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

[via llvm-commits]

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@@ -2391,6 +2390,18 @@ void VPlanTransforms::createInterleaveGroups(
   }
 }
 
+void VPlanTransforms::dissolveLoopRegions(VPlan &Plan) {
+  // Replace loop regions with explicity CFG.
+  SmallVector<VPRegionBlock *> LoopRegions;
+  for (VPRegionBlock *R : VPBlockUtils::blocksOnly<VPRegionBlock>(
+           vp_depth_first_deep(Plan.getEntry()))) {
+    if (!R->isReplicator())
+      LoopRegions.push_back(R);
+  }
+  for (VPRegionBlock *R : LoopRegions)
+    R->removeRegion();
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ayalz wrote:

Perhaps clearer to rename into something like
```suggestion
    R->dissolveToCFGLoop();
```
to emphasize this is not "just removing".

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