.global pg_atomic_cas
pg_atomic_cas:
+ ! "cas" only works on sparcv9 chips, and requies a compiler
+ ! that is targeting sparcv9. It will fail on a compiler
+ ! targeting sparcv8, and of course will not be understood
+ ! by a sparcv8 CPU. If this fails on existing Solaris
+ ! systems, we need to use a !defined(__sparcv9) test
+ ! to fall back to the old "ldstub" call for sparcv8 compiles.
+ ! gcc continues to use "ldstub" because there is no indication
+ ! which sparc version it is targeting.
+ !
+ ! There actually is a trick for embedding "cas" for a compiler
+ ! that is targeting sparcv8:
+ !
+ ! http://cvs.opensolaris.org/source/xref/on/usr/src/lib/libc/sparc/threads/sparc.il
+ !
+ ! This might work for sparc8:
+ ! ldstub [%o0],%o1 ! moves only a byte
+
cas [%o0],%o2,%o1
mov %o1,%o0
retl
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.152 2006/04/29 11:55:19 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/s_lock.h,v 1.153 2006/05/17 23:57:03 momjian Exp $
*
*-------------------------------------------------------------------------
*/
{
register slock_t _res;
+ /*
+ * See comment in /pg/backend/port/tas/solaris_sparc.s for why this
+ * uses "ldstub", and that file uses "cas".
+ */
__asm__ __volatile__(
" ldstub [%2], %0 \n"
: "=r"(_res), "+m"(*lock)