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09c76a74 | 1 | /* Single-thread optimization definitions. Linux version. |
688903eb | 2 | Copyright (C) 2017-2018 Free Software Foundation, Inc. |
09c76a74 AZ |
3 | |
4 | This file is part of the GNU C Library. | |
5 | ||
6 | The GNU C Library is free software; you can redistribute it and/or | |
7 | modify it under the terms of the GNU Lesser General Public | |
8 | License as published by the Free Software Foundation; either | |
9 | version 2.1 of the License, or (at your option) any later version. | |
10 | ||
11 | The GNU C Library is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
14 | Lesser General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU Lesser General Public | |
17 | License along with the GNU C Library; if not, see | |
18 | <http://www.gnu.org/licenses/>. */ | |
19 | ||
20 | #include <sysdep.h> | |
21 | #include <tls.h> | |
22 | #include <nptl/pthreadP.h> | |
23 | ||
24 | /* The default way to check if the process is single thread is by using the | |
25 | pthread_t 'multiple_threads' field. However for some architectures it | |
26 | is faster to either use an extra field on TCB or global varibles | |
27 | (the TCB field is also used on x86 for some single-thread atomic | |
28 | optimizations). | |
29 | ||
30 | The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single | |
31 | thread check to use global variables instead of the pthread_t | |
32 | field. */ | |
33 | ||
34 | #ifdef SINGLE_THREAD_BY_GLOBAL | |
35 | # if IS_IN (libc) | |
36 | extern int __libc_multiple_threads; | |
37 | # define SINGLE_THREAD_P \ | |
38 | __glibc_likely (__libc_multiple_threads == 0) | |
39 | # elif IS_IN (libpthread) | |
40 | extern int __pthread_multiple_threads; | |
41 | # define SINGLE_THREAD_P \ | |
42 | __glibc_likely (__pthread_multiple_threads == 0) | |
43 | # elif IS_IN (librt) | |
44 | # define SINGLE_THREAD_P \ | |
45 | __glibc_likely (THREAD_GETMEM (THREAD_SELF, \ | |
46 | header.multiple_threads) == 0) | |
47 | # else | |
48 | /* For rtld, et cetera. */ | |
49 | # define SINGLE_THREAD_P (1) | |
50 | # endif | |
51 | #else /* SINGLE_THREAD_BY_GLOBAL */ | |
52 | # if IS_IN (libc) || IS_IN (libpthread) || IS_IN (librt) | |
53 | # define SINGLE_THREAD_P \ | |
54 | __glibc_likely (THREAD_GETMEM (THREAD_SELF, \ | |
55 | header.multiple_threads) == 0) | |
56 | # else | |
57 | /* For rtld, et cetera. */ | |
58 | # define SINGLE_THREAD_P (1) | |
59 | # endif | |
60 | #endif /* SINGLE_THREAD_BY_GLOBAL */ | |
61 | ||
62 | #define RTLD_SINGLE_THREAD_P \ | |
63 | __glibc_likely (THREAD_GETMEM (THREAD_SELF, \ | |
64 | header.multiple_threads) == 0) |