[llvm] r237407 - [ValueTracking] refactor: extract method haveNoCommonBitsSet
Jingyue Wu
jingyue at google.com
Thu May 14 16:53:19 PDT 2015
Author: jingyue
Date: Thu May 14 18:53:19 2015
New Revision: 237407
URL: http://llvm.org/viewvc/llvm-project?rev=237407&view=rev
Log:
[ValueTracking] refactor: extract method haveNoCommonBitsSet
Summary:
Extract method haveNoCommonBitsSet so that we don't have to duplicate this logic in
InstCombine and SeparateConstOffsetFromGEP.
This patch also makes SeparateConstOffsetFromGEP more precise by passing
DominatorTree to computeKnownBits.
Test Plan: value-tracking-domtree.ll that tests ValueTracking indeed leverages dominating conditions
Reviewers: broune, meheff, majnemer
Reviewed By: majnemer
Subscribers: jholewinski, llvm-commits
Differential Revision: http://reviews.llvm.org/D9734
Added:
llvm/trunk/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll
Modified:
llvm/trunk/include/llvm/Analysis/ValueTracking.h
llvm/trunk/lib/Analysis/ValueTracking.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/trunk/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp
Modified: llvm/trunk/include/llvm/Analysis/ValueTracking.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ValueTracking.h?rev=237407&r1=237406&r2=237407&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ValueTracking.h (original)
+++ llvm/trunk/include/llvm/Analysis/ValueTracking.h Thu May 14 18:53:19 2015
@@ -47,6 +47,11 @@ namespace llvm {
/// \p KnownZero the set of bits that are known to be zero
void computeKnownBitsFromRangeMetadata(const MDNode &Ranges,
APInt &KnownZero);
+ /// Returns true if LHS and RHS have no common bits set.
+ bool haveNoCommonBitsSet(Value *LHS, Value *RHS, const DataLayout &DL,
+ AssumptionCache *AC = nullptr,
+ const Instruction *CxtI = nullptr,
+ const DominatorTree *DT = nullptr);
/// ComputeSignBit - Determine whether the sign bit is known to be zero or
/// one. Convenience wrapper around computeKnownBits.
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=237407&r1=237406&r2=237407&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Thu May 14 18:53:19 2015
@@ -138,6 +138,21 @@ void llvm::computeKnownBits(Value *V, AP
Query(AC, safeCxtI(V, CxtI), DT));
}
+bool llvm::haveNoCommonBitsSet(Value *LHS, Value *RHS, const DataLayout &DL,
+ AssumptionCache *AC, const Instruction *CxtI,
+ const DominatorTree *DT) {
+ assert(LHS->getType() == RHS->getType() &&
+ "LHS and RHS should have the same type");
+ assert(LHS->getType()->isIntOrIntVectorTy() &&
+ "LHS and RHS should be integers");
+ IntegerType *IT = cast<IntegerType>(LHS->getType()->getScalarType());
+ APInt LHSKnownZero(IT->getBitWidth(), 0), LHSKnownOne(IT->getBitWidth(), 0);
+ APInt RHSKnownZero(IT->getBitWidth(), 0), RHSKnownOne(IT->getBitWidth(), 0);
+ computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, DL, 0, AC, CxtI, DT);
+ computeKnownBits(RHS, RHSKnownZero, RHSKnownOne, DL, 0, AC, CxtI, DT);
+ return (LHSKnownZero | RHSKnownZero).isAllOnesValue();
+}
+
static void ComputeSignBit(Value *V, bool &KnownZero, bool &KnownOne,
const DataLayout &DL, unsigned Depth,
const Query &Q);
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=237407&r1=237406&r2=237407&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Thu May 14 18:53:19 2015
@@ -1160,20 +1160,8 @@ Instruction *InstCombiner::visitAdd(Bina
return ReplaceInstUsesWith(I, V);
// A+B --> A|B iff A and B have no bits set in common.
- if (IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
- APInt LHSKnownOne(IT->getBitWidth(), 0);
- APInt LHSKnownZero(IT->getBitWidth(), 0);
- computeKnownBits(LHS, LHSKnownZero, LHSKnownOne, 0, &I);
- if (LHSKnownZero != 0) {
- APInt RHSKnownOne(IT->getBitWidth(), 0);
- APInt RHSKnownZero(IT->getBitWidth(), 0);
- computeKnownBits(RHS, RHSKnownZero, RHSKnownOne, 0, &I);
-
- // No bits in common -> bitwise or.
