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[PATCH] Optimized __cxa_guard_{acquire,release,abort} for Linux (take 2)
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Benjamin Kosnik <bkoz at redhat dot com>
- Cc: Jason Merrill <jason at redhat dot com>, gcc-patches at gcc dot gnu dot org, libstdc++ at gcc dot gnu dot org
- Date: Mon, 7 Jan 2008 07:19:57 -0500
- Subject: [PATCH] Optimized __cxa_guard_{acquire,release,abort} for Linux (take 2)
- References: <20071231133948.GQ20451@devserv.devel.redhat.com> <20080104165012.7aff650f@wabash.artheist.org>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, Jan 04, 2008 at 04:50:12PM -0600, Benjamin Kosnik wrote:
> Which means you might as well move it toplevel and avoid the
> duplication if possible. Thoughts?
Here is an updated patch, with configury bits shared between libstdc++-v3
and libgomp through config/futex.m4 and __sync_lock_test_and_set instead
of a loop with atomic builtins for __cxa_guard_{release,abort}.
Regtested on x86_64-linux, with default configury, --disable-linux-futex
and --enable-linux-futex.
On a testcase where 40 threads do 50000 local static initializations (each
thread encounters the same ones in the same order) on 4way x86_64 this patch
improved real time more than 10x:
~/timing env LD_LIBRARY_PATH=/usr/src/gcc/obj/x86_64-unknown-linux-gnu/libstdc++-v3.vanilla/src/.libs/ /tmp/y
Strip out best and worst realtime result
minimum: 0.438622440 sec real / 0.000026746 sec CPU
maximum: 0.517794519 sec real / 0.000042939 sec CPU
average: 0.492126735 sec real / 0.000032287 sec CPU
stdev : 0.010437645 sec real / 0.000004436 sec CPU
~/timing env LD_LIBRARY_PATH=/usr/src/gcc/obj/x86_64-unknown-linux-gnu/libstdc++-v3.patched/src/.libs/ /tmp/y
Strip out best and worst realtime result
minimum: 0.018293436 sec real / 0.000027173 sec CPU
maximum: 0.031488578 sec real / 0.000053532 sec CPU
average: 0.019910465 sec real / 0.000033658 sec CPU
stdev : 0.001380772 sec real / 0.000005685 sec CPU
2008-01-07 Jakub Jelinek <jakub@redhat.com>
libstdc++-v3/
* configure.ac (--enable-linux-futex): Add new configure option.
(HAVE_LINUX_FUTEX): New AC_DEFINE.
* Makefile.in: Rebuilt.
* aclocal.m4: Rebuilt.
* configure: Rebuilt.
* config.h.in: Rebuilt.
* config/cpu/generic/cxxabi_tweaks.h (_GLIBCXX_GUARD_BIT,
_GLIBCXX_GUARD_PENDING_BIT, _GLIBCXX_GUARD_WAITING_BIT): Define.
* config/cpu/arm/cxxabi_tweaks.h (_GLIBCXX_GUARD_BIT,
_GLIBCXX_GUARD_PENDING_BIT, _GLIBCXX_GUARD_WAITING_BIT): Define.
* libsupc++/guard.cc: Include climits and syscall.h.
(_GLIBCXX_USE_FUTEX): Define if futex syscall and atomic builtins
are supported.
(_GLIBCXX_FUTEX_WAIT, _GLIBCXX_FUTEX_WAKE): Likewise.
(__guard_test_bit): New static inline.
(__cxa_guard_acquire, __cxa_guard_release, __cxa_guard_abort): Use
atomic builtins and futex syscall if _GLIBCXX_USE_FUTEX.
config/
* futex.m4: New file.
libgomp/
* configure.ac: Move futex checking into ../config/futex.m4.
* configure: Rebuilt.
* aclocal.m4: Rebuilt.
* Makefile.in: Rebuilt.
* configure.tgt: Rename have_tls to gcc_cv_have_tls to match
2007-10-15 ../config/tls.m4 change.
--- libgomp/configure.ac.jj 2007-11-26 11:02:26.000000000 +0100
+++ libgomp/configure.ac 2008-01-07 11:21:47.000000000 +0100
@@ -15,12 +15,6 @@ LIBGOMP_ENABLE(version-specific-runtime-
permit yes|no)
AC_MSG_RESULT($enable_version_specific_runtime_libs)
-AC_MSG_CHECKING([for --enable-linux-futex])
-LIBGOMP_ENABLE(linux-futex, default, ,
- [Use the Linux futex system call],
- permit yes|no|default)
-AC_MSG_RESULT($enable_linux_futex)
-
# We would like our source tree to be readonly. However when releases or
# pre-releases are generated, the flex/bison generated files as well as the
# various formats of manuals need to be included along with the rest of the
@@ -192,50 +186,10 @@ case "$host" in
AC_DEFINE(HAVE_BROKEN_POSIX_SEMAPHORES, 1,
Define if the POSIX Semaphores do not work on your system.)
