e2875a9fca
The changes made in commit bc59e28bf6b0f70ff345aef80356d0076f44a0e7 (issue #3399) fixed introspection of the GThread API. However, they introduced a trampoline in every threading function. So with those changes applied, the disassembly of `g_mutex_lock()` (for example) was: ``` 0x7ffff7f038b0 <g_mutex_lock> jmp 0x7ffff7f2f440 <g_mutex_lock_impl> 0x7ffff7f038b5 data16 cs nopw 0x0(%rax,%rax,1) ``` i.e. It jumps straight to the `_impl` function, even with an optimised build. Since `g_mutex_lock()` (and various other GThread functions) are frequently run hot paths, this additional `jmp` to a function which has ended up in a different code page is a slowdown which we’d rather avoid. So, this commit reworks things to define all the `_impl` functions as `G_ALWAYS_INLINE static inline` (which typically expands to `__attribute__((__always_inline__)) static inline`), and to move them into the same compilation unit as `gthread.c` so that they can be inlined without the need for link-time optimisation to be enabled. It makes the code a little less readable, but not much worse than what commit bc59e28bf6b0f70ff345aef80356d0076f44a0e7 already did. And perhaps the addition of the `inline` decorations to all the `_impl` functions will make it a bit clearer what their intended purpose is (platform-specific implementations). After applying this commit, the disassembly of `g_mutex_lock()` successfully contains the inlining for me: ``` => 0x00007ffff7f03d80 <+0>: xor %eax,%eax 0x00007ffff7f03d82 <+2>: mov $0x1,%edx 0x00007ffff7f03d87 <+7>: lock cmpxchg %edx,(%rdi) 0x00007ffff7f03d8b <+11>: jne 0x7ffff7f03d8e <g_mutex_lock+14> 0x00007ffff7f03d8d <+13>: ret 0x00007ffff7f03d8e <+14>: jmp 0x7ffff7f03610 <g_mutex_lock_slowpath> ``` I considered making a similar change to the other APIs touched in #3399 (GContentType, GAppInfo, GSpawn), but they are all much less performance critical, so it’s probably not worth making their code more complex for that sake. Signed-off-by: Philip Withnall <pwithnall@gnome.org> Fixes: #3417
GLib
GLib is the low-level core library that forms the basis for projects such as GTK and GNOME. It provides data structure handling for C, portability wrappers, and interfaces for such runtime functionality as an event loop, threads, dynamic loading, and an object system.
The official download locations are: https://download.gnome.org/sources/glib
The official web site is: https://www.gtk.org/
Installation
See the file ‘INSTALL.md’. There is separate and more in-depth documentation for building GLib on Windows.
Supported versions
Upstream GLib only supports the most recent stable release series, the previous stable release series, and the current development release series. All older versions are not supported upstream and may contain bugs, some of which may be exploitable security vulnerabilities.
See SECURITY.md for more details.
Documentation
API documentation is available online for GLib for the:
Discussion
If you have a question about how to use GLib, seek help on GNOME’s Discourse
instance. Alternatively, ask a question
on StackOverflow and tag it glib.
Reporting bugs
Bugs should be reported to the GNOME issue tracking system. You will need to create an account for yourself. You may also submit bugs by e-mail (without an account) by e-mailing incoming+gnome-glib-658-issue-@gitlab.gnome.org, but this will give you a degraded experience.
Bugs are for reporting problems in GLib itself, not for asking questions about how to use it. To ask questions, use one of our discussion forums.
In bug reports please include:
- Information about your system. For instance:
- What operating system and version
- For Linux, what version of the C library
- And anything else you think is relevant.
- How to reproduce the bug.
- If you can reproduce it with one of the test programs that are built
in the
tests/subdirectory, that will be most convenient. Otherwise, please include a short test program that exhibits the behavior. As a last resort, you can also provide a pointer to a larger piece of software that can be downloaded.
- If you can reproduce it with one of the test programs that are built
in the
- If the bug was a crash, the exact text that was printed out when the crash occurred.
- Further information such as stack traces may be useful, but is not necessary.
Contributing to GLib
Please follow the contribution guide to know how to start contributing to GLib.
Patches should be submitted as merge requests to gitlab.gnome.org. If the patch fixes an existing issue, please refer to the issue in your commit message with the following notation (for issue 123):
Closes: #123
Otherwise, create a new merge request that introduces the change. Filing a separate issue is not required.