- if ((LHSKnownZero|RHSKnownZero).isAllOnesValue())
- return BinaryOperator::CreateOr(LHS, RHS);
- }
- }
+ if (haveNoCommonBitsSet(LHS, RHS, DL, AC, &I, DT))
+ return BinaryOperator::CreateOr(LHS, RHS);
if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
Value *X;
Modified: llvm/trunk/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp?rev=237407&r1=237406&r2=237407&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/SeparateConstOffsetFromGEP.cpp Thu May 14 18:53:19 2015
@@ -160,6 +160,7 @@
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
@@ -202,7 +203,7 @@ namespace {
/// 5); nor can we transform (3 * (a + 5)) to (3 * a + 5), however in this case,
/// -instcombine probably already optimized (3 * (a + 5)) to (3 * a + 15).
class ConstantOffsetExtractor {
- public:
+public:
/// Extracts a constant offset from the given GEP index. It returns the
/// new index representing the remainder (equal to the original index minus
/// the constant offset), or nullptr if we cannot extract a constant offset.
@@ -210,15 +211,18 @@ class ConstantOffsetExtractor {
/// \p GEP The given GEP
/// \p UserChainTail Outputs the tail of UserChain so that we can
/// garbage-collect unused instructions in UserChain.
- static Value *Extract(Value *Idx, GetElementPtrInst *GEP,
- User *&UserChainTail);
+ static Value *Extract(Value *Idx, GetElementPtrInst *GEP,
+ User *&UserChainTail, const DominatorTree *DT);
/// Looks for a constant offset from the given GEP index without extracting
/// it. It returns the numeric value of the extracted constant offset (0 if
/// failed). The meaning of the arguments are the same as Extract.
- static int64_t Find(Value *Idx, GetElementPtrInst *GEP);
+ static int64_t Find(Value *Idx, GetElementPtrInst *GEP,
+ const DominatorTree *DT);
- private:
- ConstantOffsetExtractor(Instruction *InsertionPt) : IP(InsertionPt) {}
+private:
+ ConstantOffsetExtractor(Instruction *InsertionPt, const DominatorTree *DT)
+ : IP(InsertionPt), DL(InsertionPt->getModule()->getDataLayout()), DT(DT) {
+ }
/// Searches the expression that computes V for a non-zero constant C s.t.
/// V can be reassociated into the form V' + C. If the searching is
/// successful, returns C and update UserChain as a def-use chain from C to V;
@@ -276,13 +280,6 @@ class ConstantOffsetExtractor {
/// returns "sext i32 (zext i16 V to i32) to i64".
Value *applyExts(Value *V);
- /// Returns true if LHS and RHS have no bits in common, i.e., for every n
- /// the n-th bit of either LHS, or RHS is 0.
- bool NoCommonBits(Value *LHS, Value *RHS) const;
- /// Computes which bits are known to be one or zero.
- /// \p KnownOne Mask of all bits that are known to be one.
- /// \p KnownZero Mask of all bits that are known to be zero.
- void ComputeKnownBits(Value *V, APInt &KnownOne, APInt &KnownZero) const;
/// A helper function that returns whether we can trace into the operands
/// of binary operator BO for a constant offset.
///
@@ -304,28 +301,35 @@ class ConstantOffsetExtractor {
/// sext/zext instructions along UserChain.
SmallVector<CastInst *, 16> ExtInsts;
Instruction *IP; /// Insertion position of cloned instructions.