;;
- *-linux*)
- case "$enable_linux_futex" in
- default)
- # If headers don't have gettid/futex syscalls definition, then
- # default to no, otherwise there will be compile time failures.
- # Otherwise, default to yes. If we don't detect we are
- # compiled/linked against NPTL and not cross-compiling, check
- # if programs are run by default against NPTL and if not, issue
- # a warning.
- enable_linux_futex=no
- AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [#include <sys/syscall.h>
- int lk;],
- [syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);])],
- [AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [#ifndef _GNU_SOURCE
- #define _GNU_SOURCE 1
- #endif
- #include <pthread.h>
- pthread_t th; void *status;],
- [pthread_tryjoin_np (th, &status);])],[enable_linux_futex=yes],
- [if test x$cross_compiling = xno; then
- if getconf GNU_LIBPTHREAD_VERSION 2>/dev/null \
- | LC_ALL=C grep -i NPTL > /dev/null 2>/dev/null; then
- AC_MSG_WARN([The kernel might not support futex or gettid syscalls.
-If so, please configure with --disable-linux-futex])
- fi
- fi
- enable_linux_futex=yes])])
- ;;
- yes)
- AC_LINK_IFELSE(
- [AC_LANG_PROGRAM(
- [#include <sys/syscall.h>
- int lk;],
- [syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);])],[],
- [AC_MSG_ERROR([SYS_gettid and SYS_futex required for --enable-linux-futex])])
- ;;
- esac
- ;;
esac
+GCC_LINUX_FUTEX(:)
+
# Check for pthread_{,attr_}[sg]etaffinity_np.
AC_LINK_IFELSE(
[AC_LANG_PROGRAM(
--- libgomp/configure.tgt.jj 2007-05-04 21:20:40.000000000 +0200
+++ libgomp/configure.tgt 2008-01-07 12:05:23.000000000 +0100
@@ -11,7 +11,7 @@
# XLDFLAGS Add extra link flags to use.
# Optimize TLS usage by avoiding the overhead of dynamic allocation.
-if test $have_tls = yes ; then
+if test $gcc_cv_have_tls = yes ; then
case "${target}" in
*-*-linux*)
--- libgomp/configure.jj 2007-11-26 11:02:26.000000000 +0100
+++ libgomp/configure 2008-01-07 11:25:12.000000000 +0100
@@ -1003,8 +1003,6 @@ Optional Features:
--enable-version-specific-runtime-libs
Specify that runtime libraries should be installed
in a compiler-specific directory [default=no]
- --enable-linux-futex Use the Linux futex system call
- [default=default]
--enable-generated-files-in-srcdir
put copies of generated files in source dir intended
for creating source tarballs for users without
@@ -1021,6 +1019,8 @@ Optional Features:
--disable-libtool-lock avoid locking (might break parallel builds)
--enable-maintainer-mode enable make rules and dependencies not useful
(and sometimes confusing) to the casual installer
+ --enable-linux-futex use the Linux futex system call
+ [default=default]
--enable-tls Use thread-local storage [default=yes]
--enable-symvers=STYLE enables symbol versioning of the shared library
[default=yes]
@@ -1518,26 +1518,6 @@ fi;
echo "$as_me:$LINENO: result: $enable_version_specific_runtime_libs" >&5
echo "${ECHO_T}$enable_version_specific_runtime_libs" >&6
-echo "$as_me:$LINENO: checking for --enable-linux-futex" >&5
-echo $ECHO_N "checking for --enable-linux-futex... $ECHO_C" >&6
- # Check whether --enable-linux-futex or --disable-linux-futex was given.
-if test "${enable_linux_futex+set}" = set; then
- enableval="$enable_linux_futex"
-
- case "$enableval" in
- yes|no|default) ;;
- *) { { echo "$as_me:$LINENO: error: Unknown argument to enable/disable linux-futex" >&5
-echo "$as_me: error: Unknown argument to enable/disable linux-futex" >&2;}
- { (exit 1); exit 1; }; } ;;
- esac
-
-else
- enable_linux_futex=default
-fi;
-
-echo "$as_me:$LINENO: result: $enable_linux_futex" >&5
-echo "${ECHO_T}$enable_linux_futex" >&6
-
# We would like our source tree to be readonly. However when releases or
# pre-releases are generated, the flex/bison generated files as well as the
# various formats of manuals need to be included along with the rest of the
@@ -16661,6 +16641,24 @@ cat >>confdefs.h <<\_ACEOF
_ACEOF
;;
+esac
+
+ # Check whether --enable-linux-futex or --disable-linux-futex was given.
