[llvm] [VPlan] Use VPlan predecessors in VPWidenPHIRecipe (NFC). (PR #126388)

[via llvm-commits]

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@@ -136,19 +136,22 @@ void PlainCFGBuilder::fixPhiNodes() {
       // predecessor is the first operand of the recipe.
       assert(Phi->getNumOperands() == 2);
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ayalz wrote:

(independent) Error message.

https://github.com/llvm/llvm-project/pull/126388