| 1 | /* Copyright (C) 2002-2024 Free Software Foundation, Inc. |
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| 2 | This file is part of the GNU C Library. |
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| 3 | |
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| 4 | The GNU C Library is free software; you can redistribute it and/or |
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| 5 | modify it under the terms of the GNU Lesser General Public |
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| 6 | License as published by the Free Software Foundation; either |
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| 7 | version 2.1 of the License, or (at your option) any later version. |
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| 8 | |
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| 9 | The GNU C Library is distributed in the hope that it will be useful, |
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 12 | Lesser General Public License for more details. |
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| 13 | |
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| 14 | You should have received a copy of the GNU Lesser General Public |
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| 15 | License along with the GNU C Library; if not, see |
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| 16 | <https://www.gnu.org/licenses/>. */ |
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| 17 | |
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| 18 | #include <sysdep.h> |
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| 19 | #include <errno.h> |
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| 20 | #include <shlib-compat.h> |
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| 21 | |
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| 22 | ENTRY(__pthread_spin_trylock) |
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| 23 | xorl %ecx, %ecx |
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| 24 | /* xchg has implicit LOCK prefix. */ |
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| 25 | xchgl %ecx, (%rdi) |
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| 26 | |
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| 27 | /* Branch on result. Expectation is the use of trylock will be |
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| 28 | branching on success/failure so this branch can be used to |
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| 29 | to predict the coming branch. It has the benefit of |
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| 30 | breaking the likely expensive memory dependency on (%rdi). */ |
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| 31 | cmpl $1, %ecx |
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| 32 | jnz 1f |
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| 33 | xorl %eax, %eax |
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| 34 | ret |
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| 35 | 1: |
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| 36 | movl $EBUSY, %eax |
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| 37 | ret |
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| 38 | END(__pthread_spin_trylock) |
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| 39 | versioned_symbol (libc, __pthread_spin_trylock, pthread_spin_trylock, |
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| 40 | GLIBC_2_34) |
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| 41 | |
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| 42 | #if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_2, GLIBC_2_34) |
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| 43 | compat_symbol (libpthread, __pthread_spin_trylock, pthread_spin_trylock, |
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| 44 | GLIBC_2_2) |
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| 45 | #endif |
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| 46 | |
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