[DAG] SelectionDAG::canCreateUndefOrPoison - add ISD::FMA/FMAD + tests (#152187)

In SelectionDAG::canCreateUndefOrPoison add case ISD::FMA/FMAD + tests.
Fixing #147693

---------

Co-authored-by: Matt Arsenault <[email protected]>

Author: Seraphimt

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5628,6 +5628,8 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
   case ISD::FDIV:
   case ISD::FREM:
   case ISD::FCOPYSIGN:
+  case ISD::FMA:
+  case ISD::FMAD:
   case ISD::FP_EXTEND:
     // No poison except from flags (which is handled above)
     return false;

llvm/test/CodeGen/AArch64/fma-fneg-combine.ll

@@ -0,0 +1,47 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc < %s -mtriple=aarch64-- | FileCheck %s --check-prefixes=CHECK
+
+define float @positive_case_fma(float %a0, float %a1, float %a2) {
+; CHECK-LABEL: positive_case_fma:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    fnmadd s0, s0, s1, s2
+; CHECK-NEXT:    ret
+  %fma = call float @llvm.fma.f32(float %a0, float %a1, float %a2)
+  %freeze = freeze float %fma
+  %fneg = fneg float %freeze
+  ret float %fneg
+}
+
+define float @negative_case_fma(float %a0, float %a1) {
+; CHECK-LABEL: negative_case_fma:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    fnmadd s0, s0, s1, s0
+; CHECK-NEXT:    ret
+  %fma = call float @llvm.fma.f32(float %a0, float %a1, float poison)
+  %freeze = freeze float %fma
+  %fneg = fneg float %freeze
+  ret float %fneg
+}
+
+define float @positive_case_fmad(float %a0, float %a1, float %a2) {
+; CHECK-LABEL: positive_case_fmad:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    fnmadd s0, s0, s1, s2
+; CHECK-NEXT:    ret
+  %fma = call float @llvm.fma.f32(float %a0, float %a1, float %a2)
+  %freeze = freeze float %fma
+  %fneg = fneg float %freeze
+  ret float %fneg
+}
+
+define float @negative_case_fmad(float %a0, float %a1) {
+; CHECK-LABEL: negative_case_fmad:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    fnmadd s0, s0, s1, s0
+; CHECK-NEXT:    ret
+  %fmad = call float @llvm.fmuladd.f32(float %a0, float %a1, float poison)
+  %freeze = freeze float %fmad
+  %fneg = fneg float %freeze
+  ret float %fneg
+}
+