[PATCH] D128128: [GlobalOpt] Perform store->dominated load forwarding for stored once globals

[Johannes Doerfert via Phabricator via llvm-commits]

jdoerfert added a comment.

This breaks in the presence of synchronization.

  static int X = 42;
  
  int foo(int Arg) {
    sync();
    X = Arg;
    sync();
    return X;
  }

Two threads call `foo` with two values of `Arg` and the `sync` will ensure they proceed "one after another":

      X = 42;
  sync
  T1: X = Arg1;
  sync
  T2: X = Arg2;
  sync
  T1, T2: return Arg2

Whereas replacing the load will result

  T1, T2, return Arg{1,2}

Right?


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  https://reviews.llvm.org/D128128/new/

https://reviews.llvm.org/D128128