* [PATCH, libgfortran] Replace sync builtins with atomic builtins
@ 2018-11-09 11:13 Janne Blomqvist
2018-11-09 20:56 ` Jakub Jelinek
0 siblings, 1 reply; 5+ messages in thread
From: Janne Blomqvist @ 2018-11-09 11:13 UTC (permalink / raw)
To: fortran, gcc-patches; +Cc: Janne Blomqvist
The old __sync builtins have been deprecated for a long time now in
favor of the __atomic builtins following the C++11/C11 memory model.
This patch converts libgfortran to use the modern __atomic builtins.
At the same time I weakened the consistency to acquire-release as that
should be enough for this particular case. Jakub, as the original
author of the algorithm, do you concur?
Regtested on x86_64-pc-linux-gnu, Ok for trunk?
libgfortran/ChangeLog:
2018-11-09 Janne Blomqvist <jb@gcc.gnu.org>
* acinclude.m4 (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Rename and test
presence of atomic builtins instead of sync builtins.
* configure.ac (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Call new test.
* io/io.h (inc_waiting_locked): Use __atomic_fetch_add.
(predec_waiting_locked): Use __atomic_add_fetch.
(dec_waiting_unlocked): Use __atomic_fetch_add.
* config.h.in: Regenerated.
* configure: Regenerated.
---
libgfortran/acinclude.m4 | 20 ++++++++++----------
libgfortran/configure.ac | 4 ++--
libgfortran/io/io.h | 12 ++++++------
3 files changed, 18 insertions(+), 18 deletions(-)
diff --git a/libgfortran/acinclude.m4 b/libgfortran/acinclude.m4
index dd5429ac0d2..5b0c094e716 100644
--- a/libgfortran/acinclude.m4
+++ b/libgfortran/acinclude.m4
@@ -59,17 +59,17 @@ extern void bar(void) __attribute__((alias("foo")));]],
[Define to 1 if the target supports __attribute__((alias(...))).])
fi])
-dnl Check whether the target supports __sync_fetch_and_add.
-AC_DEFUN([LIBGFOR_CHECK_SYNC_FETCH_AND_ADD], [
- AC_CACHE_CHECK([whether the target supports __sync_fetch_and_add],
- libgfor_cv_have_sync_fetch_and_add, [
+dnl Check whether the target supports __atomic_fetch_add.
+AC_DEFUN([LIBGFOR_CHECK_ATOMIC_FETCH_ADD], [
+ AC_CACHE_CHECK([whether the target supports __atomic_fetch_add],
+ libgfor_cv_have_atomic_fetch_add, [
AC_LINK_IFELSE([AC_LANG_PROGRAM([[int foovar = 0;]], [[
-if (foovar <= 0) return __sync_fetch_and_add (&foovar, 1);
-if (foovar > 10) return __sync_add_and_fetch (&foovar, -1);]])],
- libgfor_cv_have_sync_fetch_and_add=yes, libgfor_cv_have_sync_fetch_and_add=no)])
- if test $libgfor_cv_have_sync_fetch_and_add = yes; then
- AC_DEFINE(HAVE_SYNC_FETCH_AND_ADD, 1,
- [Define to 1 if the target supports __sync_fetch_and_add])
+if (foovar <= 0) return __atomic_fetch_add (&foovar, 1, __ATOMIC_ACQ_REL);
+if (foovar > 10) return __atomic_add_fetch (&foovar, -1, __ATOMIC_ACQ_REL);]])],
+ libgfor_cv_have_atomic_fetch_add=yes, libgfor_cv_have_atomic_fetch_add=no)])
+ if test $libgfor_cv_have_atomic_fetch_add = yes; then
+ AC_DEFINE(HAVE_ATOMIC_FETCH_ADD, 1,
+ [Define to 1 if the target supports __atomic_fetch_add])
fi])
dnl Check for pragma weak.
diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
index 76007d38f6f..30ff8734760 100644
--- a/libgfortran/configure.ac
+++ b/libgfortran/configure.ac
@@ -608,8 +608,8 @@ fi
LIBGFOR_CHECK_ATTRIBUTE_VISIBILITY
LIBGFOR_CHECK_ATTRIBUTE_ALIAS
-# Check out sync builtins support.
-LIBGFOR_CHECK_SYNC_FETCH_AND_ADD
+# Check out atomic builtins support.
