| // locks.h - Thread synchronization primitives. AArch64 implementation. |
| |
| #ifndef __SYSDEP_LOCKS_H__ |
| #define __SYSDEP_LOCKS_H__ |
| |
| typedef size_t obj_addr_t; /* Integer type big enough for object */ |
| /* address. */ |
| |
| // Atomically replace *addr by new_val if it was initially equal to old. |
| // Return true if the comparison succeeded. |
| // Assumed to have acquire semantics, i.e. later memory operations |
| // cannot execute before the compare_and_swap finishes. |
| inline static bool |
| compare_and_swap(volatile obj_addr_t *addr, |
| obj_addr_t old, |
| obj_addr_t new_val) |
| { |
| return __sync_bool_compare_and_swap(addr, old, new_val); |
| } |
| |
| // Set *addr to new_val with release semantics, i.e. making sure |
| // that prior loads and stores complete before this |
| // assignment. |
| inline static void |
| release_set(volatile obj_addr_t *addr, obj_addr_t new_val) |
| { |
| __sync_synchronize(); |
| *addr = new_val; |
| } |
| |
| // Compare_and_swap with release semantics instead of acquire semantics. |
| // On many architecture, the operation makes both guarantees, so the |
| // implementation can be the same. |
| inline static bool |
| compare_and_swap_release(volatile obj_addr_t *addr, |
| obj_addr_t old, |
| obj_addr_t new_val) |
| { |
| return __sync_bool_compare_and_swap(addr, old, new_val); |
| } |
| |
| // Ensure that subsequent instructions do not execute on stale |
| // data that was loaded from memory before the barrier. |
| inline static void |
| read_barrier() |
| { |
| __sync_synchronize(); |
| } |
| |
| // Ensure that prior stores to memory are completed with respect to other |
| // processors. |
| inline static void |
| write_barrier() |
| { |
| __sync_synchronize(); |
| } |
| #endif |