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We require threse bits to be zero, too.

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This shouldn't happen in practice because the icmp would be a constant.
Add a check so we don't miscompile code if something goes wrong.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130446 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer 2011-04-28 21:38:51 +00:00
parent 7a2ba2fbe4
commit b0884f3f13
1 changed files with 2 additions and 2 deletions
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4
lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
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@ -772,7 +772,7 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
// (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2 // (trunc x) == C1 & (and x, CA) == C2 -> (and x, CA|CMAX) == C1|C2
// where CMAX is the all ones value for the truncated type, // where CMAX is the all ones value for the truncated type,
// iff the lower bits of CA are zero. // iff the lower bits of C2 and CA are zero.
if (LHSCC == RHSCC && ICmpInst::isEquality(LHSCC) && if (LHSCC == RHSCC && ICmpInst::isEquality(LHSCC) &&
LHS->hasOneUse() && RHS->hasOneUse()) { LHS->hasOneUse() && RHS->hasOneUse()) {
Value *V; Value *V;
@ -797,7 +797,7 @@ Value *InstCombiner::FoldAndOfICmps(ICmpInst *LHS, ICmpInst *RHS) {
// Check that the low bits are zero. // Check that the low bits are zero.
APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize); APInt Low = APInt::getLowBitsSet(BigBitSize, SmallBitSize);
if ((Low & AndCst->getValue()) == 0) { if ((Low & AndCst->getValue()) == 0 && (Low & BigCst->getValue()) == 0) {
Value *NewAnd = Builder->CreateAnd(V, Low | AndCst->getValue()); Value *NewAnd = Builder->CreateAnd(V, Low | AndCst->getValue());
APInt N = SmallCst->getValue().zext(BigBitSize) | BigCst->getValue(); APInt N = SmallCst->getValue().zext(BigBitSize) | BigCst->getValue();
Value *NewVal = ConstantInt::get(AndCst->getType()->getContext(), N); Value *NewVal = ConstantInt::get(AndCst->getType()->getContext(), N);