Tom,
> -class LLVMEnsureMultithreaded {
> -public:
> - LLVMEnsureMultithreaded()
> - {
> - llvm_start_multithreaded();
> - }
> -};
> -
> -static LLVMEnsureMultithreaded lLVMEnsureMultithreaded;
Removing this leads to crashes in llvm with applications that concurrently
work on different gl contexts.
When I did this change I also provided a testcase that never made it into
piglit. See:
http://lists.freedesktop.org/archives/piglit/2012-August/003100.html
I had addresssed the concerns at that time with a v2 patch but got lost
without being checked in. May be somebody can push this now?
Regarding the point where this funciton is called I had choosen static
initialization time since llvm requires this function to be called single
threaded which we cannot guarantee in any case. Keep in mind that you need to
ensure this function called non concurrently even against applications that
itself already use the llvm libs in some way while the driver is loaded.
But the best bet is to do this in the dynamic loder which is itself
serialized, so I could avoid calling this function concurrently by
initialization of different contexts. That should at least shield against
applications that itself do the same trick by calling this funtion in the
dlopen phase in some static initializer ...
We may get around part of this problem with dlopening the driver with better
isolation but up to now the problem can get that far.
You can find more thoughts about that problem regarding llvmpipe which still
has this problem is written down here:
http://lists.freedesktop.org/archives/mesa-dev/2013-January/033015.html
So, a better place where you can switch llvm to be multithreaded is
apprecheated. But please make sure it happens at some point, the earlier, the
better.
If you want to have plain c files that behaves the same like what we have today
you can use a gcc extension (untested):
static void r600_llvm_init() __attribute__ ((__constructor__));
void r600_llvm_init()
{
llvm_start_multithreaded();
}
Greetings
Mathias
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