+if test "${enable_linux_futex+set}" = set; then
+ enableval="$enable_linux_futex"
+
+ case "$enableval" in
+ yes|no|default) ;;
+ *) { { echo "$as_me:$LINENO: error: Unknown argument to enable/disable linux-futex" >&5
+echo "$as_me: error: Unknown argument to enable/disable linux-futex" >&2;}
+ { (exit 1); exit 1; }; } ;;
+ esac
+
+else
+ enable_linux_futex=default
+fi;
+
+case "$target" in
*-linux*)
case "$enable_linux_futex" in
default)
@@ -16709,7 +16707,9 @@ if { (eval echo "$as_me:$LINENO: \"$ac_l
ac_status=$?
echo "$as_me:$LINENO: \$? = $ac_status" >&5
(exit $ac_status); }; }; then
- cat >conftest.$ac_ext <<_ACEOF
+ save_LIBS="$LIBS"
+ LIBS="-lpthread $LIBS"
+ cat >conftest.$ac_ext <<_ACEOF
/* confdefs.h. */
_ACEOF
cat confdefs.h >>conftest.$ac_ext
@@ -16757,7 +16757,7 @@ sed 's/^/| /' conftest.$ac_ext >&5
if test x$cross_compiling = xno; then
if getconf GNU_LIBPTHREAD_VERSION 2>/dev/null \
- | LC_ALL=C grep -i NPTL > /dev/null 2>/dev/null; then
+ | LC_ALL=C grep -i NPTL > /dev/null 2>/dev/null; then :; else
{ echo "$as_me:$LINENO: WARNING: The kernel might not support futex or gettid syscalls.
If so, please configure with --disable-linux-futex" >&5
echo "$as_me: WARNING: The kernel might not support futex or gettid syscalls.
@@ -16768,6 +16768,7 @@ If so, please configure with --disable-l
fi
rm -f conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
+ LIBS="$save_LIBS"
else
echo "$as_me: failed program was:" >&5
sed 's/^/| /' conftest.$ac_ext >&5
@@ -16776,7 +16777,7 @@ fi
rm -f conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
;;
- yes)
+ yes)
cat >conftest.$ac_ext <<_ACEOF
/* confdefs.h. */
_ACEOF
@@ -16829,7 +16830,14 @@ rm -f conftest.err conftest.$ac_objext \
;;
esac
;;
+ *)
+ enable_linux_futex=no
+ ;;
esac
+if test x$enable_linux_futex = xyes; then
+ :
+fi
+
# Check for pthread_{,attr_}[sg]etaffinity_np.
cat >conftest.$ac_ext <<_ACEOF
--- libgomp/Makefile.in.jj 2007-11-29 19:28:27.000000000 +0100
+++ libgomp/Makefile.in 2008-01-07 11:19:54.000000000 +0100
@@ -55,7 +55,8 @@ am__aclocal_m4_deps = $(top_srcdir)/../c
$(top_srcdir)/../config/lead-dot.m4 \
$(top_srcdir)/../config/multi.m4 \
$(top_srcdir)/../config/stdint.m4 \
- $(top_srcdir)/../config/tls.m4 $(top_srcdir)/../ltoptions.m4 \
+ $(top_srcdir)/../config/tls.m4 \
+ $(top_srcdir)/../config/futex.m4 $(top_srcdir)/../ltoptions.m4 \
$(top_srcdir)/../ltsugar.m4 $(top_srcdir)/../ltversion.m4 \
$(top_srcdir)/../lt~obsolete.m4 $(top_srcdir)/acinclude.m4 \
$(top_srcdir)/../libtool.m4 $(top_srcdir)/configure.ac
--- libgomp/aclocal.m4.jj 2007-07-12 13:59:12.000000000 +0200
+++ libgomp/aclocal.m4 2008-01-07 11:19:01.000000000 +0100
@@ -863,6 +863,7 @@ m4_include([../config/lead-dot.m4])
m4_include([../config/multi.m4])
m4_include([../config/stdint.m4])
m4_include([../config/tls.m4])
+m4_include([../config/futex.m4])
m4_include([../ltoptions.m4])
m4_include([../ltsugar.m4])
m4_include([../ltversion.m4])
--- config/futex.m4.jj 2008-01-07 10:48:54.000000000 +0100
+++ config/futex.m4 2008-01-07 12:02:06.000000000 +0100
@@ -0,0 +1,64 @@
+dnl ----------------------------------------------------------------------
+dnl This whole bit snagged from libgomp.
