[IVDescriptors] Add isFPMinMaxNumRecurrenceKind helper (NFC).

Add helper to check for FMinNum and FMaxNum recurrence kinds, as
suggested in llvm#161735.

Author: fhahn

llvm/include/llvm/Analysis/IVDescriptors.h

@@ -251,12 +251,18 @@ class RecurrenceDescriptor {
            Kind == RecurKind::SMin || Kind == RecurKind::SMax;
   }
 
+  /// Returns true if the recurrence kind is a floating-point minnum/maxnum
+  /// kind.
+  static bool isFPMinMaxNumRecurrenceKind(RecurKind Kind) {
+    return Kind == RecurKind::FMinNum || Kind == RecurKind::FMaxNum;
+  }
+
   /// Returns true if the recurrence kind is a floating-point min/max kind.
   static bool isFPMinMaxRecurrenceKind(RecurKind Kind) {
     return Kind == RecurKind::FMin || Kind == RecurKind::FMax ||
-           Kind == RecurKind::FMinNum || Kind == RecurKind::FMaxNum ||
            Kind == RecurKind::FMinimum || Kind == RecurKind::FMaximum ||
-           Kind == RecurKind::FMinimumNum || Kind == RecurKind::FMaximumNum;
+           Kind == RecurKind::FMinimumNum || Kind == RecurKind::FMaximumNum ||
+           isFPMinMaxNumRecurrenceKind(Kind);
   }
 
   /// Returns true if the recurrence kind is any min/max kind.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -4264,8 +4264,8 @@ bool LoopVectorizationPlanner::isCandidateForEpilogueVectorization(
   if (any_of(OrigLoop->getHeader()->phis(), [&](PHINode &Phi) {
         if (!Legal->isReductionVariable(&Phi))
           return Legal->isFixedOrderRecurrence(&Phi);
-        RecurKind RK = Legal->getRecurrenceDescriptor(&Phi).getRecurrenceKind();
-        return RK == RecurKind::FMinNum || RK == RecurKind::FMaxNum;
+        return RecurrenceDescriptor::isFPMinMaxNumRecurrenceKind(
+            Legal->getRecurrenceDescriptor(&Phi).getRecurrenceKind());
       }))
     return false;
 

llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp

@@ -840,8 +840,8 @@ bool VPlanTransforms::handleMaxMinNumReductions(VPlan &Plan) {
     // TODO: Support multiple MaxNum/MinNum reductions and other reductions.
     if (RedPhiR)
       return false;
-    if (Cur->getRecurrenceKind() != RecurKind::FMaxNum &&
-        Cur->getRecurrenceKind() != RecurKind::FMinNum) {
+    if (!RecurrenceDescriptor::isFPMinMaxNumRecurrenceKind(
+            Cur->getRecurrenceKind())) {
       HasUnsupportedPhi = true;
       continue;
     }
@@ -861,10 +861,9 @@ bool VPlanTransforms::handleMaxMinNumReductions(VPlan &Plan) {
   if (!MinMaxOp)
     return false;
 
-  RecurKind RedPhiRK = RedPhiR->getRecurrenceKind();
-  assert((RedPhiRK == RecurKind::FMaxNum || RedPhiRK == RecurKind::FMinNum) &&
+  assert(RecurrenceDescriptor::isFPMinMaxNumRecurrenceKind(
+             RedPhiR->getRecurrenceKind()) &&
          "unsupported reduction");
-  (void)RedPhiRK;
 
   /// Check if the vector loop of \p Plan can early exit and restart
   /// execution of last vector iteration in the scalar loop. This requires all