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mirror of https://sourceware.org/git/glibc.git synced 2025-11-02 09:33:31 +03:00

atomics: Remove unused atomics

Remove all unused atomics.  Replace uses of catomic_increment and
catomic_decrement with atomic_fetch_add_relaxed which maps to a standard
compiler builtin. Relaxed memory ordering is correct for simple counters
since they only need atomicity.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Wilco Dijkstra
2025-09-10 09:07:39 +00:00
parent 245ea60b0e
commit 210ee29503
7 changed files with 13 additions and 830 deletions

View File

@@ -19,18 +19,11 @@
#ifndef _ATOMIC_H
#define _ATOMIC_H 1
/* This header defines three types of macros:
/* This header defines two types of macros:
- atomic arithmetic and logic operation on memory. They all
have the prefix "atomic_".
- conditionally atomic operations of the same kinds. These
always behave identical but can be faster when atomicity
is not really needed since only one thread has access to
the memory location. In that case the code is slower in
the multi-thread case. The interfaces have the prefix
"catomic_".
- support functions like barriers. They also have the prefix
"atomic_".
@@ -48,41 +41,6 @@
#include <atomic-machine.h>
/* Wrapper macros to call pre_NN_post (mem, ...) where NN is the
bit width of *MEM. The calling macro puts parens around MEM
and following args. */
#define __atomic_val_bysize(pre, post, mem, ...) \
({ \
__typeof ((__typeof (*(mem))) *(mem)) __atg1_result; \
if (sizeof (*mem) == 1) \
__atg1_result = pre##_8_##post (mem, __VA_ARGS__); \
else if (sizeof (*mem) == 2) \
__atg1_result = pre##_16_##post (mem, __VA_ARGS__); \
else if (sizeof (*mem) == 4) \
__atg1_result = pre##_32_##post (mem, __VA_ARGS__); \
else if (sizeof (*mem) == 8) \
__atg1_result = pre##_64_##post (mem, __VA_ARGS__); \
else \
abort (); \
__atg1_result; \
})
#define __atomic_bool_bysize(pre, post, mem, ...) \
({ \
int __atg2_result; \
if (sizeof (*mem) == 1) \
__atg2_result = pre##_8_##post (mem, __VA_ARGS__); \
else if (sizeof (*mem) == 2) \
__atg2_result = pre##_16_##post (mem, __VA_ARGS__); \
else if (sizeof (*mem) == 4) \
__atg2_result = pre##_32_##post (mem, __VA_ARGS__); \
else if (sizeof (*mem) == 8) \
__atg2_result = pre##_64_##post (mem, __VA_ARGS__); \
else \
abort (); \
__atg2_result; \
})
#if USE_ATOMIC_COMPILER_BUILTINS
# undef atomic_compare_and_exchange_val_acq
# define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
@@ -107,159 +65,6 @@
!atomic_compare_exchange_acquire (mem, (void*)&__atg3_old, newval); \
})
# undef atomic_exchange_and_add
# define atomic_exchange_and_add(mem, val) atomic_fetch_add_relaxed(mem,val)
#endif
/* Atomically store NEWVAL in *MEM if *MEM is equal to OLDVAL.
Return the old *MEM value. */
#if !defined atomic_compare_and_exchange_val_acq \
&& defined __arch_compare_and_exchange_val_32_acq
# define atomic_compare_and_exchange_val_acq(mem, newval, oldval) \
__atomic_val_bysize (__arch_compare_and_exchange_val,acq, \
mem, newval, oldval)
#endif
#ifndef catomic_compare_and_exchange_val_acq
# ifdef __arch_c_compare_and_exchange_val_32_acq
# define catomic_compare_and_exchange_val_acq(mem, newval, oldval) \
__atomic_val_bysize (__arch_c_compare_and_exchange_val,acq, \
mem, newval, oldval)
# else
# define catomic_compare_and_exchange_val_acq(mem, newval, oldval) \
atomic_compare_and_exchange_val_acq (mem, newval, oldval)
# endif
#endif
#ifndef catomic_compare_and_exchange_val_rel
# ifndef atomic_compare_and_exchange_val_rel
# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \
catomic_compare_and_exchange_val_acq (mem, newval, oldval)
# else
# define catomic_compare_and_exchange_val_rel(mem, newval, oldval) \
atomic_compare_and_exchange_val_rel (mem, newval, oldval)
# endif
#endif
#ifndef atomic_compare_and_exchange_val_rel
# define atomic_compare_and_exchange_val_rel(mem, newval, oldval) \
atomic_compare_and_exchange_val_acq (mem, newval, oldval)
#endif
/* Atomically store NEWVAL in *MEM if *MEM is equal to OLDVAL.
