[llvm] [LV] Add vplan folds for (X - (X & Y)) -> (X & ~Y) (PR #226466)

[David Sherwood via llvm-commits]

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@@ -1528,6 +1528,15 @@ static VPSingleDefRecipe *combineRecipe(VPlan &Plan, VPSingleDefRecipe *Def,
   }
 
   const APInt *APC;
+
+  // (X - (X & Y)) -> (X & ~Y)
+  if (CanCreateNewRecipe &&
+      match(Def,
+            m_Sub(m_VPValue(X), m_c_BinaryAnd(m_Deferred(X), m_VPValue(Y)))) &&
+      match(Y, m_APInt(APC)))
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david-arm wrote:

Oh yeah you're right. I think this is because I was originally trying to also add support for non-constant folds too, but then limited it to purely constants.

https://github.com/llvm/llvm-project/pull/226466