[llvm] [PredicateInfo] Reserve adjacent LN_Last defs for the same phi use (PR #164577)

[Nikita Popov via llvm-commits]

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@@ -261,8 +261,14 @@ bool PredicateInfoBuilder::stackIsInScope(const ValueDFSStack &Stack,
   // the stack when we hit the end of the phi uses for a given def.
   const ValueDFS &Top = *Stack.back().V;
   if (Top.LocalNum == LN_Last && Top.PInfo) {
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nikic wrote:

Just as a side node, this Top.PInfo check looks unnecessary. The stack only contains defs.

https://github.com/llvm/llvm-project/pull/164577