[PATCH 09/22] arm: Consolidade atomic-machine.h and Remove ununsed atomic macros
Adhemerval Zanella
adhemerval.zanella@linaro.org
Thu Sep 11 13:49:35 GMT 2025
The libgcc provides the required support to calling the kernel
auxiliary routines for !__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4.
---
sysdeps/arm/atomic-machine.h | 118 +------------------
sysdeps/unix/sysv/linux/arm/atomic-machine.h | 115 ------------------
2 files changed, 1 insertion(+), 232 deletions(-)
delete mode 100644 sysdeps/unix/sysv/linux/arm/atomic-machine.h
diff --git a/sysdeps/arm/atomic-machine.h b/sysdeps/arm/atomic-machine.h
index 39cdef1715..1ba328c546 100644
--- a/sysdeps/arm/atomic-machine.h
+++ b/sysdeps/arm/atomic-machine.h
@@ -17,122 +17,6 @@
<https://www.gnu.org/licenses/>. */
#define __HAVE_64B_ATOMICS 0
-#define USE_ATOMIC_COMPILER_BUILTINS 1
#define ATOMIC_EXCHANGE_USES_CAS 1
-void __arm_link_error (void);
-
-#ifdef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
-# define atomic_full_barrier() __sync_synchronize ()
-#else
-# define atomic_full_barrier() __arm_assisted_full_barrier ()
-#endif
-
-/* An OS-specific atomic-machine.h file will define this macro if
- the OS can provide something. If not, we'll fail to build
- with a compiler that doesn't supply the operation. */
-#ifndef __arm_assisted_full_barrier
-# define __arm_assisted_full_barrier() __arm_link_error()
-#endif
-
-/* 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_exchange_acq(mem, value) \
- __atomic_val_bysize (__arch_exchange, int, mem, value, __ATOMIC_ACQUIRE)
-
-# define atomic_exchange_rel(mem, value) \
- __atomic_val_bysize (__arch_exchange, int, mem, value, __ATOMIC_RELEASE)
-
-/* Atomic exchange (without compare). */
-
-# define __arch_exchange_8_int(mem, newval, model) \
- (__arm_link_error (), (typeof (*mem)) 0)
-
-# define __arch_exchange_16_int(mem, newval, model) \
- (__arm_link_error (), (typeof (*mem)) 0)
-
-# define __arch_exchange_32_int(mem, newval, model) \
- __atomic_exchange_n (mem, newval, model)
-
-# define __arch_exchange_64_int(mem, newval, model) \
- (__arm_link_error (), (typeof (*mem)) 0)
-
-/* Compare and exchange with "acquire" semantics, ie barrier after. */
-
-# define atomic_compare_and_exchange_bool_acq(mem, new, old) \
- __atomic_bool_bysize (__arch_compare_and_exchange_bool, int, \
- mem, new, old, __ATOMIC_ACQUIRE)
-
-# define atomic_compare_and_exchange_val_acq(mem, new, old) \
- __atomic_val_bysize (__arch_compare_and_exchange_val, int, \
- mem, new, old, __ATOMIC_ACQUIRE)
-
-/* Compare and exchange with "release" semantics, ie barrier before. */
-
-# define atomic_compare_and_exchange_val_rel(mem, new, old) \
- __atomic_val_bysize (__arch_compare_and_exchange_val, int, \
- mem, new, old, __ATOMIC_RELEASE)
-
-/* Compare and exchange.
