From a58d8deb3a9cde087c770cf18ca31a1b09302040 Mon Sep 17 00:00:00 2001 From: Dmitry Venikov Date: Tue, 2 Jan 2018 05:58:11 +0000 Subject: [InstCombine] Missed optimization in math expression: squashing sqrt functions Summary: This patch enables folding under -ffast-math flag sqrt(a) * sqrt(b) -> sqrt(a*b) Reviewers: hfinkel, spatel, davide Reviewed By: spatel, davide Subscribers: davide, llvm-commits Differential Revision: https://reviews.llvm.org/D41322 llvm-svn: 321637 --- .../lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index 541dde6c47d..38604830b88 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -728,6 +728,23 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) { } } + // sqrt(a) * sqrt(b) -> sqrt(a * b) + if (AllowReassociate && + Op0->hasOneUse() && Op1->hasOneUse()) { + Value *Opnd0 = nullptr; + Value *Opnd1 = nullptr; + if (match(Op0, m_Intrinsic(m_Value(Opnd0))) && + match(Op1, m_Intrinsic(m_Value(Opnd1)))) { + BuilderTy::FastMathFlagGuard Guard(Builder); + Builder.setFastMathFlags(I.getFastMathFlags()); + Value *FMulVal = Builder.CreateFMul(Opnd0, Opnd1); + Value *Sqrt = Intrinsic::getDeclaration(I.getModule(), + Intrinsic::sqrt, I.getType()); + Value *SqrtCall = Builder.CreateCall(Sqrt, FMulVal); + return replaceInstUsesWith(I, SqrtCall); + } + } + // Handle symmetric situation in a 2-iteration loop Value *Opnd0 = Op0; Value *Opnd1 = Op1; -- cgit v1.2.3