+LIBGFOR_CHECK_ATOMIC_FETCH_ADD
# Check out #pragma weak.
LIBGFOR_GTHREAD_WEAK
diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
index 902eb412848..36245cbff1f 100644
--- a/libgfortran/io/io.h
+++ b/libgfortran/io/io.h
@@ -961,8 +961,8 @@ internal_proto(free_ionml);
static inline void
inc_waiting_locked (gfc_unit *u)
{
-#ifdef HAVE_SYNC_FETCH_AND_ADD
- (void) __sync_fetch_and_add (&u->waiting, 1);
+#ifdef HAVE_ATOMIC_FETCH_ADD
+ (void) __atomic_fetch_add (&u->waiting, 1, __ATOMIC_ACQ_REL);
#else
u->waiting++;
#endif
@@ -971,8 +971,8 @@ inc_waiting_locked (gfc_unit *u)
static inline int
predec_waiting_locked (gfc_unit *u)
{
-#ifdef HAVE_SYNC_FETCH_AND_ADD
- return __sync_add_and_fetch (&u->waiting, -1);
+#ifdef HAVE_ATOMIC_FETCH_ADD
+ return __atomic_add_fetch (&u->waiting, -1, __ATOMIC_ACQ_REL);
#else
return --u->waiting;
#endif
@@ -981,8 +981,8 @@ predec_waiting_locked (gfc_unit *u)
static inline void
dec_waiting_unlocked (gfc_unit *u)
{
-#ifdef HAVE_SYNC_FETCH_AND_ADD
- (void) __sync_fetch_and_add (&u->waiting, -1);
+#ifdef HAVE_ATOMIC_FETCH_ADD
+ (void) __atomic_fetch_add (&u->waiting, -1, __ATOMIC_ACQ_REL);
#else
__gthread_mutex_lock (&unit_lock);
u->waiting--;
--
2.17.1
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH, libgfortran] Replace sync builtins with atomic builtins
2018-11-09 11:13 [PATCH, libgfortran] Replace sync builtins with atomic builtins Janne Blomqvist
@ 2018-11-09 20:56 ` Jakub Jelinek
2018-11-12 14:05 ` [PATCH] " Janne Blomqvist
0 siblings, 1 reply; 5+ messages in thread
From: Jakub Jelinek @ 2018-11-09 20:56 UTC (permalink / raw)
To: Janne Blomqvist; +Cc: fortran, gcc-patches
On Fri, Nov 09, 2018 at 01:13:28PM +0200, Janne Blomqvist wrote:
> The old __sync builtins have been deprecated for a long time now in
> favor of the __atomic builtins following the C++11/C11 memory model.
> This patch converts libgfortran to use the modern __atomic builtins.
>
> At the same time I weakened the consistency to acquire-release as that
> should be enough for this particular case. Jakub, as the original
> author of the algorithm, do you concur?
As mentioned on IRC, I think this could use just __ATOMIC_RELAXED,
but am not 100% sure.
> 2018-11-09 Janne Blomqvist <jb@gcc.gnu.org>
>
> * acinclude.m4 (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Rename and test
> presence of atomic builtins instead of sync builtins.
> * configure.ac (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Call new test.
> * io/io.h (inc_waiting_locked): Use __atomic_fetch_add.
> (predec_waiting_locked): Use __atomic_add_fetch.
> (dec_waiting_unlocked): Use __atomic_fetch_add.
> * config.h.in: Regenerated.
> * configure: Regenerated.
Jakub
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH] Replace sync builtins with atomic builtins
2018-11-09 20:56 ` Jakub Jelinek
@ 2018-11-12 14:05 ` Janne Blomqvist
2018-11-19 7:38 ` Janne Blomqvist
0 siblings, 1 reply; 5+ messages in thread
From: Janne Blomqvist @ 2018-11-12 14:05 UTC (permalink / raw)
To: fortran, gcc-patches; +Cc: Janne Blomqvist
The old __sync builtins have been deprecated for a long time now in
favor of the __atomic builtins following the C++11/C11 memory model.
This patch converts libgfortran to use the modern __atomic builtins.
At the same time I weakened the consistency to relaxed for
incrementing and decrementing the counter, and acquire-release when
decrementing to check whether the counter is 0 and the unit can be
freed. This is similar to e.g. std::shared_ptr in C++. Jakub, as the
original author of the algorithm, do you concur?
Regtested on x86_64-pc-linux-gnu, Ok for trunk?
libgfortran/ChangeLog:
2018-11-12 Janne Blomqvist <jb@gcc.gnu.org>
* acinclude.m4 (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Rename and test
presence of atomic builtins instead of sync builtins.
