mesa: Resurrect SPARC asm code.

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>

1 files changed, 13 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index a57e5b3ea7..2f3f0beff1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -307,6 +307,13 @@ if test "x$enable_asm" = xyes; then
             ;;
         esac
         ;;
+    sparc*)
+        case "$host_os" in
+        linux*)
+            asm_arch=sparc
+            ;;
+        esac
+        ;;
     esac
 
     case "$asm_arch" in
@@ -327,6 +334,12 @@ if test "x$enable_asm" = xyes; then
         MESA_ASM_SOURCES='$(PPC_SOURCES)'
         AC_MSG_RESULT([yes, ppc])
         ;;
+    sparc)
+        ASM_FLAGS="-DUSE_SPARC_ASM"
+        MESA_ASM_SOURCES='$(SPARC_SOURCES)'
+        GLAPI_ASM_SOURCES='$(SPARC_API)'
+        AC_MSG_RESULT([yes, sparc])
+        ;;
     *)
         AC_MSG_RESULT([no, platform not supported])
         ;;