConstant>(SI->first))
+ continue;
+ // The other stride has no uses, don't reuse it.
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator UI =
+ IU->IVUsesByStride.find(IU->StrideOrder[NewStride]);
+ if (UI->second->Users.empty())
+ continue;
+ int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
+ if (SI->first != Stride &&
+ (unsigned(abs64(SInt)) < SSInt || (SInt % SSInt) != 0))
+ continue;
+ int64_t Scale = SInt / SSInt;
+ // Check that this stride is valid for all the types used for loads and
+ // stores; if it can be used for some and not others, we might as well use
+ // the original stride everywhere, since we have to create the IV for it
+ // anyway. If the scale is 1, then we don't need to worry about folding
+ // multiplications.
+ if (Scale == 1 ||
+ (AllUsesAreAddresses &&
+ ValidScale(HasBaseReg, Scale, UsersToProcess))) {
+ // Prefer to reuse an IV with a base of zero.
+ for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(),
+ IE = SI->second.IVs.end(); II != IE; ++II)
+ // Only reuse previous IV if it would not require a type conversion
+ // and if the base difference can be folded.
+ if (II->Base->isZero() &&
+ !RequiresTypeConversion(II->Base->getType(), Ty)) {
+ IV = *II;
+ return SE->getIntegerSCEV(Scale, Stride->getType());
+ }
+ // Otherwise, settle for an IV with a foldable base.
+ if (AllUsesAreAddresses)
+ for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(),
+ IE = SI->second.IVs.end(); II != IE; ++II)
+ // Only reuse previous IV if it would not require a type conversion
+ // and if the base difference can be folded.
+ if (SE->getEffectiveSCEVType(II->Base->getType()) ==
+ SE->getEffectiveSCEVType(Ty) &&
+ isa<SCEVConstant>(II->Base)) {
+ int64_t Base =
+ cast<SCEVConstant>(II->Base)->getValue()->getSExtValue();
+ if (Base > INT32_MIN && Base <= INT32_MAX &&
+ ValidOffset(HasBaseReg, -Base * Scale,
+ Scale, UsersToProcess)) {
+ IV = *II;
+ return SE->getIntegerSCEV(Scale, Stride->getType());
+ }
+ }
+ }
+ }
+ } else if (AllUsesAreOutsideLoop) {
+ // Accept nonconstant strides here; it is really really right to substitute
+ // an existing IV if we can.
+ for (unsigned NewStride = 0, e = IU->StrideOrder.size();
+ NewStride != e; ++NewStride) {
+ std::map<const SCEV *, IVsOfOneStride>::iterator SI =
+ IVsByStride.find(IU->StrideOrder[NewStride]);
+ if (SI == IVsByStride.end() || !isa<SCEVConstant>(SI->first))
+ continue;
+ int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
+ if (SI->first != Stride && SSInt != 1)
+ continue;
+ for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(),
+ IE = SI->second.IVs.end(); II != IE; ++II)
+ // Accept nonzero base here.
+ // Only reuse previous IV if it would not require a type conversion.
+ if (!RequiresTypeConversion(II->Base->getType(), Ty)) {
+ IV = *II;
+ return Stride;
}
+ }
+ // Special case, old IV is -1*x and this one is x. Can treat this one as
+ // -1*old.
+ for (unsigned NewStride = 0, e = IU->StrideOrder.size();
+ NewStride != e; ++NewStride) {
+ std::map<const SCEV *, IVsOfOneStride>::iterator SI =
+ IVsByStride.find(IU->StrideOrder[NewStride]);
+ if (SI == IVsByStride.end())
+ continue;
+ if (const SCEVMulExpr *ME = dyn_cast<SCEVMulExpr>(SI->first))
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(ME->getOperand(0)))
+ if (Stride == ME->getOperand(1) &&
+ SC->getValue()->getSExtValue() == -1LL)
+ for (std::vector<IVExpr>::iterator II = SI->second.IVs.begin(),
+ IE = SI->second.IVs.end(); II != IE; ++II)
+ // Accept nonzero base here.
+ // Only reuse previous IV if it would not require type conversion.
+ if (!RequiresTypeConversion(II->Base->getType(), Ty)) {
+ IV = *II;
+ return SE->getIntegerSCEV(-1LL, Stride->getType());
+ }
+ }
+ }
+ return SE->getIntegerSCEV(0, Stride->getType());
+}
+
+/// PartitionByIsUseOfPostIncrementedValue - Simple boolean predicate that
+/// returns true if Val's isUseOfPostIncrementedValue is true.
+static bool PartitionByIsUseOfPostIncrementedValue(const BasedUser &Val) {
+ return Val.isUseOfPostIncrementedValue;
+}
+
+/// isNonConstantNegative - Return true if the specified scev is negated, but
+/// not a constant.
+static bool isNonConstantNegative(const SCEV *Expr) {
+ const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(Expr);
+ if (!Mul) return false;
+
+ // If there is a constant factor, it will be first.
+ const SCEVConstant *SC = dyn_cast<SCEVConstant>(Mul->getOperand(0));
+ if (!SC) return false;
+
+ // Return true if the value is negative, this matches things like (-42 * V).
+ return SC->getValue()->getValue().isNegative();
+}
+
+/// CollectIVUsers - Transform our list of users and offsets to a bit more
+/// complex table. In this new vector, each 'BasedUser' contains 'Base', the
+/// base of the strided accesses, as well as the old information from Uses. We
+/// progressively move information from the Base field to the Imm field, until
+/// we eventually have the full access expression to rewrite the use.
+const SCEV *LoopStrengthReduce::CollectIVUsers(const SCEV *Stride,
+ IVUsersOfOneStride &Uses,
+ Loop *L,
+ bool &AllUsesAreAddresses,
+ bool &AllUsesAreOutsideLoop,
+ std::vector<BasedUser> &UsersToProcess) {
+ // FIXME: Generalize to non-affine IV's.
+ if (!Stride->isLoopInvariant(L))
+ return SE->getIntegerSCEV(0, Stride->getType());
+
+ UsersToProcess.reserve(Uses.Users.size());
+ for (ilist<IVStrideUse>::iterator I = Uses.Users.begin(),
+ E = Uses.Users.end(); I != E; ++I) {
+ UsersToProcess.push_back(BasedUser(*I, SE));
+
+ // Move any loop variant operands from the offset field to the immediate
+ // field of the use, so that we don't try to use something before it is
+ // computed.
+ MoveLoopVariantsToImmediateField(UsersToProcess.back().Base,
+ UsersToProcess.back().Imm, L, SE);
+ assert(UsersToProcess.back().Base->isLoopInvariant(L) &&
+ "Base value is not loop invariant!");
+ }
+
+ // We now have a whole bunch of uses of like-strided induction variables, but
+ // they might all have different bases. We want to emit one PHI node for this
+ // stride which we fold as many common expressions (between the IVs) into as
+ // possible. Start by identifying the common expressions in the base values
+ // for the strides (e.g. if we have "A+C+B" and "A+B+D" as our bases, find
+ // "A+B"), emit it to the preheader, then remove the expression from the
+ // UsersToProcess base values.
+ const SCEV *CommonExprs =
+ RemoveCommonExpressionsFromUseBases(UsersToProcess, SE, L, TLI);
+
+ // Next, figure out what we can represent in the immediate fields of
+ // instructions. If we can represent anything there, move it to the imm
+ // fields of the BasedUsers. We do this so that it increases the commonality
+ // of the remaining uses.
+ unsigned NumPHI = 0;
+ bool HasAddress = false;
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) {
+ // If the user is not in the current loop, this means it is using the exit
+ // value of the IV. Do not put anything in the base, make sure it's all in
+ // the immediate field to allow as much factoring as possible.
+ if (!L->contains(UsersToProcess[i].Inst)) {
+ UsersToProcess[i].Imm = SE->getAddExpr(UsersToProcess[i].Imm,
+ UsersToProcess[i].Base);
+ UsersToProcess[i].Base =
+ SE->getIntegerSCEV(0, UsersToProcess[i].Base->getType());
+ } else {
+ // Not all uses are outside the loop.
+ AllUsesAreOutsideLoop = false;
+
+ // Addressing modes can be folded into loads and stores. Be careful that
+ // the store is through the expression, not of the expression though.
+ bool isPHI = false;
+ bool isAddress = isAddressUse(UsersToProcess[i].Inst,
+ UsersToProcess[i].OperandValToReplace);
+ if (isa<PHINode>(UsersToProcess[i].Inst)) {
+ isPHI = true;
+ ++NumPHI;
}
- } else {
- Value *FullV = Expand(UserInst, L, IVIncInsertPos,
- Rewriter, DeadInsts, SE, DT);
- // If this is reuse-by-noop-cast, insert the noop cast.
- if (FullV->getType() != OpTy) {
- Instruction *Cast =
- CastInst::Create(CastInst::getCastOpcode(FullV, false, OpTy, false),
- FullV, OpTy, "tmp", UserInst);
- FullV = Cast;
- }
-
- // Update the user.
- UserInst->replaceUsesOfWith(OperandValToReplace, FullV);
- }
-
- DeadInsts.push_back(OperandValToReplace);
-}
-
-void LSRUse::print(raw_ostream &OS) const {
- OS << "LSR Use: Kind=";
- switch (Kind) {
- case Basic: OS << "Basic"; break;
- case Special: OS << "Special"; break;
- case ICmpZero: OS << "ICmpZero"; break;
- case Address:
- OS << "Address of ";
- if (isa<PointerType>(AccessTy))
- OS << "pointer"; // the full pointer type could be really verbose
- else
- OS << *AccessTy;
+ if (isAddress)
+ HasAddress = true;
+
+ // If this use isn't an address, then not all uses are addresses.
+ if (!isAddress && !isPHI)
+ AllUsesAreAddresses = false;
+
+ MoveImmediateValues(TLI, UsersToProcess[i].Inst, UsersToProcess[i].Base,
+ UsersToProcess[i].Imm, isAddress, L, SE);
+ }
}
- OS << ", UserInst=";
- // Store is common and interesting enough to be worth special-casing.
- if (StoreInst *Store = dyn_cast<StoreInst>(UserInst)) {
- OS << "store ";
- WriteAsOperand(OS, Store->getOperand(0), /*PrintType=*/false);
- } else if (UserInst->getType()->isVoidTy())
- OS << UserInst->getOpcodeName();
- else
- WriteAsOperand(OS, UserInst, /*PrintType=*/false);
+ // If one of the use is a PHI node and all other uses are addresses, still
+ // allow iv reuse. Essentially we are trading one constant multiplication
+ // for one fewer iv.
+ if (NumPHI > 1)
+ AllUsesAreAddresses = false;
- OS << ", OperandValToReplace=";
- WriteAsOperand(OS, OperandValToReplace, /*PrintType=*/false);
+ // There are no in-loop address uses.
+ if (AllUsesAreAddresses && (!HasAddress && !AllUsesAreOutsideLoop))
+ AllUsesAreAddresses = false;
- if (PostIncLoop) {
- OS << ", PostIncLoop=";
- WriteAsOperand(OS, PostIncLoop->getHeader(), /*PrintType=*/false);
- }
+ return CommonExprs;
}
-void LSRUse::dump() const {
- print(errs()); errs() << '\n';
-}
+/// ShouldUseFullStrengthReductionMode - Test whether full strength-reduction
+/// is valid and profitable for the given set of users of a stride. In
+/// full strength-reduction mode, all addresses at the current stride are
+/// strength-reduced all the way down to pointer arithmetic.
+///
+bool LoopStrengthReduce::ShouldUseFullStrengthReductionMode(
+ const std::vector<BasedUser> &UsersToProcess,
+ const Loop *L,
+ bool AllUsesAreAddresses,
+ const SCEV *Stride) {
+ if (!EnableFullLSRMode)
+ return false;
-namespace {
+ // The heuristics below aim to avoid increasing register pressure, but
+ // fully strength-reducing all the addresses increases the number of
+ // add instructions, so don't do this when optimizing for size.
+ // TODO: If the loop is large, the savings due to simpler addresses
+ // may oughtweight the costs of the extra increment instructions.
+ if (L->getHeader()->getParent()->hasFnAttr(Attribute::OptimizeForSize))
+ return false;
-/// Score - This class is used to measure and compare candidate formulae.
-class Score {
- unsigned NumRegs;
- unsigned NumPhis;
- unsigned NumIVMuls;
- unsigned NumBaseAdds;
- unsigned NumImms;
-
-public:
- Score()
- : NumRegs(0), NumPhis(0), NumIVMuls(0), NumBaseAdds(0), NumImms(0) {}
-
- void RateInitial(SmallVector<LSRUse, 16> const &Uses, const Loop *L,
- ScalarEvolution &SE);
-
- void Rate(const SCEV *Reg, const SmallBitVector &Bits,
- const SmallVector<LSRUse, 16> &Uses, const Loop *L,
- ScalarEvolution &SE);
-
- unsigned getNumRegs() const { return NumRegs; }
-
- bool operator<(const Score &Other) const;
-
- void print_details(raw_ostream &OS, const SCEV *Reg,
- const SmallPtrSet<const SCEV *, 8> &Regs) const;
-
- void print(raw_ostream &OS) const;
- void dump() const;
-
-private:
- void RateRegister(const SCEV *Reg, SmallPtrSet<const SCEV *, 8> &Regs,
- const Loop *L);
- void RateFormula(const Formula &F, SmallPtrSet<const SCEV *, 8> &Regs,
- const Loop *L);
-
- void Loose();
-};
-
-}
-
-/// RateRegister - Tally up interesting quantities from the given register.
-void Score::RateRegister(const SCEV *Reg,
- SmallPtrSet<const SCEV *, 8> &Regs,
- const Loop *L) {
- if (Regs.insert(Reg))
- if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(Reg)) {
- NumPhis += AR->getLoop() == L;
-
- // Add the step value register, if it needs one.
- if (!AR->isAffine() || !isa<SCEVConstant>(AR->getOperand(1)))
- RateRegister(AR->getOperand(1), Regs, L);
- }
-}
-
-void Score::RateFormula(const Formula &F,
- SmallPtrSet<const SCEV *, 8> &Regs,
- const Loop *L) {
- // Tally up the registers.
- if (F.ScaledReg)
- RateRegister(F.ScaledReg, Regs, L);
- for (SmallVectorImpl<const SCEV *>::const_iterator I = F.BaseRegs.begin(),
- E = F.BaseRegs.end(); I != E; ++I) {
- const SCEV *BaseReg = *I;
- RateRegister(BaseReg, Regs, L);
-
- NumIVMuls += isa<SCEVMulExpr>(BaseReg) &&
- BaseReg->hasComputableLoopEvolution(L);
- }
-
- if (F.BaseRegs.size() > 1)
- NumBaseAdds += F.BaseRegs.size() - 1;
-
- // Tally up the non-zero immediates.
- if (F.AM.BaseGV || F.AM.BaseOffs != 0)
- ++NumImms;
-}
-
-/// Loose - Set this score to a loosing value.
-void Score::Loose() {
- NumRegs = ~0u;
- NumPhis = ~0u;
- NumIVMuls = ~0u;
- NumBaseAdds = ~0u;
- NumImms = ~0u;
-}
-
-/// RateInitial - Compute a score for the initial "fully reduced" solution.
-void Score::RateInitial(SmallVector<LSRUse, 16> const &Uses, const Loop *L,
- ScalarEvolution &SE) {
- SmallPtrSet<const SCEV *, 8> Regs;
- for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),
- E = Uses.end(); I != E; ++I)
- RateFormula(I->Formulae.front(), Regs, L);
- NumRegs += Regs.size();
-
- DEBUG(print_details(dbgs(), 0, Regs));
-}
-
-/// Rate - Compute a score for the solution where the reuse associated with
-/// putting Reg in a register is selected.
-void Score::Rate(const SCEV *Reg, const SmallBitVector &Bits,
- const SmallVector<LSRUse, 16> &Uses, const Loop *L,
- ScalarEvolution &SE) {
- SmallPtrSet<const SCEV *, 8> Regs;
- for (size_t i = 0, e = Uses.size(); i != e; ++i) {
- const LSRUse &LU = Uses[i];
-
- const Formula *BestFormula = 0;
- if (i >= Bits.size() || !Bits.test(i))
- // This use doesn't use the current register. Just go with the current
- // leading candidate formula.
- BestFormula = &LU.Formulae.front();
- else
- // Find the best formula for this use that uses the current register.
- for (SmallVectorImpl<Formula>::const_iterator I = LU.Formulae.begin(),
- E = LU.Formulae.end(); I != E; ++I) {
- const Formula &F = *I;
- if (F.referencesReg(Reg) &&
- (!BestFormula || ComplexitySorter()(F, *BestFormula)))
- BestFormula = &F;
- }
-
- // If we didn't find *any* forumlae, because earlier we eliminated some
- // in greedy fashion, skip the current register's reuse opportunity.
- if (!BestFormula) {
- DEBUG(dbgs() << "Reuse with reg " << *Reg
- << " wouldn't help any users.\n");
- Loose();
- return;
- }
-
- // For an in-loop post-inc user, don't allow multiple base registers,
- // because that would require an awkward in-loop add after the increment.
- if (LU.PostIncLoop && LU.PostIncLoop->contains(LU.UserInst) &&
- BestFormula->BaseRegs.size() > 1) {
- DEBUG(dbgs() << "Reuse with reg " << *Reg
- << " would require an in-loop post-inc add: ";
- BestFormula->dump());
- Loose();
- return;
- }
-
- RateFormula(*BestFormula, Regs, L);
- }
- NumRegs += Regs.size();
-
- DEBUG(print_details(dbgs(), Reg, Regs));
-}
-
-/// operator< - Choose the better score.
-bool Score::operator<(const Score &Other) const {
- if (NumRegs != Other.NumRegs)
- return NumRegs < Other.NumRegs;
- if (NumPhis != Other.NumPhis)
- return NumPhis < Other.NumPhis;
- if (NumIVMuls != Other.NumIVMuls)
- return NumIVMuls < Other.NumIVMuls;
- if (NumBaseAdds != Other.NumBaseAdds)
- return NumBaseAdds < Other.NumBaseAdds;
- return NumImms < Other.NumImms;
-}
-
-void Score::print_details(raw_ostream &OS,
- const SCEV *Reg,
- const SmallPtrSet<const SCEV *, 8> &Regs) const {
- if (Reg) OS << "Reuse with reg " << *Reg << " would require ";
- else OS << "The initial solution would require ";
- print(OS);
- OS << ". Regs:";
- for (SmallPtrSet<const SCEV *, 8>::const_iterator I = Regs.begin(),
- E = Regs.end(); I != E; ++I)
- OS << ' ' << **I;
- OS << '\n';
-}
-
-void Score::print(raw_ostream &OS) const {
- OS << NumRegs << " reg" << (NumRegs == 1 ? "" : "s");
- if (NumPhis != 0)
- OS << ", including " << NumPhis << " PHI" << (NumPhis == 1 ? "" : "s");
- if (NumIVMuls != 0)
- OS << ", plus " << NumIVMuls << " IV mul" << (NumIVMuls == 1 ? "" : "s");
- if (NumBaseAdds != 0)
- OS << ", plus " << NumBaseAdds << " base add"
- << (NumBaseAdds == 1 ? "" : "s");
- if (NumImms != 0)
- OS << ", plus " << NumImms << " imm" << (NumImms == 1 ? "" : "s");
-}
+ // TODO: For now, don't do full strength reduction if there could
+ // potentially be greater-stride multiples of the current stride
+ // which could reuse the current stride IV.
+ if (IU->StrideOrder.back() != Stride)
+ return false;
+
+ // Iterate through the uses to find conditions that automatically rule out
+ // full-lsr mode.
