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[IndVars] Remove a bit of manual constant folding [NFC] 

SCEV is more than capable of folding (add x, trunc(0)) to x.  

llvm-svn: 364693
This commit is contained in:
Philip Reames 2019-06-29 00:19:31 +00:00
parent da47e2cac3
commit 1504b6ee7e
1 changed files with 7 additions and 12 deletions
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19
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -2353,21 +2353,16 @@ static Value *genLoopLimit(PHINode *IndVar, BasicBlock *ExitingBB,
// were generated on top of case #2, which is not expected.
assert(AR->getStepRecurrence(*SE)->isOne() && "only handles unit stride");
const SCEV *IVLimit = nullptr;
// For unit stride, IVCount = Start + BECount with 2's complement overflow.
// For non-zero Start, compute IVCount here.
if (AR->getStart()->isZero())
IVLimit = IVCount;
else {
const SCEV *IVInit = AR->getStart();
const SCEV *IVInit = AR->getStart();
// For integer IVs, truncate the IV before computing IVInit + BECount.
if (SE->getTypeSizeInBits(IVInit->getType())
> SE->getTypeSizeInBits(IVCount->getType()))
IVInit = SE->getTruncateExpr(IVInit, IVCount->getType());
// For integer IVs, truncate the IV before computing IVInit + BECount.
if (SE->getTypeSizeInBits(IVInit->getType())
> SE->getTypeSizeInBits(IVCount->getType()))
IVInit = SE->getTruncateExpr(IVInit, IVCount->getType());
IVLimit = SE->getAddExpr(IVInit, IVCount);
}
const SCEV *IVLimit = SE->getAddExpr(IVInit, IVCount);
// Expand the code for the iteration count.
BranchInst *BI = cast<BranchInst>(ExitingBB->getTerminator());
IRBuilder<> Builder(BI);