Address final review

Author: SamTebbs33

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -3723,7 +3723,8 @@ tryToMatchAndCreateMulAccumulateReduction(VPReductionRecipe *Red,
     // -> reduce.add(mul(wider_ext(A), wider_ext(B)))
     // The inner extends must either have the same opcode as the outer extend or
     // be the same, in which case the multiply can never result in a negative
-    // value and the outer extend opcode doesn't matter
+    // value and the outer extend can be folded away by doing wider
+    // extends for the operands of the mul.
     if (Ext0 && Ext1 &&
         (Ext->getOpcode() == Ext0->getOpcode() || Ext0 == Ext1) &&
         Ext0->getOpcode() == Ext1->getOpcode() &&