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[InstCombine] refactor sdiv by APInt transforms (NFC) 

There's at least one more fold to do here:
https://llvm.org/bugs/show_bug.cgi?id=28153

llvm-svn: 273904
This commit is contained in:
Sanjay Patel 2016-06-27 18:38:40 +00:00
parent cbfeb9f7cd
commit bedd1f9d3d
1 changed files with 10 additions and 9 deletions
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19
llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
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@ -1139,16 +1139,17 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
if (Instruction *Common = commonIDivTransforms(I))
return Common;
// sdiv X, -1 == -X
if (match(Op1, m_AllOnes()))
return BinaryOperator::CreateNeg(Op0);
// sdiv exact X, C --> ashr exact X, log2(C)
const APInt *Op1C;
if (match(Op1, m_APInt(Op1C)) && I.isExact() && Op1C->isNonNegative() &&
Op1C->isPowerOf2()) {
Value *ShAmt = ConstantInt::get(Op1->getType(), Op1C->exactLogBase2());
return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
if (match(Op1, m_APInt(Op1C))) {
// sdiv X, -1 == -X
if (Op1C->isAllOnesValue())
return BinaryOperator::CreateNeg(Op0);
// sdiv exact X, C --> ashr exact X, log2(C)
if (I.isExact() && Op1C->isNonNegative() && Op1C->isPowerOf2()) {
Value *ShAmt = ConstantInt::get(Op1->getType(), Op1C->exactLogBase2());
return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
}
}
if (Constant *RHS = dyn_cast<Constant>(Op1)) {