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

[via llvm-commits]

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@@ -9238,11 +9259,25 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
          "VPBasicBlock");
   RecipeBuilder.fixHeaderPhis();
 
+  if (Legal->hasUncountableEarlyExit()) {
+    assert(Legal->getUncountableExitingBlocks().size() == 1 &&
+           "Only single uncountable exiting bock supported");
+    VPlanTransforms::handleUncountableEarlyExit(
+        *Plan, *PSE.getSE(), OrigLoop, Legal->getUncountableExitingBlocks()[0],
+        RecipeBuilder);
+  }
   addScalarResumePhis(RecipeBuilder, *Plan);
   SetVector<VPIRInstruction *> ExitUsersToFix = collectUsersInExitBlocks(
       OrigLoop, RecipeBuilder, *Plan, Legal->getInductionVars());
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ayalz wrote:

Better have `collectUsersInExitBlocks()` indicate failure, than `addUsersInExitBlocks()`, which follows `addExitUsersForFirstOrderRecurrences()`?

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