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ) {
+ const SCEV *Base = UsersToProcess[i].Base;
+ const SCEV *Imm = UsersToProcess[i].Imm;
+ // If any users have a loop-variant component, they can't be fully
+ // strength-reduced.
+ if (Imm && !Imm->isLoopInvariant(L))
+ return false;
+ // If there are to users with the same base and the difference between
+ // the two Imm values can't be folded into the address, full
+ // strength reduction would increase register pressure.
+ do {
+ const SCEV *CurImm = UsersToProcess[i].Imm;
+ if ((CurImm || Imm) && CurImm != Imm) {
+ if (!CurImm) CurImm = SE->getIntegerSCEV(0, Stride->getType());
+ if (!Imm) Imm = SE->getIntegerSCEV(0, Stride->getType());
+ const Instruction *Inst = UsersToProcess[i].Inst;
+ const Type *AccessTy = getAccessType(Inst);
+ const SCEV *Diff = SE->getMinusSCEV(UsersToProcess[i].Imm, Imm);
+ if (!Diff->isZero() &&
+ (!AllUsesAreAddresses ||
+ !fitsInAddressMode(Diff, AccessTy, TLI, /*HasBaseReg=*/true)))
+ return false;
+ }
+ } while (++i != e && Base == UsersToProcess[i].Base);
+ }
+
+ // If there's exactly one user in this stride, fully strength-reducing it
+ // won't increase register pressure. If it's starting from a non-zero base,
+ // it'll be simpler this way.
+ if (UsersToProcess.size() == 1 && !UsersToProcess[0].Base->isZero())
+ return true;
+
+ // Otherwise, if there are any users in this stride that don't require
+ // a register for their base, full strength-reduction will increase
+ // register pressure.
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i)
+ if (UsersToProcess[i].Base->isZero())
+ return false;
-void Score::dump() const {
- print(errs()); errs() << '\n';
+ // Otherwise, go for it.
+ return true;
}
-/// isAddressUse - Returns true if the specified instruction is using the
-/// specified value as an address.
-static bool isAddressUse(Instruction *Inst, Value *OperandVal) {
- bool isAddress = isa<LoadInst>(Inst);
- if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
- if (SI->getOperand(1) == OperandVal)
- isAddress = true;
- } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
- // Addressing modes can also be folded into prefetches and a variety
- // of intrinsics.
- switch (II->getIntrinsicID()) {
- default: break;
- case Intrinsic::prefetch:
- case Intrinsic::x86_sse2_loadu_dq:
- case Intrinsic::x86_sse2_loadu_pd:
- case Intrinsic::x86_sse_loadu_ps:
- case Intrinsic::x86_sse_storeu_ps:
- case Intrinsic::x86_sse2_storeu_pd:
- case Intrinsic::x86_sse2_storeu_dq:
- case Intrinsic::x86_sse2_storel_dq:
- if (II->getOperand(1) == OperandVal)
- isAddress = true;
- break;
- }
- }
- return isAddress;
-}
+/// InsertAffinePhi Create and insert a PHI node for an induction variable
+/// with the specified start and step values in the specified loop.
+///
+/// If NegateStride is true, the stride should be negated by using a
+/// subtract instead of an add.
+///
+/// Return the created phi node.
+///
+static PHINode *InsertAffinePhi(const SCEV *Start, const SCEV *Step,
+ Instruction *IVIncInsertPt,
+ const Loop *L,
+ SCEVExpander &Rewriter) {
+ assert(Start->isLoopInvariant(L) && "New PHI start is not loop invariant!");
+ assert(Step->isLoopInvariant(L) && "New PHI stride is not loop invariant!");
-/// getAccessType - Return the type of the memory being accessed.
-static const Type *getAccessType(const Instruction *Inst) {
- const Type *AccessTy = Inst->getType();
- if (const StoreInst *SI = dyn_cast<StoreInst>(Inst))
- AccessTy = SI->getOperand(0)->getType();
- else if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) {
- // Addressing modes can also be folded into prefetches and a variety
- // of intrinsics.
- switch (II->getIntrinsicID()) {
- default: break;
- case Intrinsic::x86_sse_storeu_ps:
- case Intrinsic::x86_sse2_storeu_pd:
- case Intrinsic::x86_sse2_storeu_dq:
- case Intrinsic::x86_sse2_storel_dq:
- AccessTy = II->getOperand(1)->getType();
- break;
- }
+ BasicBlock *Header = L->getHeader();
+ BasicBlock *Preheader = L->getLoopPreheader();
+ BasicBlock *LatchBlock = L->getLoopLatch();
+ const Type *Ty = Start->getType();
+ Ty = Rewriter.SE.getEffectiveSCEVType(Ty);
+
+ PHINode *PN = PHINode::Create(Ty, "lsr.iv", Header->begin());
+ PN->addIncoming(Rewriter.expandCodeFor(Start, Ty, Preheader->getTerminator()),
+ Preheader);
+
+ // If the stride is negative, insert a sub instead of an add for the
+ // increment.
+ bool isNegative = isNonConstantNegative(Step);
+ const SCEV *IncAmount = Step;
+ if (isNegative)
+ IncAmount = Rewriter.SE.getNegativeSCEV(Step);
+
+ // Insert an add instruction right before the terminator corresponding
+ // to the back-edge or just before the only use. The location is determined
+ // by the caller and passed in as IVIncInsertPt.
+ Value *StepV = Rewriter.expandCodeFor(IncAmount, Ty,
+ Preheader->getTerminator());
+ Instruction *IncV;
+ if (isNegative) {
+ IncV = BinaryOperator::CreateSub(PN, StepV, "lsr.iv.next",
+ IVIncInsertPt);
+ } else {
+ IncV = BinaryOperator::CreateAdd(PN, StepV, "lsr.iv.next",
+ IVIncInsertPt);
}
- return AccessTy;
-}
+ if (!isa<ConstantInt>(StepV)) ++NumVariable;
-/// DeleteTriviallyDeadInstructions - If any of the instructions is the
-/// specified set are trivially dead, delete them and see if this makes any of
-/// their operands subsequently dead.
-static bool
-DeleteTriviallyDeadInstructions(SmallVectorImpl<WeakVH> &DeadInsts) {
- bool Changed = false;
+ PN->addIncoming(IncV, LatchBlock);
- while (!DeadInsts.empty()) {
- Instruction *I = dyn_cast_or_null<Instruction>(DeadInsts.pop_back_val());
+ ++NumInserted;
+ return PN;
+}
- if (I == 0 || !isInstructionTriviallyDead(I))
- continue;
+static void SortUsersToProcess(std::vector<BasedUser> &UsersToProcess) {
+ // We want to emit code for users inside the loop first. To do this, we
+ // rearrange BasedUser so that the entries at the end have
+ // isUseOfPostIncrementedValue = false, because we pop off the end of the
+ // vector (so we handle them first).
+ std::partition(UsersToProcess.begin(), UsersToProcess.end(),
+ PartitionByIsUseOfPostIncrementedValue);
- for (User::op_iterator OI = I->op_begin(), E = I->op_end(); OI != E; ++OI)
- if (Instruction *U = dyn_cast<Instruction>(*OI)) {
- *OI = 0;
- if (U->use_empty())
- DeadInsts.push_back(U);
- }
+ // Sort this by base, so that things with the same base are handled
+ // together. By partitioning first and stable-sorting later, we are
+ // guaranteed that within each base we will pop off users from within the
+ // loop before users outside of the loop with a particular base.
+ //
+ // We would like to use stable_sort here, but we can't. The problem is that
+ // const SCEV *'s don't have a deterministic ordering w.r.t to each other, so
+ // we don't have anything to do a '<' comparison on. Because we think the
+ // number of uses is small, do a horrible bubble sort which just relies on
+ // ==.
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) {
+ // Get a base value.
+ const SCEV *Base = UsersToProcess[i].Base;
- I->eraseFromParent();
- Changed = true;
+ // Compact everything with this base to be consecutive with this one.
+ for (unsigned j = i+1; j != e; ++j) {
+ if (UsersToProcess[j].Base == Base) {
+ std::swap(UsersToProcess[i+1], UsersToProcess[j]);
+ ++i;
+ }
+ }
}
-
- return Changed;
}
-namespace {
-
-/// LSRInstance - This class holds state for the main loop strength
-/// reduction logic.
-class LSRInstance {
- IVUsers &IU;
- ScalarEvolution &SE;
- DominatorTree &DT;
- const TargetLowering *const TLI;
- Loop *const L;
- bool Changed;
-
- /// IVIncInsertPos - This is the insert position that the current loop's
- /// induction variable increment should be placed. In simple loops, this is
- /// the latch block's terminator. But in more complicated cases, this is
- /// a position which will dominate all the in-loop post-increment users.
- Instruction *IVIncInsertPos;
-
- /// CurrentArbitraryRegIndex - To ensure a deterministic ordering, assign an
- /// arbitrary index value to each register as a sort tie breaker.
- unsigned CurrentArbitraryRegIndex;
-
- /// MaxNumRegs - To help prune the search for solutions, identify the number
- /// of registers needed by the initial solution. No formula should require
- /// more than this.
- unsigned MaxNumRegs;
-
- /// Factors - Interesting factors between use strides.
- SmallSetVector<int64_t, 4> Factors;
-
- /// Types - Interesting use types, to facilitate truncation reuse.
- SmallSetVector<const Type *, 4> Types;
-
- /// Uses - The list of interesting uses.
- SmallVector<LSRUse, 16> Uses;
-
- // TODO: Reorganize these data structures.
- typedef DenseMap<const SCEV *, RegSortData> RegUsesTy;
- RegUsesTy RegUses;
- SmallVector<const SCEV *, 16> RegSequence;
-
- void OptimizeShadowIV();
- bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse,
- const SCEV* &CondStride);
- ICmpInst *OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse);
- bool StrideMightBeShared(const SCEV* Stride);
- bool OptimizeLoopTermCond();
-
- LSRUse &getNewUse() {
- Uses.push_back(LSRUse());
- return Uses.back();
- }
-
- void CountRegister(const SCEV *Reg, uint32_t Complexity, size_t LUIdx);
- void CountRegisters(const Formula &F, size_t LUIdx);
-
- bool InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F);
-
- void GenerateSymbolicOffsetReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base);
- void GenerateICmpZeroScaledReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base);
- void GenerateFormulaeFromReplacedBaseReg(LSRUse &LU,
- unsigned LUIdx,
- const Formula &Base, unsigned i,
- const SmallVectorImpl<const SCEV *>
- &AddOps);
- void GenerateReassociationReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base);
- void GenerateCombinationReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base);
- void GenerateScaledReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base);
- void GenerateTruncateReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base);
-
- void GenerateConstantOffsetReuse();
-
- void GenerateAllReuseFormulae();
-
- void GenerateLoopInvariantRegisterUses();
-
-public:
- LSRInstance(const TargetLowering *tli, Loop *l, Pass *P);
-
- bool getChanged() const { return Changed; }
-
- void print(raw_ostream &OS) const;
- void dump() const;
-};
-
+/// PrepareToStrengthReduceFully - Prepare to fully strength-reduce
+/// UsersToProcess, meaning lowering addresses all the way down to direct
+/// pointer arithmetic.
+///
+void
+LoopStrengthReduce::PrepareToStrengthReduceFully(
+ std::vector<BasedUser> &UsersToProcess,
+ const SCEV *Stride,
+ const SCEV *CommonExprs,
+ const Loop *L,
+ SCEVExpander &PreheaderRewriter) {
+ DEBUG(dbgs() << " Fully reducing all users\n");
+
+ // Rewrite the UsersToProcess records, creating a separate PHI for each
+ // unique Base value.
+ Instruction *IVIncInsertPt = L->getLoopLatch()->getTerminator();
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ) {
+ // TODO: The uses are grouped by base, but not sorted. We arbitrarily
+ // pick the first Imm value here to start with, and adjust it for the
+ // other uses.
+ const SCEV *Imm = UsersToProcess[i].Imm;
+ const SCEV *Base = UsersToProcess[i].Base;
+ const SCEV *Start = SE->getAddExpr(CommonExprs, Base, Imm);
+ PHINode *Phi = InsertAffinePhi(Start, Stride, IVIncInsertPt, L,
+ PreheaderRewriter);
+ // Loop over all the users with the same base.
+ do {
+ UsersToProcess[i].Base = SE->getIntegerSCEV(0, Stride->getType());
+ UsersToProcess[i].Imm = SE->getMinusSCEV(UsersToProcess[i].Imm, Imm);
+ UsersToProcess[i].Phi = Phi;
+ assert(UsersToProcess[i].Imm->isLoopInvariant(L) &&
+ "ShouldUseFullStrengthReductionMode should reject this!");
+ } while (++i != e && Base == UsersToProcess[i].Base);
+ }
}
-/// OptimizeShadowIV - If IV is used in a int-to-float cast
-/// inside the loop then try to eliminate the cast opeation.
-void LSRInstance::OptimizeShadowIV() {
- const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
- if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
- return;
+/// FindIVIncInsertPt - Return the location to insert the increment instruction.
+/// If the only use if a use of postinc value, (must be the loop termination
+/// condition), then insert it just before the use.
+static Instruction *FindIVIncInsertPt(std::vector<BasedUser> &UsersToProcess,
+ const Loop *L) {
+ if (UsersToProcess.size() == 1 &&
+ UsersToProcess[0].isUseOfPostIncrementedValue &&
+ L->contains(UsersToProcess[0].Inst))
+ return UsersToProcess[0].Inst;
+ return L->getLoopLatch()->getTerminator();
+}
- for (size_t StrideIdx = 0, e = IU.StrideOrder.size();
- StrideIdx != e; ++StrideIdx) {
- std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
- IU.IVUsesByStride.find(IU.StrideOrder[StrideIdx]);
- assert(SI != IU.IVUsesByStride.end() && "Stride doesn't exist!");
- if (!isa<SCEVConstant>(SI->first))
+/// PrepareToStrengthReduceWithNewPhi - Insert a new induction variable for the
+/// given users to share.
+///
+void
+LoopStrengthReduce::PrepareToStrengthReduceWithNewPhi(
+ std::vector<BasedUser> &UsersToProcess,
+ const SCEV *Stride,
+ const SCEV *CommonExprs,
+ Value *CommonBaseV,
+ Instruction *IVIncInsertPt,
+ const Loop *L,
+ SCEVExpander &PreheaderRewriter) {
+ DEBUG(dbgs() << " Inserting new PHI:\n");
+
+ PHINode *Phi = InsertAffinePhi(SE->getUnknown(CommonBaseV),
+ Stride, IVIncInsertPt, L,
+ PreheaderRewriter);
+
+ // Remember this in case a later stride is multiple of this.
+ IVsByStride[Stride].addIV(Stride, CommonExprs, Phi);
+
+ // All the users will share this new IV.
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i)
+ UsersToProcess[i].Phi = Phi;
+
+ DEBUG(dbgs() << " IV=");
+ DEBUG(WriteAsOperand(dbgs(), Phi, /*PrintType=*/false));
+ DEBUG(dbgs() << "\n");
+}
+
+/// PrepareToStrengthReduceFromSmallerStride - Prepare for the given users to
+/// reuse an induction variable with a stride that is a factor of the current
+/// induction variable.
+///
+void
+LoopStrengthReduce::PrepareToStrengthReduceFromSmallerStride(
+ std::vector<BasedUser> &UsersToProcess,
+ Value *CommonBaseV,
+ const IVExpr &ReuseIV,
+ Instruction *PreInsertPt) {
+ DEBUG(dbgs() << " Rewriting in terms of existing IV of STRIDE "
+ << *ReuseIV.Stride << " and BASE " << *ReuseIV.Base << "\n");
+
+ // All the users will share the reused IV.
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i)
+ UsersToProcess[i].Phi = ReuseIV.PHI;
+
+ Constant *C = dyn_cast<Constant>(CommonBaseV);
+ if (C &&
+ (!C->isNullValue() &&
+ !fitsInAddressMode(SE->getUnknown(CommonBaseV), CommonBaseV->getType(),
+ TLI, false)))
+ // We want the common base emitted into the preheader! This is just
+ // using cast as a copy so BitCast (no-op cast) is appropriate
+ CommonBaseV = new BitCastInst(CommonBaseV, CommonBaseV->getType(),
+ "commonbase", PreInsertPt);
+}
+
+static bool IsImmFoldedIntoAddrMode(GlobalValue *GV, int64_t Offset,
+ const Type *AccessTy,
+ std::vector<BasedUser> &UsersToProcess,
+ const TargetLowering *TLI) {
+ SmallVector<Instruction*, 16> AddrModeInsts;
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i) {
+ if (UsersToProcess[i].isUseOfPostIncrementedValue)
continue;
+ ExtAddrMode AddrMode =
+ AddressingModeMatcher::Match(UsersToProcess[i].OperandValToReplace,
+ AccessTy, UsersToProcess[i].Inst,
+ AddrModeInsts, *TLI);
+ if (GV && GV != AddrMode.BaseGV)
+ return false;
+ if (Offset && !AddrMode.BaseOffs)
+ // FIXME: How to accurate check it's immediate offset is folded.
+ return false;
+ AddrModeInsts.clear();
+ }
+ return true;
+}
- for (ilist<IVStrideUse>::iterator UI = SI->second->Users.begin(),
- E = SI->second->Users.end(); UI != E; /* empty */) {
- ilist<IVStrideUse>::iterator CandidateUI = UI;
- ++UI;
- Instruction *ShadowUse = CandidateUI->getUser();
- const Type *DestTy = NULL;
-
- /* If shadow use is a int->float cast then insert a second IV
- to eliminate this cast.
-
- for (unsigned i = 0; i < n; ++i)
- foo((double)i);
+/// StrengthReduceIVUsersOfStride - Strength reduce all of the users of a single
+/// stride of IV. All of the users may have different starting values, and this
+/// may not be the only stride.
+void
+LoopStrengthReduce::StrengthReduceIVUsersOfStride(const SCEV *Stride,
+ IVUsersOfOneStride &Uses,
+ Loop *L) {
+ // If all the users are moved to another stride, then there is nothing to do.
+ if (Uses.Users.empty())
+ return;
- is transformed into
+ // Keep track if every use in UsersToProcess is an address. If they all are,
+ // we may be able to rewrite the entire collection of them in terms of a
+ // smaller-stride IV.
+ bool AllUsesAreAddresses = true;
+
+ // Keep track if every use of a single stride is outside the loop. If so,
+ // we want to be more aggressive about reusing a smaller-stride IV; a
+ // multiply outside the loop is better than another IV inside. Well, usually.
+ bool AllUsesAreOutsideLoop = true;
+
+ // Transform our list of users and offsets to a bit more complex table. In
+ // this new vector, each 'BasedUser' contains 'Base' the base of the
+ // strided accessas well as the old information from Uses. We progressively
+ // move information from the Base field to the Imm field, until we eventually
+ // have the full access expression to rewrite the use.
+ std::vector<BasedUser> UsersToProcess;
+ const SCEV *CommonExprs = CollectIVUsers(Stride, Uses, L, AllUsesAreAddresses,
+ AllUsesAreOutsideLoop,
+ UsersToProcess);
+
+ // Sort the UsersToProcess array so that users with common bases are
+ // next to each other.
+ SortUsersToProcess(UsersToProcess);
+
+ // If we managed to find some expressions in common, we'll need to carry
+ // their value in a register and add it in for each use. This will take up
+ // a register operand, which potentially restricts what stride values are
+ // valid.
+ bool HaveCommonExprs = !CommonExprs->isZero();
+ const Type *ReplacedTy = CommonExprs->getType();
+
+ // If all uses are addresses, consider sinking the immediate part of the
+ // common expression back into uses if they can fit in the immediate fields.
