[llvm] Reapply "[VPlan] Extract reverse mask from reverse accesses" (PR #189930)

[Florian Hahn via llvm-commits]

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@@ -1046,8 +1045,13 @@ InstructionCost VPRecipeWithIRFlags::getCostForRecipeWithOpcode(
         return dyn_cast<VPRecipeBase>(*R->user_begin());
       };
       if (VPRecipeBase *Recipe = GetOnlyUser(this)) {
-        if (match(Recipe, m_Reverse(m_VPValue())))
-          Recipe = GetOnlyUser(cast<VPInstruction>(Recipe));
+        if (match(Recipe,
+                  m_CombineOr(m_Reverse(m_VPValue()),
+                              m_Intrinsic<Intrinsic::experimental_vp_reverse>(
+                                  m_VPValue(), m_VPValue(), m_VPValue())))) {
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fhahn wrote:

this may deserve a dedicated matcher?

https://github.com/llvm/llvm-project/pull/189930