[LoopUtils] Pass sentinel value directly to createFindLastIVRed (NFC).

Now that there is only a single FindLastIV recurrence kind, simply pass
the sentinel value instead of the full recurrence descriptor to tighten
the interface.

Author: fhahn

llvm/include/llvm/Transforms/Utils/LoopUtils.h

@@ -419,10 +419,9 @@ Value *createAnyOfReduction(IRBuilderBase &B, Value *Src, Value *InitVal,
                             PHINode *OrigPhi);
 
 /// Create a reduction of the given vector \p Src for a reduction of the
-/// kind RecurKind::IFindLastIV or RecurKind::FFindLastIV. The reduction
-/// operation is described by \p Desc.
+/// kind RecurKind::FindLastIV.
 Value *createFindLastIVReduction(IRBuilderBase &B, Value *Src, Value *Start,
-                                 const RecurrenceDescriptor &Desc);
+                                 Value *Sentinel);
 
 /// Create an ordered reduction intrinsic using the given recurrence
 /// kind \p RdxKind.

llvm/lib/Transforms/Utils/LoopUtils.cpp

@@ -1237,12 +1237,7 @@ Value *llvm::createAnyOfReduction(IRBuilderBase &Builder, Value *Src,
 }
 
 Value *llvm::createFindLastIVReduction(IRBuilderBase &Builder, Value *Src,
-                                       Value *Start,
-                                       const RecurrenceDescriptor &Desc) {
-  assert(RecurrenceDescriptor::isFindLastIVRecurrenceKind(
-             Desc.getRecurrenceKind()) &&
-         "Unexpected reduction kind");
-  Value *Sentinel = Desc.getSentinelValue();
+                                       Value *Start, Value *Sentinel) {
   Value *MaxRdx = Src->getType()->isVectorTy()
                       ? Builder.CreateIntMaxReduce(Src, true)
                       : Src;

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -626,7 +626,8 @@ Value *VPInstruction::generate(VPTransformState &State) {
     }
 
     return createFindLastIVReduction(Builder, ReducedPartRdx,
-                                     State.get(getOperand(1), true), RdxDesc);
+                                     State.get(getOperand(1), true),
+                                     RdxDesc.getSentinelValue());
   }
   case VPInstruction::ComputeReductionResult: {
     // FIXME: The cross-recipe dependency on VPReductionPHIRecipe is temporary