[llvm] r314517 - Use the basic cost if a GEP is not used as addressing mode
Jun Bum Lim via llvm-commits
llvm-commits at lists.llvm.org
Fri Sep 29 07:50:16 PDT 2017
Author: junbuml
Date: Fri Sep 29 07:50:16 2017
New Revision: 314517
URL: http://llvm.org/viewvc/llvm-project?rev=314517&view=rev
Log:
Use the basic cost if a GEP is not used as addressing mode
Summary:
Currently, getGEPCost() returns TCC_FREE whenever a GEP is a legal addressing mode in the target.
However, since it doesn't check its actual users, it will return FREE even in cases
where the GEP cannot be folded away as a part of actual addressing mode.
For example, if an user of the GEP is a call instruction taking the GEP as a parameter,
then the GEP may not be folded in isel.
Reviewers: hfinkel, efriedma, mcrosier, jingyue, haicheng
Reviewed By: hfinkel
Subscribers: javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D38085
Modified:
llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h
llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h
llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h
llvm/trunk/include/llvm/IR/Operator.h
llvm/trunk/lib/Analysis/TargetTransformInfo.cpp
llvm/trunk/lib/Transforms/Scalar/NaryReassociate.cpp
llvm/trunk/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
llvm/trunk/test/Analysis/CostModel/AArch64/gep.ll
llvm/trunk/test/Analysis/CostModel/X86/vector_gep.ll
Modified: llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/TargetTransformInfo.h Fri Sep 29 07:50:16 2017
@@ -193,6 +193,13 @@ public:
int getGEPCost(Type *PointeeType, const Value *Ptr,
ArrayRef<const Value *> Operands) const;
+ /// \brief Estimate the cost of a GEP operation when lowered.
+ ///
+ /// This user-based overload adds the ability to check if the GEP can be
+ /// folded into its users.
+ int getGEPCost(const GEPOperator *GEP,
+ ArrayRef<const Value *> Operands) const;
+
/// \brief Estimate the cost of a EXT operation when lowered.
///
/// The contract for this function is the same as \c getOperationCost except
@@ -251,9 +258,9 @@ public:
/// \brief Estimate the cost of a given IR user when lowered.
///
/// This can estimate the cost of either a ConstantExpr or Instruction when
- /// lowered. It has two primary advantages over the \c getOperationCost and
- /// \c getGEPCost above, and one significant disadvantage: it can only be
- /// used when the IR construct has already been formed.
+ /// lowered. It has two primary advantages over the \c getOperationCost above,
+ /// and one significant disadvantage: it can only be used when the IR
+ /// construct has already been formed.
///
/// The advantages are that it can inspect the SSA use graph to reason more
/// accurately about the cost. For example, all-constant-GEPs can often be
@@ -932,6 +939,8 @@ public:
virtual int getOperationCost(unsigned Opcode, Type *Ty, Type *OpTy) = 0;
virtual int getGEPCost(Type *PointeeType, const Value *Ptr,
ArrayRef<const Value *> Operands) = 0;
+ virtual int getGEPCost(const GEPOperator *GEP,
+ ArrayRef<const Value *> Operands) = 0;
virtual int getExtCost(const Instruction *I, const Value *Src) = 0;
virtual int getCallCost(FunctionType *FTy, int NumArgs) = 0;
virtual int getCallCost(const Function *F, int NumArgs) = 0;
@@ -1113,6 +1122,10 @@ public:
ArrayRef<const Value *> Operands) override {
return Impl.getGEPCost(PointeeType, Ptr, Operands);
}
+ int getGEPCost(const GEPOperator *GEP,
+ ArrayRef<const Value *> Operands) override {
+ return Impl.getGEPCost(GEP, Operands);
+ }
int getExtCost(const Instruction *I, const Value *Src) override {
return Impl.getExtCost(I, Src);
}
Modified: llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h (original)
+++ llvm/trunk/include/llvm/Analysis/TargetTransformInfoImpl.h Fri Sep 29 07:50:16 2017
@@ -726,6 +726,35 @@ public:
return TTI::TCC_Basic;
}
+ int getGEPCost(const GEPOperator *GEP, ArrayRef<const Value *> Operands) {
+ Type *PointeeType = GEP->getSourceElementType();
+ const Value *Ptr = GEP->getPointerOperand();
+
+ if (getGEPCost(PointeeType, Ptr, Operands) == TTI::TCC_Free) {
+ // Should check if the GEP is actually used in load / store instructions.
