diff options
author | James Almer <jamrial@gmail.com> | 2014-10-27 22:48:08 -0300 |
---|---|---|
committer | James Almer <jamrial@gmail.com> | 2014-10-29 14:09:58 -0300 |
commit | faa9d2982969c999ab0e443a226eff116f7f8e4b (patch) | |
tree | b0b06cfff37c8d773202dfde877201e0129cf3cd | |
parent | 931da6a5e9dd54563fe5d4d30b7bd4d0a0218c87 (diff) |
lavu/atomic: add support for the new memory model aware gcc built-ins
__sync built-ins are considered legacy and will be deprecated.
These new memory model aware built-ins have been available since GCC 4.7.0
Use them by default when available except for __atomic_compare_exchange_n(),
which is slower, and is instead implemented as a fallback for when and if gcc
removes the legacy __sync built-ins.
Reviewed-by: Michael Niedermayer <michaelni@gmx.at>
Signed-off-by: James Almer <jamrial@gmail.com>
-rwxr-xr-x | configure | 4 | ||||
-rw-r--r-- | libavutil/atomic_gcc.h | 17 |
2 files changed, 20 insertions, 1 deletions
@@ -1602,6 +1602,7 @@ ARCH_FEATURES=" BUILTIN_LIST=" atomic_cas_ptr + atomic_compare_exchange machine_rw_barrier MemoryBarrier mm_empty @@ -2028,7 +2029,7 @@ simd_align_16_if_any="altivec neon sse" symver_if_any="symver_asm_label symver_gnu_asm" # threading support -atomics_gcc_if="sync_val_compare_and_swap" +atomics_gcc_if_any="sync_val_compare_and_swap atomic_compare_exchange" atomics_suncc_if="atomic_cas_ptr machine_rw_barrier" atomics_win32_if="MemoryBarrier" atomics_native_if_any="$ATOMICS_LIST" @@ -4681,6 +4682,7 @@ if ! disabled network; then fi check_builtin atomic_cas_ptr atomic.h "void **ptr; void *oldval, *newval; atomic_cas_ptr(ptr, oldval, newval)" +check_builtin atomic_compare_exchange "" "int *ptr, *oldval; int newval; __atomic_compare_exchange_n(ptr, oldval, newval, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)" check_builtin machine_rw_barrier mbarrier.h "__machine_rw_barrier()" check_builtin MemoryBarrier windows.h "MemoryBarrier()" check_builtin sarestart signal.h "SA_RESTART" diff --git a/libavutil/atomic_gcc.h b/libavutil/atomic_gcc.h index 2bb43c3cea..5f9fc49ba0 100644 --- a/libavutil/atomic_gcc.h +++ b/libavutil/atomic_gcc.h @@ -28,27 +28,40 @@ #define avpriv_atomic_int_get atomic_int_get_gcc static inline int atomic_int_get_gcc(volatile int *ptr) { +#if HAVE_ATOMIC_COMPARE_EXCHANGE + return __atomic_load_n(ptr, __ATOMIC_SEQ_CST); +#else __sync_synchronize(); return *ptr; +#endif } #define avpriv_atomic_int_set atomic_int_set_gcc static inline void atomic_int_set_gcc(volatile int *ptr, int val) { +#if HAVE_ATOMIC_COMPARE_EXCHANGE + __atomic_store_n(ptr, val, __ATOMIC_SEQ_CST); +#else *ptr = val; __sync_synchronize(); +#endif } #define avpriv_atomic_int_add_and_fetch atomic_int_add_and_fetch_gcc static inline int atomic_int_add_and_fetch_gcc(volatile int *ptr, int inc) { +#if HAVE_ATOMIC_COMPARE_EXCHANGE + return __atomic_add_fetch(ptr, inc, __ATOMIC_SEQ_CST); +#else return __sync_add_and_fetch(ptr, inc); +#endif } #define avpriv_atomic_ptr_cas atomic_ptr_cas_gcc static inline void *atomic_ptr_cas_gcc(void * volatile *ptr, void *oldval, void *newval) { +#if HAVE_SYNC_VAL_COMPARE_AND_SWAP #ifdef __ARMCC_VERSION // armcc will throw an error if ptr is not an integer type volatile uintptr_t *tmp = (volatile uintptr_t*)ptr; @@ -56,6 +69,10 @@ static inline void *atomic_ptr_cas_gcc(void * volatile *ptr, #else return __sync_val_compare_and_swap(ptr, oldval, newval); #endif +#else + __atomic_compare_exchange_n(ptr, &oldval, newval, 0, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST); + return oldval; +#endif } #endif /* AVUTIL_ATOMIC_GCC_H */ |