From 1d3acddf0e9b49ad3d489aafc61ea90c71724ba2 Mon Sep 17 00:00:00 2001 From: Duncan Sands Date: Fri, 16 Nov 2012 18:55:49 +0000 Subject: Fix PR14361: wrong simplification of A+B==B+A. You may think that the old logic replaced by this patch is equivalent to the new logic, but you'd be wrong, and that's exactly where the bug was. There's a similar bug in instsimplify which manifests itself as instsimplify failing to simplify this, rather than doing it wrong, see next commit. llvm-svn: 168181 --- llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp index 8cb4a59cba9..e223a049f0b 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp @@ -2356,8 +2356,20 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { // Try not to increase register pressure. BO0->hasOneUse() && BO1->hasOneUse()) { // Determine Y and Z in the form icmp (X+Y), (X+Z). - Value *Y = (A == C || A == D) ? B : A; - Value *Z = (C == A || C == B) ? D : C; + Value *Y, *Z; + if (A == C) { + Y = B; + Z = D; + } else if (A == D) { + Y = B; + Z = C; + } else if (B == C) { + Y = A; + Z = D; + } else if (B == D) { + Y = A; + Z = C; + } return new ICmpInst(Pred, Y, Z); } -- cgit v1.2.3