[llvm] [VPlan] Extract reverse mask from reverse accesses (PR #155579)

[Luke Lau via llvm-commits]

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@@ -7167,10 +7162,14 @@ static bool planContainsAdditionalSimplifications(VPlan &Plan,
                 RepR->getUnderlyingInstr(), VF))
           return true;
       }
+
+      // vp.reverse is generated during EVL tail folding transformation.
+      if (match(&R, m_Intrinsic<Intrinsic::experimental_vp_reverse>()))
+        return true;
+
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lukel97 wrote:

Is this still needed after 0b7bb951993cd82c6defa82bb47ebe0f4b8f5844? I quickly tried commenting it out and check-llvm-transforms-loopvectorize seems to pass

https://github.com/llvm/llvm-project/pull/155579