[llvm] [VPlan] Replace VPRegionBlock with explicit CFG before execute (NFCI). (PR #117506)

[Alexey Bataev via llvm-commits]

================
@@ -2239,6 +2239,45 @@ class VPWidenPointerInductionRecipe : public VPHeaderPHIRecipe,
 #endif
 };
 
+/// Recipe to generate a scalar PHI. Used to generate code for recipes that
+/// produce scalar header phis, including VPCanonicalIVPHIRecipe and
+/// VPEVLBasedIVPHIRecipe.
+class VPScalarPHIRecipe : public VPHeaderPHIRecipe {
+  std::string Name;
----------------
alexey-bataev wrote:

```suggestion
  SmallString Name;
```

https://github.com/llvm/llvm-project/pull/117506