Return zero if *MEM was changed or non-zero if no exchange happened. */
#ifndef atomic_compare_and_exchange_bool_acq
# ifdef __arch_compare_and_exchange_bool_32_acq
# define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
__atomic_bool_bysize (__arch_compare_and_exchange_bool,acq, \
mem, newval, oldval)
# else
# define atomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
({ /* Cannot use __oldval here, because macros later in this file might \
call this macro with __oldval argument. */ \
__typeof (oldval) __atg3_old = (oldval); \
atomic_compare_and_exchange_val_acq (mem, newval, __atg3_old) \
!= __atg3_old; \
})
# endif
#endif
#ifndef catomic_compare_and_exchange_bool_acq
# ifdef __arch_c_compare_and_exchange_bool_32_acq
# define catomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
__atomic_bool_bysize (__arch_c_compare_and_exchange_bool,acq, \
mem, newval, oldval)
# else
# define catomic_compare_and_exchange_bool_acq(mem, newval, oldval) \
({ /* Cannot use __oldval here, because macros later in this file might \
call this macro with __oldval argument. */ \
__typeof (oldval) __atg4_old = (oldval); \
catomic_compare_and_exchange_val_acq (mem, newval, __atg4_old) \
!= __atg4_old; \
})
# endif
#endif
/* Store NEWVALUE in *MEM and return the old value. */
#ifndef atomic_exchange_acq
# define atomic_exchange_acq(mem, newvalue) \
({ __typeof ((__typeof (*(mem))) *(mem)) __atg5_oldval; \
__typeof (mem) __atg5_memp = (mem); \
__typeof ((__typeof (*(mem))) *(mem)) __atg5_value = (newvalue); \
\
do \
__atg5_oldval = *__atg5_memp; \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg5_memp, __atg5_value, \
__atg5_oldval), 0)); \
\
__atg5_oldval; })
#endif
#ifndef atomic_exchange_rel
# define atomic_exchange_rel(mem, newvalue) atomic_exchange_acq (mem, newvalue)
#endif
/* Add VALUE to *MEM and return the old value of *MEM. */
#ifndef atomic_exchange_and_add_acq
# ifdef atomic_exchange_and_add
# define atomic_exchange_and_add_acq(mem, value) \
atomic_exchange_and_add (mem, value)
# else
# define atomic_exchange_and_add_acq(mem, value) \
({ __typeof (*(mem)) __atg6_oldval; \
__typeof (mem) __atg6_memp = (mem); \
__typeof (*(mem)) __atg6_value = (value); \
\
do \
__atg6_oldval = *__atg6_memp; \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg6_memp, \
__atg6_oldval \
+ __atg6_value, \
__atg6_oldval), 0)); \
\
__atg6_oldval; })
# endif
#endif
#ifndef atomic_exchange_and_add_rel
# define atomic_exchange_and_add_rel(mem, value) \
atomic_exchange_and_add_acq(mem, value)
#endif
#ifndef atomic_exchange_and_add
# define atomic_exchange_and_add(mem, value) \
atomic_exchange_and_add_acq(mem, value)
#endif
#ifndef catomic_exchange_and_add
# define catomic_exchange_and_add(mem, value) \
({ __typeof (*(mem)) __atg7_oldv; \
__typeof (mem) __atg7_memp = (mem); \
__typeof (*(mem)) __atg7_value = (value); \
\
do \
__atg7_oldv = *__atg7_memp; \
while (__builtin_expect \
(catomic_compare_and_exchange_bool_acq (__atg7_memp, \
