From 560a17d3bc8d3a3f6be179d428d31abd64498283 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Mon, 17 Oct 2005 17:49:32 +0000 Subject: [PATCH] relax this a bit, as we only support the default rounding mode git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23771 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/InstructionCombining.cpp | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index cf4af791691..67a54018c37 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -694,8 +694,10 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return ReplaceInstUsesWith(I, RHS); // X + 0 --> X - if (!I.getType()->isFloatingPoint() && // -0 + +0 = +0, so it's not a noop - RHSC->isNullValue()) + // NOTE: -0 + +0 = +0 in non-default rounding modes. When we support them + // we must disable this. Note that 0.0-0.0 = -0.0, so this doesn't hold + // for SUB. + if (RHSC->isNullValue()) return ReplaceInstUsesWith(I, LHS); // X + (signbit) --> X ^ signbit