* configure.ac (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Call new test.
* io/io.h (inc_waiting_locked): Use __atomic_fetch_add.
(predec_waiting_locked): Use __atomic_add_fetch.
(dec_waiting_unlocked): Use __atomic_fetch_add.
* config.h.in: Regenerated.
* configure: Regenerated.
---
libgfortran/acinclude.m4 | 20 ++++++++++----------
libgfortran/configure.ac | 4 ++--
libgfortran/io/io.h | 24 ++++++++++++++++++------
3 files changed, 30 insertions(+), 18 deletions(-)
diff --git a/libgfortran/acinclude.m4 b/libgfortran/acinclude.m4
index dd5429ac0d2..5b0c094e716 100644
--- a/libgfortran/acinclude.m4
+++ b/libgfortran/acinclude.m4
@@ -59,17 +59,17 @@ extern void bar(void) __attribute__((alias("foo")));]],
[Define to 1 if the target supports __attribute__((alias(...))).])
fi])
-dnl Check whether the target supports __sync_fetch_and_add.
-AC_DEFUN([LIBGFOR_CHECK_SYNC_FETCH_AND_ADD], [
- AC_CACHE_CHECK([whether the target supports __sync_fetch_and_add],
- libgfor_cv_have_sync_fetch_and_add, [
+dnl Check whether the target supports __atomic_fetch_add.
+AC_DEFUN([LIBGFOR_CHECK_ATOMIC_FETCH_ADD], [
+ AC_CACHE_CHECK([whether the target supports __atomic_fetch_add],
+ libgfor_cv_have_atomic_fetch_add, [
AC_LINK_IFELSE([AC_LANG_PROGRAM([[int foovar = 0;]], [[
-if (foovar <= 0) return __sync_fetch_and_add (&foovar, 1);
-if (foovar > 10) return __sync_add_and_fetch (&foovar, -1);]])],
- libgfor_cv_have_sync_fetch_and_add=yes, libgfor_cv_have_sync_fetch_and_add=no)])
- if test $libgfor_cv_have_sync_fetch_and_add = yes; then
- AC_DEFINE(HAVE_SYNC_FETCH_AND_ADD, 1,
- [Define to 1 if the target supports __sync_fetch_and_add])
+if (foovar <= 0) return __atomic_fetch_add (&foovar, 1, __ATOMIC_ACQ_REL);
+if (foovar > 10) return __atomic_add_fetch (&foovar, -1, __ATOMIC_ACQ_REL);]])],
+ libgfor_cv_have_atomic_fetch_add=yes, libgfor_cv_have_atomic_fetch_add=no)])
+ if test $libgfor_cv_have_atomic_fetch_add = yes; then
+ AC_DEFINE(HAVE_ATOMIC_FETCH_ADD, 1,
+ [Define to 1 if the target supports __atomic_fetch_add])
fi])
dnl Check for pragma weak.
diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
index 76007d38f6f..30ff8734760 100644
--- a/libgfortran/configure.ac
+++ b/libgfortran/configure.ac
@@ -608,8 +608,8 @@ fi
LIBGFOR_CHECK_ATTRIBUTE_VISIBILITY
LIBGFOR_CHECK_ATTRIBUTE_ALIAS
-# Check out sync builtins support.
-LIBGFOR_CHECK_SYNC_FETCH_AND_ADD
+# Check out atomic builtins support.