__atg7_oldv \
+ __atg7_value, \
__atg7_oldv), 0)); \
\
__atg7_oldv; })
#endif
#ifndef atomic_max
# define atomic_max(mem, value) \
do { \
@@ -277,107 +82,6 @@
#endif
#ifndef catomic_max
# define catomic_max(mem, value) \
do { \
__typeof (*(mem)) __atg9_oldv; \
__typeof (mem) __atg9_memp = (mem); \
__typeof (*(mem)) __atg9_value = (value); \
do { \
__atg9_oldv = *__atg9_memp; \
if (__atg9_oldv >= __atg9_value) \
break; \
} while (__builtin_expect \
(catomic_compare_and_exchange_bool_acq (__atg9_memp, \
__atg9_value, \
__atg9_oldv), 0)); \
} while (0)
#endif
#ifndef atomic_min
# define atomic_min(mem, value) \
do { \
__typeof (*(mem)) __atg10_oldval; \
__typeof (mem) __atg10_memp = (mem); \
__typeof (*(mem)) __atg10_value = (value); \
do { \
__atg10_oldval = *__atg10_memp; \
if (__atg10_oldval <= __atg10_value) \
break; \
} while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg10_memp, \
__atg10_value, \
__atg10_oldval), 0)); \
} while (0)
#endif
#ifndef atomic_add
# define atomic_add(mem, value) (void) atomic_exchange_and_add ((mem), (value))
#endif
#ifndef catomic_add
# define catomic_add(mem, value) \
(void) catomic_exchange_and_add ((mem), (value))
#endif
#ifndef atomic_increment
# define atomic_increment(mem) atomic_add ((mem), 1)
#endif
#ifndef catomic_increment
# define catomic_increment(mem) catomic_add ((mem), 1)
#endif
#ifndef atomic_increment_val
# define atomic_increment_val(mem) (atomic_exchange_and_add ((mem), 1) + 1)
#endif
#ifndef catomic_increment_val
# define catomic_increment_val(mem) (catomic_exchange_and_add ((mem), 1) + 1)
#endif
/* Add one to *MEM and return true iff it's now zero. */
#ifndef atomic_increment_and_test
# define atomic_increment_and_test(mem) \
(atomic_exchange_and_add ((mem), 1) + 1 == 0)
#endif
#ifndef atomic_decrement
# define atomic_decrement(mem) atomic_add ((mem), -1)
#endif
#ifndef catomic_decrement
# define catomic_decrement(mem) catomic_add ((mem), -1)
#endif
#ifndef atomic_decrement_val
# define atomic_decrement_val(mem) (atomic_exchange_and_add ((mem), -1) - 1)
#endif
#ifndef catomic_decrement_val
# define catomic_decrement_val(mem) (catomic_exchange_and_add ((mem), -1) - 1)
#endif
/* Subtract 1 from *MEM and return true iff it's now zero. */
#ifndef atomic_decrement_and_test
# define atomic_decrement_and_test(mem) \
(atomic_exchange_and_add ((mem), -1) == 1)
#endif
/* Decrement *MEM if it is > 0, and return the old value. */
#ifndef atomic_decrement_if_positive
# define atomic_decrement_if_positive(mem) \
@@ -398,142 +102,6 @@
#endif
#ifndef atomic_add_negative
# define atomic_add_negative(mem, value) \
({ __typeof (value) __atg12_value = (value); \
atomic_exchange_and_add (mem, __atg12_value) < -__atg12_value; })
#endif
#ifndef atomic_add_zero
# define atomic_add_zero(mem, value) \
({ __typeof (value) __atg13_value = (value); \
atomic_exchange_and_add (mem, __atg13_value) == -__atg13_value; })
#endif
#ifndef atomic_bit_set
