[llvm] r369390 - [InstCombine] improve readability for icmp with cast folds; NFC
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 20 07:56:45 PDT 2019
Author: spatel
Date: Tue Aug 20 07:56:44 2019
New Revision: 369390
URL: http://llvm.org/viewvc/llvm-project?rev=369390&view=rev
Log:
[InstCombine] improve readability for icmp with cast folds; NFC
1. Update function name and stale code comments.
2. Use variable names that are less ambiguous.
3. Move operand checks into the function as early exits.
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=369390&r1=369389&r2=369390&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Tue Aug 20 07:56:44 2019
@@ -4026,74 +4026,78 @@ Instruction *InstCombiner::foldICmpEqual
return nullptr;
}
-/// Handle icmp (cast x to y), (cast/cst). We only handle extending casts so
-/// far.
-Instruction *InstCombiner::foldICmpWithCastAndCast(ICmpInst &ICmp) {
- const CastInst *LHSCI = cast<CastInst>(ICmp.getOperand(0));
- Value *LHSCIOp = LHSCI->getOperand(0);
- Type *SrcTy = LHSCIOp->getType();
- Type *DestTy = LHSCI->getType();
+/// Handle icmp (cast x), (cast or constant).
+Instruction *InstCombiner::foldICmpWithCastOp(ICmpInst &ICmp) {
+ auto *CastOp0 = dyn_cast<CastInst>(ICmp.getOperand(0));
+ if (!CastOp0)
+ return nullptr;
+ if (!isa<Constant>(ICmp.getOperand(1)) && !isa<CastInst>(ICmp.getOperand(1)))
+ return nullptr;
+
+ Value *Op0Src = CastOp0->getOperand(0);
+ Type *SrcTy = CastOp0->getSrcTy();
+ Type *DestTy = CastOp0->getDestTy();
// Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the
// integer type is the same size as the pointer type.
- const auto& CompatibleSizes = [&](Type* SrcTy, Type* DestTy) -> bool {
+ auto CompatibleSizes = [&](Type *SrcTy, Type *DestTy) {
if (isa<VectorType>(SrcTy)) {
SrcTy = cast<VectorType>(SrcTy)->getElementType();
DestTy = cast<VectorType>(DestTy)->getElementType();
}
return DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth();
};
- if (LHSCI->getOpcode() == Instruction::PtrToInt &&
+ if (CastOp0->getOpcode() == Instruction::PtrToInt &&
CompatibleSizes(SrcTy, DestTy)) {
- Value *RHSOp = nullptr;
- if (auto *RHSC = dyn_cast<PtrToIntOperator>(ICmp.getOperand(1))) {
- Value *RHSCIOp = RHSC->getOperand(0);
- if (RHSCIOp->getType()->getPointerAddressSpace() ==
- LHSCIOp->getType()->getPointerAddressSpace()) {
- RHSOp = RHSC->getOperand(0);
+ Value *NewOp1 = nullptr;
+ if (auto *PtrToIntOp1 = dyn_cast<PtrToIntOperator>(ICmp.getOperand(1))) {
+ Value *PtrSrc = PtrToIntOp1->getOperand(0);
+ if (PtrSrc->getType()->getPointerAddressSpace() ==
+ Op0Src->getType()->getPointerAddressSpace()) {
+ NewOp1 = PtrToIntOp1->getOperand(0);
// If the pointer types don't match, insert a bitcast.
- if (LHSCIOp->getType() != RHSOp->getType())
- RHSOp = Builder.CreateBitCast(RHSOp, LHSCIOp->getType());
+ if (Op0Src->getType() != NewOp1->getType())
+ NewOp1 = Builder.CreateBitCast(NewOp1, Op0Src->getType());
}
} else if (auto *RHSC = dyn_cast<Constant>(ICmp.getOperand(1))) {
- RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy);
+ NewOp1 = ConstantExpr::getIntToPtr(RHSC, SrcTy);
}
- if (RHSOp)
- return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSOp);
+ if (NewOp1)
+ return new ICmpInst(ICmp.getPredicate(), Op0Src, NewOp1);
}
// The code below only handles extension cast instructions, so far.
// Enforce this.
- if (LHSCI->getOpcode() != Instruction::ZExt &&
- LHSCI->getOpcode() != Instruction::SExt)
+ if (CastOp0->getOpcode() != Instruction::ZExt &&
+ CastOp0->getOpcode() != Instruction::SExt)
return nullptr;
- bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt;
+ bool isSignedExt = CastOp0->getOpcode() == Instruction::SExt;
bool isSignedCmp = ICmp.isSigned();
- if (auto *CI = dyn_cast<CastInst>(ICmp.getOperand(1))) {
+ if (auto *CastOp1 = dyn_cast<CastInst>(ICmp.getOperand(1))) {
// Not an extension from the same type?
