1/* Copyright (C) 2002-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <sysdep.h>
19#include <errno.h>
20#include <shlib-compat.h>
21
22ENTRY(__pthread_spin_trylock)
23 xorl %ecx, %ecx
24 /* xchg has implicit LOCK prefix. */
25 xchgl %ecx, (%rdi)
26
27 /* Branch on result. Expectation is the use of trylock will be
28 branching on success/failure so this branch can be used to
29 to predict the coming branch. It has the benefit of
30 breaking the likely expensive memory dependency on (%rdi). */
31 cmpl $1, %ecx
32 jnz 1f
33 xorl %eax, %eax
34 ret
351:
36 movl $EBUSY, %eax
37 ret
38END(__pthread_spin_trylock)
39versioned_symbol (libc, __pthread_spin_trylock, pthread_spin_trylock,
40 GLIBC_2_34)
41
42#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_2, GLIBC_2_34)
43compat_symbol (libpthread, __pthread_spin_trylock, pthread_spin_trylock,
44 GLIBC_2_2)
45#endif
46