[Mesa-dev] [PATCH 1/2] configure: check if -latomic is needed for __atomic_*

[Grazvydas Ignotas]

On Tue, Sep 19, 2017 at 2:04 PM, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 19 September 2017 at 10:12, Grazvydas Ignotas <notasas at gmail.com> wrote:
>> On Mon, Sep 18, 2017 at 11:30 PM, Matt Turner <mattst88 at gmail.com> wrote:
>>> On Mon, Sep 18, 2017 at 12:28 PM, Grazvydas Ignotas <notasas at gmail.com> wrote:
>>>> On some platforms, gcc generates library calls when __atomic_* functions
>>>> are used, but does not link the required library automatically. Detect
>>>> this and add the library when needed.
>>>>
>>>> This change was tested on armel (library was added) and on x86_64 (was
>>>> not, as expected).
>>>>
> On one hand I see the reason why things are as-is. On the other its
> rather odd that I couldn't find an official GCC doc that describes the
> lot.
> Most likely I failed at searching.

I can't find it either. there is only this wiki that looks more like a
design document:
https://gcc.gnu.org/wiki/Atomic/GCCMM

If I understand it right, when gcc can't do the operations with
instructions it emits calls, but doesn't care how they are satisfied
and leaves dealing with that to the application. libatomic is provided
since 4.8, but there is no requirement to use it (to allow using
something else?).

Gražvydas