This function uses a nsAutoString internally, and its caller stores its
returned value in a nsAutoString. So it's silly for us to have it return a
different type (nsString). With this change, the compiler should be able to
perform return value optimization and avoid the need for any
copying/reallocation of this function's return value.
Differential Revision: https://phabricator.services.mozilla.com/D3926
--HG--
extra : moz-landing-system : lando
Correctness improvements:
* UTF errors are handled safely per spec instead of dangerously truncating
strings.
* There are fewer converter implementations.
Performance improvements:
* The old code did exact buffer length math, which meant doing UTF math twice
on each input string (once for length calculation and another time for
conversion). Exact length math is more complicated when handling errors
properly, which the old code didn't do. The new code does UTF math on the
string content only once (when converting) but risks allocating more than
once. There are heuristics in place to lower the probability of
reallocation in cases where the double math avoidance isn't enough of a
saving to absorb an allocation and memcpy.
* Previously, in UTF-16 <-> UTF-8 conversions, an ASCII prefix was optimized
but a single non-ASCII code point pessimized the rest of the string. The
new code tries to get back on the fast ASCII path.
* UTF-16 to Latin1 conversion guarantees less about handling of out-of-range
input to eliminate an operation from the inner loop on x86/x86_64.
* When assigning to a pre-existing string, the new code tries to reuse the
old buffer instead of first releasing the old buffer and then allocating a
new one.
* When reallocating from the new code, the memcpy covers only the data that
is part of the logical length of the old string instead of memcpying the
whole capacity. (For old callers old excess memcpy behavior is preserved
due to bogus callers. See bug 1472113.)
* UTF-8 strings in XPConnect that are in the Latin1 range are passed to
SpiderMonkey as Latin1.
New features:
* Conversion between UTF-8 and Latin1 is added in order to enable faster
future interop between Rust code (or otherwise UTF-8-using code) and text
node and SpiderMonkey code that uses Latin1.
MozReview-Commit-ID: JaJuExfILM9
This commit adds the ability to create a different kind of DrawTargetCapture which
has a limit on the size of which its CaptureCommandList can grow before it is
synchronously flushed to its destination DrawTarget.
Special care is taken to not do a sync flush until we would need to resize
the backing store of the CaptureCommandList. This allows us to not waste
memory we've already allocated.
The async painting content clients are updated to use it, and get a default
value from a new preference.
MozReview-Commit-ID: CJL7ffvaRzR
--HG--
extra : rebase_source : 546d9838808320c51d9ceef0ed0ffcbb88a16269
This introduces the machinery needed to generate crash annotations from a YAML
file. The relevant C++ functions are updated to take a typed enum. JavaScript
calls are unaffected but they will throw if the string argument does not
correspond to one of the known entries in the C++ enum. The existing whitelists
and blacklists of annotations are also generated from the YAML file and all
duplicate code related to them has been consolidated. Once written out to the
.extra file the annotations are converted in string form and are no different
than the existing ones.
All existing annotations have been included in the list (and some obsolete ones
have been removed) and all call sites have been updated including tests where
appropriate.
--HG--
extra : source : 4f6c43f2830701ec5552e08e3f1b06fe6d045860
This commit adds the ability to create a different kind of DrawTargetCapture which
has a limit on the size of which its CaptureCommandList can grow before it is
synchronously flushed to its destination DrawTarget.
Special care is taken to not do a sync flush until we would need to resize
the backing store of the CaptureCommandList. This allows us to not waste
memory we've already allocated.
The async painting content clients are updated to use it, and get a default
value from a new preference.
MozReview-Commit-ID: CJL7ffvaRzR
--HG--
extra : rebase_source : f646862dcef7a480b21dfb7ddb1fa165338ba506
extra : source : b865a866fe5a3257615cb54b7e5e790cc9331988
Everything that goes in a PLDHashtable (and its derivatives, like
nsTHashtable) needs to inherit from PLDHashEntryHdr. But through a lack
of enforcement, copy constructors for these derived classes didn't
explicitly invoke the copy constructor for PLDHashEntryHdr (and the
compiler didn't invoke the copy constructor for us). Instead,
PLDHashTable explicitly copied around the bits that the copy constructor
would have.
The current setup has two problems:
1) Derived classes should be using move construction, not copy
construction, since anything that's shuffling hash table keys/entries
around will be using move construction.
2) Derived classes should take responsibility for transferring bits of
superclass state around, and not rely on something else to handle
that.
The second point is not a huge problem for PLDHashTable (PLDHashTable
only has to copy PLDHashEntryHdr's bits in a single place), but future
hash table implementations that might move entries around more
aggressively would have to insert compensation code all over the place.
Additionally, if moving entries is implemented via memcpy (which is
quite common), PLDHashTable copying around bits *again* is inefficient.
Let's fix all these problems in one go, by:
1) Explicitly declaring the set of constructors that PLDHashEntryHdr
implements (and does not implement). In particular, the copy
constructor is deleted, so any derived classes that attempt to make
themselves copyable will be detected at compile time: the compiler
will complain that the superclass type is not copyable.
This change on its own will result in many compiler errors, so...
2) Change any derived classes to implement move constructors instead
of copy constructors. Note that some of these move constructors are,
strictly speaking, unnecessary, since the relevant classes are moved
via memcpy in nsTHashtable and its derivatives.
Much like the component manager, many of the strings that we use for category
manager entries are statically allocated. There's no need to duplicate these
strings.
This patch changes the category manager APIs to take nsACStrings rather than
raw pointers, and to pass literal nsCStrings when we know we have a literal
string to begin with. When adding the category entry, it then skips making
copies of any strings with the LITERAL flag.
MozReview-Commit-ID: EJEcYSdNMWs
***
amend-catman
--HG--
extra : source : aa9a8f18e98f930a3d8359565eef02f3f6efc5f9
extra : absorb_source : 81a22ab26ee8017ac43321ff2c987d8096182d37
Much like the component manager, many of the strings that we use for category
manager entries are statically allocated. There's no need to duplicate these
strings.
This patch changes the category manager APIs to take nsACStrings rather than
raw pointers, and to pass literal nsCStrings when we know we have a literal
string to begin with. When adding the category entry, it then skips making
copies of any strings with the LITERAL flag.
MozReview-Commit-ID: EJEcYSdNMWs
***
amend-catman
--HG--
extra : rebase_source : 4f70e7b296ecf3b52a4892c92155c7c163d424d2
