[llvm] [LV] Support interleaving with conditional scalar assignments (PR #184099)

[Benjamin Maxwell via llvm-commits]

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@@ -326,6 +326,10 @@ void UnrollState::unrollRecipeByUF(VPRecipeBase &R) {
     Copy->insertBefore(VPBB, InsertPt);
     addRecipeForPart(&R, Copy, Part);
 
+    // Phi operands are updated once all other recipes have been unrolled.
+    if (isa<VPWidenPHIRecipe>(Copy))
+      continue;
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MacDue wrote:

The previous uses of `VPWidenPHIRecipe` (there's not many) are only added after the `unrollByUF` pass has run, so didn't need to be handled by unrolling. 

https://github.com/llvm/llvm-project/pull/184099