+ if (TLI && HaveCommonExprs && AllUsesAreAddresses) {
+ const SCEV *NewCommon = CommonExprs;
+ const SCEV *Imm = SE->getIntegerSCEV(0, ReplacedTy);
+ MoveImmediateValues(TLI, Type::getVoidTy(
+ L->getLoopPreheader()->getContext()),
+ NewCommon, Imm, true, L, SE);
+ if (!Imm->isZero()) {
+ bool DoSink = true;
+
+ // If the immediate part of the common expression is a GV, check if it's
+ // possible to fold it into the target addressing mode.
+ GlobalValue *GV = 0;
+ if (const SCEVUnknown *SU = dyn_cast<SCEVUnknown>(Imm))
+ GV = dyn_cast<GlobalValue>(SU->getValue());
+ int64_t Offset = 0;
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(Imm))
+ Offset = SC->getValue()->getSExtValue();
+ if (GV || Offset)
+ // Pass VoidTy as the AccessTy to be conservative, because
+ // there could be multiple access types among all the uses.
+ DoSink = IsImmFoldedIntoAddrMode(GV, Offset,
+ Type::getVoidTy(L->getLoopPreheader()->getContext()),
+ UsersToProcess, TLI);
+
+ if (DoSink) {
+ DEBUG(dbgs() << " Sinking " << *Imm << " back down into uses\n");
+ for (unsigned i = 0, e = UsersToProcess.size(); i != e; ++i)
+ UsersToProcess[i].Imm = SE->getAddExpr(UsersToProcess[i].Imm, Imm);
+ CommonExprs = NewCommon;
+ HaveCommonExprs = !CommonExprs->isZero();
+ ++NumImmSunk;
+ }
+ }
+ }
+
+ // Now that we know what we need to do, insert the PHI node itself.
+ //
+ DEBUG(dbgs() << "LSR: Examining IVs of TYPE " << *ReplacedTy << " of STRIDE "
+ << *Stride << ":\n"
+ << " Common base: " << *CommonExprs << "\n");
- double d = 0.0;
- for (unsigned i = 0; i < n; ++i, ++d)
- foo(d);
- */
- if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser()))
- DestTy = UCast->getDestTy();
- else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser()))
- DestTy = SCast->getDestTy();
- if (!DestTy) continue;
+ SCEVExpander Rewriter(*SE);
+ SCEVExpander PreheaderRewriter(*SE);
- if (TLI) {
- // If target does not support DestTy natively then do not apply
- // this transformation.
- EVT DVT = TLI->getValueType(DestTy);
- if (!TLI->isTypeLegal(DVT)) continue;
- }
+ BasicBlock *Preheader = L->getLoopPreheader();
+ Instruction *PreInsertPt = Preheader->getTerminator();
+ BasicBlock *LatchBlock = L->getLoopLatch();
+ Instruction *IVIncInsertPt = LatchBlock->getTerminator();
- PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
- if (!PH) continue;
- if (PH->getNumIncomingValues() != 2) continue;
+ Value *CommonBaseV = Constant::getNullValue(ReplacedTy);
- const Type *SrcTy = PH->getType();
- int Mantissa = DestTy->getFPMantissaWidth();
- if (Mantissa == -1) continue;
- if ((int)SE.getTypeSizeInBits(SrcTy) > Mantissa)
- continue;
+ const SCEV *RewriteFactor = SE->getIntegerSCEV(0, ReplacedTy);
+ IVExpr ReuseIV(SE->getIntegerSCEV(0,
+ Type::getInt32Ty(Preheader->getContext())),
+ SE->getIntegerSCEV(0,
+ Type::getInt32Ty(Preheader->getContext())),
+ 0);
+
+ // Choose a strength-reduction strategy and prepare for it by creating
+ // the necessary PHIs and adjusting the bookkeeping.
+ if (ShouldUseFullStrengthReductionMode(UsersToProcess, L,
+ AllUsesAreAddresses, Stride)) {
+ PrepareToStrengthReduceFully(UsersToProcess, Stride, CommonExprs, L,
+ PreheaderRewriter);
+ } else {
+ // Emit the initial base value into the loop preheader.
+ CommonBaseV = PreheaderRewriter.expandCodeFor(CommonExprs, ReplacedTy,
+ PreInsertPt);
+
+ // If all uses are addresses, check if it is possible to reuse an IV. The
+ // new IV must have a stride that is a multiple of the old stride; the
+ // multiple must be a number that can be encoded in the scale field of the
+ // target addressing mode; and we must have a valid instruction after this
+ // substitution, including the immediate field, if any.
+ RewriteFactor = CheckForIVReuse(HaveCommonExprs, AllUsesAreAddresses,
+ AllUsesAreOutsideLoop,
+ Stride, ReuseIV, ReplacedTy,
+ UsersToProcess);
+ if (!RewriteFactor->isZero())
+ PrepareToStrengthReduceFromSmallerStride(UsersToProcess, CommonBaseV,
+ ReuseIV, PreInsertPt);
+ else {
+ IVIncInsertPt = FindIVIncInsertPt(UsersToProcess, L);
+ PrepareToStrengthReduceWithNewPhi(UsersToProcess, Stride, CommonExprs,
+ CommonBaseV, IVIncInsertPt,
+ L, PreheaderRewriter);
+ }
+ }
- unsigned Entry, Latch;
- if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
- Entry = 0;
- Latch = 1;
- } else {
- Entry = 1;
- Latch = 0;
+ // Process all the users now, replacing their strided uses with
+ // strength-reduced forms. This outer loop handles all bases, the inner
+ // loop handles all users of a particular base.
+ while (!UsersToProcess.empty()) {
+ const SCEV *Base = UsersToProcess.back().Base;
+ Instruction *Inst = UsersToProcess.back().Inst;
+
+ // Emit the code for Base into the preheader.
+ Value *BaseV = 0;
+ if (!Base->isZero()) {
+ BaseV = PreheaderRewriter.expandCodeFor(Base, 0, PreInsertPt);
+
+ DEBUG(dbgs() << " INSERTING code for BASE = " << *Base << ":");
+ if (BaseV->hasName())
+ DEBUG(dbgs() << " Result value name = %" << BaseV->getName());
+ DEBUG(dbgs() << "\n");
+
+ // If BaseV is a non-zero constant, make sure that it gets inserted into
+ // the preheader, instead of being forward substituted into the uses. We
+ // do this by forcing a BitCast (noop cast) to be inserted into the
+ // preheader in this case.
+ if (!fitsInAddressMode(Base, getAccessType(Inst), TLI, false) &&
+ isa<Constant>(BaseV)) {
+ // We want this constant emitted into the preheader! This is just
+ // using cast as a copy so BitCast (no-op cast) is appropriate
+ BaseV = new BitCastInst(BaseV, BaseV->getType(), "preheaderinsert",
+ PreInsertPt);
}
+ }
- ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
- if (!Init) continue;
- Constant *NewInit = ConstantFP::get(DestTy, Init->getZExtValue());
-
- BinaryOperator *Incr =
- dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
- if (!Incr) continue;
- if (Incr->getOpcode() != Instruction::Add
- && Incr->getOpcode() != Instruction::Sub)
- continue;
-
- /* Initialize new IV, double d = 0.0 in above example. */
- ConstantInt *C = NULL;
- if (Incr->getOperand(0) == PH)
- C = dyn_cast<ConstantInt>(Incr->getOperand(1));
- else if (Incr->getOperand(1) == PH)
- C = dyn_cast<ConstantInt>(Incr->getOperand(0));
+ // Emit the code to add the immediate offset to the Phi value, just before
+ // the instructions that we identified as using this stride and base.
+ do {
+ // FIXME: Use emitted users to emit other users.
+ BasedUser &User = UsersToProcess.back();
+
+ DEBUG(dbgs() << " Examining ");
+ if (User.isUseOfPostIncrementedValue)
+ DEBUG(dbgs() << "postinc");
else
- continue;
-
- if (!C) continue;
-
- // Ignore negative constants, as the code below doesn't handle them
- // correctly. TODO: Remove this restriction.
- if (!C->getValue().isStrictlyPositive()) continue;
-
- /* Add new PHINode. */
- PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH);
-
- /* create new increment. '++d' in above example. */
- Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());
- BinaryOperator *NewIncr =
- BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?
- Instruction::FAdd : Instruction::FSub,
- NewPH, CFP, "IV.S.next.", Incr);
+ DEBUG(dbgs() << "preinc");
+ DEBUG(dbgs() << " use ");
+ DEBUG(WriteAsOperand(dbgs(), UsersToProcess.back().OperandValToReplace,
+ /*PrintType=*/false));
+ DEBUG(dbgs() << " in Inst: " << *User.Inst);
+
+ // If this instruction wants to use the post-incremented value, move it
+ // after the post-inc and use its value instead of the PHI.
+ Value *RewriteOp = User.Phi;
+ if (User.isUseOfPostIncrementedValue) {
+ RewriteOp = User.Phi->getIncomingValueForBlock(LatchBlock);
+ // If this user is in the loop, make sure it is the last thing in the
+ // loop to ensure it is dominated by the increment. In case it's the
+ // only use of the iv, the increment instruction is already before the
+ // use.
+ if (L->contains(User.Inst) && User.Inst != IVIncInsertPt)
+ User.Inst->moveBefore(IVIncInsertPt);
+ }
+
+ const SCEV *RewriteExpr = SE->getUnknown(RewriteOp);
+
+ if (SE->getEffectiveSCEVType(RewriteOp->getType()) !=
+ SE->getEffectiveSCEVType(ReplacedTy)) {
+ assert(SE->getTypeSizeInBits(RewriteOp->getType()) >
+ SE->getTypeSizeInBits(ReplacedTy) &&
+ "Unexpected widening cast!");
+ RewriteExpr = SE->getTruncateExpr(RewriteExpr, ReplacedTy);
+ }
+
+ // If we had to insert new instructions for RewriteOp, we have to
+ // consider that they may not have been able to end up immediately
+ // next to RewriteOp, because non-PHI instructions may never precede
+ // PHI instructions in a block. In this case, remember where the last
+ // instruction was inserted so that if we're replacing a different
+ // PHI node, we can use the later point to expand the final
+ // RewriteExpr.
+ Instruction *NewBasePt = dyn_cast<Instruction>(RewriteOp);
+ if (RewriteOp == User.Phi) NewBasePt = 0;
+
+ // Clear the SCEVExpander's expression map so that we are guaranteed
+ // to have the code emitted where we expect it.
+ Rewriter.clear();
+
+ // If we are reusing the iv, then it must be multiplied by a constant
+ // factor to take advantage of the addressing mode scale component.
+ if (!RewriteFactor->isZero()) {
+ // If we're reusing an IV with a nonzero base (currently this happens
+ // only when all reuses are outside the loop) subtract that base here.
+ // The base has been used to initialize the PHI node but we don't want
+ // it here.
+ if (!ReuseIV.Base->isZero()) {
+ const SCEV *typedBase = ReuseIV.Base;
+ if (SE->getEffectiveSCEVType(RewriteExpr->getType()) !=
+ SE->getEffectiveSCEVType(ReuseIV.Base->getType())) {
+ // It's possible the original IV is a larger type than the new IV,
+ // in which case we have to truncate the Base. We checked in
+ // RequiresTypeConversion that this is valid.
+ assert(SE->getTypeSizeInBits(RewriteExpr->getType()) <
+ SE->getTypeSizeInBits(ReuseIV.Base->getType()) &&
+ "Unexpected lengthening conversion!");
+ typedBase = SE->getTruncateExpr(ReuseIV.Base,
+ RewriteExpr->getType());
+ }
+ RewriteExpr = SE->getMinusSCEV(RewriteExpr, typedBase);
+ }
- NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
- NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
+ // Multiply old variable, with base removed, by new scale factor.
+ RewriteExpr = SE->getMulExpr(RewriteFactor,
+ RewriteExpr);
+
+ // The common base is emitted in the loop preheader. But since we
+ // are reusing an IV, it has not been used to initialize the PHI node.
+ // Add it to the expression used to rewrite the uses.
+ // When this use is outside the loop, we earlier subtracted the
+ // common base, and are adding it back here. Use the same expression
+ // as before, rather than CommonBaseV, so DAGCombiner will zap it.
+ if (!CommonExprs->isZero()) {
+ if (L->contains(User.Inst))
+ RewriteExpr = SE->getAddExpr(RewriteExpr,
+ SE->getUnknown(CommonBaseV));
+ else
+ RewriteExpr = SE->getAddExpr(RewriteExpr, CommonExprs);
+ }
+ }
- /* Remove cast operation */
- ShadowUse->replaceAllUsesWith(NewPH);
- ShadowUse->eraseFromParent();
- break;
- }
+ // Now that we know what we need to do, insert code before User for the
+ // immediate and any loop-variant expressions.
+ if (BaseV)
+ // Add BaseV to the PHI value if needed.
+ RewriteExpr = SE->getAddExpr(RewriteExpr, SE->getUnknown(BaseV));
+
+ User.RewriteInstructionToUseNewBase(RewriteExpr, NewBasePt,
+ Rewriter, L, this,
+ DeadInsts, SE);
+
+ // Mark old value we replaced as possibly dead, so that it is eliminated
+ // if we just replaced the last use of that value.
+ DeadInsts.push_back(User.OperandValToReplace);
+
+ UsersToProcess.pop_back();
+ ++NumReduced;
+
+ // If there are any more users to process with the same base, process them
+ // now. We sorted by base above, so we just have to check the last elt.
+ } while (!UsersToProcess.empty() && UsersToProcess.back().Base == Base);
+ // TODO: Next, find out which base index is the most common, pull it out.
+ }
+
+ // IMPORTANT TODO: Figure out how to partition the IV's with this stride, but
+ // different starting values, into different PHIs.
+}
+
+void LoopStrengthReduce::StrengthReduceIVUsers(Loop *L) {
+ // Note: this processes each stride/type pair individually. All users
+ // passed into StrengthReduceIVUsersOfStride have the same type AND stride.
+ // Also, note that we iterate over IVUsesByStride indirectly by using
+ // StrideOrder. This extra layer of indirection makes the ordering of
+ // strides deterministic - not dependent on map order.
+ for (unsigned Stride = 0, e = IU->StrideOrder.size(); Stride != e; ++Stride) {
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
+ IU->IVUsesByStride.find(IU->StrideOrder[Stride]);
+ assert(SI != IU->IVUsesByStride.end() && "Stride doesn't exist!");
+ // FIXME: Generalize to non-affine IV's.
+ if (!SI->first->isLoopInvariant(L))
+ continue;
+ StrengthReduceIVUsersOfStride(SI->first, *SI->second, L);
}
}
/// FindIVUserForCond - If Cond has an operand that is an expression of an IV,
/// set the IV user and stride information and return true, otherwise return
/// false.
-bool LSRInstance::FindIVUserForCond(ICmpInst *Cond,
- IVStrideUse *&CondUse,
- const SCEV* &CondStride) {
- for (unsigned StrideIdx = 0, e = IU.StrideOrder.size();
- StrideIdx != e && !CondUse; ++StrideIdx) {
+bool LoopStrengthReduce::FindIVUserForCond(ICmpInst *Cond,
+ IVStrideUse *&CondUse,
+ const SCEV* &CondStride) {
+ for (unsigned Stride = 0, e = IU->StrideOrder.size();
+ Stride != e && !CondUse; ++Stride) {
std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
- IU.IVUsesByStride.find(IU.StrideOrder[StrideIdx]);
- assert(SI != IU.IVUsesByStride.end() && "Stride doesn't exist!");
+ IU->IVUsesByStride.find(IU->StrideOrder[Stride]);
+ assert(SI != IU->IVUsesByStride.end() && "Stride doesn't exist!");
for (ilist<IVStrideUse>::iterator UI = SI->second->Users.begin(),
E = SI->second->Users.end(); UI != E; ++UI)
@@ -1610,6 +1766,287 @@
return false;
}
+namespace {
+ // Constant strides come first which in turns are sorted by their absolute
+ // values. If absolute values are the same, then positive strides comes first.
+ // e.g.
+ // 4, -1, X, 1, 2 ==> 1, -1, 2, 4, X
+ struct StrideCompare {
+ const ScalarEvolution *SE;
+ explicit StrideCompare(const ScalarEvolution *se) : SE(se) {}
+
+ bool operator()(const SCEV *LHS, const SCEV *RHS) {
+ const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(LHS);
+ const SCEVConstant *RHSC = dyn_cast<SCEVConstant>(RHS);
+ if (LHSC && RHSC) {
+ int64_t LV = LHSC->getValue()->getSExtValue();
+ int64_t RV = RHSC->getValue()->getSExtValue();
+ uint64_t ALV = (LV < 0) ? -LV : LV;
+ uint64_t ARV = (RV < 0) ? -RV : RV;
+ if (ALV == ARV) {
+ if (LV != RV)
+ return LV > RV;
+ } else {
+ return ALV < ARV;
+ }
+
+ // If it's the same value but different type, sort by bit width so
+ // that we emit larger induction variables before smaller
+ // ones, letting the smaller be re-written in terms of larger ones.
+ return SE->getTypeSizeInBits(RHS->getType()) <
+ SE->getTypeSizeInBits(LHS->getType());
+ }
+ return LHSC && !RHSC;
+ }
+ };
+}
+
+/// ChangeCompareStride - If a loop termination compare instruction is the
+/// only use of its stride, and the compaison is against a constant value,
+/// try eliminate the stride by moving the compare instruction to another
+/// stride and change its constant operand accordingly. e.g.
+///
+/// loop:
+/// ...
+/// v1 = v1 + 3
+/// v2 = v2 + 1
+/// if (v2 < 10) goto loop
+/// =>
+/// loop:
+/// ...
+/// v1 = v1 + 3
+/// if (v1 < 30) goto loop
+ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
+ IVStrideUse* &CondUse,
+ const SCEV* &CondStride,
+ bool PostPass) {
+ // If there's only one stride in the loop, there's nothing to do here.
+ if (IU->StrideOrder.size() < 2)
+ return Cond;
+ // If there are other users of the condition's stride, don't bother
+ // trying to change the condition because the stride will still
+ // remain.
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator I =
+ IU->IVUsesByStride.find(CondStride);
+ if (I == IU->IVUsesByStride.end())
+ return Cond;
+ if (I->second->Users.size() > 1) {
+ for (ilist<IVStrideUse>::iterator II = I->second->Users.begin(),
+ EE = I->second->Users.end(); II != EE; ++II) {
+ if (II->getUser() == Cond)
+ continue;
+ if (!isInstructionTriviallyDead(II->getUser()))
+ return Cond;
+ }
+ }
+ // Only handle constant strides for now.
+ const SCEVConstant *SC = dyn_cast<SCEVConstant>(CondStride);
+ if (!SC) return Cond;
+
+ ICmpInst::Predicate Predicate = Cond->getPredicate();
+ int64_t CmpSSInt = SC->getValue()->getSExtValue();
+ unsigned BitWidth = SE->getTypeSizeInBits(CondStride->getType());
+ uint64_t SignBit = 1ULL << (BitWidth-1);
+ const Type *CmpTy = Cond->getOperand(0)->getType();
+ const Type *NewCmpTy = NULL;
+ unsigned TyBits = SE->getTypeSizeInBits(CmpTy);
+ unsigned NewTyBits = 0;
+ const SCEV *NewStride = NULL;
+ Value *NewCmpLHS = NULL;
+ Value *NewCmpRHS = NULL;
+ int64_t Scale = 1;
+ const SCEV *NewOffset = SE->getIntegerSCEV(0, CmpTy);
+
+ if (ConstantInt *C = dyn_cast<ConstantInt>(Cond->getOperand(1))) {
+ int64_t CmpVal = C->getValue().getSExtValue();
+
+ // Check the relevant induction variable for conformance to
+ // the pattern.