+
+dnl
+dnl GCC_LINUX_FUTEX
+dnl (SHELL-CODE_HANDLER)
+dnl
+AC_DEFUN([GCC_LINUX_FUTEX],[dnl
+GCC_ENABLE(linux-futex,default, ,[use the Linux futex system call],
+ permit yes|no|default)
+case "$target" in
+ *-linux*)
+ case "$enable_linux_futex" in
+ default)
+ # If headers don't have gettid/futex syscalls definition, then
+ # default to no, otherwise there will be compile time failures.
+ # Otherwise, default to yes. If we don't detect we are
+ # compiled/linked against NPTL and not cross-compiling, check
+ # if programs are run by default against NPTL and if not, issue
+ # a warning.
+ enable_linux_futex=no
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <sys/syscall.h>
+ int lk;],
+ [syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);])],
+ [save_LIBS="$LIBS"
+ LIBS="-lpthread $LIBS"
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#ifndef _GNU_SOURCE
+ #define _GNU_SOURCE 1
+ #endif
+ #include <pthread.h>
+ pthread_t th; void *status;],
+ [pthread_tryjoin_np (th, &status);])],[enable_linux_futex=yes],
+ [if test x$cross_compiling = xno; then
+ if getconf GNU_LIBPTHREAD_VERSION 2>/dev/null \
+ | LC_ALL=C grep -i NPTL > /dev/null 2>/dev/null; then :; else
+ AC_MSG_WARN([The kernel might not support futex or gettid syscalls.
+If so, please configure with --disable-linux-futex])
+ fi
+ fi
+ enable_linux_futex=yes])
+ LIBS="$save_LIBS"])
+ ;;
+ yes)
+ AC_LINK_IFELSE(
+ [AC_LANG_PROGRAM(
+ [#include <sys/syscall.h>
+ int lk;],
+ [syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);])],[],
+ [AC_MSG_ERROR([SYS_gettid and SYS_futex required for --enable-linux-futex])])
+ ;;
+ esac
+ ;;
+ *)
+ enable_linux_futex=no
+ ;;
+esac
+if test x$enable_linux_futex = xyes; then
+ $1
+fi
+])
--- libstdc++-v3/config/cpu/arm/cxxabi_tweaks.h.jj 2007-12-31 20:55:23.000000000 +0100
+++ libstdc++-v3/config/cpu/arm/cxxabi_tweaks.h 2008-01-07 10:22:28.000000000 +0100
@@ -1,6 +1,6 @@
// Control various target specific ABI tweaks. ARM version.
-// Copyright (C) 2004, 2006 Free Software Foundation, Inc.
+// Copyright (C) 2004, 2006, 2008 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
@@ -46,6 +46,9 @@ namespace __cxxabiv1
// guard variable. */
#define _GLIBCXX_GUARD_TEST(x) ((*(x) & 1) != 0)
#define _GLIBCXX_GUARD_SET(x) *(x) = 1
+#define _GLIBCXX_GUARD_BIT 1
+#define _GLIBCXX_GUARD_PENDING_BIT __guard_test_bit (1, 1)
+#define _GLIBCXX_GUARD_WAITING_BIT __guard_test_bit (2, 1)
typedef int __guard;
// We also want the element size in array cookies.
@@ -62,6 +65,9 @@ namespace __cxxabiv1
// The generic ABI uses the first byte of a 64-bit guard variable.
#define _GLIBCXX_GUARD_TEST(x) (*(char *) (x) != 0)
#define _GLIBCXX_GUARD_SET(x) *(char *) (x) = 1
+#define _GLIBCXX_GUARD_BIT __guard_test_bit (0, 1)
+#define _GLIBCXX_GUARD_PENDING_BIT __guard_test_bit (1, 1)
+#define _GLIBCXX_GUARD_WAITING_BIT __guard_test_bit (2, 1)
__extension__ typedef int __guard __attribute__((mode (__DI__)));
// __cxa_vec_ctor has void return type.
--- libstdc++-v3/config/cpu/generic/cxxabi_tweaks.h.jj 2007-12-31 20:55:23.000000000 +0100
+++ libstdc++-v3/config/cpu/generic/cxxabi_tweaks.h 2008-01-07 10:21:59.000000000 +0100
@@ -1,6 +1,6 @@
// Control various target specific ABI tweaks. Generic version.
-// Copyright (C) 2004, 2006 Free Software Foundation, Inc.
+// Copyright (C) 2004, 2006, 2008 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
@@ -44,6 +44,9 @@ namespace __cxxabiv1
// The generic ABI uses the first byte of a 64-bit guard variable.
