From f5783f825d4b45b6e7d96743b0e421ea7c92c060 Mon Sep 17 00:00:00 2001 From: Owen Anderson Date: Fri, 28 Dec 2007 07:42:12 +0000 Subject: [PATCH] Repair a transform that Chris noticed a bug in. Thanks to Nicholas for pointing out my stupid mistakes when writing this patch. :-) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45384 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/InstructionCombining.cpp | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index fc1443a9be8..de528d956ab 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -4835,11 +4835,18 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { if (ConstantInt *CI = dyn_cast(Op1)) { Value *A, *B; -#if 0 - // (icmp cond (sub A B) 0) -> (icmp cond A B) - if (CI->isNullValue() && match(Op0, m_Sub(m_Value(A), m_Value(B)))) - return new ICmpInst(I.getPredicate(), A, B); -#endif + // (icmp cond (sub A B) 0) -> ... + if (CI->isNullValue() && match(Op0, m_Sub(m_Value(A), m_Value(B)))) { + // (icmp cond A B) if cond is signed or equality + if (CmpInst::isSigned(I.getPredicate()) || I.isEquality()) + return new ICmpInst(I.getPredicate(), A, B); + // (icmp ne A B) if cond is ugt + else if (I.getPredicate() == ICmpInst::ICMP_UGT) + return new ICmpInst(ICmpInst::ICMP_NE, A, B); + // (icmp eq A B) if cond is ule + else if (I.getPredicate() == ICmpInst::ICMP_ULE) + return new ICmpInst(ICmpInst::ICMP_EQ, A, B); + } switch (I.getPredicate()) { default: break;