diff options
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp | 25 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/fdiv.ll | 6 |
2 files changed, 19 insertions, 12 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index ec62beb4fe9..7c674bb83b2 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -1316,21 +1316,30 @@ static Instruction *foldFDivConstantDivisor(BinaryOperator &I) { Instruction::FMul, I.getOperand(0), RecipC, &I); } -/// Try to reassociate C / X expressions where X includes another constant. +/// Remove negation and try to reassociate constant math. static Instruction *foldFDivConstantDividend(BinaryOperator &I) { - Constant *C1; - if (!I.hasAllowReassoc() || !I.hasAllowReciprocal() || - !match(I.getOperand(0), m_Constant(C1))) + Constant *C; + if (!match(I.getOperand(0), m_Constant(C))) return nullptr; + // C / -X --> -C / X Value *X; + if (match(I.getOperand(1), m_FNeg(m_Value(X)))) { + return BinaryOperator::CreateWithCopiedFlags( + Instruction::FDiv, ConstantExpr::getFNeg(C), X, &I); + } + + if (!I.hasAllowReassoc() || !I.hasAllowReciprocal()) + return nullptr; + + // Try to reassociate C / X expressions where X includes another constant. Constant *C2, *NewC = nullptr; if (match(I.getOperand(1), m_FMul(m_Value(X), m_Constant(C2)))) { - // C1 / (X * C2) --> (C1 / C2) / X - NewC = ConstantExpr::getFDiv(C1, C2); + // C / (X * C2) --> (C / C2) / X + NewC = ConstantExpr::getFDiv(C, C2); } else if (match(I.getOperand(1), m_FDiv(m_Value(X), m_Constant(C2)))) { - // C1 / (X / C2) --> (C1 * C2) / X - NewC = ConstantExpr::getFMul(C1, C2); + // C / (X / C2) --> (C * C2) / X + NewC = ConstantExpr::getFMul(C, C2); } // Disallow denormal constants because we don't know what would happen // on all targets. diff --git a/llvm/test/Transforms/InstCombine/fdiv.ll b/llvm/test/Transforms/InstCombine/fdiv.ll index a70907eb85a..8009a89f10d 100644 --- a/llvm/test/Transforms/InstCombine/fdiv.ll +++ b/llvm/test/Transforms/InstCombine/fdiv.ll @@ -225,8 +225,7 @@ define float @fneg_dividend_constant_divisor(float %x) { define float @fneg_divisor_constant_dividend(float %x) { ; CHECK-LABEL: @fneg_divisor_constant_dividend( -; CHECK-NEXT: [[NEG:%.*]] = fsub float -0.000000e+00, [[X:%.*]] -; CHECK-NEXT: [[DIV:%.*]] = fdiv nnan float -3.000000e+00, [[NEG]] +; CHECK-NEXT: [[DIV:%.*]] = fdiv nnan float 3.000000e+00, [[X:%.*]] ; CHECK-NEXT: ret float [[DIV]] ; %neg = fsub float -0.0, %x @@ -246,8 +245,7 @@ define <2 x float> @fneg_dividend_constant_divisor_vec(<2 x float> %x) { define <2 x float> @fneg_divisor_constant_dividend_vec(<2 x float> %x) { ; CHECK-LABEL: @fneg_divisor_constant_dividend_vec( -; CHECK-NEXT: [[NEG:%.*]] = fsub <2 x float> <float -0.000000e+00, float -0.000000e+00>, [[X:%.*]] -; CHECK-NEXT: [[DIV:%.*]] = fdiv afn <2 x float> <float -3.000000e+00, float 5.000000e+00>, [[NEG]] +; CHECK-NEXT: [[DIV:%.*]] = fdiv afn <2 x float> <float 3.000000e+00, float -5.000000e+00>, [[X:%.*]] ; CHECK-NEXT: ret <2 x float> [[DIV]] ; %neg = fsub <2 x float> <float -0.0, float -0.0>, %x |