+ // For simplicity, we check only direct users of the GEP.
+ //
+ // FIXME: GEPs could also be folded away as a part of addressing mode in
+ // load/store instructions together with other instructions (e.g., other
+ // GEPs). Handling all such cases must be expensive to be performed
+ // in this function, so we stay conservative for now.
+ for (const User *U : GEP->users()) {
+ const Operator *UOP = cast<Operator>(U);
+ const Value *PointerOperand = nullptr;
+ if (auto *LI = dyn_cast<LoadInst>(UOP))
+ PointerOperand = LI->getPointerOperand();
+ else if (auto *SI = dyn_cast<StoreInst>(UOP))
+ PointerOperand = SI->getPointerOperand();
+
+ if ((!PointerOperand || PointerOperand != GEP) &&
+ !GEP->hasAllZeroIndices())
+ return TTI::TCC_Basic;
+ }
+ return TTI::TCC_Free;
+ }
+ return TTI::TCC_Basic;
+ }
+
using BaseT::getIntrinsicCost;
unsigned getIntrinsicCost(Intrinsic::ID IID, Type *RetTy,
@@ -749,11 +778,8 @@ public:
if (A->isStaticAlloca())
return TTI::TCC_Free;
- if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U)) {
- return static_cast<T *>(this)->getGEPCost(GEP->getSourceElementType(),
- GEP->getPointerOperand(),
- Operands.drop_front());
- }
+ if (const GEPOperator *GEP = dyn_cast<GEPOperator>(U))
+ return static_cast<T *>(this)->getGEPCost(GEP, Operands.drop_front());
if (auto CS = ImmutableCallSite(U)) {
const Function *F = CS.getCalledFunction();
Modified: llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h (original)
+++ llvm/trunk/include/llvm/CodeGen/BasicTTIImpl.h Fri Sep 29 07:50:16 2017
@@ -151,6 +151,10 @@ public:
return BaseT::getGEPCost(PointeeType, Ptr, Operands);
}
+ int getGEPCost(const GEPOperator *GEP, ArrayRef<const Value *> Operands) {
+ return BaseT::getGEPCost(GEP, Operands);
+ }
+
int getExtCost(const Instruction *I, const Value *Src) {
if (getTLI()->isExtFree(I))
return TargetTransformInfo::TCC_Free;
Modified: llvm/trunk/include/llvm/IR/Operator.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/Operator.h?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/Operator.h (original)
+++ llvm/trunk/include/llvm/IR/Operator.h Fri Sep 29 07:50:16 2017
@@ -456,6 +456,8 @@ public:
if (ConstantInt *C = dyn_cast<ConstantInt>(I))
if (C->isZero())
continue;
+ if (isa<ConstantAggregateZero>(I))
+ continue;
return false;
}
return true;
Modified: llvm/trunk/lib/Analysis/TargetTransformInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/TargetTransformInfo.cpp?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/TargetTransformInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/TargetTransformInfo.cpp Fri Sep 29 07:50:16 2017
@@ -88,6 +88,11 @@ int TargetTransformInfo::getGEPCost(Type
return TTIImpl->getGEPCost(PointeeType, Ptr, Operands);
}
+int TargetTransformInfo::getGEPCost(const GEPOperator *GEP,
+ ArrayRef<const Value *> Operands) const {
+ return TTIImpl->getGEPCost(GEP, Operands);
+}
+
int TargetTransformInfo::getExtCost(const Instruction *I,
const Value *Src) const {
return TTIImpl->getExtCost(I, Src);
Modified: llvm/trunk/lib/Transforms/Scalar/NaryReassociate.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/NaryReassociate.cpp?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/NaryReassociate.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/NaryReassociate.cpp Fri Sep 29 07:50:16 2017
@@ -264,7 +264,7 @@ static bool isGEPFoldable(GetElementPtrI
SmallVector<const Value*, 4> Indices;
for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
Indices.push_back(*I);
