glib/glib/gatomic.h
Philip Withnall 194df27f5a gatomic: Tweak __atomic_load*() calls to work with -Wbad-function-cast
When compiling third-party projects with -Wbad-function-cast, the inline
g_atomic_pointer_get() implementation which uses C11 __atomic_load*()
calls on GCC was causing compilation errors like:

   error: cast from function call of type ‘long unsigned int’ to non-matching type ‘void *’

While we don’t want to compile all of GLib with -Wbad-function-cast, we
should support its headers being included in projects which do enable
that warning.

It doesn’t seem to be possible to cast away the warning (e.g. by casting
the function’s result through (void)), so we have to assign to an
intermediate integer of the right size first.

The same has to be done for the bool return value from
__sync_bool_compare_and_swap(). In that case, casting from bool to
gboolean raises a -Wbad-function-cast warning, since gboolean is
secretly int.

The atomic tests have been modified to enable -Wbad-function-cast to
catch regressions of this in future. The GLib build has conversely been
modified to set -Wno-bad-function-cast, just in case people have it set
in their environment CFLAGS.

Signed-off-by: Philip Withnall <withnall@endlessm.com>

https://gitlab.gnome.org/GNOME/glib/issues/1041
2018-07-10 17:49:16 +02:00

292 lines
15 KiB
C

/*
* Copyright © 2011 Ryan Lortie
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*
* Author: Ryan Lortie <desrt@desrt.ca>
*/
#ifndef __G_ATOMIC_H__
#define __G_ATOMIC_H__
#if !defined (__GLIB_H_INSIDE__) && !defined (GLIB_COMPILATION)
#error "Only <glib.h> can be included directly."
#endif
#include <glib/gtypes.h>
G_BEGIN_DECLS
GLIB_AVAILABLE_IN_ALL
gint g_atomic_int_get (const volatile gint *atomic);
GLIB_AVAILABLE_IN_ALL
void g_atomic_int_set (volatile gint *atomic,
gint newval);
GLIB_AVAILABLE_IN_ALL
void g_atomic_int_inc (volatile gint *atomic);
GLIB_AVAILABLE_IN_ALL
gboolean g_atomic_int_dec_and_test (volatile gint *atomic);
GLIB_AVAILABLE_IN_ALL
gboolean g_atomic_int_compare_and_exchange (volatile gint *atomic,
gint oldval,
gint newval);
GLIB_AVAILABLE_IN_ALL
gint g_atomic_int_add (volatile gint *atomic,
gint val);
GLIB_AVAILABLE_IN_2_30
guint g_atomic_int_and (volatile guint *atomic,
guint val);
GLIB_AVAILABLE_IN_2_30
guint g_atomic_int_or (volatile guint *atomic,
guint val);
GLIB_AVAILABLE_IN_ALL
guint g_atomic_int_xor (volatile guint *atomic,
guint val);
GLIB_AVAILABLE_IN_ALL
gpointer g_atomic_pointer_get (const volatile void *atomic);
GLIB_AVAILABLE_IN_ALL
void g_atomic_pointer_set (volatile void *atomic,
gpointer newval);
GLIB_AVAILABLE_IN_ALL
gboolean g_atomic_pointer_compare_and_exchange (volatile void *atomic,
gpointer oldval,
gpointer newval);
GLIB_AVAILABLE_IN_ALL
gssize g_atomic_pointer_add (volatile void *atomic,
gssize val);
GLIB_AVAILABLE_IN_2_30
gsize g_atomic_pointer_and (volatile void *atomic,
gsize val);
GLIB_AVAILABLE_IN_2_30
gsize g_atomic_pointer_or (volatile void *atomic,
gsize val);
GLIB_AVAILABLE_IN_ALL
gsize g_atomic_pointer_xor (volatile void *atomic,
gsize val);
GLIB_DEPRECATED_IN_2_30_FOR(g_atomic_int_add)
gint g_atomic_int_exchange_and_add (volatile gint *atomic,
gint val);
G_END_DECLS
#if defined(G_ATOMIC_LOCK_FREE) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
/* We prefer the new C11-style atomic extension of GCC if available */
#if defined(__ATOMIC_SEQ_CST) && !defined(__clang__)
/* This assumes sizeof(int) is 4: gatomic.c statically
* asserts that (using G_STATIC_ASSERT at top-level in a header was
* problematic, see #730932) */
#define g_atomic_int_get(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ *(atomic) : 1); \
(gint) __atomic_load_4 ((atomic), __ATOMIC_SEQ_CST); \
}))
#define g_atomic_int_set(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (newval) : 1); \
__atomic_store_4 ((atomic), (newval), __ATOMIC_SEQ_CST); \
}))
#if GLIB_SIZEOF_VOID_P == 8
#define g_atomic_pointer_get(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
guint64 gapg_temp = __atomic_load_8 ((atomic), __ATOMIC_SEQ_CST); \
(gpointer) gapg_temp; \
}))
#define g_atomic_pointer_set(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
__atomic_store_8 ((atomic), (gsize) (newval), __ATOMIC_SEQ_CST); \
}))
#else /* GLIB_SIZEOF_VOID_P == 8 */
/* This assumes that if sizeof(void *) is not 8, then it is 4:
* gatomic.c statically asserts that (using G_STATIC_ASSERT
* at top-level in a header was problematic, see #730932) */
#define g_atomic_pointer_get(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
