dnl *** g_atomic_* tests ***
dnl ************************
- case $host_cpu in
- i?86|x86_64|s390|s390x|arm*|crisv32*|etrax*)
- glib_memory_barrier_needed=no
- ;;
- sparc*|alpha*|powerpc*|ia64)
- glib_memory_barrier_needed=yes
- ;;
- *)
- glib_memory_barrier_needed=yes
- ;;
- esac
-
-glib_cv_gcc_has_builtin_atomic_operations=no
-if test x"$GCC" = xyes; then
- AC_MSG_CHECKING([whether GCC supports built-in atomic intrinsics])
- AC_TRY_LINK([],
- [int i;
- __sync_synchronize ();
- __sync_bool_compare_and_swap (&i, 0, 1);
- __sync_fetch_and_add (&i, 1);
- ],
- [glib_cv_gcc_has_builtin_atomic_operations=yes],
- [glib_cv_gcc_has_builtin_atomic_operations=no])
-
- AC_MSG_RESULT($glib_cv_gcc_has_builtin_atomic_operations)
-fi
-AM_CONDITIONAL(HAVE_GCC_BUILTINS_FOR_ATOMIC_OPERATIONS,
- [test $glib_cv_gcc_has_builtin_atomic_operations = yes])
-
-AC_MSG_CHECKING([for Win32 atomic intrinsics])
-glib_cv_has_win32_atomic_operations=no
-AC_TRY_LINK([],
- [int i; _InterlockedExchangeAdd (&i, 0);],
- [glib_cv_has_win32_atomic_operations=yes],
- [glib_cv_has_win32_atomic_operations=no])
-AC_MSG_RESULT($glib_cv_has_win32_atomic_operations)
-if test "x$glib_cv_has_win32_atomic_operations" = xyes; then
- AC_DEFINE(HAVE_WIN32_BUILTINS_FOR_ATOMIC_OPERATIONS,1,[Have Win32 atomic intrinsics])
-fi
+dnl We need to decide at configure time if GLib will use real atomic
+dnl operations ("lock free") or emulated ones with a mutex. This is
+dnl because we must put this information in glibconfig.h so we know if
+dnl it is safe or not to inline using compiler intrinsics directly from
+dnl the header.
+dnl
+dnl We also publish the information via G_ATOMIC_LOCK_FREE in case the
+dnl user is interested in knowing if they can use the atomic ops across
+dnl processes.
+dnl
+dnl We can currently support the atomic ops natively when building GLib
+dnl with recent versions of GCC or MSVC. MSVC doesn't run ./configure,
+dnl so we skip that case here and define G_ATOMIC_LOCK_FREE exactly when
+dnl we are using GCC.
+dnl
+dnl Note that the atomic ops are only available with GCC on x86 when
+dnl using -march=i486 or higher. If we detect that the atomic ops are
+dnl not available but would be available given the right flags, we want
+dnl to abort and advise the user to fix their CFLAGS. It's better to do
+dnl that then to silently fall back on emulated atomic ops just because
+dnl the user had the wrong build environment.
+
+dnl We may add other compilers here in the future...
+AC_MSG_CHECKING([for lock-free atomic intrinsics])
+AC_TRY_COMPILE([],
+ [__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4;],
+ [glib_cv_g_atomic_lock_free=yes],
+ [glib_cv_g_atomic_lock_free=no])
+AC_MSG_RESULT($glib_cv_g_atomic_lock_free)
+
+if test "$glib_cv_g_atomic_lock_free" = "no"; then
+ SAVE_CFLAGS="${CFLAGS}"
+ CFLAGS="-march=i486"
+ AC_TRY_COMPILE([],
+ [__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4;],
+ [AC_MSG_ERROR([GLib must be build with -march=i486 or later.])],
+ [])
+ CFLAGS="${SAVE_CFLAGS}"
+fi
+
+dnl We need a more robust approach here...
+case $host_cpu in
+ i?86|x86_64|s390|s390x|arm*|crisv32*|etrax*)
+ glib_memory_barrier_needed=no
+ ;;
+ sparc*|alpha*|powerpc*|ia64)
+ glib_memory_barrier_needed=yes
+ ;;
+ *)
+ glib_memory_barrier_needed=yes
+ ;;
+esac
dnl ************************
dnl ** Check for futex(2) **
echo >>$outfile
echo "#define G_ATOMIC_OP_MEMORY_BARRIER_NEEDED 1" >>$outfile
fi
- if test x"$g_gcc_atomic_ops" != xno; then
+ if test x"$g_atomic_lock_free" = xyes; then
echo >>$outfile
- echo "#define G_ATOMIC_OP_USE_GCC_BUILTINS 1" >>$outfile
+ echo "#define G_ATOMIC_LOCK_FREE" >>$outfile
fi
echo >>$outfile
g_bit_sizes="16 32 64"
g_system_thread_sizeof="$glib_cv_sizeof_system_thread"
+g_atomic_lock_free="$glib_cv_g_atomic_lock_free"
g_memory_barrier_needed="$glib_memory_barrier_needed"
g_gcc_atomic_ops="$glib_cv_gcc_has_builtin_atomic_operations"
AC_CONFIG_FILES([
glib-2.0.pc
-glib-2.0-uninstalled.pc
gmodule-2.0.pc
gmodule-export-2.0.pc
gmodule-no-export-2.0.pc
-gmodule-2.0-uninstalled.pc
-gmodule-no-export-2.0-uninstalled.pc
gthread-2.0.pc
-gthread-2.0-uninstalled.pc
gobject-2.0.pc
-gobject-2.0-uninstalled.pc
gio-2.0.pc
gio-unix-2.0.pc
gio-windows-2.0.pc
-gio-2.0-uninstalled.pc
-gio-unix-2.0-uninstalled.pc
glib-zip
glib-gettextize
Makefile
projects / platform / upstream / glib.git / blobdiff