[llvm] [VPlan] Only store RecurKind + FastMathFlags in VPReductionRecipe. NFCI (PR #131300)

[David Sherwood via llvm-commits]

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@@ -2301,9 +2300,11 @@ class VPReductionRecipe : public VPRecipeWithIRFlags {
              VPSlotTracker &SlotTracker) const override;
 #endif
 
-  /// Return the recurrence decriptor for the in-loop reduction.
-  const RecurrenceDescriptor &getRecurrenceDescriptor() const {
-    return RdxDesc;
+  /// Return the recurrence kind for the in-loop reduction.
+  RecurKind getRecurrenceKind() const { return RdxKind; }
+  /// Return the opcode for the recurrence for the in-loop reduction.
+  unsigned getOpcode() const {
+    return RecurrenceDescriptor::getOpcode(RdxKind);
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david-arm wrote:

If we don't expect `RdxKind` to change during the class lifetime, is it worth just caching the opcode in the class at the time of construction?

https://github.com/llvm/llvm-project/pull/131300