[llvm] [VPlan] Dissolve replicate regions with vector live-outs. (PR #189022)

[Florian Hahn via llvm-commits]

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@@ -753,10 +758,25 @@ static void processLaneForReplicateRegion(VPlan &Plan, Type *IdxTy,
           NewR.setOperand(I, NewOp);
       }
 
+      const APInt *InsertExtractIdx;
       if (auto *Steps = dyn_cast<VPScalarIVStepsRecipe>(&NewR))
         addLaneToStartIndex(Steps, Lane, Plan, Steps);
-      else if (match(&NewR, m_ExtractElement(m_VPValue(), m_ZeroInt())))
+      else if (match(&NewR, m_ExtractElement(m_VPValue(),
+                                             m_APInt(InsertExtractIdx)))) {
+        assert(InsertExtractIdx->isZero() && "insert indices must be zero");
         NewR.setOperand(1, IdxLane);
+      } else if (isa<VPPhi>(&OldR)) {
+        // Update BuildStructVector operand for this lane.
+        VPUser *SingleUser = OldR.getVPSingleValue()->getSingleUser();
+        if (SingleUser &&
+            match(SingleUser,
+                  m_CombineOr(
+                      m_BuildVector(),
+                      m_VPInstruction<VPInstruction::BuildStructVector>()))) {
+          cast<VPRecipeBase>(SingleUser)
+              ->setOperand(Lane, NewR.getVPSingleValue());
+        }
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fhahn wrote:

Yep, all other recipes (VPInstructions) do not need handling, as extracts inserted during initial setup effectively must take care of extracting the correct lane.

https://github.com/llvm/llvm-project/pull/189022