From 5d82ecd5d952bbd92dc356bd9220be818f64993e Mon Sep 17 00:00:00 2001 From: Matt Arsenault Date: Mon, 24 Jun 2019 21:37:02 +0000 Subject: InstCombine: Preserve nuw when reassociating nuw ops [2/3] Alive says this is OK. llvm-svn: 364234 --- llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 3243d8fda3d..fcbe738aad7 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -431,8 +431,14 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) { Op0->getOpcode() == Opcode && Op1->getOpcode() == Opcode && match(Op0, m_OneUse(m_BinOp(m_Value(A), m_Constant(C1)))) && match(Op1, m_OneUse(m_BinOp(m_Value(B), m_Constant(C2))))) { - BinaryOperator *NewBO = BinaryOperator::Create(Opcode, A, B); - if (isa(NewBO)) { + bool IsNUW = hasNoUnsignedWrap(I) && + hasNoUnsignedWrap(*Op0) && + hasNoUnsignedWrap(*Op1); + BinaryOperator *NewBO = (IsNUW && Opcode == Instruction::Add) ? + BinaryOperator::CreateNUW(Opcode, A, B) : + BinaryOperator::Create(Opcode, A, B); + + if (isa(NewBO)) { FastMathFlags Flags = I.getFastMathFlags(); Flags &= Op0->getFastMathFlags(); Flags &= Op1->getFastMathFlags(); @@ -445,6 +451,8 @@ bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) { // Conservatively clear the optional flags, since they may not be // preserved by the reassociation. ClearSubclassDataAfterReassociation(I); + if (IsNUW) + I.setHasNoUnsignedWrap(true); Changed = true; continue; -- cgit v1.2.3