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

[Florian Hahn via llvm-commits]

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@@ -7850,16 +7859,18 @@ DenseMap<const SCEV *, Value *> LoopVectorizationPlanner::executePlan(
 
   ILV.printDebugTracesAtEnd();
 
-  // 4. Adjust branch weight of the branch in the middle block.
-  auto *MiddleTerm =
-      cast<BranchInst>(State.CFG.VPBB2IRBB[ExitVPBB]->getTerminator());
-  if (MiddleTerm->isConditional() &&
-      hasBranchWeightMD(*OrigLoop->getLoopLatch()->getTerminator())) {
-    // Assume that `Count % VectorTripCount` is equally distributed.
-    unsigned TripCount = BestVPlan.getUF() * State.VF.getKnownMinValue();
-    assert(TripCount > 0 && "trip count should not be zero");
-    const uint32_t Weights[] = {1, TripCount - 1};
-    setBranchWeights(*MiddleTerm, Weights, /*IsExpected=*/false);
+  // 4. Adjust branch weight of the branch in the middle block if it exists.
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fhahn wrote:

Ah yes, restored the original code, always setting the branch weights for the middle block which contains the branch on the trip count

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