.global pg_atomic_cas

!"cas" only works on sparcv9chips,andrequies a compiler

!that istargetingsparcv9. It will fail on a compiler

! targeting sparcv8,and of course willnot be understood

! by a sparcv8 CPU. gcc continues to use"ldstub" because

!there is no indication which sparc versionitis targeting.

!"cas" only works on sparcv9andsparcv8plus chips,and

!requies a compilertargetingthese CPUs. It will fail

!on a compilertargeting sparcv8,and of course willnot

!be understoodby a sparcv8 CPU. gcc continues to use

!"ldstub" becauseittargets sparcv7.

!

! It is actually possible to use"cas" for sparcv8 binaries if

! -xarch=v8plus is used for compilation. There is actually a

! trick for embedding"cas"in a sparcv8-targeted compiler, but

! it can only be run on a sparcv8pluscpus:

! There is actually a trick for embedding"cas"in a

! sparcv8-targeted compiler, but it can only be run

! on a sparcv8plus/v9cpus:

!

!http://cvs.opensolaris.org/source/xref/on/usr/src/lib/libc/sparc/threads/sparc.il

!

#ifdef__sparcv9

#if defined(__sparcv9) || defined(__sparcv8plus)

cas [%o0],%o2,%o1

ldstub [%o0],%o1