- For all "bool" routines, we return FALSE if exchange successful. */
-
-# define __arch_compare_and_exchange_bool_8_int(mem, newval, oldval, model) \
- ({__arm_link_error (); 0; })
-
-# define __arch_compare_and_exchange_bool_16_int(mem, newval, oldval, model) \
- ({__arm_link_error (); 0; })
-
-# define __arch_compare_and_exchange_bool_32_int(mem, newval, oldval, model) \
- ({ \
- typeof (*mem) __oldval = (oldval); \
- !__atomic_compare_exchange_n (mem, (void *) &__oldval, newval, 0, \
- model, __ATOMIC_RELAXED); \
- })
-
-# define __arch_compare_and_exchange_bool_64_int(mem, newval, oldval, model) \
- ({__arm_link_error (); 0; })
-
-# define __arch_compare_and_exchange_val_8_int(mem, newval, oldval, model) \
- ({__arm_link_error (); oldval; })
-
-# define __arch_compare_and_exchange_val_16_int(mem, newval, oldval, model) \
- ({__arm_link_error (); oldval; })
-
-# define __arch_compare_and_exchange_val_32_int(mem, newval, oldval, model) \
- ({ \
- typeof (*mem) __oldval = (oldval); \
- __atomic_compare_exchange_n (mem, (void *) &__oldval, newval, 0, \
- model, __ATOMIC_RELAXED); \
- __oldval; \
- })
-
-# define __arch_compare_and_exchange_val_64_int(mem, newval, oldval, model) \
- ({__arm_link_error (); oldval; })
-
-#else
-# define __arch_compare_and_exchange_val_32_acq(mem, newval, oldval) \
- __arm_assisted_compare_and_exchange_val_32_acq ((mem), (newval), (oldval))
-#endif
-
-#ifndef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
-/* We don't support atomic operations on any non-word types.
- So make them link errors. */
-# define __arch_compare_and_exchange_val_8_acq(mem, newval, oldval) \
- ({ __arm_link_error (); oldval; })
-
-# define __arch_compare_and_exchange_val_16_acq(mem, newval, oldval) \
- ({ __arm_link_error (); oldval; })
-
-# define __arch_compare_and_exchange_val_64_acq(mem, newval, oldval) \
- ({ __arm_link_error (); oldval; })
-#endif
-
-/* An OS-specific atomic-machine.h file will define this macro if
- the OS can provide something. If not, we'll fail to build
- with a compiler that doesn't supply the operation. */
-#ifndef __arm_assisted_compare_and_exchange_val_32_acq
-# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \
- ({ __arm_link_error (); oldval; })
-#endif
+#define atomic_full_barrier() __sync_synchronize ()
diff --git a/sysdeps/unix/sysv/linux/arm/atomic-machine.h b/sysdeps/unix/sysv/linux/arm/atomic-machine.h
deleted file mode 100644
index 1734bcd98d..0000000000
--- a/sysdeps/unix/sysv/linux/arm/atomic-machine.h
+++ /dev/null
@@ -1,115 +0,0 @@
-/* Atomic operations. ARM/Linux version.
- Copyright (C) 2002-2025 Free Software Foundation, Inc.
- This file is part of the GNU C Library.
-
- The GNU C Library is free software; you can redistribute it and/or
- modify it under the terms of the GNU Lesser General Public
- License as published by the Free Software Foundation; either
- version 2.1 of the License, or (at your option) any later version.
-
- The GNU C Library is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library. If not, see
- <https://www.gnu.org/licenses/>. */
-
-#include <stdint.h>
-
-/* If the compiler doesn't provide a primitive, we'll use this macro
- to get assistance from the kernel. */
-#ifdef __thumb2__
-# define __arm_assisted_full_barrier() \
- __asm__ __volatile__ \
- ("movw\tip, #0x0fa0\n\t" \
- "movt\tip, #0xffff\n\t" \
- "blx\tip" \
- : : : "ip", "lr", "cc", "memory");
-#else
-# define __arm_assisted_full_barrier() \
- __asm__ __volatile__ \
- ("mov\tip, #0xffff0fff\n\t" \
- "mov\tlr, pc\n\t" \
- "add\tpc, ip, #(0xffff0fa0 - 0xffff0fff)" \
- : : : "ip", "lr", "cc", "memory");
-#endif
-
-/* Atomic compare and exchange. This sequence relies on the kernel to
- provide a compare and exchange operation which is atomic on the
- current architecture, either via cleverness on pre-ARMv6 or via
- ldrex / strex on ARMv6.
-
- 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.