+ const DataLayout &DL;
+ const DominatorTree *DT;
};
/// \brief A pass that tries to split every GEP in the function into a variadic
/// base and a constant offset. It is a FunctionPass because searching for the
/// constant offset may inspect other basic blocks.
class SeparateConstOffsetFromGEP : public FunctionPass {
- public:
+public:
static char ID;
SeparateConstOffsetFromGEP(const TargetMachine *TM = nullptr,
bool LowerGEP = false)
- : FunctionPass(ID), TM(TM), LowerGEP(LowerGEP) {
+ : FunctionPass(ID), DL(nullptr), DT(nullptr), TM(TM), LowerGEP(LowerGEP) {
initializeSeparateConstOffsetFromGEPPass(*PassRegistry::getPassRegistry());
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.setPreservesCFG();
}
+ bool doInitialization(Module &M) override {
+ DL = &M.getDataLayout();
+ return false;
+ }
bool runOnFunction(Function &F) override;
- private:
+private:
/// Tries to split the given GEP into a variadic base and a constant offset,
/// and returns true if the splitting succeeds.
bool splitGEP(GetElementPtrInst *GEP);
@@ -372,6 +376,8 @@ class SeparateConstOffsetFromGEP : publi
/// Verify F is free of dead code.
void verifyNoDeadCode(Function &F);
+ const DataLayout *DL;
+ const DominatorTree *DT;
const TargetMachine *TM;
/// Whether to lower a GEP with multiple indices into arithmetic operations or
/// multiple GEPs with a single index.
@@ -384,6 +390,7 @@ INITIALIZE_PASS_BEGIN(
SeparateConstOffsetFromGEP, "separate-const-offset-from-gep",
"Split GEPs to a variadic base and a constant offset for better CSE", false,
false)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_END(
SeparateConstOffsetFromGEP, "separate-const-offset-from-gep",
@@ -412,7 +419,8 @@ bool ConstantOffsetExtractor::CanTraceIn
Value *LHS = BO->getOperand(0), *RHS = BO->getOperand(1);
// Do not trace into "or" unless it is equivalent to "add". If LHS and RHS
// don't have common bits, (LHS | RHS) is equivalent to (LHS + RHS).
- if (BO->getOpcode() == Instruction::Or && !NoCommonBits(LHS, RHS))
+ if (BO->getOpcode() == Instruction::Or &&
+ !haveNoCommonBitsSet(LHS, RHS, DL, nullptr, BO, DT))
return false;
// In addition, tracing into BO requires that its surrounding s/zext (if
@@ -497,9 +505,8 @@ APInt ConstantOffsetExtractor::find(Valu
ConstantOffset = CI->getValue();
} else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V)) {
// Trace into subexpressions for more hoisting opportunities.
- if (CanTraceInto(SignExtended, ZeroExtended, BO, NonNegative)) {
+ if (CanTraceInto(SignExtended, ZeroExtended, BO, NonNegative))
ConstantOffset = findInEitherOperand(BO, SignExtended, ZeroExtended);
- }
} else if (isa<SExtInst>(V)) {
ConstantOffset = find(U->getOperand(0), /* SignExtended */ true,
ZeroExtended, NonNegative).sext(BitWidth);
@@ -642,8 +649,9 @@ Value *ConstantOffsetExtractor::removeCo
}
Value *ConstantOffsetExtractor::Extract(Value *Idx, GetElementPtrInst *GEP,
- User *&UserChainTail) {
- ConstantOffsetExtractor Extractor(GEP);
+ User *&UserChainTail,
+ const DominatorTree *DT) {
+ ConstantOffsetExtractor Extractor(GEP, DT);
// Find a non-zero constant offset first.
APInt ConstantOffset =
Extractor.find(Idx, /* SignExtended */ false, /* ZeroExtended */ false,
@@ -658,37 +666,19 @@ Value *ConstantOffsetExtractor::Extract(
return IdxWithoutConstOffset;
}
-int64_t ConstantOffsetExtractor::Find(Value *Idx, GetElementPtrInst *GEP) {
+int64_t ConstantOffsetExtractor::Find(Value *Idx, GetElementPtrInst *GEP,
+ const DominatorTree *DT) {
// If Idx is an index of an inbound GEP, Idx is guaranteed to be non-negative.
