[llvm] [VPlan] Add initial CFG simplification, removing BranchOnCond true. (PR #106748)

[Florian Hahn via llvm-commits]

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@@ -2514,7 +2514,8 @@ void InnerLoopVectorizer::introduceCheckBlockInVPlan(BasicBlock *CheckIRBB) {
     auto *ResumePhi = dyn_cast<VPInstruction>(&R);
     if (!ResumePhi || ResumePhi->getOpcode() != VPInstruction::ResumePhi)
       continue;
-    ResumePhi->addOperand(ResumePhi->getOperand(1));
+    ResumePhi->addOperand(
+        ResumePhi->getOperand(ScalarPH->getNumPredecessors() == 1 ? 0 : 1));
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fhahn wrote:

Updated to use the last one + comment. ResumePhi now have incoming values for each predecessor, which is why we need to update it here.

https://github.com/llvm/llvm-project/pull/106748