+ const SCEV *IV = SE->getSCEV(Cond->getOperand(0));
+ const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);
+ if (!AR || !AR->isAffine())
+ return Cond;
+
+ const SCEVConstant *StartC = dyn_cast<SCEVConstant>(AR->getStart());
+ // Check stride constant and the comparision constant signs to detect
+ // overflow.
+ if (StartC) {
+ if ((StartC->getValue()->getSExtValue() < CmpVal && CmpSSInt < 0) ||
+ (StartC->getValue()->getSExtValue() > CmpVal && CmpSSInt > 0))
+ return Cond;
+ } else {
+ // More restrictive check for the other cases.
+ if ((CmpVal & SignBit) != (CmpSSInt & SignBit))
+ return Cond;
+ }
+
+ // Look for a suitable stride / iv as replacement.
+ for (unsigned i = 0, e = IU->StrideOrder.size(); i != e; ++i) {
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
+ IU->IVUsesByStride.find(IU->StrideOrder[i]);
+ if (!isa<SCEVConstant>(SI->first) || SI->second->Users.empty())
+ continue;
+ int64_t SSInt = cast<SCEVConstant>(SI->first)->getValue()->getSExtValue();
+ if (SSInt == CmpSSInt ||
+ abs64(SSInt) < abs64(CmpSSInt) ||
+ (SSInt % CmpSSInt) != 0)
+ continue;
+
+ Scale = SSInt / CmpSSInt;
+ int64_t NewCmpVal = CmpVal * Scale;
+
+ // If old icmp value fits in icmp immediate field, but the new one doesn't
+ // try something else.
+ if (TLI &&
+ TLI->isLegalICmpImmediate(CmpVal) &&
+ !TLI->isLegalICmpImmediate(NewCmpVal))
+ continue;
+
+ APInt Mul = APInt(BitWidth*2, CmpVal, true);
+ Mul = Mul * APInt(BitWidth*2, Scale, true);
+ // Check for overflow.
+ if (!Mul.isSignedIntN(BitWidth))
+ continue;
+ // Check for overflow in the stride's type too.
+ if (!Mul.isSignedIntN(SE->getTypeSizeInBits(SI->first->getType())))
+ continue;
+
+ // Watch out for overflow.
+ if (ICmpInst::isSigned(Predicate) &&
+ (CmpVal & SignBit) != (NewCmpVal & SignBit))
+ continue;
+
+ // Pick the best iv to use trying to avoid a cast.
+ NewCmpLHS = NULL;
+ for (ilist<IVStrideUse>::iterator UI = SI->second->Users.begin(),
+ E = SI->second->Users.end(); UI != E; ++UI) {
+ Value *Op = UI->getOperandValToReplace();
+
+ // If the IVStrideUse implies a cast, check for an actual cast which
+ // can be used to find the original IV expression.
+ if (SE->getEffectiveSCEVType(Op->getType()) !=
+ SE->getEffectiveSCEVType(SI->first->getType())) {
+ CastInst *CI = dyn_cast<CastInst>(Op);
+ // If it's not a simple cast, it's complicated.
+ if (!CI)
+ continue;
+ // If it's a cast from a type other than the stride type,
+ // it's complicated.
+ if (CI->getOperand(0)->getType() != SI->first->getType())
+ continue;
+ // Ok, we found the IV expression in the stride's type.
+ Op = CI->getOperand(0);
+ }
+
+ NewCmpLHS = Op;
+ if (NewCmpLHS->getType() == CmpTy)
+ break;
+ }
+ if (!NewCmpLHS)
+ continue;
+
+ NewCmpTy = NewCmpLHS->getType();
+ NewTyBits = SE->getTypeSizeInBits(NewCmpTy);
+ const Type *NewCmpIntTy = IntegerType::get(Cond->getContext(), NewTyBits);
+ if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
+ // Check if it is possible to rewrite it using
+ // an iv / stride of a smaller integer type.
+ unsigned Bits = NewTyBits;
+ if (ICmpInst::isSigned(Predicate))
+ --Bits;
+ uint64_t Mask = (1ULL << Bits) - 1;
+ if (((uint64_t)NewCmpVal & Mask) != (uint64_t)NewCmpVal)
+ continue;
+ }
+
+ // Don't rewrite if use offset is non-constant and the new type is
+ // of a different type.
+ // FIXME: too conservative?
+ if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->getOffset()))
+ continue;
+
+ if (!PostPass) {
+ bool AllUsesAreAddresses = true;
+ bool AllUsesAreOutsideLoop = true;
+ std::vector<BasedUser> UsersToProcess;
+ const SCEV *CommonExprs = CollectIVUsers(SI->first, *SI->second, L,
+ AllUsesAreAddresses,
+ AllUsesAreOutsideLoop,
+ UsersToProcess);
+ // Avoid rewriting the compare instruction with an iv of new stride
+ // if it's likely the new stride uses will be rewritten using the
+ // stride of the compare instruction.
+ if (AllUsesAreAddresses &&
+ ValidScale(!CommonExprs->isZero(), Scale, UsersToProcess))
+ continue;
+ }
+
+ // Avoid rewriting the compare instruction with an iv which has
+ // implicit extension or truncation built into it.
+ // TODO: This is over-conservative.
+ if (SE->getTypeSizeInBits(CondUse->getOffset()->getType()) != TyBits)
+ continue;
+
+ // If scale is negative, use swapped predicate unless it's testing
+ // for equality.
+ if (Scale < 0 && !Cond->isEquality())
+ Predicate = ICmpInst::getSwappedPredicate(Predicate);
+
+ NewStride = IU->StrideOrder[i];
+ if (!isa<PointerType>(NewCmpTy))
+ NewCmpRHS = ConstantInt::get(NewCmpTy, NewCmpVal);
+ else {
+ Constant *CI = ConstantInt::get(NewCmpIntTy, NewCmpVal);
+ NewCmpRHS = ConstantExpr::getIntToPtr(CI, NewCmpTy);
+ }
+ NewOffset = TyBits == NewTyBits
+ ? SE->getMulExpr(CondUse->getOffset(),
+ SE->getConstant(CmpTy, Scale))
+ : SE->getConstant(NewCmpIntTy,
+ cast<SCEVConstant>(CondUse->getOffset())->getValue()
+ ->getSExtValue()*Scale);
+ break;
+ }
+ }
+
+ // Forgo this transformation if it the increment happens to be
+ // unfortunately positioned after the condition, and the condition
+ // has multiple uses which prevent it from being moved immediately
+ // before the branch. See
+ // test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-*.ll
+ // for an example of this situation.
+ if (!Cond->hasOneUse()) {
+ for (BasicBlock::iterator I = Cond, E = Cond->getParent()->end();
+ I != E; ++I)
+ if (I == NewCmpLHS)
+ return Cond;
+ }
+
+ if (NewCmpRHS) {
+ // Create a new compare instruction using new stride / iv.
+ ICmpInst *OldCond = Cond;
+ // Insert new compare instruction.
+ Cond = new ICmpInst(OldCond, Predicate, NewCmpLHS, NewCmpRHS,
+ L->getHeader()->getName() + ".termcond");
+
+ DEBUG(dbgs() << " Change compare stride in Inst " << *OldCond);
+ DEBUG(dbgs() << " to " << *Cond << '\n');
+
+ // Remove the old compare instruction. The old indvar is probably dead too.
+ DeadInsts.push_back(CondUse->getOperandValToReplace());
+ OldCond->replaceAllUsesWith(Cond);
+ OldCond->eraseFromParent();
+
+ IU->IVUsesByStride[NewStride]->addUser(NewOffset, Cond, NewCmpLHS);
+ CondUse = &IU->IVUsesByStride[NewStride]->Users.back();
+ CondStride = NewStride;
+ ++NumEliminated;
+ Changed = true;
+ }
+
+ return Cond;
+}
+
/// OptimizeMax - Rewrite the loop's terminating condition if it uses
/// a max computation.
///
@@ -1650,7 +2087,7 @@
/// are designed around them. The most obvious example of this is the
/// LoopInfo analysis, which doesn't remember trip count values. It
/// expects to be able to rediscover the trip count each time it is
-/// needed, and it does this using a simple analysis that only succeeds if
+/// needed, and it does this using a simple analyis that only succeeds if
/// the loop has a canonical induction variable.
///
/// However, when it comes time to generate code, the maximum operation
@@ -1660,7 +2097,8 @@
/// rewriting their conditions from ICMP_NE back to ICMP_SLT, and deleting
/// the instructions for the maximum computation.
///
-ICmpInst *LSRInstance::OptimizeMax(ICmpInst *Cond, IVStrideUse* &CondUse) {
+ICmpInst *LoopStrengthReduce::OptimizeMax(Loop *L, ICmpInst *Cond,
+ IVStrideUse* &CondUse) {
// Check that the loop matches the pattern we're looking for.
if (Cond->getPredicate() != CmpInst::ICMP_EQ &&
Cond->getPredicate() != CmpInst::ICMP_NE)
@@ -1669,19 +2107,19 @@
SelectInst *Sel = dyn_cast<SelectInst>(Cond->getOperand(1));
if (!Sel || !Sel->hasOneUse()) return Cond;
- const SCEV *BackedgeTakenCount = SE.getBackedgeTakenCount(L);
+ const SCEV *BackedgeTakenCount = SE->getBackedgeTakenCount(L);
if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
return Cond;
- const SCEV *One = SE.getIntegerSCEV(1, BackedgeTakenCount->getType());
+ const SCEV *One = SE->getIntegerSCEV(1, BackedgeTakenCount->getType());
// Add one to the backedge-taken count to get the trip count.
- const SCEV *IterationCount = SE.getAddExpr(BackedgeTakenCount, One);
+ const SCEV *IterationCount = SE->getAddExpr(BackedgeTakenCount, One);
// Check for a max calculation that matches the pattern.
if (!isa<SCEVSMaxExpr>(IterationCount) && !isa<SCEVUMaxExpr>(IterationCount))
return Cond;
const SCEVNAryExpr *Max = cast<SCEVNAryExpr>(IterationCount);
- if (Max != SE.getSCEV(Sel)) return Cond;
+ if (Max != SE->getSCEV(Sel)) return Cond;
// To handle a max with more than two operands, this optimization would
// require additional checking and setup.
@@ -1691,13 +2129,14 @@
const SCEV *MaxLHS = Max->getOperand(0);
const SCEV *MaxRHS = Max->getOperand(1);
if (!MaxLHS || MaxLHS != One) return Cond;
+
// Check the relevant induction variable for conformance to
// the pattern.
- const SCEV *IV = SE.getSCEV(Cond->getOperand(0));
+ const SCEV *IV = SE->getSCEV(Cond->getOperand(0));
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);
if (!AR || !AR->isAffine() ||
AR->getStart() != One ||
- AR->getStepRecurrence(SE) != One)
+ AR->getStepRecurrence(*SE) != One)
return Cond;
assert(AR->getLoop() == L &&
@@ -1706,9 +2145,9 @@
// Check the right operand of the select, and remember it, as it will
// be used in the new comparison instruction.
Value *NewRHS = 0;
- if (SE.getSCEV(Sel->getOperand(1)) == MaxRHS)
+ if (SE->getSCEV(Sel->getOperand(1)) == MaxRHS)
NewRHS = Sel->getOperand(1);
- else if (SE.getSCEV(Sel->getOperand(2)) == MaxRHS)
+ else if (SE->getSCEV(Sel->getOperand(2)) == MaxRHS)
NewRHS = Sel->getOperand(2);
if (!NewRHS) return Cond;
@@ -1735,13 +2174,138 @@
return NewCond;
}
-bool LSRInstance::StrideMightBeShared(const SCEV* Stride) {
- int64_t SInt = cast<SCEVConstant>(Stride)->getValue()->getSExtValue();
- for (unsigned i = 0, e = IU.StrideOrder.size(); i != e; ++i) {
+/// OptimizeShadowIV - If IV is used in a int-to-float cast
+/// inside the loop then try to eliminate the cast opeation.
+void LoopStrengthReduce::OptimizeShadowIV(Loop *L) {
+
+ const SCEV *BackedgeTakenCount = SE->getBackedgeTakenCount(L);
+ if (isa<SCEVCouldNotCompute>(BackedgeTakenCount))
+ return;
+
+ for (unsigned Stride = 0, e = IU->StrideOrder.size(); Stride != e;
+ ++Stride) {
std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
- IU.IVUsesByStride.find(IU.StrideOrder[i]);
- const SCEV *Share = SI->first;
- if (!isa<SCEVConstant>(SI->first) || Share == Stride)
+ IU->IVUsesByStride.find(IU->StrideOrder[Stride]);
+ assert(SI != IU->IVUsesByStride.end() && "Stride doesn't exist!");
+ if (!isa<SCEVConstant>(SI->first))
+ continue;
+
+ for (ilist<IVStrideUse>::iterator UI = SI->second->Users.begin(),
+ E = SI->second->Users.end(); UI != E; /* empty */) {
+ ilist<IVStrideUse>::iterator CandidateUI = UI;
+ ++UI;
+ Instruction *ShadowUse = CandidateUI->getUser();
+ const Type *DestTy = NULL;
+
+ /* If shadow use is a int->float cast then insert a second IV
+ to eliminate this cast.
+
+ for (unsigned i = 0; i < n; ++i)
+ foo((double)i);
+
+ is transformed into
+
+ double d = 0.0;
+ for (unsigned i = 0; i < n; ++i, ++d)
+ foo(d);
+ */
+ if (UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->getUser()))
+ DestTy = UCast->getDestTy();
+ else if (SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->getUser()))
+ DestTy = SCast->getDestTy();
+ if (!DestTy) continue;
+
+ if (TLI) {
+ // If target does not support DestTy natively then do not apply
+ // this transformation.
+ EVT DVT = TLI->getValueType(DestTy);
+ if (!TLI->isTypeLegal(DVT)) continue;
+ }
+
+ PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
+ if (!PH) continue;
+ if (PH->getNumIncomingValues() != 2) continue;
+
+ const Type *SrcTy = PH->getType();
+ int Mantissa = DestTy->getFPMantissaWidth();
+ if (Mantissa == -1) continue;
+ if ((int)SE->getTypeSizeInBits(SrcTy) > Mantissa)
+ continue;
+
+ unsigned Entry, Latch;
+ if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
+ Entry = 0;
+ Latch = 1;
+ } else {
+ Entry = 1;
+ Latch = 0;
+ }
+
+ ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
+ if (!Init) continue;
+ Constant *NewInit = ConstantFP::get(DestTy, Init->getZExtValue());
+
+ BinaryOperator *Incr =
+ dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
+ if (!Incr) continue;
+ if (Incr->getOpcode() != Instruction::Add
+ && Incr->getOpcode() != Instruction::Sub)
+ continue;
+
+ /* Initialize new IV, double d = 0.0 in above example. */
+ ConstantInt *C = NULL;
+ if (Incr->getOperand(0) == PH)
+ C = dyn_cast<ConstantInt>(Incr->getOperand(1));
+ else if (Incr->getOperand(1) == PH)
+ C = dyn_cast<ConstantInt>(Incr->getOperand(0));
+ else
+ continue;
+
+ if (!C) continue;
+
+ // Ignore negative constants, as the code below doesn't handle them
+ // correctly. TODO: Remove this restriction.
+ if (!C->getValue().isStrictlyPositive()) continue;
+
+ /* Add new PHINode. */
+ PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH);
+
+ /* create new increment. '++d' in above example. */
+ Constant *CFP = ConstantFP::get(DestTy, C->getZExtValue());
+ BinaryOperator *NewIncr =
+ BinaryOperator::Create(Incr->getOpcode() == Instruction::Add ?
+ Instruction::FAdd : Instruction::FSub,
+ NewPH, CFP, "IV.S.next.", Incr);
+
+ NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
+ NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
+
+ /* Remove cast operation */
+ ShadowUse->replaceAllUsesWith(NewPH);
+ ShadowUse->eraseFromParent();
+ NumShadow++;
+ break;
+ }
+ }
+}
+
+/// OptimizeIndvars - Now that IVUsesByStride is set up with all of the indvar
+/// uses in the loop, look to see if we can eliminate some, in favor of using
+/// common indvars for the different uses.
+void LoopStrengthReduce::OptimizeIndvars(Loop *L) {
+ // TODO: implement optzns here.
+
+ OptimizeShadowIV(L);
+}
+
+bool LoopStrengthReduce::StrideMightBeShared(const SCEV* Stride, Loop *L,
+ bool CheckPreInc) {
+ int64_t SInt = cast<SCEVConstant>(Stride)->getValue()->getSExtValue();
+ for (unsigned i = 0, e = IU->StrideOrder.size(); i != e; ++i) {
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
+ IU->IVUsesByStride.find(IU->StrideOrder[i]);
+ const SCEV *Share = SI->first;
+ if (!isa<SCEVConstant>(SI->first) || Share == Stride)
continue;
int64_t SSInt = cast<SCEVConstant>(Share)->getValue()->getSExtValue();
if (SSInt == SInt)
@@ -1749,44 +2313,110 @@
if (unsigned(abs64(SSInt)) < SInt || (SSInt % SInt) != 0)
continue;
int64_t Scale = SSInt / SInt;
-
- // This AM will be used for conservative queries. At this point in the
- // process we don't know which users will have a base reg, immediate,
- // etc., so we conservatively assume that it may not, making more
- // strides valid, thus erring on the side of assuming that there
- // might be sharing.
- TargetLowering::AddrMode AM;
- AM.Scale = Scale;
-
- // Any pre-inc iv use?
- IVUsersOfOneStride &StrideUses = *IU.IVUsesByStride[Share];
- for (ilist<IVStrideUse>::iterator I = StrideUses.Users.begin(),
- E = StrideUses.Users.end(); I != E; ++I) {
- bool isAddress = isAddressUse(I->getUser(), I->getOperandValToReplace());
- if (!I->isUseOfPostIncrementedValue() &&
- isLegalUse(AM, isAddress ? LSRUse::Address : LSRUse::Basic,
- isAddress ? getAccessType(I->getUser()) : 0,
- TLI))
+ bool AllUsesAreAddresses = true;
+ bool AllUsesAreOutsideLoop = true;
+ std::vector<BasedUser> UsersToProcess;
+ const SCEV *CommonExprs = CollectIVUsers(SI->first, *SI->second, L,
+ AllUsesAreAddresses,
+ AllUsesAreOutsideLoop,
+ UsersToProcess);
+ if (AllUsesAreAddresses &&
+ ValidScale(!CommonExprs->isZero(), Scale, UsersToProcess)) {
+ if (!CheckPreInc)
return true;
+ // Any pre-inc iv use?
+ IVUsersOfOneStride &StrideUses = *IU->IVUsesByStride[Share];
+ for (ilist<IVStrideUse>::iterator I = StrideUses.Users.begin(),
+ E = StrideUses.Users.end(); I != E; ++I) {
+ if (!I->isUseOfPostIncrementedValue())
+ return true;
+ }
}
}
return false;
}
+/// isUsedByExitBranch - Return true if icmp is used by a loop terminating
+/// conditional branch or it's and / or with other conditions before being used
+/// as the condition.
