From 65144149d033e06b9fe357e32ed5d2bcabdc8d02 Mon Sep 17 00:00:00 2001 From: Roman Lebedev Date: Tue, 1 Oct 2019 17:50:09 +0000 Subject: [InstCombine] Preserve 'exact' in -(X >>u 31) -> (X >>s 31) fold https://rise4fun.com/Alive/yR4 llvm-svn: 373363 --- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'llvm/lib/Transforms/InstCombine') diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 9d640e849dc..7e3d405e906 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1676,12 +1676,16 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) { if (match(Op1, m_LShr(m_Value(X), m_APInt(ShAmt))) && *ShAmt == BitWidth - 1) { Value *ShAmtOp = cast(Op1)->getOperand(1); - return BinaryOperator::CreateAShr(X, ShAmtOp); + Instruction *NewShift = BinaryOperator::CreateAShr(X, ShAmtOp); + NewShift->copyIRFlags(Op1); + return NewShift; } if (match(Op1, m_AShr(m_Value(X), m_APInt(ShAmt))) && *ShAmt == BitWidth - 1) { Value *ShAmtOp = cast(Op1)->getOperand(1); - return BinaryOperator::CreateLShr(X, ShAmtOp); + Instruction *NewShift = BinaryOperator::CreateLShr(X, ShAmtOp); + NewShift->copyIRFlags(Op1); + return NewShift; } if (Op1->hasOneUse()) { -- cgit v1.2.3