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https://github.com/jart/cosmopolitan.git
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8b72490431
Calls to lock/unlock functions are now NOPs by default. The first time clone() is called, they get turned into CALL instructions. Doing this caused funcctions like fputc() to shrink from 85 bytes to 45+4 bytes. Since the ANSI solution of `(__threaded && lock())` inlines os much superfluous binary content into functions all over the place.
54 lines
2.4 KiB
C
54 lines
2.4 KiB
C
#ifndef COSMOPOLITAN_LIBC_INTRIN_SPINLOCK_H_
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#define COSMOPOLITAN_LIBC_INTRIN_SPINLOCK_H_
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/*───────────────────────────────────────────────────────────────────────────│─╗
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│ cosmopolitan § spinlocks ─╬─│┼
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╚────────────────────────────────────────────────────────────────────────────│─╝
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fast tiny inline synchronization routines */
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#ifdef TINY
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#define _spinlock(lock) _spinlock_tiny(lock)
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#else
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#define _spinlock(lock) _spinlock_cooperative(lock)
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#endif
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#define _spunlock(lock) __atomic_store_n(lock, 0, __ATOMIC_RELAXED)
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#define _seizelock(lock, value) \
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({ \
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autotype(lock) __lock = (lock); \
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typeof(*__lock) __x = (value); \
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__atomic_store(__lock, &__x, __ATOMIC_RELEASE); \
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})
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#define _spinlock_tiny(lock) \
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({ \
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autotype(lock) __lock = (lock); \
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while (_trylock(__lock)) { \
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__builtin_ia32_pause(); \
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} \
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0; \
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})
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#define _spinlock_cooperative(lock) \
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({ \
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autotype(lock) __lock = (lock); \
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typeof(*__lock) __x; \
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unsigned __tries = 0; \
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for (;;) { \
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__atomic_load(__lock, &__x, __ATOMIC_RELAXED); \
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if (!__x && !_trylock(__lock)) { \
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break; \
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} else if (++__tries & 7) { \
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__builtin_ia32_pause(); \
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} else { \
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_spinlock_yield(); \
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} \
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} \
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0; \
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})
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#define _trylock(lock) __atomic_test_and_set(lock, __ATOMIC_SEQ_CST)
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void _spinlock_yield(void);
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#endif /* COSMOPOLITAN_LIBC_INTRIN_SPINLOCK_H_ */
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