+static bool isUsedByExitBranch(ICmpInst *Cond, Loop *L) {
+ BasicBlock *CondBB = Cond->getParent();
+ if (!L->isLoopExiting(CondBB))
+ return false;
+ BranchInst *TermBr = dyn_cast<BranchInst>(CondBB->getTerminator());
+ if (!TermBr || !TermBr->isConditional())
+ return false;
+
+ Value *User = *Cond->use_begin();
+ Instruction *UserInst = dyn_cast<Instruction>(User);
+ while (UserInst &&
+ (UserInst->getOpcode() == Instruction::And ||
+ UserInst->getOpcode() == Instruction::Or)) {
+ if (!UserInst->hasOneUse() || UserInst->getParent() != CondBB)
+ return false;
+ User = *User->use_begin();
+ UserInst = dyn_cast<Instruction>(User);
+ }
+ return User == TermBr;
+}
+
+static bool ShouldCountToZero(ICmpInst *Cond, IVStrideUse* &CondUse,
+ ScalarEvolution *SE, Loop *L,
+ const TargetLowering *TLI = 0) {
+ if (!L->contains(Cond))
+ return false;
+
+ if (!isa<SCEVConstant>(CondUse->getOffset()))
+ return false;
+
+ // Handle only tests for equality for the moment.
+ if (!Cond->isEquality() || !Cond->hasOneUse())
+ return false;
+ if (!isUsedByExitBranch(Cond, L))
+ return false;
+
+ Value *CondOp0 = Cond->getOperand(0);
+ const SCEV *IV = SE->getSCEV(CondOp0);
+ const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(IV);
+ if (!AR || !AR->isAffine())
+ return false;
+
+ const SCEVConstant *SC = dyn_cast<SCEVConstant>(AR->getStepRecurrence(*SE));
+ if (!SC || SC->getValue()->getSExtValue() < 0)
+ // If it's already counting down, don't do anything.
+ return false;
+
+ // If the RHS of the comparison is not an loop invariant, the rewrite
+ // cannot be done. Also bail out if it's already comparing against a zero.
+ // If we are checking this before cmp stride optimization, check if it's
+ // comparing against a already legal immediate.
+ Value *RHS = Cond->getOperand(1);
+ ConstantInt *RHSC = dyn_cast<ConstantInt>(RHS);
+ if (!L->isLoopInvariant(RHS) ||
+ (RHSC && RHSC->isZero()) ||
+ (RHSC && TLI && TLI->isLegalICmpImmediate(RHSC->getSExtValue())))
+ return false;
+
+ // Make sure the IV is only used for counting. Value may be preinc or
+ // postinc; 2 uses in either case.
+ if (!CondOp0->hasNUses(2))
+ return false;
+
+ return true;
+}
+
/// OptimizeLoopTermCond - Change loop terminating condition to use the
/// postinc iv when possible.
-bool
-LSRInstance::OptimizeLoopTermCond() {
- SmallPtrSet<Instruction *, 4> PostIncs;
-
+void LoopStrengthReduce::OptimizeLoopTermCond(Loop *L) {
BasicBlock *LatchBlock = L->getLoopLatch();
+ bool LatchExit = L->isLoopExiting(LatchBlock);
SmallVector<BasicBlock*, 8> ExitingBlocks;
L->getExitingBlocks(ExitingBlocks);
for (unsigned i = 0, e = ExitingBlocks.size(); i != e; ++i) {
BasicBlock *ExitingBlock = ExitingBlocks[i];
- // Get the terminating condition for the loop if possible. If we
+ // Finally, get the terminating condition for the loop if possible. If we
// can, we want to change it to use a post-incremented version of its
// induction variable, to allow coalescing the live ranges for the IV into
// one register value.
@@ -1805,1008 +2435,291 @@
if (!FindIVUserForCond(Cond, CondUse, CondStride))
continue;
- // If the trip count is computed in terms of a max (due to ScalarEvolution
- // being unable to find a sufficient guard, for example), change the loop
- // comparison to use SLT or ULT instead of NE.
- // One consequence of doing this now is that it disrupts the count-down
- // optimization. That's not always a bad thing though, because in such
- // cases it may still be worthwhile to avoid a max.
- Cond = OptimizeMax(Cond, CondUse);
-
- // If this exiting block is the latch block, and the condition has only
- // one use inside the loop (the branch), use the post-incremented value
- // of the induction variable
- if (ExitingBlock != LatchBlock) {
- // If this exiting block dominates the latch block, it may also use
- // the post-inc value if it won't be shared with other uses.
- // Check for dominance.
- if (!DT.dominates(ExitingBlock, LatchBlock))
- continue;
- // Check for sharing within the same stride.
- bool SameStrideSharing = false;
- IVUsersOfOneStride &StrideUses = *IU.IVUsesByStride[CondStride];
- for (ilist<IVStrideUse>::iterator I = StrideUses.Users.begin(),
- E = StrideUses.Users.end(); I != E; ++I) {
- if (I->getUser() == Cond)
- continue;
- if (!I->isUseOfPostIncrementedValue()) {
- SameStrideSharing = true;
- break;
+ // If the latch block is exiting and it's not a single block loop, it's
+ // not safe to use postinc iv in other exiting blocks. FIXME: overly
+ // conservative? How about icmp stride optimization?
+ bool UsePostInc = !(e > 1 && LatchExit && ExitingBlock != LatchBlock);
+ if (UsePostInc && ExitingBlock != LatchBlock) {
+ if (!Cond->hasOneUse())
+ // See below, we don't want the condition to be cloned.
+ UsePostInc = false;
+ else {
+ // If exiting block is the latch block, we know it's safe and profitable
+ // to transform the icmp to use post-inc iv. Otherwise do so only if it
+ // would not reuse another iv and its iv would be reused by other uses.
+ // We are optimizing for the case where the icmp is the only use of the
+ // iv.
+ IVUsersOfOneStride &StrideUses = *IU->IVUsesByStride[CondStride];
+ for (ilist<IVStrideUse>::iterator I = StrideUses.Users.begin(),
+ E = StrideUses.Users.end(); I != E; ++I) {
+ if (I->getUser() == Cond)
+ continue;
+ if (!I->isUseOfPostIncrementedValue()) {
+ UsePostInc = false;
+ break;
+ }
}
}
- if (SameStrideSharing)
- continue;
- // Check for sharing from a different stride.
- if (isa<SCEVConstant>(CondStride) && StrideMightBeShared(CondStride))
- continue;
+
+ // If iv for the stride might be shared and any of the users use pre-inc
+ // iv might be used, then it's not safe to use post-inc iv.
+ if (UsePostInc &&
+ isa<SCEVConstant>(CondStride) &&
+ StrideMightBeShared(CondStride, L, true))
+ UsePostInc = false;
}
- if (!Cond->hasOneUse()) {
- bool HasOneUseInLoop = true;
- for (Value::use_iterator UI = Cond->use_begin(), UE = Cond->use_end();
- UI != UE; ++UI) {
- Instruction *U = cast<Instruction>(*UI);
- if (U == TermBr)
- continue;
- if (L->contains(U)) {
- HasOneUseInLoop = false;
- break;
- }
- }
- if (!HasOneUseInLoop)
- continue;
+
+ // If the trip count is computed in terms of a max (due to ScalarEvolution
+ // being unable to find a sufficient guard, for example), change the loop
+ // comparison to use SLT or ULT instead of NE.
+ Cond = OptimizeMax(L, Cond, CondUse);
+
+ // If possible, change stride and operands of the compare instruction to
+ // eliminate one stride. However, avoid rewriting the compare instruction
+ // with an iv of new stride if it's likely the new stride uses will be
+ // rewritten using the stride of the compare instruction.
+ if (ExitingBlock == LatchBlock && isa<SCEVConstant>(CondStride)) {
+ // If the condition stride is a constant and it's the only use, we might
+ // want to optimize it first by turning it to count toward zero.
+ if (!StrideMightBeShared(CondStride, L, false) &&
+ !ShouldCountToZero(Cond, CondUse, SE, L, TLI))
+ Cond = ChangeCompareStride(L, Cond, CondUse, CondStride);
}
+ if (!UsePostInc)
+ continue;
+
DEBUG(dbgs() << " Change loop exiting icmp to use postinc iv: "
- << *Cond << '\n');
+ << *Cond << '\n');
// It's possible for the setcc instruction to be anywhere in the loop, and
// possible for it to have multiple users. If it is not immediately before
// the exiting block branch, move it.
- if (&*++BasicBlock::iterator(Cond) != TermBr) {
+ if (&*++BasicBlock::iterator(Cond) != (Instruction*)TermBr) {
if (Cond->hasOneUse()) { // Condition has a single use, just move it.
Cond->moveBefore(TermBr);
} else {
// Otherwise, clone the terminating condition and insert into the
// loopend.
- ICmpInst *OldCond = Cond;
Cond = cast<ICmpInst>(Cond->clone());
Cond->setName(L->getHeader()->getName() + ".termcond");
ExitingBlock->getInstList().insert(TermBr, Cond);
// Clone the IVUse, as the old use still exists!
- IU.IVUsesByStride[CondStride]->addUser(CondUse->getOffset(), Cond,
+ IU->IVUsesByStride[CondStride]->addUser(CondUse->getOffset(), Cond,
CondUse->getOperandValToReplace());
- CondUse = &IU.IVUsesByStride[CondStride]->Users.back();
- TermBr->replaceUsesOfWith(OldCond, Cond);
+ CondUse = &IU->IVUsesByStride[CondStride]->Users.back();
}
}
// If we get to here, we know that we can transform the setcc instruction to
// use the post-incremented version of the IV, allowing us to coalesce the
// live ranges for the IV correctly.
- CondUse->setOffset(SE.getMinusSCEV(CondUse->getOffset(), CondStride));
+ CondUse->setOffset(SE->getMinusSCEV(CondUse->getOffset(), CondStride));
CondUse->setIsUseOfPostIncrementedValue(true);
Changed = true;
- PostIncs.insert(Cond);
- }
-
- // Determine an insertion point for the loop induction variable increment. It
- // must dominate all the post-inc comparisons we just set up, and it must
- // dominate the loop latch edge.
- IVIncInsertPos = L->getLoopLatch()->getTerminator();
- for (SmallPtrSet<Instruction *, 4>::iterator I = PostIncs.begin(),
- E = PostIncs.end(); I != E; ++I) {
- BasicBlock *BB =
- DT.findNearestCommonDominator(IVIncInsertPos->getParent(),
- (*I)->getParent());
- if (BB == (*I)->getParent())
- IVIncInsertPos = *I;
- else if (BB != IVIncInsertPos->getParent())
- IVIncInsertPos = BB->getTerminator();
+ ++NumLoopCond;
}
-
- return Changed;
}
-/// CountRegisters - Note the given register.
-void LSRInstance::CountRegister(const SCEV *Reg, uint32_t Complexity,
- size_t LUIdx) {
- std::pair<RegUsesTy::iterator, bool> Pair =
- RegUses.insert(std::make_pair(Reg, RegSortData()));
- RegSortData &BV = Pair.first->second;
- if (Pair.second) {
- BV.Index = CurrentArbitraryRegIndex++;
- BV.MaxComplexity = Complexity;
- RegSequence.push_back(Reg);
- } else {
- BV.MaxComplexity = std::max(BV.MaxComplexity, Complexity);
- }
- BV.Bits.resize(std::max(BV.Bits.size(), LUIdx + 1));
- BV.Bits.set(LUIdx);
-}
+bool LoopStrengthReduce::OptimizeLoopCountIVOfStride(const SCEV* &Stride,
+ IVStrideUse* &CondUse,
+ Loop *L) {
+ // If the only use is an icmp of a loop exiting conditional branch, then
+ // attempt the optimization.
+ BasedUser User = BasedUser(*CondUse, SE);
+ assert(isa<ICmpInst>(User.Inst) && "Expecting an ICMPInst!");
+ ICmpInst *Cond = cast<ICmpInst>(User.Inst);
-/// CountRegisters - Note which registers are used by the given formula,
-/// updating RegUses.
-void LSRInstance::CountRegisters(const Formula &F, size_t LUIdx) {
- uint32_t Complexity = F.getComplexity();
- if (F.ScaledReg)
- CountRegister(F.ScaledReg, Complexity, LUIdx);
- for (SmallVectorImpl<const SCEV *>::const_iterator I = F.BaseRegs.begin(),
- E = F.BaseRegs.end(); I != E; ++I)
- CountRegister(*I, Complexity, LUIdx);
-}
-
-/// InsertFormula - If the given formula has not yet been inserted, add it
-/// to the list, and return true. Return false otherwise.
-bool LSRInstance::InsertFormula(LSRUse &LU, unsigned LUIdx, const Formula &F) {
- // If a formula by itself would require more registers than the base solution,
- // discard it and stop searching from it, as it won't be profitable. This is
- // actually more permissive than it could be, because it doesn't include
- // registers used by non-constant strides in F.
- if (F.getNumRegs() > MaxNumRegs)
+ // Less strict check now that compare stride optimization is done.
+ if (!ShouldCountToZero(Cond, CondUse, SE, L))
return false;
- if (!LU.InsertFormula(F))
- return false;
-
- CountRegisters(LU.Formulae.back(), LUIdx);
- return true;
-}
+ Value *CondOp0 = Cond->getOperand(0);
+ PHINode *PHIExpr = dyn_cast<PHINode>(CondOp0);
+ Instruction *Incr;
+ if (!PHIExpr) {
+ // Value tested is postinc. Find the phi node.
+ Incr = dyn_cast<BinaryOperator>(CondOp0);
+ // FIXME: Just use User.OperandValToReplace here?
+ if (!Incr || Incr->getOpcode() != Instruction::Add)
+ return false;
-/// GenerateSymbolicOffsetReuse - Generate reuse formulae using symbolic
-/// offsets.
-void LSRInstance::GenerateSymbolicOffsetReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base) {
- // We can't add a symbolic offset if the address already contains one.
- if (Base.AM.BaseGV) return;
-
- for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) {
- const SCEV *G = Base.BaseRegs[i];
- GlobalValue *GV = ExtractSymbol(G, SE);
- if (G->isZero())
- continue;
- Formula F = Base;
- F.AM.BaseGV = GV;
- if (!isLegalUse(F.AM, LU.Kind, LU.AccessTy, TLI))
- continue;
- F.BaseRegs[i] = G;
- (void)InsertFormula(LU, LUIdx, F);
+ PHIExpr = dyn_cast<PHINode>(Incr->getOperand(0));
+ if (!PHIExpr)
+ return false;
+ // 1 use for preinc value, the increment.
+ if (!PHIExpr->hasOneUse())
+ return false;
+ } else {
+ assert(isa<PHINode>(CondOp0) &&
+ "Unexpected loop exiting counting instruction sequence!");
+ PHIExpr = cast<PHINode>(CondOp0);
+ // Value tested is preinc. Find the increment.
+ // A CmpInst is not a BinaryOperator; we depend on this.
+ Instruction::use_iterator UI = PHIExpr->use_begin();
+ Incr = dyn_cast<BinaryOperator>(UI);
+ if (!Incr)
+ Incr = dyn_cast<BinaryOperator>(++UI);
+ // One use for postinc value, the phi. Unnecessarily conservative?
+ if (!Incr || !Incr->hasOneUse() || Incr->getOpcode() != Instruction::Add)
+ return false;
}
-}
-
-/// GenerateICmpZeroScaledReuse - For ICmpZero, check to see if we can scale up
-/// the comparison. For example, x == y -> x*c == y*c.
-void LSRInstance::GenerateICmpZeroScaledReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base) {
- if (LU.Kind != LSRUse::ICmpZero) return;
-
- // Determine the integer type for the base formula.
- const Type *IntTy = Base.getType();
- if (!IntTy) return;
- if (SE.getTypeSizeInBits(IntTy) > 64) return;
- IntTy = SE.getEffectiveSCEVType(IntTy);
-
- assert(!Base.AM.BaseGV && "ICmpZero use is not legal!");
-
- // Check each interesting stride.
- for (SmallSetVector<int64_t, 4>::const_iterator
- I = Factors.begin(), E = Factors.end(); I != E; ++I) {
- int64_t Factor = *I;
- Formula F = Base;
-
- // Check that the multiplication doesn't overflow.
- F.AM.BaseOffs = (uint64_t)F.AM.BaseOffs * Factor;
- if ((int64_t)F.AM.BaseOffs / Factor != F.AM.BaseOffs)
- continue;
-
- // Check that this scale is legal.
- if (!isLegalUse(F.AM, LU.Kind, LU.AccessTy, TLI))
- continue;
-
- const SCEV *FactorS = SE.getSCEV(ConstantInt::get(IntTy, Factor));
-
- // Check that multiplying with each base register doesn't overflow.
- for (size_t i = 0, e = F.BaseRegs.size(); i != e; ++i) {
- F.BaseRegs[i] = SE.getMulExpr(F.BaseRegs[i], FactorS);
- if (getSDiv(F.BaseRegs[i], FactorS, SE) != Base.BaseRegs[i])
- goto next;
- }
- // Check that multiplying with the scaled register doesn't overflow.
- if (F.ScaledReg) {
- F.ScaledReg = SE.getMulExpr(F.ScaledReg, FactorS);
- if (getSDiv(F.ScaledReg, FactorS, SE) != Base.ScaledReg)
- continue;
- }
+ // Replace the increment with a decrement.
+ DEBUG(dbgs() << "LSR: Examining use ");
+ DEBUG(WriteAsOperand(dbgs(), CondOp0, /*PrintType=*/false));
+ DEBUG(dbgs() << " in Inst: " << *Cond << '\n');
+ BinaryOperator *Decr = BinaryOperator::Create(Instruction::Sub,
+ Incr->getOperand(0), Incr->getOperand(1), "tmp", Incr);
+ Incr->replaceAllUsesWith(Decr);
+ Incr->eraseFromParent();
+
+ // Substitute endval-startval for the original startval, and 0 for the
+ // original endval. Since we're only testing for equality this is OK even
+ // if the computation wraps around.
+ BasicBlock *Preheader = L->getLoopPreheader();
+ Instruction *PreInsertPt = Preheader->getTerminator();
+ unsigned InBlock = L->contains(PHIExpr->getIncomingBlock(0)) ? 1 : 0;
+ Value *StartVal = PHIExpr->getIncomingValue(InBlock);
+ Value *EndVal = Cond->getOperand(1);
+ DEBUG(dbgs() << " Optimize loop counting iv to count down ["
+ << *EndVal << " .. " << *StartVal << "]\n");
+
+ // FIXME: check for case where both are constant.
+ Constant* Zero = ConstantInt::get(Cond->getOperand(1)->getType(), 0);
+ BinaryOperator *NewStartVal = BinaryOperator::Create(Instruction::Sub,
+ EndVal, StartVal, "tmp", PreInsertPt);
+ PHIExpr->setIncomingValue(InBlock, NewStartVal);
+ Cond->setOperand(1, Zero);
+ DEBUG(dbgs() << " New icmp: " << *Cond << "\n");
- // If we make it here and it's legal, add it.
- (void)InsertFormula(LU, LUIdx, F);
- next:;
- }
-}
-
-/// GenerateFormulaeFromReplacedBaseReg - If removing base register with
-/// index i from the BaseRegs list and adding the registers in AddOps
-/// to the address forms an interesting formula, pursue it.
-void
-LSRInstance::GenerateFormulaeFromReplacedBaseReg(
- LSRUse &LU,
- unsigned LUIdx,
- const Formula &Base, unsigned i,
- const SmallVectorImpl<const SCEV *>
- &AddOps) {
- if (AddOps.empty()) return;
-
- Formula F = Base;
- std::swap(F.BaseRegs[i], F.BaseRegs.back());
- F.BaseRegs.pop_back();
- for (SmallVectorImpl<const SCEV *>::const_iterator I = AddOps.begin(),
- E = AddOps.end(); I != E; ++I)
- F.BaseRegs.push_back(*I);
- F.AM.HasBaseReg = !F.BaseRegs.empty();
- if (InsertFormula(LU, LUIdx, F))
- // If that formula hadn't been seen before, recurse to find more like it.
- GenerateReassociationReuse(LU, LUIdx, LU.Formulae.back());
-}
-
-/// GenerateReassociationReuse - Split out subexpressions from adds and
-/// the bases of addrecs.
