[llvm] [VPlan] Remove unused first mask op from VPBlendRecipe. (PR #87770)

[Florian Hahn via llvm-commits]

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@@ -8245,6 +8245,8 @@ VPBlendRecipe *VPRecipeBuilder::tryToBlend(PHINode *Phi,
              "Distinct incoming values with one having a full mask");
       break;
     }
+    if (In == 0)
+      continue;
----------------
fhahn wrote:

Unfortunately we can't use an early continue at the top, as null masks cannot be added as operands due to them not being proper VPValues. The early continue would mean we break after adding 2 incoming values but no mask. Left as is for now, but pushed 9430a4b9d272b050869958d5f0e7ef9fd9db2643 to replace `createEdgeMask` to with `getEdgeMask` to make it clear that no new edge-mask is created, only the existing one retrieved.

https://github.com/llvm/llvm-project/pull/87770