wxWidgets/build/aclocal/atomic_builtins.m4


dnl Checks for availability of GCC's atomic operations builtins.
dnl Defines HAVE_GCC_ATOMIC_BUILTINS if available.

AC_DEFUN([WX_ATOMIC_BUILTINS],
[
  AC_REQUIRE([AC_PROG_CC])
  if test -n "$GCC"; then
    AC_MSG_CHECKING([for __sync_xxx_and_fetch builtins])
    AC_CACHE_VAL(wx_cv_cc_gcc_atomic_builtins, [
      AC_TRY_LINK(
        [],
        [
          unsigned int value=0;
          volatile unsigned int r1 = __sync_add_and_fetch(&value, 2);
          volatile unsigned int r2 = __sync_sub_and_fetch(&value, 1);
        ],
        wx_cv_cc_gcc_atomic_builtins=yes,
        wx_cv_cc_gcc_atomic_builtins=no)
      ])
    AC_MSG_RESULT([$wx_cv_cc_gcc_atomic_builtins])
    if test $wx_cv_cc_gcc_atomic_builtins = yes; then
      AC_DEFINE([HAVE_GCC_ATOMIC_BUILTINS])
    fi
  fi
])
Fixed wxAtomicInc/Dec() to not use asm/atomic.h header on Linux - it's kernel internal, not available for userspace in newer kernel versions and broken for userspace on some platforms. Use GCC's builtins instead. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2007-09-10 18:27:15 -04:00
			`dnl Checks for availability of GCC's atomic operations builtins.`
			`dnl Defines HAVE_GCC_ATOMIC_BUILTINS if available.`

			`AC_DEFUN([WX_ATOMIC_BUILTINS],`
			`[`
			`AC_REQUIRE([AC_PROG_CC])`
			`if test -n "$GCC"; then`
Return the new value from wxAtomicInc() too This is easy to do and can be useful when using an atomic initialization counter. The only platform where not returning the new value might be more efficient than returning it is Solaris which is not really relevant any more and on all the other platforms the functions we were already using provided this value already (or almost, in case of using gcc builtins, when we just have to use a different one). 2022-05-10 18:12:43 -04:00			`AC_MSG_CHECKING([for __sync_xxx_and_fetch builtins])`
Fixed wxAtomicInc/Dec() to not use asm/atomic.h header on Linux - it's kernel internal, not available for userspace in newer kernel versions and broken for userspace on some platforms. Use GCC's builtins instead. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2007-09-10 18:27:15 -04:00			`AC_CACHE_VAL(wx_cv_cc_gcc_atomic_builtins, [`
when testing for GCC's atomic builtins, try to link too (see bug #1844128); also more closely mirror wx's use by using unsigned int and not int for tests git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50466 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2007-12-04 10:29:17 -05:00			`AC_TRY_LINK(`
Fixed wxAtomicInc/Dec() to not use asm/atomic.h header on Linux - it's kernel internal, not available for userspace in newer kernel versions and broken for userspace on some platforms. Use GCC's builtins instead. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2007-09-10 18:27:15 -04:00			`[],`
			`[`
when testing for GCC's atomic builtins, try to link too (see bug #1844128); also more closely mirror wx's use by using unsigned int and not int for tests git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@50466 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2007-12-04 10:29:17 -05:00			`unsigned int value=0;`
Return the new value from wxAtomicInc() too This is easy to do and can be useful when using an atomic initialization counter. The only platform where not returning the new value might be more efficient than returning it is Solaris which is not really relevant any more and on all the other platforms the functions we were already using provided this value already (or almost, in case of using gcc builtins, when we just have to use a different one). 2022-05-10 18:12:43 -04:00			`volatile unsigned int r1 = __sync_add_and_fetch(&value, 2);`
Work around g++ atomic builtins detection in configure when -Os is used. Assigning __sync_sub_and_fetch() result to an unused variable can result in it being optimized away and the function support is then not really tested for, see #4542. So do make sure this variable is kept by making it volatile. Closes #15555. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@74934 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2013-10-04 19:48:22 -04:00			`volatile unsigned int r2 = __sync_sub_and_fetch(&value, 1);`
Fixed wxAtomicInc/Dec() to not use asm/atomic.h header on Linux - it's kernel internal, not available for userspace in newer kernel versions and broken for userspace on some platforms. Use GCC's builtins instead. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@48640 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775 2007-09-10 18:27:15 -04:00			`],`
			`wx_cv_cc_gcc_atomic_builtins=yes,`
			`wx_cv_cc_gcc_atomic_builtins=no)`
			`])`
			`AC_MSG_RESULT([$wx_cv_cc_gcc_atomic_builtins])`
			`if test $wx_cv_cc_gcc_atomic_builtins = yes; then`
			`AC_DEFINE([HAVE_GCC_ATOMIC_BUILTINS])`
			`fi`
			`fi`
			`])`