#define _GLIBCXX_GUARD_TEST(x) (*(char *) (x) != 0)
#define _GLIBCXX_GUARD_SET(x) *(char *) (x) = 1
+#define _GLIBCXX_GUARD_BIT __guard_test_bit (0, 1)
+#define _GLIBCXX_GUARD_PENDING_BIT __guard_test_bit (1, 1)
+#define _GLIBCXX_GUARD_WAITING_BIT __guard_test_bit (2, 1)
__extension__ typedef int __guard __attribute__((mode (__DI__)));
// __cxa_vec_ctor has void return type.
--- libstdc++-v3/configure.ac.jj 2007-09-14 11:54:41.000000000 +0200
+++ libstdc++-v3/configure.ac 2008-01-07 11:00:45.000000000 +0100
@@ -295,9 +295,10 @@ else
# Assume we have _Unwind_GetIPInfo for cross-compiles.
AC_DEFINE(HAVE_GETIPINFO)
-
fi
+GCC_LINUX_FUTEX([AC_DEFINE(HAVE_LINUX_FUTEX, 1, [Define if futex syscall is available.])])
+
# This depends on GLIBCXX CHECK_LINKER_FEATURES, but without it assumes no.
GLIBCXX_ENABLE_SYMVERS([yes])
GLIBCXX_ENABLE_VISIBILITY([yes])
--- libstdc++-v3/configure.jj 2007-11-10 01:15:03.000000000 +0100
+++ libstdc++-v3/configure 2008-01-07 11:14:37.000000000 +0100
@@ -1053,6 +1053,8 @@ Optional Features:
memory [default=no]
--enable-tls Use thread-local storage [default=yes]
--disable-rpath do not hardcode runtime library paths
+ --enable-linux-futex use the Linux futex system call
+ [default=default]
--enable-symvers=STYLE enables symbol versioning of the shared library
[default=yes]
--enable-visibility enables visibility safe usage [default=yes]
@@ -114116,8 +114118,222 @@ _ACEOF
#define HAVE_GETIPINFO 1
_ACEOF
+fi
+
+ # Check whether --enable-linux-futex or --disable-linux-futex was given.
+if test "${enable_linux_futex+set}" = set; then
+ enableval="$enable_linux_futex"
+
+ case "$enableval" in
+ yes|no|default) ;;
+ *) { { echo "$as_me:$LINENO: error: Unknown argument to enable/disable linux-futex" >&5
+echo "$as_me: error: Unknown argument to enable/disable linux-futex" >&2;}
+ { (exit 1); exit 1; }; } ;;
+ esac
+
+else
+ enable_linux_futex=default
+fi;
+
+case "$target" in
+ *-linux*)
+ case "$enable_linux_futex" in
+ default)
+ # If headers don't have gettid/futex syscalls definition, then
+ # default to no, otherwise there will be compile time failures.
+ # Otherwise, default to yes. If we don't detect we are
+ # compiled/linked against NPTL and not cross-compiling, check
+ # if programs are run by default against NPTL and if not, issue
+ # a warning.
+ enable_linux_futex=no
+ if test x$gcc_no_link = xyes; then
+ { { echo "$as_me:$LINENO: error: Link tests are not allowed after GCC_NO_EXECUTABLES." >&5
+echo "$as_me: error: Link tests are not allowed after GCC_NO_EXECUTABLES." >&2;}
+ { (exit 1); exit 1; }; }
+fi
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h. */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h. */
+#include <sys/syscall.h>
+ int lk;
+int
+main ()
+{
+syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);
+ ;
+ return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+ (eval $ac_link) 2>conftest.er1
+ ac_status=$?
+ grep -v '^ *+' conftest.er1 >conftest.err
+ rm -f conftest.er1
+ cat conftest.err >&5
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); } &&
+ { ac_try='test -z "$ac_c_werror_flag"
+ || test ! -s conftest.err'
+ { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; } &&
+ { ac_try='test -s conftest$ac_exeext'
+ { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; }; then
+ save_LIBS="$LIBS"
+ LIBS="-lpthread $LIBS"
+ if test x$gcc_no_link = xyes; then
+ { { echo "$as_me:$LINENO: error: Link tests are not allowed after GCC_NO_EXECUTABLES." >&5
+echo "$as_me: error: Link tests are not allowed after GCC_NO_EXECUTABLES." >&2;}
+ { (exit 1); exit 1; }; }
+fi
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h. */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h. */
+#ifndef _GNU_SOURCE
+ #define _GNU_SOURCE 1
+ #endif
+ #include <pthread.h>
+ pthread_t th; void *status;
+int
+main ()
+{
+pthread_tryjoin_np (th, &status);
+ ;
+ return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+ (eval $ac_link) 2>conftest.er1
+ ac_status=$?
