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Fix GetMinTrailingZeros for SCEVSignExtend and SCEVZeroExtendExpr to 

return the correct value when the cast operand is all zeros. This ought
to be pretty rare, because it would mean that the regular SCEV folding
routines missed a case, though there are cases they might legitimately
miss. Also, it's unlikely anything currently using GetMinTrailingZeros
cares about this case.

llvm-svn: 71532
This commit is contained in:
Dan Gohman 2009-05-12 01:23:18 +00:00
parent 32efff659c
commit d6c04461a4
1 changed files with 2 additions and 2 deletions
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4
llvm/lib/Analysis/ScalarEvolution.cpp
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@ -1984,13 +1984,13 @@ static uint32_t GetMinTrailingZeros(SCEVHandle S, const ScalarEvolution &SE) {
if (const SCEVZeroExtendExpr *E = dyn_cast<SCEVZeroExtendExpr>(S)) {
uint32_t OpRes = GetMinTrailingZeros(E->getOperand(), SE);
return OpRes == SE.getTypeSizeInBits(E->getOperand()->getType()) ?
SE.getTypeSizeInBits(E->getOperand()->getType()) : OpRes;
SE.getTypeSizeInBits(E->getType()) : OpRes;
}
if (const SCEVSignExtendExpr *E = dyn_cast<SCEVSignExtendExpr>(S)) {
uint32_t OpRes = GetMinTrailingZeros(E->getOperand(), SE);
return OpRes == SE.getTypeSizeInBits(E->getOperand()->getType()) ?
SE.getTypeSizeInBits(E->getOperand()->getType()) : OpRes;
SE.getTypeSizeInBits(E->getType()) : OpRes;
}
if (const SCEVAddExpr *A = dyn_cast<SCEVAddExpr>(S)) {