Teach SelectionDAG to constant fold all-constant FMA nodes the same way that it constant folds FADD, FMUL, etc.
llvm-svn: 181555
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 15235c8..f2c512d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3261,6 +3261,21 @@
// Perform various simplifications.
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.getNode());
switch (Opcode) {
+ case ISD::FMA: {
+ ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
+ ConstantFPSDNode *N2CFP = dyn_cast<ConstantFPSDNode>(N2);
+ ConstantFPSDNode *N3CFP = dyn_cast<ConstantFPSDNode>(N3);
+ if (N1CFP && N2CFP && N3CFP) {
+ APFloat V1 = N1CFP->getValueAPF();
+ const APFloat &V2 = N2CFP->getValueAPF();
+ const APFloat &V3 = N3CFP->getValueAPF();
+ APFloat::opStatus s =
+ V1.fusedMultiplyAdd(V2, V3, APFloat::rmNearestTiesToEven);
+ if (s != APFloat::opInvalidOp)
+ return getConstantFP(V1, VT);
+ }
+ break;
+ }
case ISD::CONCAT_VECTORS:
// A CONCAT_VECTOR with all operands BUILD_VECTOR can be simplified to
// one big BUILD_VECTOR.
diff --git a/llvm/test/CodeGen/X86/fma.ll b/llvm/test/CodeGen/X86/fma.ll
index bd3514c..917eac0 100644
--- a/llvm/test/CodeGen/X86/fma.ll
+++ b/llvm/test/CodeGen/X86/fma.ll
@@ -34,6 +34,14 @@
ret x86_fp80 %call
}
+; CHECK: test_f32_cst
+; CHECK-NOT: fma
+define float @test_f32_cst() nounwind readnone ssp {
+entry:
+ %call = tail call float @llvm.fma.f32(float 3.0, float 3.0, float 3.0) nounwind readnone
+ ret float %call
+}
+
declare float @llvm.fma.f32(float, float, float) nounwind readnone
declare double @llvm.fma.f64(double, double, double) nounwind readnone
declare x86_fp80 @llvm.fma.f80(x86_fp80, x86_fp80, x86_fp80) nounwind readnone