diff options
Diffstat (limited to 'libstdc++-v3/config/cpu/arm/atomicity.h')
| -rw-r--r-- | libstdc++-v3/config/cpu/arm/atomicity.h | 187 |
1 files changed, 14 insertions, 173 deletions
diff --git a/libstdc++-v3/config/cpu/arm/atomicity.h b/libstdc++-v3/config/cpu/arm/atomicity.h index 2363edf7cdf..7b952aac365 100644 --- a/libstdc++-v3/config/cpu/arm/atomicity.h +++ b/libstdc++-v3/config/cpu/arm/atomicity.h @@ -32,51 +32,23 @@ typedef int _Atomic_word; +/* It isn't possible to write an atomic add instruction using the ARM + SWP instruction without using either a global guard variable or a + guard bit somewhere in the Atomic word. However, even with a guard + bit we need to understand the thread model (if any) in order to + make co-operatively threaded applications work correctly. + + The previous Thumb-based implementations were also completely + broken, since they failed to switch back into Thumb mode (Gas bug, + I think). */ + static inline _Atomic_word __attribute__ ((__unused__)) __exchange_and_add (volatile _Atomic_word* __mem, int __val) { - _Atomic_word __tmp, __tmp2, __result; -#ifdef __thumb__ - /* Since this function is inlined, we can't be sure of the alignment. */ - __asm__ __volatile__ ( - "ldr %0, 4f \n\t" - "bx %0 \n\t" - ".align 0 \n" - "4:\t" - ".word 0f \n\t" - ".code 32 \n" - "0:\t" - "ldr %0, [%3] \n\t" - "add %1, %0, %4 \n\t" - "swp %2, %1, [%3] \n\t" - "cmp %0, %2 \n\t" - "swpne %1, %2, [%3] \n\t" - "bne 0b \n\t" - "ldr %1, 1f \n\t" - "bx %1 \n" - "1:\t" - ".word 2f \n\t" - ".code 16 \n" - "2:\n" - : "=&l"(__result), "=&r"(__tmp), "=&r"(__tmp2) - : "r" (__mem), "r"(__val) - : "cc", "memory"); -#else - __asm__ __volatile__ ( - "\n" - "0:\t" - "ldr %0, [%3] \n\t" - "add %1, %0, %4 \n\t" - "swp %2, %1, [%3] \n\t" - "cmp %0, %2 \n\t" - "swpne %1, %2, [%3] \n\t" - "bne 0b \n\t" - "" - : "=&r"(__result), "=&r"(__tmp), "=&r"(__tmp2) - : "r" (__mem), "r"(__val) - : "cc", "memory"); -#endif + _Atomic_word __result = *__mem; + + *__mem = __result + __val; return __result; } @@ -84,138 +56,7 @@ static inline void __attribute__ ((__unused__)) __atomic_add (volatile _Atomic_word *__mem, int __val) { - _Atomic_word __tmp, __tmp2, __tmp3; -#ifdef __thumb__ - /* Since this function is inlined, we can't be sure of the alignment. */ - __asm__ __volatile__ ( - "ldr %0, 4f \n\t" - "bx %0 \n\t" - ".align 0\n" - "4:\t" - ".word 0f \n\t" - ".code 32 \n" - "0:\t" - "ldr %0, [%3] \n\t" - "add %1, %0, %4 \n\t" - "swp %2, %1, [%3] \n\t" - "cmp %0, %2 \n\t" - "swpne %1, %2,[%3] \n\t" - "bne 0b \n\t" - "ldr %1, 1f \n\t" - "bx %1 \n" - "1:\t" - ".word 2f \n\t" - ".code 16 \n" - "2:\n" - : "=&l"(__tmp), "=&r"(__tmp2), "=&r"(__tmp3) - : "r" (__mem), "r"(__val) - : "cc", "memory"); -#else - __asm__ __volatile__ ( - "\n" - "0:\t" - "ldr %0, [%3] \n\t" - "add %1, %0, %4 \n\t" - "swp %2, %1, [%3] \n\t" - "cmp %0, %2 \n\t" - "swpne %1, %2, [%3] \n\t" - "bne 0b \n\t" - "" - : "=&r"(__tmp), "=&r"(__tmp2), "=&r"(__tmp3) - : "r" (__mem), "r"(__val) - : "cc", "memory"); -#endif -} - -static inline long -__attribute__ ((__unused__)) -__always_swap (volatile long *__p, long __newval) -{ - long __result; -#ifdef __thumb__ - long __tmp; - /* Since this function is inlined, we can't be sure of the alignment. */ - __asm__ __volatile__ ( - "ldr %0, 4f \n\t" - "bx %0 \n\t" - ".align 0 \n" - "4:\t" - ".word 0f \n\t" - ".code 32\n" - "0:\t" - "swp %0, %3, [%2] \n\t" - "ldr %1, 1f \n\t" - "bx %1 \n" - "1:\t" - ".word 2f \n\t" - ".code 16 \n" - "2:\n" - : "=&l"(__result), "=&r"(__tmp) - : "r"(__p), "r"(__newval) - : "memory"); -#else - __asm__ __volatile__ ( - "\n\t" - "swp %0, %2, [%1] \n\t" - "" - : "=&r"(__result) - : "r"(__p), "r"(__newval) - : "memory"); -#endif - return __result; -} - -static inline int -__attribute__ ((__unused__)) -__test_and_set (volatile long *__p, long __newval) -{ - int __result; - long __tmp; -#ifdef __thumb__ - /* Since this function is inlined, we can't be sure of the alignment. */ - __asm__ __volatile__ ( - "ldr %0, 4f \n\t" - "bx %0 \n\t" - ".align 0 \n" - "4:\t" - ".word 0f \n\t" - ".code 32 \n" - "0:\t" - "ldr %0, [%2] \n\t" - "cmp %0, #0 \n\t" - "bne 1f \n\t" - "swp %1, %3, [%2] \n\t" - "cmp %0, %1 \n\t" - "swpne %0, %1, [%2]\n\t" - "bne 0b \n" - "1:\t" - "ldr %1, 2f \n\t" - "bx %1 \n" - "2:\t" - ".word 3f \n\t" - ".code 16 \n" - "3:" - : "=&l"(__result), "=r" (__tmp) - : "r"(__p), "r"(__newval) - : "cc", "memory"); -#else - __asm__ __volatile__ ( - "\n" - "0:\t" - "ldr %0, [%2] \n\t" - "cmp %0, #0 \n\t" - "bne 1f \n\t" - "swp %1, %3, [%2] \n\t" - "cmp %0, %1 \n\t" - "swpne %0, %1, [%2] \n\t" - "bne 0b \n" - "1:\n\t" - "" - : "=&r"(__result), "=r" (__tmp) - : "r"(__p), "r"(__newval) - : "cc", "memory"); -#endif - return __result; + __exchange_and_add (__mem, __val); } #endif /* atomicity.h */ |