[llvm] [VPlan] Optimize resume values of IVs together with other exit values. (PR #174239)

[Florian Hahn via llvm-commits]

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@@ -742,6 +751,30 @@ void VPlanTransforms::createHeaderPhiRecipes(
     PhiR->replaceAllUsesWith(HeaderPhiR);
     PhiR->eraseFromParent();
   }
+
+  for (const auto &[HeaderPhiR, ScalarPhiR] : zip_equal(
+           drop_begin(HeaderVPBB->phis()), Plan.getScalarPreheader()->phis())) {
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fhahn wrote:

Yes, this drops the canonical IV, which does not exist in the scalar loop. Added a helper, thanks

https://github.com/llvm/llvm-project/pull/174239