# define atomic_bit_set(mem, bit) \
(void) atomic_bit_test_set(mem, bit)
#endif
#ifndef atomic_bit_test_set
# define atomic_bit_test_set(mem, bit) \
({ __typeof (*(mem)) __atg14_old; \
__typeof (mem) __atg14_memp = (mem); \
__typeof (*(mem)) __atg14_mask = ((__typeof (*(mem))) 1 << (bit)); \
\
do \
__atg14_old = (*__atg14_memp); \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg14_memp, \
__atg14_old | __atg14_mask,\
__atg14_old), 0)); \
\
__atg14_old & __atg14_mask; })
#endif
/* Atomically *mem &= mask. */
#ifndef atomic_and
# define atomic_and(mem, mask) \
do { \
__typeof (*(mem)) __atg15_old; \
__typeof (mem) __atg15_memp = (mem); \
__typeof (*(mem)) __atg15_mask = (mask); \
\
do \
__atg15_old = (*__atg15_memp); \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg15_memp, \
__atg15_old & __atg15_mask, \
__atg15_old), 0)); \
} while (0)
#endif
#ifndef catomic_and
# define catomic_and(mem, mask) \
do { \
__typeof (*(mem)) __atg20_old; \
__typeof (mem) __atg20_memp = (mem); \
__typeof (*(mem)) __atg20_mask = (mask); \
\
do \
__atg20_old = (*__atg20_memp); \
while (__builtin_expect \
(catomic_compare_and_exchange_bool_acq (__atg20_memp, \
__atg20_old & __atg20_mask,\
__atg20_old), 0)); \
} while (0)
#endif
/* Atomically *mem &= mask and return the old value of *mem. */
#ifndef atomic_and_val
# define atomic_and_val(mem, mask) \
({ __typeof (*(mem)) __atg16_old; \
__typeof (mem) __atg16_memp = (mem); \
__typeof (*(mem)) __atg16_mask = (mask); \
\
do \
__atg16_old = (*__atg16_memp); \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg16_memp, \
__atg16_old & __atg16_mask,\
__atg16_old), 0)); \
\
__atg16_old; })
#endif
/* Atomically *mem |= mask and return the old value of *mem. */
#ifndef atomic_or
# define atomic_or(mem, mask) \
do { \
__typeof (*(mem)) __atg17_old; \
__typeof (mem) __atg17_memp = (mem); \
__typeof (*(mem)) __atg17_mask = (mask); \
\
do \
__atg17_old = (*__atg17_memp); \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg17_memp, \
__atg17_old | __atg17_mask, \
__atg17_old), 0)); \
} while (0)
#endif
#ifndef catomic_or
# define catomic_or(mem, mask) \
do { \
__typeof (*(mem)) __atg18_old; \
__typeof (mem) __atg18_memp = (mem); \
__typeof (*(mem)) __atg18_mask = (mask); \
\
do \
__atg18_old = (*__atg18_memp); \
while (__builtin_expect \
(catomic_compare_and_exchange_bool_acq (__atg18_memp, \
__atg18_old | __atg18_mask,\
__atg18_old), 0)); \
} while (0)
#endif
/* Atomically *mem |= mask and return the old value of *mem. */
#ifndef atomic_or_val
# define atomic_or_val(mem, mask) \
({ __typeof (*(mem)) __atg19_old; \
__typeof (mem) __atg19_memp = (mem); \
__typeof (*(mem)) __atg19_mask = (mask); \
\
do \
__atg19_old = (*__atg19_memp); \
while (__builtin_expect \
(atomic_compare_and_exchange_bool_acq (__atg19_memp, \
__atg19_old | __atg19_mask,\
__atg19_old), 0)); \
\
__atg19_old; })
#endif
#ifndef atomic_full_barrier
# define atomic_full_barrier() __asm ("" ::: "memory")
#endif