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[InstCombine] clean up foldItoFPtoI; NFC 

Mostly cosmetic improvements to variable names and logic to ease
refactoring suggested in D79116.
This commit is contained in:
Sanjay Patel 2020-05-08 12:06:38 -04:00
parent 355633860e
commit ff9045dc9c
2 changed files with 27 additions and 27 deletions
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52
llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
View File

@ -1739,19 +1739,19 @@ Instruction *InstCombiner::visitFPExt(CastInst &CI) {
return commonCastTransforms(CI);
}
// fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
// This is safe if the intermediate type has enough bits in its mantissa to
// accurately represent all values of X. For example, this won't work with
// i64 -> float -> i64.
Instruction *InstCombiner::FoldItoFPtoI(Instruction &FI) {
/// fpto{s/u}i({u/s}itofp(X)) --> X or zext(X) or sext(X) or trunc(X)
/// This is safe if the intermediate type has enough bits in its mantissa to
/// accurately represent all values of X. For example, this won't work with
/// i64 -> float -> i64.
Instruction *InstCombiner::foldItoFPtoI(CastInst &FI) {
if (!isa<UIToFPInst>(FI.getOperand(0)) && !isa<SIToFPInst>(FI.getOperand(0)))
return nullptr;
Instruction *OpI = cast<Instruction>(FI.getOperand(0));
Value *SrcI = OpI->getOperand(0);
Type *FITy = FI.getType();
Type *OpITy = OpI->getType();
Type *SrcTy = SrcI->getType();
Value *X = OpI->getOperand(0);
Type *DestType = FI.getType();
Type *FPType = OpI->getType();
Type *XType = X->getType();
bool IsInputSigned = isa<SIToFPInst>(OpI);
bool IsOutputSigned = isa<FPToSIInst>(FI);
@ -1764,34 +1764,34 @@ Instruction *InstCombiner::FoldItoFPtoI(Instruction &FI) {
// This means this is also safe for a signed input and unsigned output, since
// a negative input would lead to undefined behavior.
int InputSize = (int)SrcTy->getScalarSizeInBits() - IsInputSigned;
int OutputSize = (int)FITy->getScalarSizeInBits() - IsOutputSigned;
int ActualSize = std::min(InputSize, OutputSize);
int InputSize = (int)XType->getScalarSizeInBits() - IsInputSigned;
int OutputSize = (int)DestType->getScalarSizeInBits() - IsOutputSigned;
int MinIntWidth = std::min(InputSize, OutputSize);
if (ActualSize <= OpITy->getFPMantissaWidth()) {
if (FITy->getScalarSizeInBits() > SrcTy->getScalarSizeInBits()) {
if (IsInputSigned && IsOutputSigned)
return new SExtInst(SrcI, FITy);
return new ZExtInst(SrcI, FITy);
}
if (FITy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits())
return new TruncInst(SrcI, FITy);
if (SrcTy == FITy)
return replaceInstUsesWith(FI, SrcI);
return new BitCastInst(SrcI, FITy);
if (MinIntWidth > FPType->getFPMantissaWidth())
return nullptr;
if (DestType->getScalarSizeInBits() > XType->getScalarSizeInBits()) {
if (IsInputSigned && IsOutputSigned)
return new SExtInst(X, DestType);
return new ZExtInst(X, DestType);
}
return nullptr;
if (DestType->getScalarSizeInBits() < XType->getScalarSizeInBits())
return new TruncInst(X, DestType);
assert(XType == DestType && "Unexpected types for int to FP to int casts");
return replaceInstUsesWith(FI, X);
}
Instruction *InstCombiner::visitFPToUI(FPToUIInst &FI) {
if (Instruction *I = FoldItoFPtoI(FI))
if (Instruction *I = foldItoFPtoI(FI))
return I;
return commonCastTransforms(FI);
}
Instruction *InstCombiner::visitFPToSI(FPToSIInst &FI) {
if (Instruction *I = FoldItoFPtoI(FI))
if (Instruction *I = foldItoFPtoI(FI))
return I;
return commonCastTransforms(FI);

2
llvm/lib/Transforms/InstCombine/InstCombineInternal.h
View File

@ -419,7 +419,7 @@ public:
Instruction *visitIntToPtr(IntToPtrInst &CI);
Instruction *visitBitCast(BitCastInst &CI);
Instruction *visitAddrSpaceCast(AddrSpaceCastInst &CI);
Instruction *FoldItoFPtoI(Instruction &FI);
Instruction *foldItoFPtoI(CastInst &FI);
Instruction *visitSelectInst(SelectInst &SI);
Instruction *visitCallInst(CallInst &CI);
Instruction *visitInvokeInst(InvokeInst &II);