+ grep -v '^ *+' conftest.er1 >conftest.err
+ rm -f conftest.er1
+ cat conftest.err >&5
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); } &&
+ { ac_try='test -z "$ac_c_werror_flag"
+ || test ! -s conftest.err'
+ { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; } &&
+ { ac_try='test -s conftest$ac_exeext'
+ { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; }; then
+ enable_linux_futex=yes
+else
+ echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+if test x$cross_compiling = xno; then
+ if getconf GNU_LIBPTHREAD_VERSION 2>/dev/null \
+ | LC_ALL=C grep -i NPTL > /dev/null 2>/dev/null; then :; else
+ { echo "$as_me:$LINENO: WARNING: The kernel might not support futex or gettid syscalls.
+If so, please configure with --disable-linux-futex" >&5
+echo "$as_me: WARNING: The kernel might not support futex or gettid syscalls.
+If so, please configure with --disable-linux-futex" >&2;}
+ fi
+ fi
+ enable_linux_futex=yes
fi
+rm -f conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+ LIBS="$save_LIBS"
+else
+ echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+fi
+rm -f conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+ ;;
+ yes)
+ if test x$gcc_no_link = xyes; then
+ { { echo "$as_me:$LINENO: error: Link tests are not allowed after GCC_NO_EXECUTABLES." >&5
+echo "$as_me: error: Link tests are not allowed after GCC_NO_EXECUTABLES." >&2;}
+ { (exit 1); exit 1; }; }
+fi
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h. */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h. */
+#include <sys/syscall.h>
+ int lk;
+int
+main ()
+{
+syscall (SYS_gettid); syscall (SYS_futex, &lk, 0, 0, 0);
+ ;
+ return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+ (eval $ac_link) 2>conftest.er1
+ ac_status=$?
+ grep -v '^ *+' conftest.er1 >conftest.err
+ rm -f conftest.er1
+ cat conftest.err >&5
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); } &&
+ { ac_try='test -z "$ac_c_werror_flag"
+ || test ! -s conftest.err'
+ { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; } &&
+ { ac_try='test -s conftest$ac_exeext'
+ { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+ (eval $ac_try) 2>&5
+ ac_status=$?
+ echo "$as_me:$LINENO: \$? = $ac_status" >&5
+ (exit $ac_status); }; }; then
+ :
+else
+ echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+{ { echo "$as_me:$LINENO: error: SYS_gettid and SYS_futex required for --enable-linux-futex" >&5
+echo "$as_me: error: SYS_gettid and SYS_futex required for --enable-linux-futex" >&2;}
+ { (exit 1); exit 1; }; }
+fi
+rm -f conftest.err conftest.$ac_objext \
+ conftest$ac_exeext conftest.$ac_ext
+ ;;
+ esac
+ ;;
+ *)
+ enable_linux_futex=no
+ ;;
+esac
+if test x$enable_linux_futex = xyes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_LINUX_FUTEX 1
+_ACEOF
+
+fi
+
# This depends on GLIBCXX CHECK_LINKER_FEATURES, but without it assumes no.
--- libstdc++-v3/libsupc++/guard.cc.jj 2007-12-31 20:55:22.000000000 +0100
+++ libstdc++-v3/libsupc++/guard.cc 2008-01-07 10:20:50.000000000 +0100
@@ -35,12 +35,21 @@
#include <new>
#include <ext/atomicity.h>
#include <ext/concurrence.h>
+#if defined(__GTHREADS) && defined(__GTHREAD_HAS_COND) \
+ && defined(_GLIBCXX_ATOMIC_BUILTINS) && defined(_GLIBCXX_HAVE_LINUX_FUTEX)
+# include <climits>
+# include <syscall.h>
+# define _GLIBCXX_USE_FUTEX
+# define _GLIBCXX_FUTEX_WAIT 0
+# define _GLIBCXX_FUTEX_WAKE 1
+#endif
// The IA64/generic ABI uses the first byte of the guard variable.
// The ARM EABI uses the least significant bit.
// Thread-safe static local initialization support.
#ifdef __GTHREADS
+# ifndef _GLIBCXX_USE_FUTEX
namespace
{
// A single mutex controlling all static initializations.
@@ -75,8 +84,9 @@ namespace
}
};
}
+# endif
-#ifdef __GTHREAD_HAS_COND
+# if defined(__GTHREAD_HAS_COND) && !defined(_GLIBCXX_USE_FUTEX)
namespace
{
// A single conditional variable controlling all static initializations.
