From e9ee7b47d42b3e9f645810e65905a43b583d55c7 Mon Sep 17 00:00:00 2001 From: Sanjay Patel Date: Mon, 29 Jul 2019 13:50:25 +0000 Subject: [PATCH] [InstCombine] fold fadd+fneg with fdiv/fmul betweena The backend already does this via isNegatibleForFree(), but we may want to alter the fneg IR canonicalizations that currently exist, so we need to try harder to fold fneg in IR to avoid regressions. llvm-svn: 367227 --- llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp | 18 ++++++++++++++++++ llvm/test/Transforms/InstCombine/fadd.ll | 16 ++++++++-------- 2 files changed, 26 insertions(+), 8 deletions(-) diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp index 79d9ddd..328c5021 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp @@ -1387,6 +1387,24 @@ Instruction *InstCombiner::visitFAdd(BinaryOperator &I) { if (match(&I, m_c_FAdd(m_FNeg(m_Value(X)), m_Value(Y)))) return BinaryOperator::CreateFSubFMF(Y, X, &I); + // Similar to above, but look through fmul/fdiv for the negated term. + // (-X * Y) + Z --> Z - (X * Y) [4 commuted variants] + Value *Z; + if (match(&I, m_c_FAdd(m_OneUse(m_c_FMul(m_FNeg(m_Value(X)), m_Value(Y))), + m_Value(Z)))) { + Value *XY = Builder.CreateFMulFMF(X, Y, &I); + return BinaryOperator::CreateFSubFMF(Z, XY, &I); + } + // (-X / Y) + Z --> Z - (X / Y) [2 commuted variants] + // (X / -Y) + Z --> Z - (X / Y) [2 commuted variants] + if (match(&I, m_c_FAdd(m_OneUse(m_FDiv(m_FNeg(m_Value(X)), m_Value(Y))), + m_Value(Z))) || + match(&I, m_c_FAdd(m_OneUse(m_FDiv(m_Value(X), m_FNeg(m_Value(Y)))), + m_Value(Z)))) { + Value *XY = Builder.CreateFDivFMF(X, Y, &I); + return BinaryOperator::CreateFSubFMF(Z, XY, &I); + } + // Check for (fadd double (sitofp x), y), see if we can merge this into an // integer add followed by a promotion. Value *LHS = I.getOperand(0), *RHS = I.getOperand(1); diff --git a/llvm/test/Transforms/InstCombine/fadd.ll b/llvm/test/Transforms/InstCombine/fadd.ll index 77a6b0d..50022db 100644 --- a/llvm/test/Transforms/InstCombine/fadd.ll +++ b/llvm/test/Transforms/InstCombine/fadd.ll @@ -246,8 +246,8 @@ define float @fdiv_fneg1_extra_use2(float %x, float %y, float %z) { ; CHECK-LABEL: @fdiv_fneg1_extra_use2( ; CHECK-NEXT: [[NEG:%.*]] = fsub float -0.000000e+00, [[X:%.*]] ; CHECK-NEXT: call void @use(float [[NEG]]) -; CHECK-NEXT: [[DIV:%.*]] = fdiv float [[NEG]], [[Y:%.*]] -; CHECK-NEXT: [[R:%.*]] = fadd float [[DIV]], [[Z:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = fdiv float [[X]], [[Y:%.*]] +; CHECK-NEXT: [[R:%.*]] = fsub float [[Z:%.*]], [[TMP1]] ; CHECK-NEXT: ret float [[R]] ; %neg = fsub float -0.000000e+00, %x @@ -263,8 +263,8 @@ define float @fdiv_fneg2_extra_use2(float %x, float %y, float %z) { ; CHECK-LABEL: @fdiv_fneg2_extra_use2( ; CHECK-NEXT: [[NEG:%.*]] = fsub float -0.000000e+00, [[X:%.*]] ; CHECK-NEXT: call void @use(float [[NEG]]) -; CHECK-NEXT: [[DIV:%.*]] = fdiv float [[Y:%.*]], [[NEG]] -; CHECK-NEXT: [[R:%.*]] = fadd float [[DIV]], [[Z:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = fdiv float [[Y:%.*]], [[X]] +; CHECK-NEXT: [[R:%.*]] = fsub float [[Z:%.*]], [[TMP1]] ; CHECK-NEXT: ret float [[R]] ; %neg = fsub float -0.000000e+00, %x @@ -280,8 +280,8 @@ define <2 x float> @fmul_fneg1_extra_use2(<2 x float> %x, <2 x float> %y, <2 x f ; CHECK-LABEL: @fmul_fneg1_extra_use2( ; CHECK-NEXT: [[NEG:%.*]] = fsub <2 x float> , [[X:%.*]] ; CHECK-NEXT: call void @use_vec(<2 x float> [[NEG]]) -; CHECK-NEXT: [[MUL:%.*]] = fmul <2 x float> [[NEG]], [[Y:%.*]] -; CHECK-NEXT: [[R:%.*]] = fadd <2 x float> [[MUL]], [[Z:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = fmul <2 x float> [[X]], [[Y:%.*]] +; CHECK-NEXT: [[R:%.*]] = fsub <2 x float> [[Z:%.*]], [[TMP1]] ; CHECK-NEXT: ret <2 x float> [[R]] ; %neg = fsub <2 x float> , %x @@ -298,8 +298,8 @@ define float @fmul_fneg2_extra_use2(float %x, float %py, float %z) { ; CHECK-NEXT: [[Y:%.*]] = frem float -4.200000e+01, [[PY:%.*]] ; CHECK-NEXT: [[NEG:%.*]] = fsub float -0.000000e+00, [[X:%.*]] ; CHECK-NEXT: call void @use(float [[NEG]]) -; CHECK-NEXT: [[MUL:%.*]] = fmul float [[Y]], [[NEG]] -; CHECK-NEXT: [[R:%.*]] = fadd float [[MUL]], [[Z:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = fmul float [[Y]], [[X]] +; CHECK-NEXT: [[R:%.*]] = fsub float [[Z:%.*]], [[TMP1]] ; CHECK-NEXT: ret float [[R]] ; %y = frem float -42.0, %py ; thwart complexity-based canonicalization -- 2.7.4