[llvm] [VPlan] Dispatch to multiple exit blocks via middle blocks. (PR #112138)

[via llvm-commits]

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@@ -9996,12 +10031,14 @@ bool LoopVectorizePass::processLoop(Loop *L) {
   }
 
   if (LVL.hasUncountableEarlyExit()) {
-    reportVectorizationFailure("Auto-vectorization of loops with uncountable "
-                               "early exit is not yet supported",
-                               "Auto-vectorization of loops with uncountable "
-                               "early exit is not yet supported",
-                               "UncountableEarlyExitLoopsUnsupported", ORE, L);
-    return false;
+    if (!EnableEarlyExitVectorization) {
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ayalz wrote:

```suggestion
    if (LVL.hasUncountableEarlyExit() && !EnableEarlyExitVectorization) {
```

https://github.com/llvm/llvm-project/pull/112138