mirror of
git://gcc.gnu.org/git/gcc.git
synced 2025-04-08 00:31:03 +08:00
b204d7722d
This makes it possible to use std::thread without including the whole of <thread>. It also makes this_thread::get_id() and this_thread::yield() available even when there is no gthreads support (e.g. when GCC is built with --disable-threads or --enable-threads=single). In order for the std:🧵:id return type of this_thread::get_id() to be defined, std:thread itself is defined unconditionally. However the constructor that creates new threads is not defined for single-threaded builds. The thread::join() and thread::detach() member functions are defined inline for single-threaded builds and just throw an exception (because we know the thread cannot be joinable if the constructor that creates joinable threads doesn't exit). The thread::hardware_concurrency() member function is also defined inline and returns 0 (as suggested by the standard when the value "is not computable or well-defined"). The main benefit for most targets is that other headers such as <future> do not need to include the whole of <thread> just to be able to create a std::thread. That avoids including <stop_token> and std::jthread where not required. This is another partial fix for PR 92546. This also means we can use this_thread::get_id() and this_thread::yield() in <stop_token> instead of using the gthread functions directly. This removes some preprocessor conditionals, simplifying the code. libstdc++-v3/ChangeLog: PR libstdc++/92546 * include/Makefile.am: Add new <bits/std_thread.h> header. * include/Makefile.in: Regenerate. * include/std/future: Include new header instead of <thread>. * include/std/stop_token: Include new header instead of <bits/gthr.h>. (stop_token::_S_yield()): Use this_thread::yield(). (_Stop_state_t::_M_requester): Change type to std:🧵:id. (_Stop_state_t::_M_request_stop()): Use this_thread::get_id(). (_Stop_state_t::_M_remove_callback(_Stop_cb*)): Likewise. Use __is_single_threaded() to decide whether to synchronize. * include/std/thread (thread, operator==, this_thread::get_id) (this_thread::yield): Move to new header. (operator<=>, operator!=, operator<, operator<=, operator>) (operator>=, hash<thread::id>, operator<<): Define even when gthreads not available. * src/c++11/thread.cc: Include <memory>. * include/bits/std_thread.h: New file. (thread, operator==, this_thread::get_id, this_thread::yield): Define even when gthreads not available. [!_GLIBCXX_HAS_GTHREADS] (thread::join, thread::detach) (thread::hardware_concurrency): Define inline.
This directory contains the GNU Compiler Collection (GCC). The GNU Compiler Collection is free software. See the files whose names start with COPYING for copying permission. The manuals, and some of the runtime libraries, are under different terms; see the individual source files for details. The directory INSTALL contains copies of the installation information as HTML and plain text. The source of this information is gcc/doc/install.texi. The installation information includes details of what is included in the GCC sources and what files GCC installs. See the file gcc/doc/gcc.texi (together with other files that it includes) for usage and porting information. An online readable version of the manual is in the files gcc/doc/gcc.info*. See http://gcc.gnu.org/bugs/ for how to report bugs usefully. Copyright years on GCC source files may be listed using range notation, e.g., 1987-2012, indicating that every year in the range, inclusive, is a copyrightable year that could otherwise be listed individually.