-void LSRInstance::GenerateReassociationReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base) {
- SmallVector<const SCEV *, 8> AddOps;
- for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) {
- const SCEV *BaseReg = Base.BaseRegs[i];
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(BaseReg)) {
- for (SCEVAddExpr::op_iterator J = Add->op_begin(), JE = Add->op_end();
- J != JE; ++J) {
- // Don't pull a constant into a register if the constant could be
- // folded into an immediate field.
- if (isAlwaysFoldable(*J, true, LU.Kind, LU.AccessTy, TLI, SE)) continue;
- SmallVector<const SCEV *, 8> InnerAddOps;
- for (SCEVAddExpr::op_iterator K = Add->op_begin(); K != JE; ++K)
- if (K != J)
- InnerAddOps.push_back(*K);
- // Splitting a 2-operand add both ways is redundant. Pruning this
- // now saves compile time.
- if (InnerAddOps.size() < 2 && next(J) == JE)
- continue;
- AddOps.push_back(*J);
- const SCEV *InnerAdd = SE.getAddExpr(InnerAddOps);
- AddOps.push_back(InnerAdd);
- GenerateFormulaeFromReplacedBaseReg(LU, LUIdx, Base, i, AddOps);
- AddOps.clear();
- }
- } else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(BaseReg)) {
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(AR->getStart())) {
- for (SCEVAddExpr::op_iterator J = Add->op_begin(), JE = Add->op_end();
- J != JE; ++J) {
- // Don't pull a constant into a register if the constant could be
- // folded into an immediate field.
- if (isAlwaysFoldable(*J, true, LU.Kind, LU.AccessTy, TLI, SE))
- continue;
- SmallVector<const SCEV *, 8> InnerAddOps;
- for (SCEVAddExpr::op_iterator K = Add->op_begin(); K != JE; ++K)
- if (K != J)
- InnerAddOps.push_back(*K);
- AddOps.push_back(*J);
- const SCEV *InnerAdd = SE.getAddExpr(InnerAddOps);
- AddOps.push_back(SE.getAddRecExpr(InnerAdd,
- AR->getStepRecurrence(SE),
- AR->getLoop()));
- GenerateFormulaeFromReplacedBaseReg(LU, LUIdx, Base, i, AddOps);
- AddOps.clear();
- }
- } else if (!isAlwaysFoldable(AR->getStart(), Base.BaseRegs.size() > 1,
- LU.Kind, LU.AccessTy,
- TLI, SE)) {
- AddOps.push_back(AR->getStart());
- AddOps.push_back(SE.getAddRecExpr(SE.getIntegerSCEV(0,
- BaseReg->getType()),
- AR->getStepRecurrence(SE),
- AR->getLoop()));
- GenerateFormulaeFromReplacedBaseReg(LU, LUIdx, Base, i, AddOps);
- AddOps.clear();
+ int64_t SInt = cast<SCEVConstant>(Stride)->getValue()->getSExtValue();
+ const SCEV *NewStride = 0;
+ bool Found = false;
+ for (unsigned i = 0, e = IU->StrideOrder.size(); i != e; ++i) {
+ const SCEV *OldStride = IU->StrideOrder[i];
+ if (const SCEVConstant *SC = dyn_cast<SCEVConstant>(OldStride))
+ if (SC->getValue()->getSExtValue() == -SInt) {
+ Found = true;
+ NewStride = OldStride;
+ break;
}
- }
}
-}
-/// GenerateCombinationReuse - Generate a formula consisting of all of the
-/// loop-dominating registers added into a single register.
-void LSRInstance::GenerateCombinationReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base) {
- // This method is only intersting on a plurality of registers.
- if (Base.BaseRegs.size() <= 1) return;
-
- Formula F = Base;
- F.BaseRegs.clear();
- SmallVector<const SCEV *, 4> Ops;
- for (SmallVectorImpl<const SCEV *>::const_iterator
- I = Base.BaseRegs.begin(), E = Base.BaseRegs.end(); I != E; ++I) {
- const SCEV *BaseReg = *I;
- if (BaseReg->properlyDominates(L->getHeader(), &DT) &&
- !BaseReg->hasComputableLoopEvolution(L))
- Ops.push_back(BaseReg);
- else
- F.BaseRegs.push_back(BaseReg);
- }
- if (Ops.size() > 1) {
- F.BaseRegs.push_back(SE.getAddExpr(Ops));
- (void)InsertFormula(LU, LUIdx, F);
- }
-}
-
-/// GenerateScaledReuse - Generate stride factor reuse formulae by making
-/// use of scaled-offset address modes, for example.
-void LSRInstance::GenerateScaledReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base) {
- // Determine the integer type for the base formula.
- const Type *IntTy = Base.getType();
- if (!IntTy) return;
- IntTy = SE.getEffectiveSCEVType(IntTy);
-
- // Check each interesting stride.
- for (SmallSetVector<int64_t, 4>::const_iterator
- I = Factors.begin(), E = Factors.end(); I != E; ++I) {
- int64_t Factor = *I;
-
- // If this Formula already has a scaled register, we can't add another one.
- if (Base.AM.Scale != 0)
- continue;
- Formula F = Base;
- F.AM.Scale = Factor;
- // Check whether this scale is going to be legal.
- if (!isLegalUse(F.AM, LU.Kind, LU.AccessTy, TLI)) {
- // As a special-case, handle special out-of-loop Basic users specially.
- // TODO: Reconsider this special case.
- if (LU.Kind == LSRUse::Basic &&
- isLegalUse(F.AM, LSRUse::Special, LU.AccessTy, TLI) &&
- !L->contains(LU.UserInst))
- LU.Kind = LSRUse::Special;
- else
- continue;
- }
- // For each addrec base reg, apply the scale, if possible.
- for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i)
- if (const SCEVAddRecExpr *AR =
- dyn_cast<SCEVAddRecExpr>(Base.BaseRegs[i])) {
- const SCEV *FactorS = SE.getSCEV(ConstantInt::get(IntTy, Factor));
- // Divide out the factor, ignoring high bits, since we'll be
- // scaling the value back up in the end.
- if (const SCEV *Quotient = getSDiv(AR, FactorS, SE, true)) {
- // TODO: This could be optimized to avoid all the copying.
- Formula NewF = F;
- NewF.ScaledReg = Quotient;
- std::swap(NewF.BaseRegs[i], NewF.BaseRegs.back());
- NewF.BaseRegs.pop_back();
- NewF.AM.HasBaseReg = !NewF.BaseRegs.empty();
- (void)InsertFormula(LU, LUIdx, NewF);
- }
- }
- }
-}
+ if (!Found)
+ NewStride = SE->getIntegerSCEV(-SInt, Stride->getType());
+ IU->AddUser(NewStride, CondUse->getOffset(), Cond, Cond->getOperand(0));
+ IU->IVUsesByStride[Stride]->removeUser(CondUse);
-/// GenerateTruncateReuse - Generate reuse formulae from different IV types.
-void LSRInstance::GenerateTruncateReuse(LSRUse &LU, unsigned LUIdx,
- Formula Base) {
- // This requires TargetLowering to tell us which truncates are free.
- if (!TLI) return;
-
- // Don't attempt to truncate symbolic values.
- if (Base.AM.BaseGV) return;
-
- // Determine the integer type for the base formula.
- const Type *DstTy = Base.getType();
- if (!DstTy) return;
- DstTy = SE.getEffectiveSCEVType(DstTy);
-
- for (SmallSetVector<const Type *, 4>::const_iterator
- I = Types.begin(), E = Types.end(); I != E; ++I) {
- const Type *SrcTy = *I;
- if (SrcTy != DstTy && TLI->isTruncateFree(SrcTy, DstTy)) {
- Formula F = Base;
- if (F.ScaledReg) F.ScaledReg = SE.getAnyExtendExpr(F.ScaledReg, *I);
- for (SmallVectorImpl<const SCEV *>::iterator J = F.BaseRegs.begin(),
- JE = F.BaseRegs.end(); J != JE; ++J)
- *J = SE.getAnyExtendExpr(*J, SrcTy);
- (void)InsertFormula(LU, LUIdx, F);
- }
- }
-}
+ CondUse = &IU->IVUsesByStride[NewStride]->Users.back();
+ Stride = NewStride;
-namespace {
+ ++NumCountZero;
-/// WorkItem - Helper class for GenerateConstantOffsetReuse. It's used to
-/// defer modifications so that the search phase doesn't have to worry about
-/// the data structures moving underneath it.
-struct WorkItem {
- LSRUse *LU;
- size_t LUIdx;
- int64_t Imm;
- const SCEV *OrigReg;
-
- WorkItem(LSRUse *U, size_t LI, int64_t I, const SCEV *R)
- : LU(U), LUIdx(LI), Imm(I), OrigReg(R) {}
-
- void print(raw_ostream &OS) const;
- void dump() const;
-};
-
-void WorkItem::print(raw_ostream &OS) const {
- OS << "in use ";
- LU->print(OS);
- OS << " (at index " << LUIdx << "), add offset " << Imm
- << " and compensate by adjusting refences to " << *OrigReg << "\n";
-}
-
-void WorkItem::dump() const {
- print(errs()); errs() << '\n';
-}
-
-}
-
-/// GenerateConstantOffsetReuse - Look for registers which are a constant
-/// distance apart and try to form reuse opportunities between them.
-void LSRInstance::GenerateConstantOffsetReuse() {
- // Group the registers by their value without any added constant offset.
- typedef std::map<int64_t, const SCEV *> ImmMapTy;
- typedef DenseMap<const SCEV *, ImmMapTy> RegMapTy;
- RegMapTy Map;
- SmallVector<const SCEV *, 8> Sequence;
- for (SmallVectorImpl<const SCEV *>::iterator I = RegSequence.begin(),
- E = RegSequence.end(); I != E; ++I) {
- const SCEV *Reg = *I;
- int64_t Imm = ExtractImmediate(Reg, SE);
- std::pair<RegMapTy::iterator, bool> Pair =
- Map.insert(std::make_pair(Reg, ImmMapTy()));
- if (Pair.second)
- Sequence.push_back(Reg);
- Pair.first->second.insert(std::make_pair(Imm, *I));
- }
-
- // Insert an artificial expression at offset 0 (if there isn't one already),
- // as this may lead to more reuse opportunities.
- for (SmallVectorImpl<const SCEV *>::const_iterator I = Sequence.begin(),
- E = Sequence.end(); I != E; ++I)
- Map.find(*I)->second.insert(ImmMapTy::value_type(0, 0));
-
- // Now examine each set of registers with the same base value. Build up
- // a list of work to do and do the work in a separate step so that we're
- // not adding formulae and register counts while we're searching.
- SmallVector<WorkItem, 32> WorkItems;
- for (SmallVectorImpl<const SCEV *>::const_iterator I = Sequence.begin(),
- E = Sequence.end(); I != E; ++I) {
- const SCEV *Reg = *I;
- const ImmMapTy &Imms = Map.find(Reg)->second;
- // Examine each offset.
- for (ImmMapTy::const_iterator J = Imms.begin(), JE = Imms.end();
- J != JE; ++J) {
- const SCEV *OrigReg = J->second;
- // Skip the artifical register at offset 0.
- if (!OrigReg) continue;
-
- int64_t JImm = J->first;
- const SmallBitVector &Bits = RegUses.find(OrigReg)->second.Bits;
-
- // Examine each other offset associated with the same register. This is
- // quadradic in the number of registers with the same base, but it's
- // uncommon for this to be a large number.
- for (ImmMapTy::const_iterator M = Imms.begin(); M != JE; ++M) {
- if (M == J) continue;
-
- // Compute the difference between the two.
- int64_t Imm = (uint64_t)JImm - M->first;
- for (int LUIdx = Bits.find_first(); LUIdx != -1;
- LUIdx = Bits.find_next(LUIdx))
- // Make a memo of this use, offset, and register tuple.
- WorkItems.push_back(WorkItem(&Uses[LUIdx], LUIdx, Imm, OrigReg));
- }
- }
- }
-
- // Now iterate through the worklist and add new formulae.
- for (SmallVectorImpl<WorkItem>::const_iterator I = WorkItems.begin(),
- E = WorkItems.end(); I != E; ++I) {
- const WorkItem &WI = *I;
- LSRUse &LU = *WI.LU;
- size_t LUIdx = WI.LUIdx;
- int64_t Imm = WI.Imm;
- const SCEV *OrigReg = WI.OrigReg;
-
- const Type *IntTy = SE.getEffectiveSCEVType(OrigReg->getType());
- const SCEV *NegImmS = SE.getSCEV(ConstantInt::get(IntTy,
- -(uint64_t)Imm));
-
- for (size_t L = 0, LE = LU.Formulae.size(); L != LE; ++L) {
- Formula F = LU.Formulae[L];
- // Use the immediate in the scaled register.
- if (F.ScaledReg == OrigReg) {
- int64_t Offs = (uint64_t)F.AM.BaseOffs +
- Imm * (uint64_t)F.AM.Scale;
- // Don't create 50 + reg(-50).
- if (F.referencesReg(SE.getSCEV(
- ConstantInt::get(IntTy, -(uint64_t)Offs))))
- continue;
- Formula NewF = F;
- NewF.AM.BaseOffs = Offs;
- if (!isLegalUse(NewF.AM, LU.Kind, LU.AccessTy, TLI))
- continue;
- const SCEV *Diff = SE.getAddExpr(NegImmS, NewF.ScaledReg);
- if (Diff->isZero()) continue;
- NewF.ScaledReg = Diff;
- (void)InsertFormula(LU, LUIdx, NewF);
- }
- // Use the immediate in a base register.
- for (size_t N = 0, NE = F.BaseRegs.size(); N != NE; ++N) {
- const SCEV *BaseReg = F.BaseRegs[N];
- if (BaseReg != OrigReg)
- continue;
- Formula NewF = F;
- NewF.AM.BaseOffs = (uint64_t)NewF.AM.BaseOffs + Imm;
- if (!isLegalUse(NewF.AM, LU.Kind, LU.AccessTy, TLI))
- continue;
- const SCEV *Diff = SE.getAddExpr(NegImmS, BaseReg);
- if (Diff->isZero()) continue;
- // Don't create 50 + reg(-50).
- if (Diff ==
- SE.getSCEV(ConstantInt::get(IntTy,
- -(uint64_t)NewF.AM.BaseOffs)))
- continue;
- NewF.BaseRegs[N] = Diff;
- (void)InsertFormula(LU, LUIdx, NewF);
- }
- }
- }
+ return true;
}
-/// GenerateAllReuseFormulae - Generate formulae for each use.
-void
-LSRInstance::GenerateAllReuseFormulae() {
- SmallVector<Formula, 12> Save;
- for (size_t LUIdx = 0, NumUses = Uses.size(); LUIdx != NumUses; ++LUIdx) {
- LSRUse &LU = Uses[LUIdx];
-
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateSymbolicOffsetReuse(LU, LUIdx, LU.Formulae[i]);
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateICmpZeroScaledReuse(LU, LUIdx, LU.Formulae[i]);
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateReassociationReuse(LU, LUIdx, LU.Formulae[i]);
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateCombinationReuse(LU, LUIdx, LU.Formulae[i]);
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateScaledReuse(LU, LUIdx, LU.Formulae[i]);
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateTruncateReuse(LU, LUIdx, LU.Formulae[i]);
- }
-
- GenerateConstantOffsetReuse();
-}
-
-/// GenerateLoopInvariantRegisterUses - Check for other uses of loop-invariant
-/// values which we're tracking. These other uses will pin these values in
-/// registers, making them less profitable for elimination.
-/// TODO: This currently misses non-constant addrec step registers.
-/// TODO: Should this give more weight to users inside the loop?
-void
-LSRInstance::GenerateLoopInvariantRegisterUses() {
- SmallVector<const SCEV *, 8> Worklist(RegSequence.begin(), RegSequence.end());
-
- while (!Worklist.empty()) {
- const SCEV *S = Worklist.pop_back_val();
+/// OptimizeLoopCountIV - If, after all sharing of IVs, the IV used for deciding
+/// when to exit the loop is used only for that purpose, try to rearrange things
+/// so it counts down to a test against zero.
+bool LoopStrengthReduce::OptimizeLoopCountIV(Loop *L) {
+ bool ThisChanged = false;
+ for (unsigned i = 0, e = IU->StrideOrder.size(); i != e; ++i) {
+ const SCEV *Stride = IU->StrideOrder[i];
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator SI =
+ IU->IVUsesByStride.find(Stride);
+ assert(SI != IU->IVUsesByStride.end() && "Stride doesn't exist!");
+ // FIXME: Generalize to non-affine IV's.
+ if (!SI->first->isLoopInvariant(L))
+ continue;
+ // If stride is a constant and it has an icmpinst use, check if we can
+ // optimize the loop to count down.
+ if (isa<SCEVConstant>(Stride) && SI->second->Users.size() == 1) {
+ Instruction *User = SI->second->Users.begin()->getUser();
+ if (!isa<ICmpInst>(User))
+ continue;
+ const SCEV *CondStride = Stride;
+ IVStrideUse *Use = &*SI->second->Users.begin();
+ if (!OptimizeLoopCountIVOfStride(CondStride, Use, L))
+ continue;
+ ThisChanged = true;
- if (const SCEVNAryExpr *N = dyn_cast<SCEVNAryExpr>(S))
- Worklist.insert(Worklist.end(), N->op_begin(), N->op_end());
- else if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(S))
- Worklist.push_back(C->getOperand());
- else if (const SCEVUDivExpr *D = dyn_cast<SCEVUDivExpr>(S)) {
- Worklist.push_back(D->getLHS());
- Worklist.push_back(D->getRHS());
- } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
- const Value *V = U->getValue();
- if (const Instruction *Inst = dyn_cast<Instruction>(V))
- if (L->contains(Inst)) continue;
- for (Value::use_const_iterator UI = V->use_begin(), UE = V->use_end();
- UI != UE; ++UI) {
- const Instruction *UserInst = dyn_cast<Instruction>(*UI);
- // Ignore non-instructions.
- if (!UserInst)
- continue;
- // Ignore instructions in other functions (as can happen with
- // Constants).
- if (UserInst->getParent()->getParent() != L->getHeader()->getParent())
+ // Now check if it's possible to reuse this iv for other stride uses.
+ for (unsigned j = 0, ee = IU->StrideOrder.size(); j != ee; ++j) {
+ const SCEV *SStride = IU->StrideOrder[j];
+ if (SStride == CondStride)
continue;
- // Ignore instructions not dominated by the loop.
- const BasicBlock *UseBB = !isa<PHINode>(UserInst) ?
- UserInst->getParent() :
- cast<PHINode>(UserInst)->getIncomingBlock(
- PHINode::getIncomingValueNumForOperand(UI.getOperandNo()));
- if (!DT.dominates(L->getHeader(), UseBB))
+ std::map<const SCEV *, IVUsersOfOneStride *>::iterator SII =
+ IU->IVUsesByStride.find(SStride);
+ assert(SII != IU->IVUsesByStride.end() && "Stride doesn't exist!");
+ // FIXME: Generalize to non-affine IV's.
+ if (!SII->first->isLoopInvariant(L))
continue;
- // Ignore uses which are part of other SCEV expressions, to avoid
- // analyzing them multiple times.
- if (SE.isSCEVable(UserInst->getType()) &&
- !isa<SCEVUnknown>(SE.getSCEV(const_cast<Instruction *>(UserInst))))
- continue;
- // Ignore icmp instructions which are already being analyzed.
