configure.ac | 16 ++++++++++++++++
meson-cc-tests/stdatomic-primitives-test.c | 8 ++++++++
meson.build | 4 ++++
src/fcatomic.h | 21 +++++++++++++++++++++
src/fccache.c | 2 +-
5 files changed, 50 insertions(+), 1 deletion(-)
New commits:
commit 012ffaac754543eed1d4f4f5de786626f31d5c36
Author: Alex Richardson <Alexander.Richardson@xxxxxxxxxxxx>
Date: Mon Jul 12 14:57:49 2021 +0100
Add support for C11 stdatomic atomics
This fixes deprecation warnings when building for macOS >= 10.12 systems.
Additionally, using stdatomic.h (or the more modern __atomic_ builtins)
is required when targeting CHERI-enabled architectures such as
CHERI-RISC-V or Arm's Morello since the compiler rejects __sync_* atomic
for pointer types (they only work with integers).
diff --git a/configure.ac b/configure.ac
index 7c1a697..3bbd969 100644
--- a/configure.ac
+++ b/configure.ac
@@ -663,6 +663,22 @@ dnl ===========================================================================
# Thread-safety primitives
#
+AC_CACHE_CHECK([stdatomic.h atomic primitives], fc_cv_have_stdatomic_atomic_primitives, [
+ fc_cv_have_stdatomic_atomic_primitives=false
+ AC_TRY_LINK([
+ #include <stdatomic.h>
+
+ void memory_barrier (void) { atomic_thread_fence (memory_order_acq_rel); }
+ int atomic_add (atomic_int *i) { return atomic_fetch_add_explicit (i, 1, memory_order_relaxed); }
+ int mutex_trylock (atomic_flag *m) { return atomic_flag_test_and_set_explicit (m, memory_order_acquire); }
+ void mutex_unlock (atomic_flag *m) { atomic_flag_clear_explicit (m, memory_order_release); }
+ ], [], fc_cv_have_stdatomic_atomic_primitives=true
+ )
+])
+if $fc_cv_have_stdatomic_atomic_primitives; then
+ AC_DEFINE(HAVE_STDATOMIC_PRIMITIVES, 1, [Have Intel __sync_* atomic primitives])
+fi
+
AC_CACHE_CHECK([for Intel atomic primitives], fc_cv_have_intel_atomic_primitives, [
fc_cv_have_intel_atomic_primitives=false
AC_TRY_LINK([
diff --git a/meson-cc-tests/stdatomic-primitives-test.c b/meson-cc-tests/stdatomic-primitives-test.c
new file mode 100644
index 0000000..6d11d34
--- /dev/null
+++ b/meson-cc-tests/stdatomic-primitives-test.c
@@ -0,0 +1,8 @@
+#include <stdatomic.h>
+
+void memory_barrier (void) { atomic_thread_fence (memory_order_acq_rel); }
+int atomic_add (atomic_int *i) { return atomic_fetch_add_explicit (i, 1, memory_order_relaxed); }
+int mutex_trylock (atomic_flag *m) { return atomic_flag_test_and_set_explicit (m, memory_order_acquire); }
+void mutex_unlock (atomic_flag *m) { atomic_flag_clear_explicit (m, memory_order_release); }
+
+int main(void) { return 0;}
diff --git a/meson.build b/meson.build
index 0ec3dc6..64cae44 100644
--- a/meson.build
+++ b/meson.build
@@ -190,6 +190,10 @@ else
conf.set('FLEXIBLE_ARRAY_MEMBER', 1)
endif
+if cc.links(files('meson-cc-tests/stdatomic-primitives-test.c'), name: 'stdatomic.h atomics')
+ conf.set('HAVE_STDATOMIC_PRIMITIVES', 1)
+endif
+
if cc.links(files('meson-cc-tests/intel-atomic-primitives-test.c'), name: 'Intel atomics')
conf.set('HAVE_INTEL_ATOMIC_PRIMITIVES', 1)
endif
diff --git a/src/fcatomic.h b/src/fcatomic.h
index 9f56b3d..a41b0aa 100644
--- a/src/fcatomic.h
+++ b/src/fcatomic.h
@@ -51,6 +51,25 @@ typedef <type> fc_atomic_int_t;
#define fc_atomic_ptr_cmpexch(P,O,N) *(P) == (O) ? (*(P) = (N), FcTrue) : FcFalse // atomic release
+#elif !defined(FC_NO_MT) && defined(HAVE_STDATOMIC_PRIMITIVES)
+
+#include <stdatomic.h>
+
+typedef atomic_int fc_atomic_int_t;
+#define FC_ATOMIC_INT_FORMAT "d"
+#define fc_atomic_int_add(AI, V) atomic_fetch_add (&(AI), (V))
+
+#define fc_atomic_ptr_get(P) atomic_load ((_Atomic(void *)*) (P))
+static inline FcBool _fc_atomic_ptr_cmpexch(_Atomic(void *)*P, void * O, _Atomic(void *) N) {
+ return atomic_compare_exchange_strong(P, &O, N);
+}
+#define fc_atomic_ptr_cmpexch(P,O,N) _fc_atomic_ptr_cmpexch ((_Atomic(void *)*) (P), (O), (N))
+
+/* Casting -1 to _Atomic(int) produces a compiler error with Clang (but not GCC)
+ * so we have to override FC_REF_CONSTANT_VALUE for stdatomic.h atomics.
+ * See https://bugs.llvm.org/show_bug.cgi?id=40249. */
+#define FC_REF_CONSTANT_VALUE (-1)
+
#elif !defined(FC_NO_MT) && defined(_MSC_VER) || defined(__MINGW32__)
#include "fcwindows.h"
@@ -137,7 +156,9 @@ typedef int fc_atomic_int_t;
#endif
/* reference count */
+#ifndef FC_REF_CONSTANT_VALUE
#define FC_REF_CONSTANT_VALUE ((fc_atomic_int_t) -1)
+#endif
#define FC_REF_CONSTANT {FC_REF_CONSTANT_VALUE}
typedef struct _FcRef { fc_atomic_int_t count; } FcRef;
static inline void FcRefInit (FcRef *r, int v) { r->count = v; }
diff --git a/src/fccache.c b/src/fccache.c
index b2392d3..ae3b9e3 100644
--- a/src/fccache.c
+++ b/src/fccache.c
@@ -135,7 +135,7 @@ FcCacheIsMmapSafe (int fd)
status = use ? MMAP_USE : MMAP_DONT_USE;
else
status = MMAP_CHECK_FS;
- (void) fc_atomic_ptr_cmpexch (&static_status, NULL, (void *) status);
+ (void) fc_atomic_ptr_cmpexch (&static_status, NULL, (void *) (intptr_t) status);
}
if (status == MMAP_CHECK_FS)
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