@@ -98,9 +108,9 @@ namespace
return *static_cond;
}
}
-#endif
+# endif
-#ifndef _GLIBCXX_GUARD_TEST_AND_ACQUIRE
+# ifndef _GLIBCXX_GUARD_TEST_AND_ACQUIRE
inline bool
__test_and_acquire (__cxxabiv1::__guard *g)
{
@@ -108,24 +118,24 @@ __test_and_acquire (__cxxabiv1::__guard
_GLIBCXX_READ_MEM_BARRIER;
return b;
}
-#define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __test_and_acquire (G)
-#endif
+# define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __test_and_acquire (G)
+# endif
-#ifndef _GLIBCXX_GUARD_SET_AND_RELEASE
+# ifndef _GLIBCXX_GUARD_SET_AND_RELEASE
inline void
__set_and_release (__cxxabiv1::__guard *g)
{
_GLIBCXX_WRITE_MEM_BARRIER;
_GLIBCXX_GUARD_SET (g);
}
-#define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __set_and_release (G)
-#endif
+# define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __set_and_release (G)
+# endif
#else /* !__GTHREADS */
-#undef _GLIBCXX_GUARD_TEST_AND_ACQUIRE
-#undef _GLIBCXX_GUARD_SET_AND_RELEASE
-#define _GLIBCXX_GUARD_SET_AND_RELEASE(G) _GLIBCXX_GUARD_SET (G)
+# undef _GLIBCXX_GUARD_TEST_AND_ACQUIRE
+# undef _GLIBCXX_GUARD_SET_AND_RELEASE
+# define _GLIBCXX_GUARD_SET_AND_RELEASE(G) _GLIBCXX_GUARD_SET (G)
#endif /* __GTHREADS */
@@ -176,8 +186,35 @@ namespace __gnu_cxx
// headers define a symbol __GTHREAD_HAS_COND for platforms that support POSIX
// like conditional variables. For platforms that do not support conditional
// variables, we need to fall back to the old code.
+
+// If _GLIBCXX_USE_FUTEX, no global mutex or conditional variable is used,
+// only atomic operations are used together with futex syscall.
+// Valid values of the first integer in guard are:
+// 0 No thread encountered the guarded init
+// yet or it has been aborted.
+// _GLIBCXX_GUARD_BIT The guarded static var has been successfully
+// initialized.
+// _GLIBCXX_GUARD_PENDING_BIT The guarded static var is being initialized
+// and no other thread is waiting for its
+// initialization.
+// (_GLIBCXX_GUARD_PENDING_BIT The guarded static var is being initialized
+// | _GLIBCXX_GUARD_WAITING_BIT) and some other threads are waiting until
+// it is initialized.
+
namespace __cxxabiv1
{
+#ifdef _GLIBCXX_USE_FUTEX
+ namespace
+ {
+ static inline int __guard_test_bit (const int __byte, const int __val)
+ {
+ union { int __i; char __c[sizeof (int)]; } __u = { 0 };
+ __u.__c[__byte] = __val;
+ return __u.__i;
+ }
+ }
+#endif
+
static inline int
init_in_progress_flag(__guard* g)
{ return ((char *)g)[1]; }
@@ -207,7 +244,7 @@ namespace __cxxabiv1
return 0;
if (init_in_progress_flag(g))
- throw_recursive_init_exception();
+ throw_recursive_init_exception();
set_init_in_progress_flag(g, 1);
return 1;
@@ -223,14 +260,46 @@ namespace __cxxabiv1
if (_GLIBCXX_GUARD_TEST_AND_ACQUIRE (g))
return 0;
+# ifdef _GLIBCXX_USE_FUTEX
+ // If __sync_* and futex syscall are supported, don't use any global
+ // mutex.
+ if (__gthread_active_p ())
+ {
+ int *gi = (int *) (void *) g;
+ const int guard_bit = _GLIBCXX_GUARD_BIT;
+ const int pending_bit = _GLIBCXX_GUARD_PENDING_BIT;
+ const int waiting_bit = _GLIBCXX_GUARD_WAITING_BIT;
+
+ while (1)
+ {
+ int old = __sync_val_compare_and_swap (gi, 0, pending_bit);
+ if (old == 0)
+ return 1; // This thread should do the initialization.
+
+ if (old == guard_bit)
+ return 0; // Already initialized.
+
+ if (old == pending_bit)
+ {
+ int newv = old | waiting_bit;
+ if (__sync_val_compare_and_swap (gi, old, newv) != old)
+ continue;
+
+ old = newv;
+ }
+
+ syscall (SYS_futex, gi, _GLIBCXX_FUTEX_WAIT, old, 0);
+ }
+ }
+# else
if (__gthread_active_p ())
{
mutex_wrapper mw;
while (1) // When this loop is executing, mutex is locked.
