[llvm] [VPlan] Set branch weight metadata on middle term in VPlan (NFC) (PR #143035)

[via llvm-commits]

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@@ -7273,6 +7273,33 @@ static void fixReductionScalarResumeWhenVectorizingEpilog(
       BypassBlock, MainResumePhi->getIncomingValueForBlock(BypassBlock));
 }
 
+/// Add branch weight metadata, if the \p Plan's middle block is terminated by a
+/// BranchOnCond recipe.
+static void addBranchWeightToMiddleTerminator(VPlan &Plan, ElementCount VF,
+                                              Loop *OrigLoop) {
+  // 4. Adjust branch weight of the branch in the middle block.
+  Instruction *LatchTerm = OrigLoop->getLoopLatch()->getTerminator();
+  if (!hasBranchWeightMD(*LatchTerm))
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ayalz wrote:

Note that weights are added to the new middle terminator only if the original latch terminator has weights, although the weights themselves are independent. Suffice to indicate if VPlan should introduce branch weights by noting if the original loop has any?

https://github.com/llvm/llvm-project/pull/143035