+LIBGFOR_CHECK_ATOMIC_FETCH_ADD
# Check out #pragma weak.
LIBGFOR_GTHREAD_WEAK
diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
index 902eb412848..282c1455763 100644
--- a/libgfortran/io/io.h
+++ b/libgfortran/io/io.h
@@ -961,8 +961,8 @@ internal_proto(free_ionml);
static inline void
inc_waiting_locked (gfc_unit *u)
{
-#ifdef HAVE_SYNC_FETCH_AND_ADD
- (void) __sync_fetch_and_add (&u->waiting, 1);
+#ifdef HAVE_ATOMIC_FETCH_ADD
+ (void) __atomic_fetch_add (&u->waiting, 1, __ATOMIC_RELAXED);
#else
u->waiting++;
#endif
@@ -971,8 +971,20 @@ inc_waiting_locked (gfc_unit *u)
static inline int
predec_waiting_locked (gfc_unit *u)
{
-#ifdef HAVE_SYNC_FETCH_AND_ADD
- return __sync_add_and_fetch (&u->waiting, -1);
+#ifdef HAVE_ATOMIC_FETCH_ADD
+ /* Note that the pattern
+
+ if (predec_waiting_locked (u) == 0)
+ // destroy u
+
+ could be further optimized by making this be an __ATOMIC_RELEASE,
+ and then inserting a
+
+ __atomic_thread_fence (__ATOMIC_ACQUIRE);
+
+ inside the branch before destroying. But for now, lets keep it
+ simple. */
+ return __atomic_add_fetch (&u->waiting, -1, __ATOMIC_ACQ_REL);
#else
return --u->waiting;
#endif
@@ -981,8 +993,8 @@ predec_waiting_locked (gfc_unit *u)
static inline void
dec_waiting_unlocked (gfc_unit *u)
{
-#ifdef HAVE_SYNC_FETCH_AND_ADD
- (void) __sync_fetch_and_add (&u->waiting, -1);
+#ifdef HAVE_ATOMIC_FETCH_ADD
+ (void) __atomic_fetch_add (&u->waiting, -1, __ATOMIC_RELAXED);
#else
__gthread_mutex_lock (&unit_lock);
u->waiting--;
--
2.17.1
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH] Replace sync builtins with atomic builtins
2018-11-12 14:05 ` [PATCH] " Janne Blomqvist
@ 2018-11-19 7:38 ` Janne Blomqvist
2018-11-21 19:31 ` Thomas Koenig
0 siblings, 1 reply; 5+ messages in thread
From: Janne Blomqvist @ 2018-11-19 7:38 UTC (permalink / raw)
To: Fortran List, GCC Patches
PING!
On Mon, Nov 12, 2018 at 4:05 PM Janne Blomqvist <blomqvist.janne@gmail.com>
wrote:
> The old __sync builtins have been deprecated for a long time now in
> favor of the __atomic builtins following the C++11/C11 memory model.
> This patch converts libgfortran to use the modern __atomic builtins.
>
> At the same time I weakened the consistency to relaxed for
> incrementing and decrementing the counter, and acquire-release when
> decrementing to check whether the counter is 0 and the unit can be
> freed. This is similar to e.g. std::shared_ptr in C++. Jakub, as the
> original author of the algorithm, do you concur?
>
> Regtested on x86_64-pc-linux-gnu, Ok for trunk?
>
> libgfortran/ChangeLog:
>
> 2018-11-12 Janne Blomqvist <jb@gcc.gnu.org>
>
> * acinclude.m4 (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Rename and test
> presence of atomic builtins instead of sync builtins.
> * configure.ac (LIBGFOR_CHECK_ATOMIC_FETCH_ADD): Call new test.
> * io/io.h (inc_waiting_locked): Use __atomic_fetch_add.
> (predec_waiting_locked): Use __atomic_add_fetch.
> (dec_waiting_unlocked): Use __atomic_fetch_add.
> * config.h.in: Regenerated.
> * configure: Regenerated.
> ---
> libgfortran/acinclude.m4 | 20 ++++++++++----------
> libgfortran/configure.ac | 4 ++--
> libgfortran/io/io.h | 24 ++++++++++++++++++------
> 3 files changed, 30 insertions(+), 18 deletions(-)
>
> diff --git a/libgfortran/acinclude.m4 b/libgfortran/acinclude.m4
> index dd5429ac0d2..5b0c094e716 100644
> --- a/libgfortran/acinclude.m4
> +++ b/libgfortran/acinclude.m4
> @@ -59,17 +59,17 @@ extern void bar(void) __attribute__((alias("foo")));]],
> [Define to 1 if the target supports __attribute__((alias(...))).])
> fi])
>
> -dnl Check whether the target supports __sync_fetch_and_add.
> -AC_DEFUN([LIBGFOR_CHECK_SYNC_FETCH_AND_ADD], [
> - AC_CACHE_CHECK([whether the target supports __sync_fetch_and_add],
> - libgfor_cv_have_sync_fetch_and_add, [
> +dnl Check whether the target supports __atomic_fetch_add.
