diff options
Diffstat (limited to 'libc/sysdeps')
| -rw-r--r-- | libc/sysdeps/linux/arm/bits/atomic.h | 25 |
1 files changed, 17 insertions, 8 deletions
diff --git a/libc/sysdeps/linux/arm/bits/atomic.h b/libc/sysdeps/linux/arm/bits/atomic.h index 8f63e2510..07101fbe8 100644 --- a/libc/sysdeps/linux/arm/bits/atomic.h +++ b/libc/sysdeps/linux/arm/bits/atomic.h @@ -37,7 +37,12 @@ typedef uintmax_t uatomic_max_t; void __arm_link_error (void); -#ifdef __thumb2__ +/* Use the atomic builtins provided by GCC in case the backend provides + a pattern to do this efficiently. */ + +#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 +#define atomic_full_barrier() __sync_synchronize () +#elif defined __thumb2__ #define atomic_full_barrier() \ __asm__ __volatile__ \ ("movw\tip, #0x0fa0\n\t" \ @@ -64,17 +69,21 @@ void __arm_link_error (void); #define __arch_compare_and_exchange_val_16_acq(mem, newval, oldval) \ ({ __arm_link_error (); oldval; }) +#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 +#define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \ + __sync_val_compare_and_swap ((mem), (oldval), (newval)) + /* It doesn't matter what register is used for a_oldval2, but we must specify one to work around GCC PR rtl-optimization/21223. Otherwise it may cause a_oldval or a_tmp to be moved to a different register. */ -#ifdef __thumb2__ +#elif defined __thumb2__ /* Thumb-2 has ldrex/strex. However it does not have barrier instructions, so we still need to use the kernel helper. */ #define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \ - ({ register __typeof (oldval) a_oldval __asm__ ("r0"); \ - register __typeof (oldval) a_newval __asm__ ("r1") = (newval); \ - register __typeof (mem) a_ptr __asm__ ("r2") = (mem); \ + ({ register __typeof (oldval) a_oldval __asm__ ("r0"); \ + register __typeof (oldval) a_newval __asm__ ("r1") = (newval); \ + register __typeof (mem) a_ptr __asm__ ("r2") = (mem); \ register __typeof (oldval) a_tmp __asm__ ("r3"); \ register __typeof (oldval) a_oldval2 __asm__ ("r4") = (oldval); \ __asm__ __volatile__ \ @@ -95,9 +104,9 @@ void __arm_link_error (void); a_tmp; }) #else #define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \ - ({ register __typeof (oldval) a_oldval __asm__ ("r0"); \ - register __typeof (oldval) a_newval __asm__ ("r1") = (newval); \ - register __typeof (mem) a_ptr __asm__ ("r2") = (mem); \ + ({ register __typeof (oldval) a_oldval __asm__ ("r0"); \ + register __typeof (oldval) a_newval __asm__ ("r1") = (newval); \ + register __typeof (mem) a_ptr __asm__ ("r2") = (mem); \ register __typeof (oldval) a_tmp __asm__ ("r3"); \ register __typeof (oldval) a_oldval2 __asm__ ("r4") = (oldval); \ __asm__ __volatile__ \ |