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[InstCombine] don't unnecessarily generate a constant; NFCI 

llvm-svn: 315910
This commit is contained in:
Sanjay Patel 2017-10-16 14:47:24 +00:00
parent b7d1238cfc
commit 42135beac8
1 changed files with 2 additions and 3 deletions
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5
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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@ -2069,9 +2069,8 @@ Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp,
// If the bits shifted out are known zero, compare the unshifted value: // If the bits shifted out are known zero, compare the unshifted value:
// (X & 4) >> 1 == 2 --> (X & 4) == 4. // (X & 4) >> 1 == 2 --> (X & 4) == 4.
Constant *ShiftedCmpRHS = ConstantInt::get(ShrTy, C << ShAmtVal);
if (Shr->isExact()) if (Shr->isExact())
return new ICmpInst(Pred, X, ShiftedCmpRHS); return new ICmpInst(Pred, X, ConstantInt::get(ShrTy, C << ShAmtVal));
if (Shr->hasOneUse()) { if (Shr->hasOneUse()) {
// Canonicalize the shift into an 'and': // Canonicalize the shift into an 'and':
@ -2079,7 +2078,7 @@ Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp,
APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal));
Constant *Mask = ConstantInt::get(ShrTy, Val); Constant *Mask = ConstantInt::get(ShrTy, Val);
Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask"); Value *And = Builder.CreateAnd(X, Mask, Shr->getName() + ".mask");
return new ICmpInst(Pred, And, ShiftedCmpRHS); return new ICmpInst(Pred, And, ConstantInt::get(ShrTy, C << ShAmtVal));
} }
return nullptr; return nullptr;