[llvm] [VPlan] Set branch weight metadata on middle term in VPlan (NFC) (PR #143035)
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 9 11:06:11 PDT 2025
================
@@ -7279,6 +7279,30 @@ 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 addBranchWeigthToMiddleTerminator(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))
+ return;
+
+ VPBasicBlock *MiddleVPBB = Plan.getMiddleBlock();
+ auto *MiddleTerm =
+ dyn_cast_or_null<VPInstruction>(MiddleVPBB->getTerminator());
----------------
fhahn wrote:
In VPlan, blocks with a single successor won't have a terminator recipe. Only blocks with multiple successors have (conditional) terminator recipes, which must be BranchOnCond/BranchOnCount VPInstructions (this should be checked in the verifier). I think the new and old code should be equivalent, as the removed code also checks `MiddleTerm->isConditional()` to skip unconditional branches.
https://github.com/llvm/llvm-project/pull/143035
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