Robert Haas [2011-12-19 9:31 -0500]: > -1. Absent some evidence that gcc's implementations are superior to > ours, I think we should not change stuff that works now. That's > likely to lead to subtle bugs that are hard to find and perhaps > dependent on the exact compiler version used. > > But I'm completely cool with doing this for platforms where we haven't > otherwise got an implementation. Any port in a storm.
The updated patch only uses the gcc builtins if there is no explicit implementation, but drops the arm one as this doesn't work on ARMv7 and newer, as stated in the original mail. Thanks, Martin -- Martin Pitt | http://www.piware.de Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org)
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 <mp...@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
signature.asc
Description: Digital signature
