[llvm] [VPlanTransform] Rename and narrow simplifyRecipe to VPSingleDefRecipe. nfc (PR #165568)

[Ramkumar Ramachandra via llvm-commits]

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@@ -1057,54 +1057,51 @@ static VPValue *tryToFoldLiveIns(VPSingleDefRecipe &R,
   return nullptr;
 }
 
-/// Try to simplify recipe \p R.
-static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
-  VPlan *Plan = R.getParent()->getPlan();
-
-  auto *Def = dyn_cast<VPSingleDefRecipe>(&R);
-  if (!Def)
-    return;
+/// Try to simplify VPSingleDefRecipe \p Def.
+static void simplifySingleDefRecipe(VPSingleDefRecipe &Def,
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artagnon wrote:

Not sure the rename is necessary, but looks good otherwise.

https://github.com/llvm/llvm-project/pull/165568