[llvm] [VPlan] Remove VPVectorPointer for part 0 after unrolling. (PR #149735)

[Luke Lau via llvm-commits]

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@@ -1837,6 +1837,10 @@ class VPVectorPointerRecipe : public VPRecipeWithIRFlags,
                                      getGEPNoWrapFlags(), getDebugLoc());
   }
 
+  /// Return true if this VPVectorPointerRecipe corresponds to part 0. Note that
+  /// this is only accurate after the VPlan has been unrolled.
+  bool isFirstPart() const { return getUnrollPart(*this) == 0; }
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lukel97 wrote:

FWIW in #148274 I was planning on making the VPUnrollPartAccessor methods public, similar to VPPHIAccessors. If that lands then we wouldn't need to add a method on VPVectorPointerRecipe, we could just call `R.getUnrollPart(R) == 0` directly.

https://github.com/llvm/llvm-project/pull/149735