From 3afc0721c766db6942e79597a9b2e10fe0824194 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 3 Mar 2010 19:46:03 +0000 Subject: fix incorrect folding of icmp with undef, PR6481. llvm-svn: 97659 --- llvm/lib/Analysis/InstructionSimplify.cpp | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) (limited to 'llvm/lib/Analysis') diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 1f8053afe94..8288e96eb77 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -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(RHS)) return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred)); - - if (isa(RHS)) // X icmp undef -> undef - return UndefValue::get(ITy); // icmp , - Global/Stack value // addresses never equal each other! We already know that Op0 != Op1. -- cgit v1.2.3