From cf9ba823240ec6d3682ba2ddeab5cdcf04092c77 Mon Sep 17 00:00:00 2001 From: Mon P Wang Date: Sat, 31 Jan 2009 06:07:45 +0000 Subject: If unsafe FP optimization is not set, don't allow -(A-B) => B-A because when A==B, -0.0 != +0.0. llvm-svn: 63474 --- llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp') diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp index bda9d934a41..f5287b0cf2c 100644 --- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp @@ -2357,7 +2357,8 @@ SDValue SelectionDAG::getNode(unsigned Opcode, DebugLoc DL, return Operand.getOperand(0); break; case ISD::FNEG: - if (OpOpcode == ISD::FSUB) // -(X-Y) -> (Y-X) + // -(X-Y) -> (Y-X) is unsafe because when X==Y, -0.0 != +0.0 + if (UnsafeFPMath && OpOpcode == ISD::FSUB) return getNode(ISD::FSUB, VT, Operand.getNode()->getOperand(1), Operand.getNode()->getOperand(0)); if (OpOpcode == ISD::FNEG) // --X -> X -- cgit v1.2.3