[llvm] DAG: Handle lowering unordered compare with inf (PR #100378)

[Serge Pavlov via llvm-commits]

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@@ -8610,26 +8612,36 @@ SDValue TargetLowering::expandIS_FPCLASS(EVT ResultVT, SDValue Op,
                           *IsCmp0 ? OrderedCmpOpcode : UnorderedCmpOpcode);
     }
 
-    if (Test == fcNan &&
-        isCondCodeLegalOrCustom(IsInverted ? ISD::SETO : ISD::SETUO,
-                                OperandVT.getScalarType().getSimpleVT())) {
+    if (FPTestMask == fcNan &&
+        isCondCodeLegalOrCustom(IsInvertedFP ? ISD::SETO : ISD::SETUO,
+                                OperandVT.getScalarType().getSimpleVT()))
       return DAG.getSetCC(DL, ResultVT, Op, Op,
-                          IsInverted ? ISD::SETO : ISD::SETUO);
-    }
+                          IsInvertedFP ? ISD::SETO : ISD::SETUO);
 
-    if (Test == fcInf &&
-        isCondCodeLegalOrCustom(IsInverted ? ISD::SETUNE : ISD::SETOEQ,
+    bool IsOrderedInf = FPTestMask == fcInf;
+    if ((FPTestMask == fcInf || FPTestMask == (fcInf | fcNan)) &&
+        isCondCodeLegalOrCustom(IsOrderedInf ? OrderedCmpOpcode
+                                             : UnorderedCmpOpcode,
                                 OperandVT.getScalarType().getSimpleVT()) &&
         isOperationLegalOrCustom(ISD::FABS, OperandVT.getScalarType())) {
       // isinf(x) --> fabs(x) == inf
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spavloff wrote:

The case `fcInf | fcNan` also deserves comment.

https://github.com/llvm/llvm-project/pull/100378