- if (const ICmpInst *ICI = dyn_cast<ICmpInst>(UserInst)) {
- unsigned OtherIdx = !UI.getOperandNo();
- Value *OtherOp = const_cast<Value *>(ICI->getOperand(OtherIdx));
- if (SE.getSCEV(OtherOp)->hasComputableLoopEvolution(L))
- continue;
- }
-
- LSRUse &LU = getNewUse();
- LU.UserInst = const_cast<Instruction *>(UserInst);
- LU.OperandValToReplace = UI.getUse();
- LU.InsertSupplementalFormula(U);
- CountRegisters(LU.Formulae.back(), Uses.size() - 1);
+ // FIXME: Rewrite other stride using CondStride.
}
}
}
-}
-#ifndef NDEBUG
-
-static void debug_winner(SmallVector<LSRUse, 16> const &Uses) {
- dbgs() << "LSR has selected formulae for each use:\n";
- for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),
- E = Uses.end(); I != E; ++I) {
- const LSRUse &LU = *I;
- dbgs() << " ";
- LU.print(dbgs());
- dbgs() << '\n';
- dbgs() << " ";
- LU.Formulae.front().print(dbgs());
- dbgs() << "\n";
- }
+ Changed |= ThisChanged;
+ return ThisChanged;
}
-#endif
-
-LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P)
- : IU(P->getAnalysis<IVUsers>()),
- SE(P->getAnalysis<ScalarEvolution>()),
- DT(P->getAnalysis<DominatorTree>()),
- TLI(tli), L(l), Changed(false), IVIncInsertPos(0),
- CurrentArbitraryRegIndex(0), MaxNumRegs(0) {
+bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
+ IU = &getAnalysis<IVUsers>();
+ SE = &getAnalysis<ScalarEvolution>();
+ Changed = false;
// If LoopSimplify form is not available, stay out of trouble.
- if (!L->isLoopSimplifyForm()) return;
-
- // If there's no interesting work to be done, bail early.
- if (IU.IVUsesByStride.empty()) return;
-
- DEBUG(dbgs() << "\nLSR on loop ";
- WriteAsOperand(dbgs(), L->getHeader(), /*PrintType=*/false);
- dbgs() << ":\n");
-
- // Sort the StrideOrder so we process larger strides first.
- std::stable_sort(IU.StrideOrder.begin(), IU.StrideOrder.end(),
- StrideCompare(SE));
-
- /// OptimizeShadowIV - If IV is used in a int-to-float cast
- /// inside the loop then try to eliminate the cast opeation.
- OptimizeShadowIV();
-
- // Change loop terminating condition to use the postinc iv when possible.
- Changed |= OptimizeLoopTermCond();
-
- for (SmallVectorImpl<const SCEV *>::const_iterator SIter =
- IU.StrideOrder.begin(), SEnd = IU.StrideOrder.end();
- SIter != SEnd; ++SIter) {
- const SCEV *Stride = *SIter;
-
- // Collect interesting types.
- Types.insert(SE.getEffectiveSCEVType(Stride->getType()));
-
- // Collect interesting factors.
- for (SmallVectorImpl<const SCEV *>::const_iterator NewStrideIter =
- SIter + 1; NewStrideIter != SEnd; ++NewStrideIter) {
- const SCEV *OldStride = Stride;
- const SCEV *NewStride = *NewStrideIter;
-
- if (SE.getTypeSizeInBits(OldStride->getType()) !=
- SE.getTypeSizeInBits(NewStride->getType())) {
- if (SE.getTypeSizeInBits(OldStride->getType()) >
- SE.getTypeSizeInBits(NewStride->getType()))
- NewStride = SE.getSignExtendExpr(NewStride, OldStride->getType());
- else
- OldStride = SE.getSignExtendExpr(OldStride, NewStride->getType());
- }
- if (const SCEVConstant *Factor =
- dyn_cast_or_null<SCEVConstant>(getSDiv(NewStride, OldStride,
- SE, true)))
- if (Factor->getValue()->getValue().getMinSignedBits() <= 64)
- Factors.insert(Factor->getValue()->getValue().getSExtValue());
- }
-
- std::map<const SCEV *, IVUsersOfOneStride *>::const_iterator SI =
- IU.IVUsesByStride.find(Stride);
- assert(SI != IU.IVUsesByStride.end() && "Stride doesn't exist!");
- for (ilist<IVStrideUse>::const_iterator UI = SI->second->Users.begin(),
- E = SI->second->Users.end(); UI != E; ++UI) {
- // Record the uses.
- LSRUse &LU = getNewUse();
- LU.UserInst = UI->getUser();
- LU.OperandValToReplace = UI->getOperandValToReplace();
- if (isAddressUse(LU.UserInst, LU.OperandValToReplace)) {
- LU.Kind = LSRUse::Address;
- LU.AccessTy = getAccessType(LU.UserInst);
- }
- if (UI->isUseOfPostIncrementedValue())
- LU.PostIncLoop = L;
-
- const SCEV *S = IU.getCanonicalExpr(*UI);
-
- // Equality (== and !=) ICmps are special. We can rewrite (i == N) as
- // (N - i == 0), and this allows (N - i) to be the expression that we
- // work with rather than just N or i, so we can consider the register
- // requirements for both N and i at the same time. Limiting this code
- // to equality icmps is not a problem because all interesting loops
- // use equality icmps, thanks to IndVarSimplify.
- if (ICmpInst *CI = dyn_cast<ICmpInst>(LU.UserInst))
- if (CI->isEquality()) {
- // Swap the operands if needed to put the OperandValToReplace on
- // the left, for consistency.
- Value *NV = CI->getOperand(1);
- if (NV == LU.OperandValToReplace) {
- CI->setOperand(1, CI->getOperand(0));
- CI->setOperand(0, NV);
- }
-
- // x == y --> x - y == 0
- const SCEV *N = SE.getSCEV(NV);
- if (N->isLoopInvariant(L)) {
- LU.Kind = LSRUse::ICmpZero;
- S = SE.getMinusSCEV(N, S);
- }
-
- // -1 and the negations of all interesting strides (except the
- // negation of -1) are now also interesting.
- for (size_t i = 0, e = Factors.size(); i != e; ++i)
- if (Factors[i] != -1)
- Factors.insert(-(uint64_t)Factors[i]);
- Factors.insert(-1);
- }
-
- // Set up the initial formula for this use.
- LU.InsertInitialFormula(S, L, SE, DT);
- CountRegisters(LU.Formulae.back(), Uses.size() - 1);
- }
- }
-
- // If all uses use the same type, don't bother looking for truncation-based
- // reuse.
- if (Types.size() == 1)
- Types.clear();
-
- // If there are any uses of registers that we're tracking that have escaped
- // IVUsers' attention, add trivial uses for them, so that the register
- // voting process takes the into consideration.
- GenerateLoopInvariantRegisterUses();
-
- // Start by assuming we'll assign each use its own register. This is
- // sometimes called "full" strength reduction, or "superhero" mode.
- // Sometimes this is the best solution, but if there are opportunities for
- // reuse we may find a better solution.
- Score CurScore;
- CurScore.RateInitial(Uses, L, SE);
-
- MaxNumRegs = CurScore.getNumRegs();
-
- // Now use the reuse data to generate a bunch of interesting ways
- // to formulate the values needed for the uses.
- GenerateAllReuseFormulae();
-
- // Sort the formulae. TODO: This is redundantly sorted below.
- for (SmallVectorImpl<LSRUse>::iterator I = Uses.begin(), E = Uses.end();
- I != E; ++I) {
- LSRUse &LU = *I;
- std::stable_sort(LU.Formulae.begin(), LU.Formulae.end(),
- ComplexitySorter());
- }
-
- // Ok, we've now collected all the uses and noted their register uses. The
- // next step is to start looking at register reuse possibilities.
- DEBUG(print(dbgs()); dbgs() << '\n'; IU.dump());
-
- // Create a sorted list of registers with those with the most uses appearing
- // earlier in the list. We'll visit them first, as they're the most likely
- // to represent profitable reuse opportunities.
- SmallVector<RegCount, 8> RegOrder;
- for (SmallVectorImpl<const SCEV *>::const_iterator I =
- RegSequence.begin(), E = RegSequence.end(); I != E; ++I)
- RegOrder.push_back(RegCount(*I, RegUses.find(*I)->second));
- std::stable_sort(RegOrder.begin(), RegOrder.end());
-
- // Visit each register. Determine which ones represent profitable reuse
- // opportunities and remember them.
- // TODO: Extract this code into a function.
- for (SmallVectorImpl<RegCount>::const_iterator I = RegOrder.begin(),
- E = RegOrder.end(); I != E; ++I) {
- const SCEV *Reg = I->Reg;
- const SmallBitVector &Bits = I->Sort.Bits;
-
- // Registers with only one use don't represent reuse opportunities, so
- // when we get there, we're done.
- if (Bits.count() <= 1) break;
-
- DEBUG(dbgs() << "Reg " << *Reg << ": ";
- I->Sort.print(dbgs());
- dbgs() << '\n');
-
- // Determine the total number of registers will be needed if we make use
- // of the reuse opportunity represented by the current register.
- Score NewScore;
- NewScore.Rate(Reg, Bits, Uses, L, SE);
-
- // Now decide whether this register's reuse opportunity is an overall win.
- // Currently the decision is heavily skewed for register pressure.
- if (!(NewScore < CurScore)) {
- continue;
- }
-
- // Ok, use this opportunity.
- DEBUG(dbgs() << "This candidate has been accepted.\n");
- CurScore = NewScore;
-
- // Now that we've selected a new reuse opportunity, delete formulae that
- // do not participate in that opportunity.
- for (int j = Bits.find_first(); j != -1; j = Bits.find_next(j)) {
- LSRUse &LU = Uses[j];
- for (unsigned k = 0, h = LU.Formulae.size(); k != h; ++k) {
- Formula &F = LU.Formulae[k];
- if (!F.referencesReg(Reg)) {
- std::swap(LU.Formulae[k], LU.Formulae.back());
- LU.Formulae.pop_back();
- --k; --h;
- }
- }
- // Also re-sort the list to put the formulae with the fewest registers
- // at the front.
- // TODO: Do this earlier, we don't need it each time.
- std::stable_sort(LU.Formulae.begin(), LU.Formulae.end(),
- ComplexitySorter());
- }
- }
-
- // Ok, we've now made all our decisions. The first formula for each use
- // will be used.
- DEBUG(dbgs() << "Concluding, we need "; CurScore.print(dbgs());
- dbgs() << ".\n";
- debug_winner(Uses));
-
- // Free memory no longer needed.
- RegOrder.clear();
- Factors.clear();
- Types.clear();
- RegUses.clear();
- RegSequence.clear();
-
- // Keep track of instructions we may have made dead, so that
- // we can remove them after we are done working.
- SmallVector<WeakVH, 16> DeadInsts;
-
- SCEVExpander Rewriter(SE);
- Rewriter.disableCanonicalMode();
- Rewriter.setIVIncInsertPos(L, IVIncInsertPos);
-
- // Expand the new value definitions and update the users.
- for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),
- E = Uses.end(); I != E; ++I) {
- // Formulae should be legal.
- DEBUG(for (SmallVectorImpl<Formula>::const_iterator J = I->Formulae.begin(),
- JE = I->Formulae.end(); J != JE; ++J)
- assert(isLegalUse(J->AM, I->Kind, I->AccessTy, TLI) &&
- "Illegal formula generated!"));
-
- // Expand the new code and update the user.
- I->Rewrite(L, IVIncInsertPos, Rewriter, DeadInsts, SE, DT, P);
- Changed = true;
- }
-
- // Clean up after ourselves. This must be done before deleting any
- // instructions.
- Rewriter.clear();
-
- Changed |= DeleteTriviallyDeadInstructions(DeadInsts);
-}
-
-void LSRInstance::print(raw_ostream &OS) const {
- if (MaxNumRegs != 0)
- OS << "LSR is considering " << MaxNumRegs << " to be the maximum "
- "number of registers needed.\n";
+ if (!L->getLoopPreheader() || !L->getLoopLatch())
+ return false;
- OS << "LSR has identified the following interesting factors and types: ";
- bool First = true;
+ if (!IU->IVUsesByStride.empty()) {
+ DEBUG(dbgs() << "\nLSR on \"" << L->getHeader()->getParent()->getName()
+ << "\" ";
+ L->print(dbgs()));
+
+ // Sort the StrideOrder so we process larger strides first.
+ std::stable_sort(IU->StrideOrder.begin(), IU->StrideOrder.end(),
+ StrideCompare(SE));
+
+ // Optimize induction variables. Some indvar uses can be transformed to use
+ // strides that will be needed for other purposes. A common example of this
+ // is the exit test for the loop, which can often be rewritten to use the
+ // computation of some other indvar to decide when to terminate the loop.
+ OptimizeIndvars(L);
+
+ // Change loop terminating condition to use the postinc iv when possible
+ // and optimize loop terminating compare. FIXME: Move this after
+ // StrengthReduceIVUsersOfStride?
+ OptimizeLoopTermCond(L);
+
+ // FIXME: We can shrink overlarge IV's here. e.g. if the code has
+ // computation in i64 values and the target doesn't support i64, demote
+ // the computation to 32-bit if safe.
+
+ // FIXME: Attempt to reuse values across multiple IV's. In particular, we
+ // could have something like "for(i) { foo(i*8); bar(i*16) }", which should
+ // be codegened as "for (j = 0;; j+=8) { foo(j); bar(j+j); }" on X86/PPC.
+ // Need to be careful that IV's are all the same type. Only works for
+ // intptr_t indvars.
+
+ // IVsByStride keeps IVs for one particular loop.
+ assert(IVsByStride.empty() && "Stale entries in IVsByStride?");
+
+ StrengthReduceIVUsers(L);
+
+ // After all sharing is done, see if we can adjust the loop to test against
+ // zero instead of counting up to a maximum. This is usually faster.
+ OptimizeLoopCountIV(L);
- for (SmallSetVector<int64_t, 4>::const_iterator
- I = Factors.begin(), E = Factors.end(); I != E; ++I) {
- if (!First) OS << ", ";
- First = false;
- OS << '*' << *I;
- }
+ // We're done analyzing this loop; release all the state we built up for it.
+ IVsByStride.clear();
- for (SmallSetVector<const Type *, 4>::const_iterator
- I = Types.begin(), E = Types.end(); I != E; ++I) {
- if (!First) OS << ", ";
- First = false;
- OS << '(' << **I << ')';
+ // Clean up after ourselves
+ DeleteTriviallyDeadInstructions();
}
- OS << '\n';
-
- OS << "LSR is examining the following uses, and candidate formulae:\n";
- for (SmallVectorImpl<LSRUse>::const_iterator I = Uses.begin(),
- E = Uses.end(); I != E; ++I) {
- const LSRUse &LU = *I;
- dbgs() << " ";
- LU.print(OS);
- OS << '\n';
- for (SmallVectorImpl<Formula>::const_iterator J = LU.Formulae.begin(),
- JE = LU.Formulae.end(); J != JE; ++J) {
- OS << " ";
- J->print(OS);
- OS << "\n";
- }
- }
-}
-
-void LSRInstance::dump() const {
- print(errs()); errs() << '\n';
-}
-
-namespace {
-
-class LoopStrengthReduce : public LoopPass {
- /// TLI - Keep a pointer of a TargetLowering to consult for determining
- /// transformation profitability.
- const TargetLowering *const TLI;
-
-public:
- static char ID; // Pass ID, replacement for typeid
- explicit LoopStrengthReduce(const TargetLowering *tli = NULL);
-
-private:
- bool runOnLoop(Loop *L, LPPassManager &LPM);
- void getAnalysisUsage(AnalysisUsage &AU) const;
-};
-
-}
-
-char LoopStrengthReduce::ID = 0;
-static RegisterPass<LoopStrengthReduce>
-X("loop-reduce", "Loop Strength Reduction");
-
-Pass *llvm::createLoopStrengthReducePass(const TargetLowering *TLI) {
- return new LoopStrengthReduce(TLI);
-}
-
-LoopStrengthReduce::LoopStrengthReduce(const TargetLowering *tli)
- : LoopPass(&ID), TLI(tli) {}
-
-void LoopStrengthReduce::getAnalysisUsage(AnalysisUsage &AU) const {
- // We split critical edges, so we change the CFG. However, we do update
- // many analyses if they are around.
- AU.addPreservedID(LoopSimplifyID);
- AU.addPreserved<LoopInfo>();
- AU.addPreserved("domfrontier");
-
- AU.addRequiredID(LoopSimplifyID);
- AU.addRequired<DominatorTree>();
- AU.addPreserved<DominatorTree>();
- AU.addRequired<ScalarEvolution>();
- AU.addPreserved<ScalarEvolution>();
- AU.addRequired<IVUsers>();
- AU.addPreserved<IVUsers>();
-}
-
-bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager & /*LPM*/) {
- bool Changed = false;
-
- // Run the main LSR transformation.
- Changed |= LSRInstance(TLI, L, this).getChanged();
// At this point, it is worth checking to see if any recurrence PHIs are also
// dead, so that we can remove them as well.
Modified: llvm/trunk/test/CodeGen/ARM/arm-negative-stride.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/arm-negative-stride.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/arm-negative-stride.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/arm-negative-stride.ll Thu Jan 21 18:46:49 2010
@@ -1,32 +1,7 @@
; RUN: llc < %s -march=arm | FileCheck %s
-; This loop is rewritten with an indvar which counts down, which
-; frees up a register from holding the trip count.
-
define void @test(i32* %P, i32 %A, i32 %i) nounwind {
entry:
-; CHECK: str r1, [{{r.*}}, +{{r.*}}, lsl #2]
- icmp eq i32 %i, 0 ; <i1>:0 [#uses=1]
- br i1 %0, label %return, label %bb
-
-bb: ; preds = %bb, %entry
- %indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
- %i_addr.09.0 = sub i32 %i, %indvar ; <i32> [#uses=1]
- %tmp2 = getelementptr i32* %P, i32 %i_addr.09.0 ; <i32*> [#uses=1]
- store i32 %A, i32* %tmp2
- %indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
- icmp eq i32 %indvar.next, %i ; <i1>:1 [#uses=1]
- br i1 %1, label %return, label %bb
-
-return: ; preds = %bb, %entry
- ret void
-}
-
-; This loop has a non-address use of the count-up indvar, so
-; it'll remain. Now the original store uses a negative-stride address.
-
-define void @test_with_forced_iv(i32* %P, i32 %A, i32 %i) nounwind {
-entry:
; CHECK: str r1, [{{r.*}}, -{{r.*}}, lsl #2]
icmp eq i32 %i, 0 ; <i1>:0 [#uses=1]
br i1 %0, label %return, label %bb
@@ -36,7 +11,6 @@
%i_addr.09.0 = sub i32 %i, %indvar ; <i32> [#uses=1]
%tmp2 = getelementptr i32* %P, i32 %i_addr.09.0 ; <i32*> [#uses=1]
store i32 %A, i32* %tmp2
- store i32 %indvar, i32* null
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
icmp eq i32 %indvar.next, %i ; <i1>:1 [#uses=1]
br i1 %1, label %return, label %bb
Modified: llvm/trunk/test/CodeGen/ARM/lsr-code-insertion.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/lsr-code-insertion.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/lsr-code-insertion.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/lsr-code-insertion.ll Thu Jan 21 18:46:49 2010
@@ -1,5 +1,5 @@
-; RUN: llc < %s -stats |& grep {39.*Number of machine instrs printed}
-; RUN: llc < %s -stats |& not grep {.*Number of re-materialization}
+; RUN: llc < %s -stats |& grep {40.*Number of machine instrs printed}
+; RUN: llc < %s -stats |& grep {.*Number of re-materialization}
; This test really wants to check that the resultant "cond_true" block only
; has a single store in it, and that cond_true55 only has code to materialize
; the constant and do a store. We do *not* want something like this:
Modified: llvm/trunk/test/CodeGen/ARM/remat.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/remat.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/remat.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/remat.ll Thu Jan 21 18:46:49 2010
@@ -1,4 +1,5 @@
-; RUN: llc < %s -mtriple=arm-apple-darwin -stats -info-output-file - | not grep "Number of re-materialization"
+; RUN: llc < %s -mtriple=arm-apple-darwin
+; RUN: llc < %s -mtriple=arm-apple-darwin -stats -info-output-file - | grep "Number of re-materialization" | grep 3
%struct.CONTENTBOX = type { i32, i32, i32, i32, i32 }
%struct.LOCBOX = type { i32, i32, i32, i32 }
Modified: llvm/trunk/test/CodeGen/Thumb2/lsr-deficiency.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb2/lsr-deficiency.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Thumb2/lsr-deficiency.ll (original)
+++ llvm/trunk/test/CodeGen/Thumb2/lsr-deficiency.ll Thu Jan 21 18:46:49 2010
@@ -1,29 +1,25 @@
; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 -relocation-model=pic | FileCheck %s
; rdar://7387640
-; This now reduces to a single induction variable.
