diff options
| -rw-r--r-- | llvm/lib/Analysis/InstructionSimplify.cpp | 16 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstSimplify/fast-math.ll | 9 |
2 files changed, 14 insertions, 11 deletions
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp index 2b8e23b9569..773c3ec0f6e 100644 --- a/llvm/lib/Analysis/InstructionSimplify.cpp +++ b/llvm/lib/Analysis/InstructionSimplify.cpp @@ -4315,11 +4315,17 @@ static Value *SimplifyFRemInst(Value *Op0, Value *Op1, FastMathFlags FMF, if (isa<UndefValue>(Op0) || isa<UndefValue>(Op1)) return ConstantFP::getNaN(Op0->getType()); - // 0 % X -> 0 - // Requires that NaNs are off (X could be zero) and signed zeroes are - // ignored (X could be positive or negative, so the output sign is unknown). - if (FMF.noNaNs() && FMF.noSignedZeros() && match(Op0, m_AnyZero())) - return Op0; + // Unlike fdiv, the result of frem always matches the sign of the dividend. + // The constant match may include undef elements in a vector, so return a full + // zero constant as the result. + if (FMF.noNaNs()) { + // 0 % X -> 0 + if (match(Op0, m_Zero())) + return ConstantFP::getNullValue(Op0->getType()); + // -0 % X -> -0 + if (match(Op0, m_NegZero())) + return ConstantFP::getNegativeZero(Op0->getType()); + } return nullptr; } diff --git a/llvm/test/Transforms/InstSimplify/fast-math.ll b/llvm/test/Transforms/InstSimplify/fast-math.ll index 8b7472f2878..bed39fbc836 100644 --- a/llvm/test/Transforms/InstSimplify/fast-math.ll +++ b/llvm/test/Transforms/InstSimplify/fast-math.ll @@ -241,8 +241,7 @@ define <2 x double> @fdiv_zero_by_x_vec_undef(<2 x double> %x) { define double @frem_zero_by_x(double %x) { ; CHECK-LABEL: @frem_zero_by_x( -; CHECK-NEXT: [[R:%.*]] = frem nnan double 0.000000e+00, [[X:%.*]] -; CHECK-NEXT: ret double [[R]] +; CHECK-NEXT: ret double 0.000000e+00 ; %r = frem nnan double 0.0, %x ret double %r @@ -253,8 +252,7 @@ define double @frem_zero_by_x(double %x) { define double @frem_negzero_by_x(double %x) { ; CHECK-LABEL: @frem_negzero_by_x( -; CHECK-NEXT: [[R:%.*]] = frem nnan double -0.000000e+00, [[X:%.*]] -; CHECK-NEXT: ret double [[R]] +; CHECK-NEXT: ret double -0.000000e+00 ; %r = frem nnan double -0.0, %x ret double %r @@ -262,8 +260,7 @@ define double @frem_negzero_by_x(double %x) { define <2 x double> @frem_negzero_by_x_vec_undef(<2 x double> %x) { ; CHECK-LABEL: @frem_negzero_by_x_vec_undef( -; CHECK-NEXT: [[R:%.*]] = frem nnan <2 x double> <double undef, double -0.000000e+00>, [[X:%.*]] -; CHECK-NEXT: ret <2 x double> [[R]] +; CHECK-NEXT: ret <2 x double> <double -0.000000e+00, double -0.000000e+00> ; %r = frem nnan <2 x double> <double undef, double -0.0>, %x ret <2 x double> %r |
