Add isKnownNeverNaN test

Author: wzssyqa

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5760,6 +5760,17 @@ bool SelectionDAG::isKnownNeverNaN(SDValue Op, const APInt &DemandedElts,
         return false;
     return true;
   }
+  case ISD::AssertNoFPClass: {
+    SDValue SDNoFPClass = Op.getOperand(1);
+    assert(isa<ConstantSDNode>(SDNoFPClass) && "NoFPClass is not Constant");
+    FPClassTest NoFPClass = static_cast<FPClassTest>(
+        dyn_cast<ConstantSDNode>(SDNoFPClass)->getZExtValue());
+    if (NoFPClass & fcNan)
+      return true;
+    if (SNaN && (NoFPClass & fcSNan))
+      return true;
+    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1);
+  }
   default:
     if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::INTRINSIC_WO_CHAIN ||
         Opcode == ISD::INTRINSIC_W_CHAIN || Opcode == ISD::INTRINSIC_VOID) {
@@ -7409,7 +7420,7 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
   case ISD::AssertNoFPClass:
     assert(N1.getValueType().isFloatingPoint() &&
            "AssertNoFPClass is used for a non-floating type");
-    return N1;
+    break;
   case ISD::AssertSext:
   case ISD::AssertZext: {
     EVT EVT = cast<VTSDNode>(N2)->getVT();

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

@@ -11848,6 +11848,16 @@ void SelectionDAGISel::LowerArguments(const Function &F) {
     SDValue Res = DAG.getMergeValues(ArrayRef(ArgValues.data(), NumValues),
                                      SDB->getCurSDLoc());
 
+    FPClassTest NoFPClass = Arg.getNoFPClass();
+    if (NoFPClass != fcNone) {
+      EVT I64EVT = EVT::getIntegerVT(*DAG.getContext(), 64);
+      SDValue SDNoFPClass =
+          DAG.getConstant(static_cast<uint64_t>(NoFPClass), dl, I64EVT);
+      SDNodeFlags ResFlags = Res->getFlags();
+      Res = DAG.getNode(ISD::AssertNoFPClass, dl, Res.getValueType(), Res,
+                        SDNoFPClass, ResFlags);
+    }
+
     SDB->setValue(&Arg, Res);
     if (!TM.Options.EnableFastISel && Res.getOpcode() == ISD::BUILD_PAIR) {
       // We want to associate the argument with the frame index, among

llvm/test/CodeGen/AArch64/nofpclass.ll

@@ -0,0 +1,12 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc --mtriple=aarch64-linux-gnu < %s | FileCheck %s
+
+define nofpclass(nzero) float @f(float noundef nofpclass(nan) %a, float noundef nofpclass(nan) %b) {
+; CHECK-LABEL: f:
+; CHECK:       // %bb.0: // %entry
+; CHECK-NEXT:    fmaxnm s0, s0, s1
+; CHECK-NEXT:    ret
+entry:
+  %cond = tail call float @llvm.maximumnum.f32(float %a, float %b)
+  ret float %cond
+}