Description: Use gcc/intel cc builtin atomic operations for test-and-set, if available (http://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Atomic-Builtins.html). Remove the custom implementation for arm as it does not work with recent hardware (like -mthumb2).
Author: Martin Pitt <mpitt@debian.org>

Index: postgresql-9.1-9.1.2/configure.in
===================================================================
--- postgresql-9.1-9.1.2.orig/configure.in	2011-12-01 22:47:20.000000000 +0100
+++ postgresql-9.1-9.1.2/configure.in	2011-12-19 16:54:00.619535943 +0100
@@ -1522,6 +1522,18 @@
 AC_SUBST(LDAP_LIBS_FE)
 AC_SUBST(LDAP_LIBS_BE)
 
+# gcc and intel compiler provide builtin functions for atomic test-and-set
+AC_MSG_CHECKING([whether the C compiler provides atomic builtins])
+AC_TRY_LINK([], [int lock = 0; __sync_lock_test_and_set(&lock, 1); __sync_lock_release(&lock);],
+  [have_cc_atomics="yes"],
+  [have_cc_atomics="no"]
+)
+if test "$have_cc_atomics" = yes; then
+  AC_MSG_RESULT(yes)
+  AC_DEFINE(HAVE_CC_ATOMICS, 1, [Define to 1 if compiler provides atomic builtins])
+else
+  AC_MSG_RESULT(no)
+fi
 
 # This test makes sure that run tests work at all.  Sometimes a shared
 # library is found by the linker, but the runtime linker can't find it.
Index: postgresql-9.1-9.1.2/configure
===================================================================
--- postgresql-9.1-9.1.2.orig/configure	2011-12-01 22:47:20.000000000 +0100
+++ postgresql-9.1-9.1.2/configure	2011-12-19 16:54:00.635535943 +0100
@@ -23602,6 +23602,69 @@
 
 
 
+# gcc and intel compiler provide builtin functions for atomic test-and-set
+{ $as_echo "$as_me:$LINENO: checking whether the C compiler provides atomic builtins" >&5
+$as_echo_n "checking whether the C compiler provides atomic builtins... " >&6; }
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+int lock = 0; __sync_lock_test_and_set(&lock, 1); __sync_lock_release(&lock);
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (ac_try="$ac_link"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_link") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest$ac_exeext && {
+	 test "$cross_compiling" = yes ||
+	 $as_test_x conftest$ac_exeext
+       }; then
+  have_cc_atomics="yes"
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	have_cc_atomics="no"
+
+fi
+
+rm -rf conftest.dSYM
+rm -f core conftest.err conftest.$ac_objext conftest_ipa8_conftest.oo \
+      conftest$ac_exeext conftest.$ac_ext
+if test "$have_cc_atomics" = yes; then
+  { $as_echo "$as_me:$LINENO: result: yes" >&5
+$as_echo "yes" >&6; }
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_CC_ATOMICS 1
+_ACEOF
+
+else
+  { $as_echo "$as_me:$LINENO: result: no" >&5
+$as_echo "no" >&6; }
+fi
 
 # This test makes sure that run tests work at all.  Sometimes a shared
 # library is found by the linker, but the runtime linker can't find it.
Index: postgresql-9.1-9.1.2/src/include/pg_config.h.in
===================================================================
--- postgresql-9.1-9.1.2.orig/src/include/pg_config.h.in	2011-12-01 22:47:20.000000000 +0100
+++ postgresql-9.1-9.1.2/src/include/pg_config.h.in	2011-12-19 16:54:00.639535943 +0100
@@ -87,6 +87,9 @@
 /* Define to 1 if you have the `cbrt' function. */
 #undef HAVE_CBRT
 
+/* Define to 1 if compiler provides atomic builtins */
+#undef HAVE_CC_ATOMICS
+
 /* Define to 1 if you have the `class' function. */
 #undef HAVE_CLASS
 
Index: postgresql-9.1-9.1.2/src/include/storage/s_lock.h
===================================================================
--- postgresql-9.1-9.1.2.orig/src/include/storage/s_lock.h	2011-12-01 22:47:20.000000000 +0100
+++ postgresql-9.1-9.1.2/src/include/storage/s_lock.h	2011-12-19 16:56:31.135541667 +0100
@@ -252,29 +252,6 @@
 #endif	 /* __ia64__ || __ia64 */
 
 
-#if defined(__arm__) || defined(__arm)
-#define HAS_TEST_AND_SET
-
-typedef unsigned char slock_t;
-
-#define TAS(lock) tas(lock)
-
-static __inline__ int
-tas(volatile slock_t *lock)
-{
-	register slock_t _res = 1;
-
-	__asm__ __volatile__(
-		"	swpb 	%0, %0, [%2]	\n"
-:		"+r"(_res), "+m"(*lock)
-:		"r"(lock)
-:		"memory");
-	return (int) _res;
-}
-
-#endif	 /* __arm__ */
-
-
 /* S/390 and S/390x Linux (32- and 64-bit zSeries) */
 #if defined(__s390__) || defined(__s390x__)
 #define HAS_TEST_AND_SET
@@ -859,6 +836,24 @@
 
 #endif	/* !defined(HAS_TEST_AND_SET) */
 
+/*************************************************************************
+ * Use compiler provided atomic builtins if available (in particular, gcc and
+ * Intel provide them for many platforms).
+ */
+#if !defined(HAS_TEST_AND_SET) && HAVE_CC_ATOMICS
+#define HAS_TEST_AND_SET
+typedef int slock_t;
+
+#define TAS(lock) tas(lock)
+#define S_UNLOCK(lock) __sync_lock_release(lock)
+
+static __inline__ int
+tas(volatile slock_t *lock)
+{
+	return __sync_lock_test_and_set (lock, 1);
+}
+#endif
+
 
 /* Blow up if we didn't have any way to do spinlocks */
 #ifndef HAS_TEST_AND_SET