[llvm] [VPlan] Explicitly handle scalar pointer inductions. (PR #83068)

[via llvm-commits]

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@@ -490,6 +519,10 @@ Value *VPInstruction::generateInstruction(VPTransformState &State,
 
     return ReducedPartRdx;
   }
+  case VPInstruction::PtrAdd:
+    assert(vputils::onlyFirstLaneUsed(this) &&
+           "can only generate first lane for PtrAdd");
+    return generatePerLane(State, VPIteration(Part, 0));
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ayalz wrote:

Would this be more consistent:
```
  Value *Ptr = State.get(getOperand(0), Part, /* IsScalar */ true);
  Value *Addend = State.get(getOperand(1), Part, /* IsScalar */ true);
  return Builder.CreatePtrAdd(Ptr, Addend, Name);
```
?

https://github.com/llvm/llvm-project/pull/83068