guint32 gapg_temp = __atomic_load_4 ((atomic), __ATOMIC_SEQ_CST); \
(gpointer) gapg_temp; \
}))
#define g_atomic_pointer_set(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
__atomic_store_4 ((atomic), (gsize) (newval), __ATOMIC_SEQ_CST); \
}))
#endif /* GLIB_SIZEOF_VOID_P == 8 */
#else /* defined(__ATOMIC_SEQ_CST) */
#define g_atomic_int_get(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ *(atomic) : 1); \
__sync_synchronize (); \
(gint) *(atomic); \
}))
#define g_atomic_int_set(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (newval) : 1); \
*(atomic) = (newval); \
__sync_synchronize (); \
}))
#define g_atomic_pointer_get(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
__sync_synchronize (); \
(gpointer) *(atomic); \
}))
#define g_atomic_pointer_set(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
*(atomic) = (__typeof__ (*(atomic))) (gsize) (newval); \
__sync_synchronize (); \
}))
#endif /* !defined(__ATOMIC_SEQ_CST) */
#define g_atomic_int_inc(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ *(atomic) : 1); \
(void) __sync_fetch_and_add ((atomic), 1); \
}))
#define g_atomic_int_dec_and_test(atomic) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ *(atomic) : 1); \
__sync_fetch_and_sub ((atomic), 1) == 1; \
}))
#define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (newval) ^ (oldval) : 1); \
__sync_bool_compare_and_swap ((atomic), (oldval), (newval)) ? TRUE : FALSE; \
}))
#define g_atomic_int_add(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (val) : 1); \
(gint) __sync_fetch_and_add ((atomic), (val)); \
}))
#define g_atomic_int_and(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (val) : 1); \
(guint) __sync_fetch_and_and ((atomic), (val)); \
}))
#define g_atomic_int_or(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (val) : 1); \
(guint) __sync_fetch_and_or ((atomic), (val)); \
}))
#define g_atomic_int_xor(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (val) : 1); \
(guint) __sync_fetch_and_xor ((atomic), (val)); \
}))
#define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
__sync_bool_compare_and_swap ((atomic), (oldval), (newval)) ? TRUE : FALSE; \
}))
#define g_atomic_pointer_add(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
(void) (0 ? (val) ^ (val) : 1); \
(gssize) __sync_fetch_and_add ((atomic), (val)); \
}))
#define g_atomic_pointer_and(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
(void) (0 ? (val) ^ (val) : 1); \
(gsize) __sync_fetch_and_and ((atomic), (val)); \
}))
#define g_atomic_pointer_or(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
(void) (0 ? (val) ^ (val) : 1); \
(gsize) __sync_fetch_and_or ((atomic), (val)); \
}))
#define g_atomic_pointer_xor(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
(void) (0 ? (val) ^ (val) : 1); \
(gsize) __sync_fetch_and_xor ((atomic), (val)); \
}))
#else /* defined(G_ATOMIC_LOCK_FREE) && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4) */
#define g_atomic_int_get(atomic) \
(g_atomic_int_get ((gint *) (atomic)))
#define g_atomic_int_set(atomic, newval) \
(g_atomic_int_set ((gint *) (atomic), (gint) (newval)))
#define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \
(g_atomic_int_compare_and_exchange ((gint *) (atomic), (oldval), (newval)))
#define g_atomic_int_add(atomic, val) \
(g_atomic_int_add ((gint *) (atomic), (val)))
#define g_atomic_int_and(atomic, val) \
(g_atomic_int_and ((guint *) (atomic), (val)))
#define g_atomic_int_or(atomic, val) \
(g_atomic_int_or ((guint *) (atomic), (val)))
#define g_atomic_int_xor(atomic, val) \
(g_atomic_int_xor ((guint *) (atomic), (val)))
#define g_atomic_int_inc(atomic) \
(g_atomic_int_inc ((gint *) (atomic)))
#define g_atomic_int_dec_and_test(atomic) \
(g_atomic_int_dec_and_test ((gint *) (atomic)))
#define g_atomic_pointer_get(atomic) \
(g_atomic_pointer_get (atomic))
#define g_atomic_pointer_set(atomic, newval) \
(g_atomic_pointer_set ((atomic), (gpointer) (newval)))
#define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
(g_atomic_pointer_compare_and_exchange ((atomic), (gpointer) (oldval), (gpointer) (newval)))
#define g_atomic_pointer_add(atomic, val) \
(g_atomic_pointer_add ((atomic), (gssize) (val)))
#define g_atomic_pointer_and(atomic, val) \
(g_atomic_pointer_and ((atomic), (gsize) (val)))
#define g_atomic_pointer_or(atomic, val) \
(g_atomic_pointer_or ((atomic), (gsize) (val)))
#define g_atomic_pointer_xor(atomic, val) \
(g_atomic_pointer_xor ((atomic), (gsize) (val)))
#endif /* defined(__GNUC__) && defined(G_ATOMIC_OP_USE_GCC_BUILTINS) */
#endif /* __G_ATOMIC_H__ */