[PATCH] D93585: [AArch64] Enable out-of-line atomics by default.

[Tim Northover via Phabricator via llvm-commits]

t.p.northover added a comment.

> Outline atomics were added with gcc 9.3.1 and turned on by default in gcc 10.1. Consequently most of distributions had libgcc with outline atomics already.

I think that works for people who use the packages that come with their distro (if they have post-now Clang they ought to have that GCC available). But we release binaries for an LTS Linux distribution too (Ubuntu 16.04 currently) and that only has 5.3.1.

I think this ought to be a Clang patch that detects which platform and  libgcc it's targeting before adding the attribute.

> Don't know about iOs and MacOs, I guess they are compiling with LSE enabled, so outline atomics should not affect them.

Most iOS compilation still targets baseline ARMv8.0 so doesn't use LSE. The latest OS still supports phones that lack the instructions, and we'll allow back-deployment of user apps even after that stops being true.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D93585/new/

https://reviews.llvm.org/D93585