- Value *RHSCIOp = CI->getOperand(0);
- if (RHSCIOp->getType() != LHSCIOp->getType())
+ Value *Op1Src = CastOp1->getOperand(0);
+ if (Op1Src->getType() != Op0Src->getType())
return nullptr;
// If the signedness of the two casts doesn't agree (i.e. one is a sext
// and the other is a zext), then we can't handle this.
- if (CI->getOpcode() != LHSCI->getOpcode())
+ if (CastOp1->getOpcode() != CastOp0->getOpcode())
return nullptr;
// Deal with equality cases early.
if (ICmp.isEquality())
- return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp);
+ return new ICmpInst(ICmp.getPredicate(), Op0Src, Op1Src);
// A signed comparison of sign extended values simplifies into a
// signed comparison.
if (isSignedCmp && isSignedExt)
- return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp);
+ return new ICmpInst(ICmp.getPredicate(), Op0Src, Op1Src);
// The other three cases all fold into an unsigned comparison.
- return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, RHSCIOp);
+ return new ICmpInst(ICmp.getUnsignedPredicate(), Op0Src, Op1Src);
}
// If we aren't dealing with a constant on the RHS, exit early.
@@ -4104,21 +4108,21 @@ Instruction *InstCombiner::foldICmpWithC
// Compute the constant that would happen if we truncated to SrcTy then
// re-extended to DestTy.
Constant *Res1 = ConstantExpr::getTrunc(C, SrcTy);
- Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy);
+ Constant *Res2 = ConstantExpr::getCast(CastOp0->getOpcode(), Res1, DestTy);
// If the re-extended constant didn't change...
if (Res2 == C) {
// Deal with equality cases early.
if (ICmp.isEquality())
- return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1);
+ return new ICmpInst(ICmp.getPredicate(), Op0Src, Res1);
// A signed comparison of sign extended values simplifies into a
// signed comparison.
if (isSignedExt && isSignedCmp)
- return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1);
+ return new ICmpInst(ICmp.getPredicate(), Op0Src, Res1);
// The other three cases all fold into an unsigned comparison.
- return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, Res1);
+ return new ICmpInst(ICmp.getUnsignedPredicate(), Op0Src, Res1);
}
// The re-extended constant changed, partly changed (in the case of a vector),
@@ -4137,7 +4141,7 @@ Instruction *InstCombiner::foldICmpWithC
// We're performing an unsigned comp with a sign extended value.
// This is true if the input is >= 0. [aka >s -1]
Constant *NegOne = Constant::getAllOnesValue(SrcTy);
- Value *Result = Builder.CreateICmpSGT(LHSCIOp, NegOne, ICmp.getName());
+ Value *Result = Builder.CreateICmpSGT(Op0Src, NegOne, ICmp.getName());
// Finally, return the value computed.
if (ICmp.getPredicate() == ICmpInst::ICMP_ULT)
@@ -5212,17 +5216,8 @@ Instruction *InstCombiner::visitICmpInst
if (Instruction *Res = foldICmpBitCast(I, Builder))
return Res;
- if (isa<CastInst>(Op0)) {
- // Handle the special case of: icmp (cast bool to X), <cst>
- // This comes up when you have code like
- // int X = A < B;
- // if (X) ...
- // For generality, we handle any zero-extension of any operand comparison
- // with a constant or another cast from the same type.
- if (isa<Constant>(Op1) || isa<CastInst>(Op1))
- if (Instruction *R = foldICmpWithCastAndCast(I))
- return R;
- }
+ if (Instruction *R = foldICmpWithCastOp(I))
+ return R;
if (Instruction *Res = foldICmpBinOp(I))
return Res;
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=369390&r1=369389&r2=369390&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Tue Aug 20 07:56:44 2019
@@ -861,7 +861,7 @@ private:
Constant *RHSC);
Instruction *foldICmpAddOpConst(Value *X, const APInt &C,
ICmpInst::Predicate Pred);
- Instruction *foldICmpWithCastAndCast(ICmpInst &ICI);
+ Instruction *foldICmpWithCastOp(ICmpInst &ICI);
Instruction *foldICmpUsingKnownBits(ICmpInst &Cmp);
Instruction *foldICmpWithDominatingICmp(ICmpInst &Cmp);
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