[PATCH] D75664: [Coroutines] Also check lifetime intrinsic for local variable when build coroutine frame

[JunMa via Phabricator via llvm-commits]

junparser added a comment.

In D75664#1907758 <https://reviews.llvm.org/D75664#1907758>, @wenlei wrote:

> Nice change, thanks @junparser! The improved dataflow analysis using lifetime instead of allocation point and the resulting shrink-wrapping style opt for alloca would definitely be beneficial.
>
> For data race however, I'm not sure if I understand it correctly, could you elaborate (perhaps with a concrete example..) why this is compiler's fault?


For

  auto await_suspend(std::experimental::coroutine_handle<> h) {
      auto& pr = h.promise();
      if (pr._ex) {
          // schedule to another thread
          pr._ex->schedule([&pr]() {
              pr._continuation.resume();
          });
      }
  }

This case shows data race with inline, and does not when not inlined. It looks like both the current thread and schedule thread  access some fields of std::function when I dig into the ir. I'm not sure whether this is caused by std::function constructor/destructor or move allocas to frame. I get such conclusion based on ir.


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https://reviews.llvm.org/D75664