[llvm] [CodeGen] Fix legalization of minimum/maximum (PR #206097)

[Matt Arsenault via llvm-commits]

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@@ -10122,6 +10122,22 @@ SDValue TargetLowering::expandFMINNUM_FMAXNUM(SDNode *Node,
   return SDValue();
 }
 
+static SDValue isSpecificZeroAfterMaybeRounding(SelectionDAG &DAG,
+                                                const TargetLowering &TLI,
+                                                SDLoc DL, SDValue Val,
+                                                FPClassTest FPClass) {
+  EVT VT = Val.getValueType();
+  EVT CCVT = TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), VT);
+  EVT IntVT = VT.changeTypeToInteger();
+  EVT FloatVT = VT.changeElementType(*DAG.getContext(), MVT::f32);
+  SDValue TestZero = DAG.getTargetConstant(FPClass, DL, MVT::i32);
+  if (!TLI.isTypeLegal(IntVT) &&
+      !TLI.isOperationLegalOrCustom(ISD::IS_FPCLASS, VT))
+    Val = DAG.getNode(ISD::FP_ROUND, DL, FloatVT, Val,
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arsenm wrote:

Technically this should try to find the best type accounting for legal float types, and cheapest conversion to that type

https://github.com/llvm/llvm-project/pull/206097