> +AC_DEFUN([LIBGFOR_CHECK_ATOMIC_FETCH_ADD], [
> + AC_CACHE_CHECK([whether the target supports __atomic_fetch_add],
> + libgfor_cv_have_atomic_fetch_add, [
> AC_LINK_IFELSE([AC_LANG_PROGRAM([[int foovar = 0;]], [[
> -if (foovar <= 0) return __sync_fetch_and_add (&foovar, 1);
> -if (foovar > 10) return __sync_add_and_fetch (&foovar, -1);]])],
> - libgfor_cv_have_sync_fetch_and_add=yes,
> libgfor_cv_have_sync_fetch_and_add=no)])
> - if test $libgfor_cv_have_sync_fetch_and_add = yes; then
> - AC_DEFINE(HAVE_SYNC_FETCH_AND_ADD, 1,
> - [Define to 1 if the target supports __sync_fetch_and_add])
> +if (foovar <= 0) return __atomic_fetch_add (&foovar, 1, __ATOMIC_ACQ_REL);
> +if (foovar > 10) return __atomic_add_fetch (&foovar, -1,
> __ATOMIC_ACQ_REL);]])],
> + libgfor_cv_have_atomic_fetch_add=yes,
> libgfor_cv_have_atomic_fetch_add=no)])
> + if test $libgfor_cv_have_atomic_fetch_add = yes; then
> + AC_DEFINE(HAVE_ATOMIC_FETCH_ADD, 1,
> + [Define to 1 if the target supports __atomic_fetch_add])
> fi])
>
> dnl Check for pragma weak.
> diff --git a/libgfortran/configure.ac b/libgfortran/configure.ac
> index 76007d38f6f..30ff8734760 100644
> --- a/libgfortran/configure.ac
> +++ b/libgfortran/configure.ac
> @@ -608,8 +608,8 @@ fi
> LIBGFOR_CHECK_ATTRIBUTE_VISIBILITY
> LIBGFOR_CHECK_ATTRIBUTE_ALIAS
>
> -# Check out sync builtins support.
> -LIBGFOR_CHECK_SYNC_FETCH_AND_ADD
> +# Check out atomic builtins support.
> +LIBGFOR_CHECK_ATOMIC_FETCH_ADD
>
> # Check out #pragma weak.
> LIBGFOR_GTHREAD_WEAK
> diff --git a/libgfortran/io/io.h b/libgfortran/io/io.h
> index 902eb412848..282c1455763 100644
> --- a/libgfortran/io/io.h
> +++ b/libgfortran/io/io.h
> @@ -961,8 +961,8 @@ internal_proto(free_ionml);
> static inline void
> inc_waiting_locked (gfc_unit *u)
> {
> -#ifdef HAVE_SYNC_FETCH_AND_ADD
> - (void) __sync_fetch_and_add (&u->waiting, 1);
> +#ifdef HAVE_ATOMIC_FETCH_ADD
> + (void) __atomic_fetch_add (&u->waiting, 1, __ATOMIC_RELAXED);
> #else
> u->waiting++;
> #endif
> @@ -971,8 +971,20 @@ inc_waiting_locked (gfc_unit *u)
> static inline int
> predec_waiting_locked (gfc_unit *u)
> {
> -#ifdef HAVE_SYNC_FETCH_AND_ADD
> - return __sync_add_and_fetch (&u->waiting, -1);
> +#ifdef HAVE_ATOMIC_FETCH_ADD
> + /* Note that the pattern
> +
> + if (predec_waiting_locked (u) == 0)
> + // destroy u
> +
> + could be further optimized by making this be an __ATOMIC_RELEASE,
> + and then inserting a
> +
> + __atomic_thread_fence (__ATOMIC_ACQUIRE);
> +
> + inside the branch before destroying. But for now, lets keep it
> + simple. */
> + return __atomic_add_fetch (&u->waiting, -1, __ATOMIC_ACQ_REL);
> #else
> return --u->waiting;
> #endif
> @@ -981,8 +993,8 @@ predec_waiting_locked (gfc_unit *u)
> static inline void
> dec_waiting_unlocked (gfc_unit *u)
> {
> -#ifdef HAVE_SYNC_FETCH_AND_ADD
> - (void) __sync_fetch_and_add (&u->waiting, -1);
> +#ifdef HAVE_ATOMIC_FETCH_ADD
> + (void) __atomic_fetch_add (&u->waiting, -1, __ATOMIC_RELAXED);
> #else
> __gthread_mutex_lock (&unit_lock);
> u->waiting--;
> --
> 2.17.1
>
>
--
Janne Blomqvist
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-11-21 19:31 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-11-09 11:13 [PATCH, libgfortran] Replace sync builtins with atomic builtins Janne Blomqvist
2018-11-09 20:56 ` Jakub Jelinek
2018-11-12 14:05 ` [PATCH] " Janne Blomqvist
2018-11-19 7:38 ` Janne Blomqvist
2018-11-21 19:31 ` Thomas Koenig
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).