stef...@apache.org wrote on Thu, Mar 08, 2012 at 20:07:43 -0000: > Author: stefan2 > Date: Thu Mar 8 20:07:43 2012 > New Revision: 1298554 > > URL: http://svn.apache.org/viewvc?rev=1298554&view=rev > Log: > Teach subversion to detect the availability of GCC's atomic built-ins > for 64 bit items. This code was taken from APR and tweaked slightly. > > * build/ac-macros/svn-macros.m4 > (SVN_CHECK_FOR_ATOMIC_BUILTINS): new macro > * configure.ac > call the new macro, set SVN_HAS_ATOMIC_BUILTINS #define > > Modified: > subversion/branches/revprop-cache/build/ac-macros/svn-macros.m4 > subversion/branches/revprop-cache/configure.ac > > Modified: subversion/branches/revprop-cache/build/ac-macros/svn-macros.m4 > URL: > http://svn.apache.org/viewvc/subversion/branches/revprop-cache/build/ac-macros/svn-macros.m4?rev=1298554&r1=1298553&r2=1298554&view=diff > ============================================================================== > --- subversion/branches/revprop-cache/build/ac-macros/svn-macros.m4 (original) > +++ subversion/branches/revprop-cache/build/ac-macros/svn-macros.m4 Thu Mar > 8 20:07:43 2012 > @@ -202,3 +202,44 @@ AC_DEFUN([SVN_REMOVE_STANDARD_LIB_DIRS], > printf "%s" "${output_flags# }" > fi > ]) > + > +AC_DEFUN([SVN_CHECK_FOR_ATOMIC_BUILTINS], > +[ > + AC_CACHE_CHECK([whether the compiler provides atomic builtins], > [ap_cv_atomic_builtins],
How does this interact with http://subversion.apache.org/docs/release-notes/1.7#rhel-2-issue ? (which says: "Workarounds include using a more recent gcc or configuring APR with --disable-nonportable-atomics.") Should the new code be disabled for old gcc's? > + [AC_TRY_RUN([ > + int main() > + { > + unsigned long long val = 1010, tmp, *mem = &val; > + > + if (__sync_fetch_and_add(&val, 1010) != 1010 || val != 2020) > + return 1; > + > + tmp = val; > + > + if (__sync_fetch_and_sub(mem, 1010) != tmp || val != 1010) > + return 1; > + > + if (__sync_sub_and_fetch(&val, 1010) != 0 || val != 0) > + return 1; > + > + tmp = 3030; > + > + if (__sync_val_compare_and_swap(mem, 0, tmp) != 0 || val != tmp) > + return 1; > + > + if (__sync_lock_test_and_set(&val, 4040) != 3030) > + return 1; > + > + mem = &tmp; > + > + if (__sync_val_compare_and_swap(&mem, &tmp, &val) != &tmp) > + return 1; > + > + __sync_synchronize(); > + > + if (mem != &val) > + return 1; > + > + return 0; > + }], [ap_cv_atomic_builtins=yes], [ap_cv_atomic_builtins=no], > [ap_cv_atomic_builtins=no])]) > +]) > > Modified: subversion/branches/revprop-cache/configure.ac > URL: > http://svn.apache.org/viewvc/subversion/branches/revprop-cache/configure.ac?rev=1298554&r1=1298553&r2=1298554&view=diff > ============================================================================== > --- subversion/branches/revprop-cache/configure.ac (original) > +++ subversion/branches/revprop-cache/configure.ac Thu Mar 8 20:07:43 2012 > @@ -184,6 +184,12 @@ if test -n "$sqlite_compat_ver" && test > CFLAGS="-DSVN_SQLITE_MIN_VERSION_NUMBER=$sqlite_compat_ver_num $CFLAGS" > fi > > +SVN_CHECK_FOR_ATOMIC_BUILTINS > + > +if test "$ap_cv_atomic_builtins" = "yes"; then > + AC_DEFINE(SVN_HAS_ATOMIC_BUILTINS, 1, [Define if compiler provides > atomic builtins]) > +fi > + > dnl Set up a number of directories --------------------- > > dnl Create SVN_BINDIR for proper substitution > >
