From 9907d3c8b4accff34f451f5737fec81d21a12098 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Sun, 24 Feb 2019 16:57:45 +0000 Subject: [InstCombine] canonicalize add/sub with bool add A, sext(B) --> sub A, zext(B) We have to choose 1 of these forms, so I'm opting for the zext because that's easier for value tracking. The backend should be prepared for this change after: D57401 rL353433 This is also a preliminary step towards reducing the amount of bit hackery that we do in IR to optimize icmp/select. That should be waiting to happen at a later optimization stage. The seeming regression in the fuzzer test was discussed in: D58359 We were only managing that fold in instcombine by luck, and other passes should be able to deal with that better anyway. llvm-svn: 354748 --- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp') diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index bf92b5dc559..e2d4774b71f 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1118,6 +1118,12 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return BinaryOperator::CreateSub(RHS, A); } + // Canonicalize sext to zext for better value tracking potential. + // add A, sext(B) --> sub A, zext(B) + if (match(&I, m_c_Add(m_Value(A), m_OneUse(m_SExt(m_Value(B))))) && + B->getType()->isIntOrIntVectorTy(1)) + return BinaryOperator::CreateSub(A, Builder.CreateZExt(B, Ty)); + // A + -B --> A - B if (match(RHS, m_Neg(m_Value(B)))) return BinaryOperator::CreateSub(LHS, B); -- cgit v1.2.3