Add comments that Solaris Sun compiler only supports sparc9 ASM,

diff --git a/src/backend/port/tas/solaris_sparc.s b/src/backend/port/tas/solaris_sparc.s
index d35a854..59c4487 100644 (file)
--- a/src/backend/port/tas/solaris_sparc.s
+++ b/src/backend/port/tas/solaris_sparc.s
@@ -16,6 +16,23 @@
        .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

diff --git a/src/include/storage/s_lock.h b/src/include/storage/s_lock.h
index 67ac619..6a13565 100644 (file)
--- a/src/include/storage/s_lock.h
+++ b/src/include/storage/s_lock.h
@@ -66,7 +66,7 @@
  * 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 $
  *
  *-------------------------------------------------------------------------
  */
@@ -311,6 +311,10 @@ tas(volatile slock_t *lock)
 {
        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)