Drivers and state trackers that use LLVM for generating code, must
register the targets they use with LLVM's global TargetRegistry.
The TargetRegistry is not thread-safe, so all targets must be added
to the registry before it can be queried for target information.
When drivers and state trackers initialize their own targets, they need
a way to force gallivm to initialize its targets at the same time.
Otherwise, there can be a race condition in some multi-threaded
applications (e.g. glx-multihreaded-shader-compile in piglit),
when one thread creates a context for a driver that uses LLVM (e.g.
radeonsi) and another thread creates a gallivm context (glxContextCreate
does this).
The race happens when the driver thread initializes its LLVM targets and
then starts using the registry before the gallivm thread has a chance to
register its targets.
This patch allows users to force gallivm to register its targets by
calling the gallivm_init_llvm_targets() function.
v2:
- Use call_once and remove mutexes and static initializations.
- Replace gallivm_init_llvm_{begin,end}() with
gallivm_init_llvm_targets().
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Mathias Fröhlich <Mathias.Froehlich@web.de>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>
CC: "10.6 11.0" <mesa-stable@lists.freedesktop.org>
Tom Stellard
76cfd6f1da