- return TTI->getGEPCost(GEP->getSourceElementType(), GEP->getPointerOperand(),
+ return TTI->getGEPCost(cast<GEPOperator>(GEP),
Indices) == TargetTransformInfo::TCC_Free;
}
Modified: llvm/trunk/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/StraightLineStrengthReduce.cpp Fri Sep 29 07:50:16 2017
@@ -239,7 +239,7 @@ static bool isGEPFoldable(GetElementPtrI
SmallVector<const Value*, 4> Indices;
for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I)
Indices.push_back(*I);
- return TTI->getGEPCost(GEP->getSourceElementType(), GEP->getPointerOperand(),
+ return TTI->getGEPCost(cast<GEPOperator>(GEP),
Indices) == TargetTransformInfo::TCC_Free;
}
Modified: llvm/trunk/test/Analysis/CostModel/AArch64/gep.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/CostModel/AArch64/gep.ll?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/CostModel/AArch64/gep.ll (original)
+++ llvm/trunk/test/Analysis/CostModel/AArch64/gep.ll Fri Sep 29 07:50:16 2017
@@ -290,3 +290,49 @@ define i64 @test36(i64* %p) {
%v = load i64, i64* %a
ret i64 %v
}
+
+; CHECK-LABEL: test37
+; CHECK: cost of 1 for instruction: {{.*}} = getelementptr inbounds i8*, i8**
+define i8 @test37(i64 %j, i8** readonly %P) {
+entry:
+ %arrayidx0 = getelementptr inbounds i8*, i8** %P, i64 %j
+ %l1 = call i8* @func(i8** %arrayidx0)
+ ret i8 0
+}
+
+; CHECK-LABEL: test38
+; CHECK: cost of 1 for instruction: {{.*}} = getelementptr inbounds i8*, i8**
+define i8 @test38(i8** readonly %P) {
+entry:
+ %arrayidx0 = getelementptr inbounds i8*, i8** %P, i64 10
+ %l1 = call i8* @func(i8** %arrayidx0)
+ ret i8 0
+}
+
+; CHECK-LABEL:test39
+; CHECK: cost of 0 for instruction: {{.*}} = getelementptr inbounds i8*, i8**
+define i8 @test39(i8** readonly %P) {
+entry:
+ %arrayidx0 = getelementptr inbounds i8*, i8** %P, i64 0
+ %l1 = call i8* @func(i8** %arrayidx0)
+ ret i8 0
+}
+
+; CHECK-LABEL:test40
+; CHECK: cost of 1 for instruction: {{.*}} = getelementptr inbounds i8*, i8**
+define i8** @test40(i8** readonly %P) {
+entry:
+ %arrayidx0 = getelementptr inbounds i8*, i8** %P, i64 10
+ ret i8** %arrayidx0
+}
+
+; CHECK-LABEL:test41
+; CHECK: cost of 1 for instruction: {{.*}} = getelementptr inbounds i8, i8*
+define i8 @test41(i8* %V, i8** readonly %P) {
+entry:
+ %arrayidx0 = getelementptr inbounds i8, i8* %V, i64 10
+ store i8* %arrayidx0, i8** %P
+ ret i8 0
+}
+
+declare i8* @func(i8**)
Modified: llvm/trunk/test/Analysis/CostModel/X86/vector_gep.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/CostModel/X86/vector_gep.ll?rev=314517&r1=314516&r2=314517&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/CostModel/X86/vector_gep.ll (original)
+++ llvm/trunk/test/Analysis/CostModel/X86/vector_gep.ll Fri Sep 29 07:50:16 2017
@@ -10,7 +10,7 @@ define <4 x i32> @foov(<4 x %struct.S*>
%vector = shufflevector <4 x i64> %temp, <4 x i64> undef, <4 x i32> zeroinitializer
;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds %struct.S
%B = getelementptr inbounds %struct.S, <4 x %struct.S*> %s, <4 x i32> zeroinitializer, <4 x i32> zeroinitializer
-;CHECK: cost of 0 for instruction: {{.*}} getelementptr inbounds [1000 x i32]
+;CHECK: cost of 1 for instruction: {{.*}} getelementptr inbounds [1000 x i32]
%arrayidx = getelementptr inbounds [1000 x i32], <4 x [1000 x i32]*> %B, <4 x i64> zeroinitializer, <4 x i64> %vector
%res = call <4 x i32> @llvm.masked.gather.v4i32.v4p0i32(<4 x i32*> %arrayidx, i32 4, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i32> undef)
ret <4 x i32> %res
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