Re: [PATCH] Detect whether target can use -fprofile-update=atomic

[Nathan Sidwell <nathan at acm dot org>]

On 08/16/16 08:55, Martin Liška wrote:
> Hello.
>
> As reported in [1], m68k has been broken since I installed the patch. Reason is that the target
> does not support atomic operations (add, or) for a mode of gcov_type. Because of that, we see
> an undefined symbols.
>
> Proper fix contains of 2 parts:
> a) compiler emission must verify that -fprofile-update=atomic is doable for a given target; it's done
> via a new function can_generate_atomic_builtin
> b) libgcc must detect whether __atomic_fetch_add_x can be expanded on the target; that requires configure
> support and if the target is not capable to expand these, we must conditionally remove all gcov_.*profiler_atomic
> functions from libgcov.a.

I'm fine with the coverage-pecific changes, but the new hooks etc are not 
something I can approve.

gcc/ChangeLog:

2016-08-12  Martin Liska  <mliska@suse.cz>

	* optabs.c (can_generate_atomic_builtin): New function.
	* optabs.h (can_generate_atomic_builtin): Declare the function.
Need GWM or similar review

	* tree-profile.c (tree_profiling):  Detect whether target can use
	-fprofile-update=atomic.
ok

gcc/testsuite/ChangeLog:

2016-08-12  Martin Liska  <mliska@suse.cz>

	* gcc.dg/profile-update-warning.c: New test.
ok

libgcc/ChangeLog:

2016-08-16  Martin Liska  <mliska@suse.cz>

	* acinclude.m4: New file.
	* config.in: New macro defines.
	* configure: Regenerated.
	* configure.ac: Detect atomic operations.
need GWM or similar review

	* libgcov-profiler.c: Detect GCOV_SUPPORTS_ATOMIC and
	conditionaly enable/disable *_atomic functions.
OK.

nathan