- return ConstantOffsetExtractor(GEP)
+ return ConstantOffsetExtractor(GEP, DT)
.find(Idx, /* SignExtended */ false, /* ZeroExtended */ false,
GEP->isInBounds())
.getSExtValue();
}
-void ConstantOffsetExtractor::ComputeKnownBits(Value *V, APInt &KnownOne,
- APInt &KnownZero) const {
- IntegerType *IT = cast<IntegerType>(V->getType());
- KnownOne = APInt(IT->getBitWidth(), 0);
- KnownZero = APInt(IT->getBitWidth(), 0);
- const DataLayout &DL = IP->getModule()->getDataLayout();
- llvm::computeKnownBits(V, KnownZero, KnownOne, DL, 0);
-}
-
-bool ConstantOffsetExtractor::NoCommonBits(Value *LHS, Value *RHS) const {
- assert(LHS->getType() == RHS->getType() &&
- "LHS and RHS should have the same type");
- APInt LHSKnownOne, LHSKnownZero, RHSKnownOne, RHSKnownZero;
- ComputeKnownBits(LHS, LHSKnownOne, LHSKnownZero);
- ComputeKnownBits(RHS, RHSKnownOne, RHSKnownZero);
- return (LHSKnownZero | RHSKnownZero).isAllOnesValue();
-}
-
bool SeparateConstOffsetFromGEP::canonicalizeArrayIndicesToPointerSize(
GetElementPtrInst *GEP) {
bool Changed = false;
- const DataLayout &DL = GEP->getModule()->getDataLayout();
- Type *IntPtrTy = DL.getIntPtrType(GEP->getType());
+ Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
gep_type_iterator GTI = gep_type_begin(*GEP);
for (User::op_iterator I = GEP->op_begin() + 1, E = GEP->op_end();
I != E; ++I, ++GTI) {
@@ -709,19 +699,18 @@ SeparateConstOffsetFromGEP::accumulateBy
NeedsExtraction = false;
int64_t AccumulativeByteOffset = 0;
gep_type_iterator GTI = gep_type_begin(*GEP);
- const DataLayout &DL = GEP->getModule()->getDataLayout();
for (unsigned I = 1, E = GEP->getNumOperands(); I != E; ++I, ++GTI) {
if (isa<SequentialType>(*GTI)) {
// Tries to extract a constant offset from this GEP index.
int64_t ConstantOffset =
- ConstantOffsetExtractor::Find(GEP->getOperand(I), GEP);
+ ConstantOffsetExtractor::Find(GEP->getOperand(I), GEP, DT);
if (ConstantOffset != 0) {
NeedsExtraction = true;
// A GEP may have multiple indices. We accumulate the extracted
// constant offset to a byte offset, and later offset the remainder of
// the original GEP with this byte offset.
AccumulativeByteOffset +=
- ConstantOffset * DL.getTypeAllocSize(GTI.getIndexedType());
+ ConstantOffset * DL->getTypeAllocSize(GTI.getIndexedType());
}
} else if (LowerGEP) {
StructType *StTy = cast<StructType>(*GTI);
@@ -730,7 +719,7 @@ SeparateConstOffsetFromGEP::accumulateBy
if (Field != 0) {
NeedsExtraction = true;
AccumulativeByteOffset +=
- DL.getStructLayout(StTy)->getElementOffset(Field);
+ DL->getStructLayout(StTy)->getElementOffset(Field);
}
}
}
@@ -740,8 +729,7 @@ SeparateConstOffsetFromGEP::accumulateBy
void SeparateConstOffsetFromGEP::lowerToSingleIndexGEPs(
GetElementPtrInst *Variadic, int64_t AccumulativeByteOffset) {
IRBuilder<> Builder(Variadic);
- const DataLayout &DL = Variadic->getModule()->getDataLayout();
- Type *IntPtrTy = DL.getIntPtrType(Variadic->getType());
+ Type *IntPtrTy = DL->getIntPtrType(Variadic->getType());
Type *I8PtrTy =
Builder.getInt8PtrTy(Variadic->getType()->getPointerAddressSpace());
@@ -761,7 +749,7 @@ void SeparateConstOffsetFromGEP::lowerTo
continue;
APInt ElementSize = APInt(IntPtrTy->getIntegerBitWidth(),
- DL.getTypeAllocSize(GTI.getIndexedType()));
+ DL->getTypeAllocSize(GTI.getIndexedType()));
// Scale the index by element size.
