Currently static atoms are stored on the heap, but their char buffers are
stored in read-only static memory.
This patch changes the representation of nsStaticAtom (thus making it a
non-trivial subclass of nsAtom). Instead of a pointer to the string, it now has
an mStringOffset field which is a 32-bit offset to the string. (This requires
placement of the string and the atom within the same object so that the offset
is known to be small. The docs and macros in nsStaticAtom.h handle that.)
Static and dynamic atoms now store their chars in different ways: nsStaticAtom
stores them inline, nsDynamicAtom has a pointer to separate storage. So
`mString` and GetStringBuffer() move from nsAtom to nsDynamicAtom.
The change to static atoms means they can be made constexpr and stored in
read-only memory instead of on the heap. On 64-bit this reduces the per-process
overhead by 16 bytes; on 32-bit the saving is 12 bytes. (Further reductions
will be possible in follow-up patches.)
The increased use of constexpr required multiple workarounds for MSVC.
- Multiple uses of MOZ_{PUSH,POP}_DISABLE_INTEGRAL_CONSTANT_OVERFLOW_WARNING to
disable warnings about (well-defined!) overflow of unsigned integer
arithmetic.
- The use of -Zc:externConstexpr on all files defining static atoms, to make
MSVC follow the C++ standard(!) and let constexpr variables have external
linkage.
- The use of -constexpr:steps300000 to increase the number of operations
allowed in a constexpr value, in order to handle gGkAtoms, which requires
hashing ~2,500 atom strings.
The patch also changes how HTML5 atoms are handled. They are now treated as
dynamic atoms, i.e. we have "dynamic normal" atoms and "dynamic HTML5 atoms",
and "dynamic atoms" covers both cases, and both are represented via
nsDynamicAtom. The main difference between the two kinds is that dynamic HTML5
atoms still aren't allowed to be used in various operations, most notably
AddRef()/Release(). All this also required moving nsDynamicAtom into the header
file.
There is a slight performance cost to all these changes: now that nsStaticAtom
and nsDynamicAtom store their chars in different ways, a conditional branch is
required in the following functions: Equals(), GetUTF16String(),
WeakAtom::as_slice().
Finally, in about:memory the "explicit/atoms/static/atom-objects" value is no
longer needed, because that memory is static instead of heap-allocated.
MozReview-Commit-ID: 4AxPv05ngZy
The Windows and OSX code paths were essentially doing the same thing,
and the Unix fallback was using an old convention that is pretty much
outdated.
Under normal conditions (XPCOM initialized by Firefox),
NS_XPCOM_INIT_CURRENT_PROCESS_DIR is set from BinaryPath anyways, so
this only really affects adhoc XPCOM initialization from e.g. C++ unit
tests.
--HG--
extra : rebase_source : b3151fffd4c82159b633a48dead86f2c3b0a03d6
The Windows and OSX code paths were essentially doing the same thing,
and the Unix fallback was using an old convention that is pretty much
outdated.
Under normal conditions (XPCOM initialized by Firefox),
NS_XPCOM_INIT_CURRENT_PROCESS_DIR is set from BinaryPath anyways, so
this only really affects adhoc XPCOM initialization from e.g. C++ unit
tests.
--HG--
extra : rebase_source : b3151fffd4c82159b633a48dead86f2c3b0a03d6
The Windows and OSX code paths were essentially doing the same thing,
and the Unix fallback was using an old convention that is pretty much
outdated.
Under normal conditions (XPCOM initialized by Firefox),
NS_XPCOM_INIT_CURRENT_PROCESS_DIR is set from BinaryPath anyways, so
this only really affects adhoc XPCOM initialization from e.g. C++ unit
tests.
--HG--
extra : rebase_source : f7faa6f22ffc56fb4da7ae96eb571a35fa6f615d
Changes ExtensionProtocolHandler to use remote streams for
moz-extension loads of file and JAR URI's to allow for
filesystem read-access sandboxing.
Adds messaging to PNecko to allow child processes to
request an input stream or file descriptor for moz-extension
URI's.
Add ExtensionProtocolHandler singleton so that NeckoParent can
call methods directly and ExtensionProtocolHandler::NewFD
can use a new member variable |mFileOpenerThread| to open files.
Adds FileDescriptorFile, a limited implementation of nsIFile
that wraps a file descriptor, to be sideloaded into
nsJARChannels so that extension JAR files can be read
using a file descriptor without accessing the filesystem
directly.
MozReview-Commit-ID: 1pcnIpjz2yR
--HG--
extra : rebase_source : 9d7334778fc81837b11b98d4e32603f7e5eb3a27
Changes ExtensionProtocolHandler to use remote streams for
moz-extension loads of file and JAR URI's to allow for
filesystem read-access sandboxing.
Adds messaging to PNecko to allow child processes to
request an input stream or file descriptor for moz-extension
URI's.
Add ExtensionProtocolHandler singleton so that NeckoParent can
call methods directly and ExtensionProtocolHandler::NewFD
can use a new member variable |mFileOpenerThread| to open files.
Adds FileDescriptorFile, a limited implementation of nsIFile
that wraps a file descriptor, to be sideloaded into
nsJARChannels so that extension JAR files can be read
using a file descriptor without accessing the filesystem
directly.
MozReview-Commit-ID: 1pcnIpjz2yR
--HG--
extra : rebase_source : c3f2ede3dbfb29d98af6b194dbe58669d93d4197
This removes the unnecessary setting of c-basic-offset from all
python-mode files.
This was automatically generated using
perl -pi -e 's/; *c-basic-offset: *[0-9]+//'
... on the affected files.
The bulk of these files are moz.build files but there a few others as
well.
MozReview-Commit-ID: 2pPf3DEiZqx
--HG--
extra : rebase_source : 0a7dcac80b924174a2c429b093791148ea6ac204
As part of unblocking building with VS2015u1 in automation, I'm mass
disabling compiler warnings that are turned into errors. This is not
the preferred mechanism to fix compilation warnings. So hopefully
this patch never lands because someone insists of fixing the underlying
problem instead. But if it does land, hopefully the workaround is
only temporary.
MozReview-Commit-ID: 9AkkAUDMln6
--HG--
extra : rebase_source : 76126361de678729344b0e9eaeac1d523f88ebb4
The patch removes 455 occurrences of FAIL_ON_WARNINGS from moz.build files, and
adds 78 instances of ALLOW_COMPILER_WARNINGS. About half of those 78 are in
code we control and which should be removable with a little effort.
--HG--
extra : rebase_source : 82e3387abfbd5f1471e953961d301d3d97ed2973
Honza Bambas
Andrea Marchesini
Nicholas Nethercote
Sebastian Hengst
Sylvestre Ledru
Mike Hommey
Masatoshi Kimura
Haik Aftandilian
Phil Ringnalda
Tom Tromey
Chris Peterson
Gregory Szorc
Wilmer Paulino
David Major
Ben Kelly
Ehsan Akhgari
Aaron Klotz
Daniel Holbert