From c229cfeb7a7e8c9fefafac6b8576f8a0aa1dee3a Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Fri, 26 Jul 2019 11:19:18 +0000 Subject: [InstCombine] remove flop from lerp patterns (Y * (1.0 - Z)) + (X * Z) --> Y - (Y * Z) + (X * Z) --> Y + Z * (X - Y) This is part of solving: https://bugs.llvm.org/show_bug.cgi?id=42716 Factoring eliminates an instruction, so that should be a good canonicalization. The potential conversion to FMA would be handled by the backend based on target capabilities. Differential Revision: https://reviews.llvm.org/D65305 llvm-svn: 367101 --- .../lib/Transforms/InstCombine/InstCombineAddSub.cpp | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'llvm/lib') diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index ba15b023f2a..891370e2c76 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1308,6 +1308,22 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) { return Changed ? &I : nullptr; } +/// Eliminate an op from a linear interpolation (lerp) pattern. +static Instruction *factorizeLerp(BinaryOperator &I, + InstCombiner::BuilderTy &Builder) { + Value *X, *Y, *Z; + if (!match(&I, m_c_FAdd(m_OneUse(m_c_FMul(m_Value(Y), + m_OneUse(m_FSub(m_FPOne(), + m_Value(Z))))), + m_OneUse(m_c_FMul(m_Value(X), m_Deferred(Z)))))) + return nullptr; + + // (Y * (1.0 - Z)) + (X * Z) --> Y + Z * (X - Y) [8 commuted variants] + Value *XY = Builder.CreateFSubFMF(X, Y, &I); + Value *MulZ = Builder.CreateFMulFMF(Z, XY, &I); + return BinaryOperator::CreateFAddFMF(Y, MulZ, &I); +} + /// Factor a common operand out of fadd/fsub of fmul/fdiv. static Instruction *factorizeFAddFSub(BinaryOperator &I, InstCombiner::BuilderTy &Builder) { @@ -1315,6 +1331,10 @@ static Instruction *factorizeFAddFSub(BinaryOperator &I, I.getOpcode() == Instruction::FSub) && "Expecting fadd/fsub"); assert(I.hasAllowReassoc() && I.hasNoSignedZeros() && "FP factorization requires FMF"); + + if (Instruction *Lerp = factorizeLerp(I, Builder)) + return Lerp; + Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *X, *Y, *Z; bool IsFMul; -- cgit v1.2.3