if (ElementSize != 1) {
if (ElementSize.isPowerOf2()) {
@@ -794,8 +782,7 @@ void
SeparateConstOffsetFromGEP::lowerToArithmetics(GetElementPtrInst *Variadic,
int64_t AccumulativeByteOffset) {
IRBuilder<> Builder(Variadic);
- const DataLayout &DL = Variadic->getModule()->getDataLayout();
- Type *IntPtrTy = DL.getIntPtrType(Variadic->getType());
+ Type *IntPtrTy = DL->getIntPtrType(Variadic->getType());
Value *ResultPtr = Builder.CreatePtrToInt(Variadic->getOperand(0), IntPtrTy);
gep_type_iterator GTI = gep_type_begin(*Variadic);
@@ -811,7 +798,7 @@ SeparateConstOffsetFromGEP::lowerToArith
continue;
APInt ElementSize = APInt(IntPtrTy->getIntegerBitWidth(),
- DL.getTypeAllocSize(GTI.getIndexedType()));
+ DL->getTypeAllocSize(GTI.getIndexedType()));
// Scale the index by element size.
if (ElementSize != 1) {
if (ElementSize.isPowerOf2()) {
@@ -887,7 +874,7 @@ bool SeparateConstOffsetFromGEP::splitGE
Value *OldIdx = GEP->getOperand(I);
User *UserChainTail;
Value *NewIdx =
- ConstantOffsetExtractor::Extract(OldIdx, GEP, UserChainTail);
+ ConstantOffsetExtractor::Extract(OldIdx, GEP, UserChainTail, DT);
if (NewIdx != nullptr) {
// Switches to the index with the constant offset removed.
GEP->setOperand(I, NewIdx);
@@ -969,10 +956,9 @@ bool SeparateConstOffsetFromGEP::splitGE
// Per ANSI C standard, signed / unsigned = unsigned and signed % unsigned =
// unsigned.. Therefore, we cast ElementTypeSizeOfGEP to signed because it is
// used with unsigned integers later.
- const DataLayout &DL = GEP->getModule()->getDataLayout();
int64_t ElementTypeSizeOfGEP = static_cast<int64_t>(
- DL.getTypeAllocSize(GEP->getType()->getElementType()));
- Type *IntPtrTy = DL.getIntPtrType(GEP->getType());
+ DL->getTypeAllocSize(GEP->getType()->getElementType()));
+ Type *IntPtrTy = DL->getIntPtrType(GEP->getType());
if (AccumulativeByteOffset % ElementTypeSizeOfGEP == 0) {
// Very likely. As long as %gep is natually aligned, the byte offset we
// extracted should be a multiple of sizeof(*%gep).
@@ -1019,6 +1005,8 @@ bool SeparateConstOffsetFromGEP::runOnFu
if (DisableSeparateConstOffsetFromGEP)
return false;
+ DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+
bool Changed = false;
for (Function::iterator B = F.begin(), BE = F.end(); B != BE; ++B) {
for (BasicBlock::iterator I = B->begin(), IE = B->end(); I != IE; ) {
Added: llvm/trunk/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll?rev=237407&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll (added)
+++ llvm/trunk/test/Transforms/SeparateConstOffsetFromGEP/NVPTX/value-tracking-domtree.ll Thu May 14 18:53:19 2015
@@ -0,0 +1,33 @@
+; RUN: opt < %s -separate-const-offset-from-gep -value-tracking-dom-conditions -reassociate-geps-verify-no-dead-code -S | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "nvptx64-unknown-unknown"
+
+; if (i == 4)
+; p = &input[i | 3];
+;
+; =>
+;
+; if (i == 4) {
+; base = &input[i];
+; p = &base[3];
+; }
+;
+; We should treat (i | 3) as (i + 3) because i is guaranteed to be 4, which
+; does not share any set bits with 3.
+define float* @guarded_or(float* %input, i64 %i) {
+; CHECK-LABEL: @guarded_or(
+entry:
+ %is4 = icmp eq i64 %i, 4
+ br i1 %is4, label %then, label %exit
+
+then:
+ %or = or i64 %i, 3
+ %p = getelementptr inbounds float, float* %input, i64 %or
+; CHECK: [[base:[^ ]+]] = getelementptr float, float* %input, i64 %i
+; CHECK: getelementptr float, float* [[base]], i64 3
+ ret float* %p
+
+exit:
+ ret float* null
+}
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