[llvm] [VPlan] Introduce VPlanConstantFolder (PR #125365)

[Florian Hahn via llvm-commits]

================
@@ -1047,15 +1049,27 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
     R.setOperand(0, Y);
     return;
   }
+
+  // Constant folding.
+  VPConstantFolder Folder(DL, TypeInfo);
+  TypeSwitch<VPRecipeBase *, void>(&R)
+      .Case<VPInstruction, VPWidenRecipe, VPWidenCastRecipe, VPHistogramRecipe,
+            VPPartialReductionRecipe, VPReplicateRecipe>([&](auto *I) {
+        VPlan *Plan = R.getParent()->getPlan();
+        ArrayRef<VPValue *> Ops{I->op_begin(), I->op_end()};
----------------
fhahn wrote:

```suggestion
        ArrayRef<VPValue *> Ops(I->op_begin(), I->op_end());
```

`()` for constructors is much more common in the LVLM code base AFAICT

https://github.com/llvm/llvm-project/pull/125365