[llvm] [VPlan] Update scalar induction resume values in VPlan. (PR #110577)

[via llvm-commits]

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@@ -2626,27 +2635,22 @@ PHINode *InnerLoopVectorizer::createInductionResumeValue(
     }
   }
 
-  // Create phi nodes to merge from the backedge-taken check block.
-  PHINode *BCResumeVal =
-      PHINode::Create(OrigPhi->getType(), 3, "bc.resume.val",
-                      LoopScalarPreHeader->getFirstNonPHIIt());
-  // Copy original phi DL over to the new one.
-  BCResumeVal->setDebugLoc(OrigPhi->getDebugLoc());
-
-  // The new PHI merges the original incoming value, in case of a bypass,
-  // or the value at the end of the vectorized loop.
-  BCResumeVal->addIncoming(EndValue, LoopMiddleBlock);
-
-  // Fix the scalar body counter (PHI node).
-  // The old induction's phi node in the scalar body needs the truncated
-  // value.
-  for (BasicBlock *BB : BypassBlocks)
-    BCResumeVal->addIncoming(II.getStartValue(), BB);
+  auto *ResumePhiRecipe = ScalarPHBuilder.createNaryOp(
+      VPInstruction::ResumePhi,
+      {Plan.getOrAddLiveIn(EndValue), Plan.getOrAddLiveIn(II.getStartValue())},
+      OrigPhi->getDebugLoc(), "bc.resume.val");
+  auto *ScalarLoopHeader = Plan.getScalarHeader();
+  for (VPRecipeBase &R : *ScalarLoopHeader) {
+    auto *IRI = cast<VPIRInstruction>(&R);
+    if (&IRI->getInstruction() == OrigPhi) {
+      IRI->addOperand(ResumePhiRecipe);
+      break;
+    }
+  }
 
   if (AdditionalBypass.first)
-    BCResumeVal->setIncomingValueForBlock(AdditionalBypass.first,
-                                          EndValueFromAdditionalBypass);
-  return BCResumeVal;
+    InductionBypassValues[OrigPhi] = {AdditionalBypass.first,
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ayalz wrote:

Worth asserting OrigPhi is not already there?

https://github.com/llvm/llvm-project/pull/110577