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This rewrites the sparc GLAPI code so that it's PIC friendly and works
with all of the TLS/PTHREADS/64-bit/32-bit combinations properly.
As a result we can turn SPARC asm back on. Currently it's only
enabled on Linux, as that's the only place where I can test this
stuff out.
For the moment the cliptest SPARC asm routines are disabled as they
are non-working. The problem is that they use register %g7 as a
temporary which is where the threading libraries store the thread
pointer on SPARC. I will fix that code up in a future change as it's
a pretty important routine to optimize.
Like x86 we do the runtime patch as a pthread once-invoked initializer
in init_glapi_relocs().
Unlike x86, however, our GLAPI stubs on SPARC are just two instruction
sequences that branch to a trampoline and put the GLAPI offset into a
register. The trampoline is what we run-time patch. The stubs thus
all look like:
glFoo:
ba __glapi_sparc_foo_stub
sethi GLAPI_OFFSET(glFOO) * PTR_SIZE, %g3
This actually makes generate_entrypoint() a lot simpler on SPARC. For
this case in generate_entrypoint() we generate stubs using a 'call'
instead of the 'ba' above to make sure it can reach.
In order to get a proper tail call going here, in the unpatched case,
we do several tricks. To get the current PC, for example, we save the
return address register into a temporary, do a call, save the return
address register written by the call to another temporary, then
restore the original return address register value. This is to
avoid having to allocate a stack frame.
This is necessary for PIC address formation.
This new GLAPI scheme lets us get rid of the ugly SPARC GLAPI hacks in
__glXInitialize() and one_time_init().
Signed-off-by: David S. Miller <davem@davemloft.net>
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