{
-#ifdef __GTHREAD_HAS_COND
- // The static is allready initialized.
+# ifdef __GTHREAD_HAS_COND
+ // The static is already initialized.
if (_GLIBCXX_GUARD_TEST(g))
return 0; // The mutex will be unlocked via wrapper
@@ -247,7 +316,7 @@ namespace __cxxabiv1
set_init_in_progress_flag(g, 1);
return 1; // The mutex will be unlocked via wrapper.
}
-#else
+# else
// This provides compatibility with older systems not supporting
// POSIX like conditional variables.
if (acquire(g))
@@ -256,9 +325,10 @@ namespace __cxxabiv1
return 1; // The mutex still locked.
}
return 0; // The mutex will be unlocked via wrapper.
-#endif
+# endif
}
}
+# endif
#endif
return acquire (g);
@@ -267,7 +337,20 @@ namespace __cxxabiv1
extern "C"
void __cxa_guard_abort (__guard *g)
{
-#ifdef __GTHREAD_HAS_COND
+#ifdef _GLIBCXX_USE_FUTEX
+ // If __sync_* and futex syscall are supported, don't use any global
+ // mutex.
+ if (__gthread_active_p ())
+ {
+ int *gi = (int *) (void *) g;
+ const int waiting_bit = _GLIBCXX_GUARD_WAITING_BIT;
+ int old = __sync_lock_test_and_set (gi, 0);
+
+ if ((old & waiting_bit) != 0)
+ syscall (SYS_futex, gi, _GLIBCXX_FUTEX_WAKE, INT_MAX);
+ return;
+ }
+#elif defined(__GTHREAD_HAS_COND)
if (__gthread_active_p())
{
mutex_wrapper mw;
@@ -293,7 +376,21 @@ namespace __cxxabiv1
extern "C"
void __cxa_guard_release (__guard *g)
{
-#ifdef __GTHREAD_HAS_COND
+#ifdef _GLIBCXX_USE_FUTEX
+ // If __sync_* and futex syscall are supported, don't use any global
+ // mutex.
+ if (__gthread_active_p ())
+ {
+ int *gi = (int *) (void *) g;
+ const int guard_bit = _GLIBCXX_GUARD_BIT;
+ const int waiting_bit = _GLIBCXX_GUARD_WAITING_BIT;
+ int old = __sync_lock_test_and_set (gi, guard_bit);
+
+ if ((old & waiting_bit) != 0)
+ syscall (SYS_futex, gi, _GLIBCXX_FUTEX_WAKE, INT_MAX);
+ return;
+ }
+#elif defined(__GTHREAD_HAS_COND)
if (__gthread_active_p())
{
mutex_wrapper mw;
--- libstdc++-v3/Makefile.in.jj 2007-09-14 11:54:41.000000000 +0200
+++ libstdc++-v3/Makefile.in 2008-01-07 11:06:44.000000000 +0100
@@ -54,6 +54,7 @@ am__aclocal_m4_deps = $(top_srcdir)/../c
$(top_srcdir)/../config/multi.m4 \
$(top_srcdir)/../config/no-executables.m4 \
$(top_srcdir)/../config/unwind_ipinfo.m4 \
+ $(top_srcdir)/../config/futex.m4 \
$(top_srcdir)/../libtool.m4 $(top_srcdir)/../ltoptions.m4 \
$(top_srcdir)/../ltsugar.m4 $(top_srcdir)/../ltversion.m4 \
$(top_srcdir)/crossconfig.m4 $(top_srcdir)/linkage.m4 \
--- libstdc++-v3/aclocal.m4.jj 2007-05-30 14:54:59.000000000 +0200
+++ libstdc++-v3/aclocal.m4 2008-01-07 11:01:36.000000000 +0100
@@ -589,6 +589,7 @@ m4_include([../config/lib-prefix.m4])
m4_include([../config/multi.m4])
m4_include([../config/no-executables.m4])
m4_include([../config/unwind_ipinfo.m4])
+m4_include([../config/futex.m4])
m4_include([../libtool.m4])
m4_include([../ltoptions.m4])
m4_include([../ltsugar.m4])
--- libstdc++-v3/config.h.in.jj 2007-10-19 14:39:59.000000000 +0200
+++ libstdc++-v3/config.h.in 2008-01-07 11:11:03.000000000 +0100
@@ -232,6 +232,9 @@
/* Only used in build directory testsuite_hooks.h. */
#undef HAVE_LIMIT_VMEM
+/* Define if futex syscall is available. */
+#undef HAVE_LINUX_FUTEX
+
/* Define to 1 if you have the <locale.h> header file. */
#undef HAVE_LOCALE_H
Jakub