-
-; TODO: It still gets a GPR shuffle at the end of the loop
-; This is because something in instruction selection has decided
-; that comparing the pre-incremented value with zero is better
-; than comparing the post-incremented value with -4.
+; FIXME: We still need to rewrite array reference iv of stride -4 with loop
+; count iv of stride -1.
@G = external global i32 ; <i32*> [#uses=2]
@array = external global i32* ; <i32**> [#uses=1]
define arm_apcscc void @t() nounwind optsize {
; CHECK: t:
-; CHECK: mov.w r2, #1000
+; CHECK: mov.w r2, #4000
+; CHECK: movw r3, #1001
entry:
%.pre = load i32* @G, align 4 ; <i32> [#uses=1]
br label %bb
bb: ; preds = %bb, %entry
; CHECK: LBB1_1:
-; CHECK: cmp r2, #0
-; CHECK: sub.w r9, r2, #1
-; CHECK: mov r2, r9
-
+; CHECK: subs r3, #1
+; CHECK: cmp r3, #0
+; CHECK: sub.w r2, r2, #4
%0 = phi i32 [ %.pre, %entry ], [ %3, %bb ] ; <i32> [#uses=1]
%indvar = phi i32 [ 0, %entry ], [ %indvar.next, %bb ] ; <i32> [#uses=2]
%tmp5 = sub i32 1000, %indvar ; <i32> [#uses=1]
Modified: llvm/trunk/test/CodeGen/Thumb2/thumb2-ifcvt1.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb2/thumb2-ifcvt1.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Thumb2/thumb2-ifcvt1.ll (original)
+++ llvm/trunk/test/CodeGen/Thumb2/thumb2-ifcvt1.ll Thu Jan 21 18:46:49 2010
@@ -1,6 +1,6 @@
; RUN: llc < %s -mtriple=thumbv7-apple-darwin | FileCheck %s
-define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) nounwind {
+define i32 @t1(i32 %a, i32 %b, i32 %c, i32 %d) {
; CHECK: t1:
; CHECK: it ne
; CHECK: cmpne
@@ -20,12 +20,12 @@
}
; FIXME: Check for # of unconditional branch after adding branch folding post ifcvt.
-define i32 @t2(i32 %a, i32 %b) nounwind {
+define i32 @t2(i32 %a, i32 %b) {
entry:
; CHECK: t2:
-; CHECK: ite gt
-; CHECK: subgt
+; CHECK: ite le
; CHECK: suble
+; CHECK: subgt
%tmp1434 = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp1434, label %bb17, label %bb.outer
@@ -60,14 +60,14 @@
@x = external global i32* ; <i32**> [#uses=1]
-define void @foo(i32 %a) nounwind {
+define void @foo(i32 %a) {
entry:
%tmp = load i32** @x ; <i32*> [#uses=1]
store i32 %a, i32* %tmp
ret void
}
-define void @t3(i32 %a, i32 %b) nounwind {
+define void @t3(i32 %a, i32 %b) {
entry:
; CHECK: t3:
; CHECK: it lt
Modified: llvm/trunk/test/CodeGen/X86/2006-05-11-InstrSched.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2006-05-11-InstrSched.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/2006-05-11-InstrSched.ll (original)
+++ llvm/trunk/test/CodeGen/X86/2006-05-11-InstrSched.ll Thu Jan 21 18:46:49 2010
@@ -1,5 +1,5 @@
; RUN: llc < %s -march=x86 -mattr=+sse2 -stats -realign-stack=0 |&\
-; RUN: grep {asm-printer} | grep 34
+; RUN: grep {asm-printer} | grep 31
target datalayout = "e-p:32:32"
define void @foo(i32* %mc, i32* %bp, i32* %ms, i32* %xmb, i32* %mpp, i32* %tpmm, i32* %ip, i32* %tpim, i32* %dpp, i32* %tpdm, i32* %bpi, i32 %M) nounwind {
@@ -40,7 +40,7 @@
%tmp137.upgrd.7 = bitcast i32* %tmp137 to <2 x i64>* ; <<2 x i64>*> [#uses=1]
store <2 x i64> %tmp131, <2 x i64>* %tmp137.upgrd.7
%tmp147 = add nsw i32 %tmp.10, 8 ; <i32> [#uses=1]
- %tmp.upgrd.8 = icmp ne i32 %tmp147, %M ; <i1> [#uses=1]
+ %tmp.upgrd.8 = icmp slt i32 %tmp147, %M ; <i1> [#uses=1]
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
br i1 %tmp.upgrd.8, label %cond_true, label %return
Modified: llvm/trunk/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll (original)
+++ llvm/trunk/test/CodeGen/X86/2007-11-30-LoadFolding-Bug.ll Thu Jan 21 18:46:49 2010
@@ -35,7 +35,7 @@
bb.i28.i: ; preds = %bb.i28.i, %cond_next36.i
; CHECK: %bb.i28.i
; CHECK: addl $2
-; CHECK: addl $-2
+; CHECK: addl $2
%j.0.reg2mem.0.i16.i = phi i32 [ 0, %cond_next36.i ], [ %indvar.next39.i, %bb.i28.i ] ; <i32> [#uses=2]
%din_addr.1.reg2mem.0.i17.i = phi double [ 0.000000e+00, %cond_next36.i ], [ %tmp16.i25.i, %bb.i28.i ] ; <double> [#uses=1]
%tmp1.i18.i = fptosi double %din_addr.1.reg2mem.0.i17.i to i32 ; <i32> [#uses=2]
Modified: llvm/trunk/test/CodeGen/X86/iv-users-in-other-loops.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/iv-users-in-other-loops.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/iv-users-in-other-loops.ll (original)
+++ llvm/trunk/test/CodeGen/X86/iv-users-in-other-loops.ll Thu Jan 21 18:46:49 2010
@@ -1,11 +1,11 @@
; RUN: llc < %s -march=x86-64 -o %t
-; RUN: not grep inc %t
+; RUN: grep inc %t | count 1
; RUN: grep dec %t | count 2
-; RUN: grep addq %t | count 10
+; RUN: grep addq %t | count 13
; RUN: not grep addb %t
; RUN: grep leaq %t | count 9
-; RUN: grep leal %t | count 2
-; RUN: grep movq %t | count 10
+; RUN: grep leal %t | count 3
+; RUN: grep movq %t | count 5
; IV users in each of the loops from other loops shouldn't cause LSR
; to insert new induction variables. Previously it would create a
Modified: llvm/trunk/test/CodeGen/X86/loop-strength-reduce4.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/loop-strength-reduce4.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/loop-strength-reduce4.ll (original)
+++ llvm/trunk/test/CodeGen/X86/loop-strength-reduce4.ll Thu Jan 21 18:46:49 2010
@@ -1,19 +1,5 @@
-; RUN: llc < %s -march=x86 -relocation-model=static -mtriple=i686-apple-darwin | FileCheck %s -check-prefix=STATIC
-; RUN: llc < %s -march=x86 -relocation-model=pic | FileCheck %s -check-prefix=PIC
-
-; By starting the IV at -64 instead of 0, a cmp is eliminated,
-; as the flags from the add can be used directly.
-
-; STATIC: movl $-64, %ecx
-
-; STATIC: movl %eax, _state+76(%ecx)
-; STATIC: addl $16, %ecx
-; STATIC: jne
-
-; In PIC mode the symbol can't be folded, so the change-compare-stride
-; trick applies.
-
-; PIC: cmpl $64
+; RUN: llc < %s -march=x86 | grep cmp | grep 64
+; RUN: llc < %s -march=x86 | not grep inc
@state = external global [0 x i32] ; <[0 x i32]*> [#uses=4]
@S = external global [0 x i32] ; <[0 x i32]*> [#uses=4]
Modified: llvm/trunk/test/CodeGen/X86/loop-strength-reduce8.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/loop-strength-reduce8.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/loop-strength-reduce8.ll (original)
+++ llvm/trunk/test/CodeGen/X86/loop-strength-reduce8.ll Thu Jan 21 18:46:49 2010
@@ -1,10 +1,4 @@
-; RUN: llc < %s -mtriple=i386-apple-darwin | FileCheck %s
-
-; CHECK: leal 16(%eax), %edx
-; CHECK: align
-; CHECK: addl $4, %edx
-; CHECK: decl %ecx
-; CHECK: jne LBB1_2
+; RUN: llc < %s -mtriple=i386-apple-darwin | grep leal | not grep 16
%struct.CUMULATIVE_ARGS = type { i32, i32, i32, i32, i32, i32, i32 }
%struct.bitmap_element = type { %struct.bitmap_element*, %struct.bitmap_element*, i32, [2 x i64] }
Removed: llvm/trunk/test/CodeGen/X86/lsr-reuse.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/lsr-reuse.ll?rev=94122&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/lsr-reuse.ll (original)
+++ llvm/trunk/test/CodeGen/X86/lsr-reuse.ll (removed)
@@ -1,159 +0,0 @@
-; RUN: llc < %s -march=x86-64 | FileCheck %s
-target datalayout = "e-p:64:64:64"
-target triple = "x86_64-unknown-unknown"
-
-; Full strength reduction reduces register pressure from 5 to 4 here.
-
-; CHECK: full_me:
-; CHECK: movsd (%rsi), %xmm0
-; CHECK: mulsd (%rdx), %xmm0
-; CHECK: movsd %xmm0, (%rdi)
-; CHECK: addq $8, %rsi
-; CHECK: addq $8, %rdx
-; CHECK: addq $8, %rdi
-; CHECK: decq %rcx
-; CHECK: jne
-
-define void @full_me(double* nocapture %A, double* nocapture %B, double* nocapture %C, i64 %n) nounwind {
-entry:
- %t0 = icmp sgt i64 %n, 0
- br i1 %t0, label %loop, label %return
-
-loop:
- %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
- %Ai = getelementptr inbounds double* %A, i64 %i
- %Bi = getelementptr inbounds double* %B, i64 %i
- %Ci = getelementptr inbounds double* %C, i64 %i
- %t1 = load double* %Bi
- %t2 = load double* %Ci
- %m = fmul double %t1, %t2
- store double %m, double* %Ai
- %i.next = add nsw i64 %i, 1
- %exitcond = icmp eq i64 %i.next, %n
- br i1 %exitcond, label %return, label %loop
-
-return:
- ret void
-}
-
-; In this test, the counting IV exit value is used, so full strength reduction
-; would not reduce register pressure. IndVarSimplify ought to simplify such
-; cases away, but it's useful here to verify that LSR's register pressure
-; heuristics are working as expected.
-
-; CHECK: count_me_0:
-; CHECK: movsd (%rsi,%rax,8), %xmm0
-; CHECK: mulsd (%rdx,%rax,8), %xmm0
-; CHECK: movsd %xmm0, (%rdi,%rax,8)
-; CHECK: incq %rax
-; CHECK: cmpq %rax, %rcx
-; CHECK: jne
-
-define i64 @count_me_0(double* nocapture %A, double* nocapture %B, double* nocapture %C, i64 %n) nounwind {
-entry:
- %t0 = icmp sgt i64 %n, 0
- br i1 %t0, label %loop, label %return
-
-loop:
- %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
- %Ai = getelementptr inbounds double* %A, i64 %i
- %Bi = getelementptr inbounds double* %B, i64 %i
- %Ci = getelementptr inbounds double* %C, i64 %i
- %t1 = load double* %Bi
- %t2 = load double* %Ci
- %m = fmul double %t1, %t2
- store double %m, double* %Ai
- %i.next = add nsw i64 %i, 1
- %exitcond = icmp eq i64 %i.next, %n
- br i1 %exitcond, label %return, label %loop
-
-return:
- %q = phi i64 [ 0, %entry ], [ %i.next, %loop ]
- ret i64 %q
-}
-
-; In this test, the trip count value is used, so full strength reduction
-; would not reduce register pressure.
-; (though it would reduce register pressure inside the loop...)
-
-; CHECK: count_me_1:
-; CHECK: movsd (%rsi,%rax,8), %xmm0
-; CHECK: mulsd (%rdx,%rax,8), %xmm0
-; CHECK: movsd %xmm0, (%rdi,%rax,8)
-; CHECK: incq %rax
-; CHECK: cmpq %rax, %rcx
-; CHECK: jne
-
-define i64 @count_me_1(double* nocapture %A, double* nocapture %B, double* nocapture %C, i64 %n) nounwind {
-entry:
- %t0 = icmp sgt i64 %n, 0
- br i1 %t0, label %loop, label %return
-
-loop:
- %i = phi i64 [ %i.next, %loop ], [ 0, %entry ]
- %Ai = getelementptr inbounds double* %A, i64 %i
- %Bi = getelementptr inbounds double* %B, i64 %i
- %Ci = getelementptr inbounds double* %C, i64 %i
- %t1 = load double* %Bi
- %t2 = load double* %Ci
- %m = fmul double %t1, %t2
- store double %m, double* %Ai
- %i.next = add nsw i64 %i, 1
- %exitcond = icmp eq i64 %i.next, %n
- br i1 %exitcond, label %return, label %loop
-
-return:
- %q = phi i64 [ 0, %entry ], [ %n, %loop ]
- ret i64 %q
-}
-
-; This should be fully strength-reduced to reduce register pressure, however
-; the current heuristics get distracted by all the reuse with the stride-1
-; induction variable first.
-
-; But even so, be clever and start the stride-1 variable at a non-zero value
-; to eliminate an in-loop immediate value.
-
-; CHECK: count_me_2:
-; CHECK: movl $5, %eax
-; CHECK: align
-; CHECK: BB4_1:
-; CHECK: movsd (%rdi,%rax,8), %xmm0
-; CHECK: addsd (%rsi,%rax,8), %xmm0
-; CHECK: movsd %xmm0, (%rdx,%rax,8)
-; CHECK: movsd 40(%rdi,%rax,8), %xmm0
-; CHECK: addsd 40(%rsi,%rax,8), %xmm0
-; CHECK: movsd %xmm0, 40(%rdx,%rax,8)
-; CHECK: incq %rax
-; CHECK: cmpq $5005, %rax
-; CHECK: jne
-
-define void @count_me_2(double* nocapture %A, double* nocapture %B, double* nocapture %C) nounwind {
-entry:
- br label %loop
-
-loop:
- %i = phi i64 [ 0, %entry ], [ %i.next, %loop ]
- %i5 = add i64 %i, 5
- %Ai = getelementptr double* %A, i64 %i5
- %t2 = load double* %Ai
- %Bi = getelementptr double* %B, i64 %i5
- %t4 = load double* %Bi
- %t5 = fadd double %t2, %t4
- %Ci = getelementptr double* %C, i64 %i5
- store double %t5, double* %Ci
- %i10 = add i64 %i, 10
- %Ai10 = getelementptr double* %A, i64 %i10
- %t9 = load double* %Ai10
- %Bi10 = getelementptr double* %B, i64 %i10
- %t11 = load double* %Bi10
- %t12 = fadd double %t9, %t11
- %Ci10 = getelementptr double* %C, i64 %i10
- store double %t12, double* %Ci10
- %i.next = add i64 %i, 1
- %exitcond = icmp eq i64 %i.next, 5000
- br i1 %exitcond, label %return, label %loop
-
-return:
- ret void
-}
Modified: llvm/trunk/test/CodeGen/X86/masked-iv-safe.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/masked-iv-safe.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/masked-iv-safe.ll (original)
+++ llvm/trunk/test/CodeGen/X86/masked-iv-safe.ll Thu Jan 21 18:46:49 2010
@@ -4,9 +4,9 @@
; RUN: not grep sar %t
; RUN: not grep shl %t
; RUN: grep add %t | count 2
-; RUN: grep inc %t | count 3
+; RUN: grep inc %t | count 4
; RUN: grep dec %t | count 2
-; RUN: grep lea %t | count 3
+; RUN: grep lea %t | count 2
; Optimize away zext-inreg and sext-inreg on the loop induction
; variable using trip-count information.
@@ -127,9 +127,6 @@
ret void
}
-; TODO: If we could handle all the loads and stores as post-inc users, we could
-; use {-1,+,1} in the induction variable register, and we'd get another inc,
-; one fewer add, and a comparison with zero.
define void @another_count_up(double* %d, i64 %n) nounwind {
entry:
br label %loop
Modified: llvm/trunk/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll (original)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/2008-08-06-CmpStride.ll Thu Jan 21 18:46:49 2010
@@ -1,4 +1,5 @@
-; RUN: llc -march=x86-64 < %s -o - | grep {cmpl \\$\[1\], %}
+; RUN: opt < %s -loop-reduce -S | grep ugt
+; PR2535
@.str = internal constant [4 x i8] c"%d\0A\00"
@@ -15,7 +16,7 @@
%add166 = or i32 %mul15, 1 ; <i32> [#uses=1] *
call i32 (i8*, ...)* @printf( i8* noalias getelementptr ([4 x i8]* @.str, i32 0, i32 0), i32 %add166 ) nounwind
%inc = add i32 %i.0, 1 ; <i32> [#uses=3]
- %cmp = icmp ne i32 %inc, 1027 ; <i1> [#uses=1]
+ %cmp = icmp ult i32 %inc, 1027 ; <i1> [#uses=1]
br i1 %cmp, label %forbody, label %afterfor
afterfor: ; preds = %forcond
Modified: llvm/trunk/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll (original)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/change-compare-stride-trickiness-0.ll Thu Jan 21 18:46:49 2010
@@ -1,9 +1,10 @@
-; RUN: llc < %s -o - | grep {testl %ecx, %ecx}
+; RUN: llc %s -o - --x86-asm-syntax=att | grep {cmpl \$4}
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
target triple = "x86_64-apple-darwin9"
-; The comparison happens before the relevant use, but it can still be rewritten
-; to compare with zero.
+; This is like change-compare-stride-trickiness-1.ll except the comparison
+; happens before the relevant use, so the comparison stride can't be
+; easily changed.
define void @foo() nounwind {
entry:
Modified: llvm/trunk/test/Transforms/LoopStrengthReduce/count-to-zero.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/count-to-zero.ll?rev=94123&r1=94122&r2=94123&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/count-to-zero.ll (original)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/count-to-zero.ll Thu Jan 21 18:46:49 2010
@@ -19,7 +19,7 @@
%tmp4 = add i32 %c_addr.1, -1 ; <i32> [#uses=1]
%c_addr.1.be = select i1 %tmp2, i32 %tmp3, i32 %tmp4 ; <i32> [#uses=1]
%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=1]
-; CHECK: add i32 %lsr.iv, -1
+; CHECK: sub i32 %lsr.iv, 1
br label %bb6
bb6: ; preds = %bb3, %entry
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