[PATCH] D115302: GlobalsModRef should treat functions w/o nosync conservatively.

Thu Dec 9 14:43:05 PST 2021

tra added a comment.

In D115302#3183952 <https://reviews.llvm.org/D115302#3183952>, @efriedma wrote:

> The bug being fixed here isn't exclusive to intrinsics.  The following shows the same issue using a spinloop:
> Given that, I don't think this whole tangent about the control flow graph and hardcoding which intrinsics are nocallback is relevant to this bug.

My suggestion was about listing the intrinsics that act as a barrier.  I.e. teach GlobalModRef that `@llvm.nvvm.barrier0` is a `ModRef` for all values. While it's not a proper fix, it does force LLVM to be more conservative about memory accesses on both sizes of it and prevents miscompilation. While not pretty, the work-around is narrow in scope and does not block general work on having these issues fixed properly.

Intrinsics being treated differently from functions because of assumed `nocallback` is an independent issue.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D115302/new/

https://reviews.llvm.org/D115302