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fix incorrect folding of icmp with undef, PR6481.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97659 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-03-03 19:46:03 +00:00
parent fec8657351
commit c8e14b3d37
3 changed files with 15 additions and 6 deletions
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lib/Analysis/InstructionSimplify.cpp
+3 -4
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@@ -194,11 +194,10 @@ Value *llvm::SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
const Type *ITy = GetCompareTy(LHS);
// icmp X, X -> true/false
if (LHS == RHS)
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
// because X could be 0.
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
if (isa<UndefValue>(RHS)) // X icmp undef -> undef
return UndefValue::get(ITy);
// icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
// addresses never equal each other! We already know that Op0 != Op1.