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i386: Remove bogus THREAD_ATOMIC_* macros

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The x86 defines optimized THREAD_ATOMIC_* macros where reference always
the current thread instead of the one indicated by input 'descr' argument.
It work as long the input is the self thread pointer, however it generates
wrong code if the semantic is to set a bit atomicialy from another thread.

This is not an issue for current GLIBC usage, however the new cancellation
code expects that some synchronization code to atomically set bits from
different threads.

If some usage indeed proves to be a hotspot we can add an extra macro
with a more descriptive name (THREAD_ATOMIC_BIT_SET_SELF for instance)
where i386 might optimize it.

Checked on i686-linux-gnu.

	* sysdeps/i686/nptl/tls.h (THREAD_ATOMIC_CMPXCHG_VAL,
	THREAD_ATOMIC_AND, THREAD_ATOMIC_BIT_SET): Remove macros.
This commit is contained in:
Adhemerval Zanella 2018-05-09 10:39:49 -03:00
parent 85c828a462
commit 0b13e25581
2 changed files with 3 additions and 37 deletions
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3
ChangeLog
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@ -1,5 +1,8 @@
2019-01-03 Adhemerval Zanella <adhemerval.zanella@linaro.org> 2019-01-03 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* sysdeps/i386/nptl/tls.h (THREAD_ATOMIC_CMPXCHG_VAL,
THREAD_ATOMIC_AND, THREAD_ATOMIC_BIT_SET): Remove macros.
* sysdeps/x86_64/nptl/tls.h (THREAD_ATOMIC_CMPXCHG_VAL, * sysdeps/x86_64/nptl/tls.h (THREAD_ATOMIC_CMPXCHG_VAL,
THREAD_ATOMIC_AND, THREAD_ATOMIC_BIT_SET): Remove macros. THREAD_ATOMIC_AND, THREAD_ATOMIC_BIT_SET): Remove macros.

37
sysdeps/i386/nptl/tls.h
View File

@ -362,43 +362,6 @@ tls_fill_user_desc (union user_desc_init *desc,
}}) }})
/* Atomic compare and exchange on TLS, returning old value. */
#define THREAD_ATOMIC_CMPXCHG_VAL(descr, member, newval, oldval) \
({ __typeof (descr->member) __ret; \
__typeof (oldval) __old = (oldval); \
if (sizeof (descr->member) == 4) \
asm volatile (LOCK_PREFIX "cmpxchgl %2, %%gs:%P3" \
: "=a" (__ret) \
: "0" (__old), "r" (newval), \
"i" (offsetof (struct pthread, member))); \
else \
/* Not necessary for other sizes in the moment. */ \
abort (); \
__ret; })
/* Atomic logical and. */
#define THREAD_ATOMIC_AND(descr, member, val) \
(void) ({ if (sizeof ((descr)->member) == 4) \
asm volatile (LOCK_PREFIX "andl %1, %%gs:%P0" \
:: "i" (offsetof (struct pthread, member)), \
"ir" (val)); \
else \
/* Not necessary for other sizes in the moment. */ \
abort (); })
/* Atomic set bit. */
#define THREAD_ATOMIC_BIT_SET(descr, member, bit) \
(void) ({ if (sizeof ((descr)->member) == 4) \
asm volatile (LOCK_PREFIX "orl %1, %%gs:%P0" \
:: "i" (offsetof (struct pthread, member)), \
"ir" (1 << (bit))); \
else \
/* Not necessary for other sizes in the moment. */ \
abort (); })
/* Set the stack guard field in TCB head. */ /* Set the stack guard field in TCB head. */
#define THREAD_SET_STACK_GUARD(value) \ #define THREAD_SET_STACK_GUARD(value) \
THREAD_SETMEM (THREAD_SELF, header.stack_guard, value) THREAD_SETMEM (THREAD_SELF, header.stack_guard, value)