mirror of
https://github.com/mozilla/gecko-dev.git
synced 2024-11-25 13:51:41 +00:00
Read-only Git mirror of the Mercurial gecko repositories at https://hg.mozilla.org. How to contribute: https://firefox-source-docs.mozilla.org/contributing/contribution_quickref.html
117f140c46
The IPC::Message header is surrounded by:
#pragma pack(push,2)
...
#pragma pack(pop)
which (at least on GCC) specifies that structure members defined lexically
within the pragma should be two-byte aligned, rather than the ABI's declared
alignment.
But for IPC::Message::Header, this is a silly requirement, as everything there
is four bytes; there's no reason to pack the members any tighter. And packing
tighter means that strict alignment platforms (like ARM) need to use more
complex code for something as simple as storing to one of the members--like
when we set a message's request ID, over and over and over. The current code
for setting a message's request ID on ARM looks like:
264: 6863 ldr r3, [r4, #4]
266: 696a ldr r2, [r5, #20]
268: 809a strh r2, [r3, #4]
26a: 0c12 lsrs r2, r2, #16
26c: 80da strh r2, [r3, #6]
With the patch, it looks like:
264: 6863 ldr r3, [r4, #4]
266: 696a ldr r2, [r5, #20]
268: 605a str r2, [r3, #4]
Only four bytes, but multiplied over several hundred set_routing_id calls, it
saves some code size and runtime. I verified that the header's length doesn't
change by looking at debug information.
|
||
|---|---|---|
| accessible | ||
| addon-sdk | ||
| b2g | ||
| browser | ||
| build | ||
| caps | ||
| chrome | ||
| config | ||
| content | ||
| db/sqlite3 | ||
| docshell | ||
| dom | ||
| editor | ||
| embedding | ||
| extensions | ||
| gfx | ||
| hal | ||
| image | ||
| intl | ||
| ipc | ||
| js | ||
| layout | ||
| media | ||
| memory | ||
| mfbt | ||
| mobile | ||
| modules | ||
| mozglue | ||
| netwerk | ||
| nsprpub | ||
| other-licenses | ||
| parser | ||
| probes | ||
| profile | ||
| python | ||
| rdf | ||
| security | ||
| services | ||
| startupcache | ||
| storage | ||
| testing | ||
| toolkit | ||
| tools | ||
| uriloader | ||
| view | ||
| webapprt | ||
| widget | ||
| xpcom | ||
| xpfe | ||
| xulrunner | ||
| .gdbinit | ||
| .gitignore | ||
| .hgignore | ||
| .hgtags | ||
| aclocal.m4 | ||
| Android.mk | ||
| AUTHORS | ||
| client.mk | ||
| client.py | ||
| CLOBBER | ||
| configure.in | ||
| LEGAL | ||
| LICENSE | ||
| mach | ||
| Makefile.in | ||
| moz.build | ||
| mozilla-config.h.in | ||
| README.txt | ||
An explanation of the Mozilla Source Code Directory Structure and links to
project pages with documentation can be found at:
https://developer.mozilla.org/en/Mozilla_Source_Code_Directory_Structure
For information on how to build Mozilla from the source code, see:
http://developer.mozilla.org/en/docs/Build_Documentation
To have your bug fix / feature added to Mozilla, you should create a patch and
submit it to Bugzilla (https://bugzilla.mozilla.org). Instructions are at:
http://developer.mozilla.org/en/docs/Creating_a_patch
http://developer.mozilla.org/en/docs/Getting_your_patch_in_the_tree
If you have a question about developing Mozilla, and can't find the solution
on http://developer.mozilla.org, you can try asking your question in a
mozilla.* Usenet group, or on IRC at irc.mozilla.org. [The Mozilla news groups
are accessible on Google Groups, or news.mozilla.org with a NNTP reader.]
You can download nightly development builds from the Mozilla FTP server.
Keep in mind that nightly builds, which are used by Mozilla developers for
testing, may be buggy. Firefox nightlies, for example, can be found at:
ftp://ftp.mozilla.org/pub/firefox/nightly/latest-trunk/
- or -
http://nightly.mozilla.org/