Tested on x86_64, aarch64-linux, x86_64-darwin confirming manually that the
available routines are now detected at configure-time (no change in c++ or
libstdc++ test-suite from this). OK for trunk?
thanks
Iain
--- 8< ---
When _POSIX_TIMERS (and _POSIX_MONOTONIC_CLOCK) are set to -1 that indicates
the implementation is not claiming POSIX compliance; it does not indicate
that either timespec or any specific APIs are actually absent. We have been
gating the configure tests on _POSIX_TIMERS/_POSIX_MONOTONIC_CLOCK which is
preventing the discovery of nanosleep/clock_gettime on Darwin where these
have been present for quite some time (nanosleep since at least Darwin8
and clock_gettime since Darwin12).
The proposal here is that we should test for the APIs and not guard the
use of timespec - if the implementation does not have timespec that will
be correctly reflected in the config tests failing. There is some small
risk that an implementation could define timespec, clock_gettime and the
CLOCK_MONOTONIC and CLOCK_REALTIME while in some way meaning something
radically different from the POSIX intent. Howeever, this seems like an
unlikely edge-case that should be handled by that platform and does not
warrant avoiding the tests for the APIs. On modern Darwin these tests are
all positive with the changes here.
libstdc++-v3/ChangeLog:
* acinclude.m4: Do not gate the use of 'timespec' with
_POSIX_TIMERS > 0. For the auto case, set ac_has_clock_monotonic
and ac_has_clock_realtime for Darwin versions that implement them.
* configure: Regenerate.
Signed-off-by: Iain Sandoe <[email protected]>
---
libstdc++-v3/acinclude.m4 | 30 ++++++++++++++++++------------
libstdc++-v3/configure | 23 +++++++++++++----------
2 files changed, 31 insertions(+), 22 deletions(-)
diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4
index 8c44e618cb8..a8be306c127 100644
--- a/libstdc++-v3/acinclude.m4
+++ b/libstdc++-v3/acinclude.m4
@@ -1741,9 +1741,12 @@ dnl --disable-libstdcxx-time
dnl disables the checks completely
dnl
dnl N.B. Darwin provides nanosleep but doesn't support the whole POSIX
-dnl Timers option, so doesn't define _POSIX_TIMERS. Because the test
-dnl below fails Darwin unconditionally defines _GLIBCXX_USE_NANOSLEEP in
-dnl os_defines.h and also defines _GLIBCXX_USE_SCHED_YIELD.
+dnl Timers option, so defines _POSIX_TIMERS (and _POSIX_MONOTONIC_CLOCK)
+dnl to -1 (indicating no claim to POSIX compliance). Nevertheless, the OS
+dnl has reliable mechanisms and exports those via the nanosleep (and other
+dnl clock_gettime() APIs). To handle this, we check the APIs directly here
+dnl and Darwin unconditionally defines _GLIBCXX_USE_NANOSLEEP and
+dnl _GLIBCXX_USE_SCHED_YIELD in os_defines.h.
dnl
AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
@@ -1774,6 +1777,13 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
darwin*)
ac_has_nanosleep=yes
ac_has_sched_yield=yes
+ case "${target_os}" in
+ darwin1[[6-9]]* | darwin2*)
+ # clock_gettime() is available from Darwin12.
+ ac_has_clock_monotonic=yes
+ ac_has_clock_realtime=yes
+ ;;
+ esac
;;
# VxWorks has nanosleep as soon as the kernel is configured with
# INCLUDE_POSIX_TIMERS, which is normally/most-often the case.
@@ -1859,9 +1869,8 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
[[#include <unistd.h>
#include <time.h>
]],
- [[#if _POSIX_TIMERS > 0 && defined(_POSIX_MONOTONIC_CLOCK)
+ [[
timespec tp;
- #endif
clock_gettime(CLOCK_MONOTONIC, &tp);
]])], [ac_has_clock_monotonic=yes], [ac_has_clock_monotonic=no])
@@ -1872,9 +1881,8 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
[[#include <unistd.h>
#include <time.h>
]],
- [[#if _POSIX_TIMERS > 0
+ [[
timespec tp;
- #endif
clock_gettime(CLOCK_REALTIME, &tp);
]])], [ac_has_clock_realtime=yes], [ac_has_clock_realtime=no])
@@ -1885,9 +1893,8 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
[[#include <unistd.h>
#include <time.h>
]],
- [[#if _POSIX_TIMERS > 0
+ [[
timespec tp;
- #endif
nanosleep(&tp, 0);
]])], [ac_has_nanosleep=yes], [ac_has_nanosleep=no])
@@ -1904,9 +1911,8 @@ AC_DEFUN([GLIBCXX_ENABLE_LIBSTDCXX_TIME], [
#include <time.h>
#include <sys/syscall.h>
]],
- [[#if _POSIX_TIMERS > 0 && defined(_POSIX_MONOTONIC_CLOCK)
- timespec tp;
- #endif
+ [[
+ timespec tp;
syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &tp);
syscall(SYS_clock_gettime, CLOCK_REALTIME, &tp);
]])], [ac_has_clock_gettime_syscall=yes],
[ac_has_clock_gettime_syscall=no])
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 577640fcb75..849659c9993 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -21462,6 +21462,13 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
darwin*)
ac_has_nanosleep=yes
ac_has_sched_yield=yes
+ case "${target_os}" in
+ darwin1[6-9]* | darwin2*)
+ # clock_gettime() is available from Darwin12.
+ ac_has_clock_monotonic=yes
+ ac_has_clock_realtime=yes
+ ;;
+ esac
;;
# VxWorks has nanosleep as soon as the kernel is configured with
# INCLUDE_POSIX_TIMERS, which is normally/most-often the case.
@@ -21808,9 +21815,8 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
int
main ()
{
-#if _POSIX_TIMERS > 0 && defined(_POSIX_MONOTONIC_CLOCK)
+
timespec tp;
- #endif
clock_gettime(CLOCK_MONOTONIC, &tp);
;
@@ -21841,9 +21847,8 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
int
main ()
{
-#if _POSIX_TIMERS > 0
+
timespec tp;
- #endif
clock_gettime(CLOCK_REALTIME, &tp);
;
@@ -21874,9 +21879,8 @@ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
int
main ()
{
-#if _POSIX_TIMERS > 0
+
timespec tp;
- #endif
nanosleep(&tp, 0);
;
@@ -21910,9 +21914,8 @@ $as_echo_n "checking for clock_gettime syscall... "
>&6; }
int
main ()
{
-#if _POSIX_TIMERS > 0 && defined(_POSIX_MONOTONIC_CLOCK)
- timespec tp;
- #endif
+
+ timespec tp;
syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &tp);
syscall(SYS_clock_gettime, CLOCK_REALTIME, &tp);
@@ -53737,7 +53740,7 @@ $as_echo "$glibcxx_cv_libbacktrace_atomics" >&6; }
CXXFLAGS='-O0 -S'
cat > conftest.$ac_ext << EOF
-#line 53740 "configure"
+#line 53743 "configure"
#include <stddef.h>
int main()
{
--
2.50.1 (Apple Git-155)
