[llvm] [Mem2Reg] Replace block maps with block numbers (PR #101391)

[Alexis Engelke via llvm-commits]

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@@ -743,6 +741,8 @@ void PromoteMem2Reg::run() {
   AllocaDbgUsers.resize(Allocas.size());
   AllocaATInfo.resize(Allocas.size());
   AllocaDPUsers.resize(Allocas.size());
+  BBNumPreds.resize(F.getMaxBlockNumber());
+  Visited.resize(F.getMaxBlockNumber());
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aengelke wrote:

I moved the initialization more downwards to their first users, but ultimately, when PHI nodes need to be inserted, I don't think we can avoid the initialization.

https://github.com/llvm/llvm-project/pull/101391