-
- We use the union trick rather than simply using __typeof (...) in the
- declarations of A_OLDVAL et al because when NEWVAL or OLDVAL is of the
- form *PTR and PTR has a 'volatile ... *' type, then __typeof (*PTR) has
- a 'volatile ...' type and this triggers -Wvolatile-register-var to
- complain about 'register volatile ... asm ("reg")'.
-
- We use the same union trick in the declaration of A_PTR because when
- MEM is of the from *PTR and PTR has a 'const ... *' type, then __typeof
- (*PTR) has a 'const ...' type and this enables the compiler to substitute
- the variable with its initializer in asm statements, which may cause the
- corresponding operand to appear in a different register. */
-#ifdef __thumb2__
-/* Thumb-2 has ldrex/strex. However it does not have barrier instructions,
- so we still need to use the kernel helper. */
-# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \
- ({ union { __typeof (mem) a; uint32_t v; } mem_arg = { .a = (mem) }; \
- union { __typeof (oldval) a; uint32_t v; } oldval_arg = { .a = (oldval) };\
- union { __typeof (newval) a; uint32_t v; } newval_arg = { .a = (newval) };\
- register uint32_t a_oldval asm ("r0"); \
- register uint32_t a_newval asm ("r1") = newval_arg.v; \
- register uint32_t a_ptr asm ("r2") = mem_arg.v; \
- register uint32_t a_tmp asm ("r3"); \
- register uint32_t a_oldval2 asm ("r4") = oldval_arg.v; \
- __asm__ __volatile__ \
- ("0:\tldr\t%[tmp],[%[ptr]]\n\t" \
- "cmp\t%[tmp], %[old2]\n\t" \
- "bne\t1f\n\t" \
- "mov\t%[old], %[old2]\n\t" \
- "movw\t%[tmp], #0x0fc0\n\t" \
- "movt\t%[tmp], #0xffff\n\t" \
- "blx\t%[tmp]\n\t" \
- "bcc\t0b\n\t" \
- "mov\t%[tmp], %[old2]\n\t" \
- "1:" \
- : [old] "=&r" (a_oldval), [tmp] "=&r" (a_tmp) \
- : [new] "r" (a_newval), [ptr] "r" (a_ptr), \
- [old2] "r" (a_oldval2) \
- : "ip", "lr", "cc", "memory"); \
- (__typeof (oldval)) a_tmp; })
-#else
-# define __arm_assisted_compare_and_exchange_val_32_acq(mem, newval, oldval) \
- ({ union { __typeof (mem) a; uint32_t v; } mem_arg = { .a = (mem) }; \
- union { __typeof (oldval) a; uint32_t v; } oldval_arg = { .a = (oldval) };\
- union { __typeof (newval) a; uint32_t v; } newval_arg = { .a = (newval) };\
- register uint32_t a_oldval asm ("r0"); \
- register uint32_t a_newval asm ("r1") = newval_arg.v; \
- register uint32_t a_ptr asm ("r2") = mem_arg.v; \
- register uint32_t a_tmp asm ("r3"); \
- register uint32_t a_oldval2 asm ("r4") = oldval_arg.v; \
- __asm__ __volatile__ \
- ("0:\tldr\t%[tmp],[%[ptr]]\n\t" \
- "cmp\t%[tmp], %[old2]\n\t" \
- "bne\t1f\n\t" \
- "mov\t%[old], %[old2]\n\t" \
- "mov\t%[tmp], #0xffff0fff\n\t" \
- "mov\tlr, pc\n\t" \
- "add\tpc, %[tmp], #(0xffff0fc0 - 0xffff0fff)\n\t" \
- "bcc\t0b\n\t" \
- "mov\t%[tmp], %[old2]\n\t" \
- "1:" \
- : [old] "=&r" (a_oldval), [tmp] "=&r" (a_tmp) \
- : [new] "r" (a_newval), [ptr] "r" (a_ptr), \
- [old2] "r" (a_oldval2) \
- : "ip", "lr", "cc", "memory"); \
- (__typeof (oldval)) a_tmp; })
-#endif
-
-#include <sysdeps/arm/atomic-machine.h>
--
2.43.0
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