Add comment above tryTocreateAbstractPartialReductionRecipe

Author: SamTebbs33

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -2345,7 +2345,8 @@ class VPPartialReductionRecipe : public VPReductionRecipe {
                           FastMathFlags(), ReductionInst,
                           ArrayRef<VPValue *>({Op0, Op1}), Cond, false, {}),
         Opcode(Opcode) {
-    [[maybe_unused]] auto *AccumulatorRecipe = getChainOp()->getDefiningRecipe();
+    [[maybe_unused]] auto *AccumulatorRecipe =
+        getChainOp()->getDefiningRecipe();
     assert((isa<VPReductionPHIRecipe>(AccumulatorRecipe) ||
             isa<VPPartialReductionRecipe>(AccumulatorRecipe)) &&
            "Unexpected operand order for partial reduction recipe");

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -2437,6 +2437,8 @@ static void tryToCreateAbstractReductionRecipe(VPReductionRecipe *Red,
   Red->replaceAllUsesWith(AbstractR);
 }
 
+/// This function tries to create an abstract recipe from a partial reduction to
+/// hide its mul and extends from cost estimation.
 static void
 tryToCreateAbstractPartialReductionRecipe(VPPartialReductionRecipe *PRed) {
   if (PRed->getOpcode() != Instruction::Add)