By moving the LHS and RHS pointers used by rope strings into a
RopeString subclass, we shrink PrimitiveString by 16 bytes. Most strings
are not rope strings, so this ends up saving quite a bit of memory.
Previously, all `GC::Cell` derived classes were Weakable. Marking only
those classes that require this functionality as Weakable allows us to
reduce the memory footprint of some frequently used classes.
PrimitiveString is now internally either UTF-8, UTF-16, or both.
We no longer convert them to/from ByteString anywhere, nor does VM have
a ByteString cache.
If we don't have parameter expressions, we don't need to collect
metadata about whether instantiated var names collide with parameter
names or function names, as these flags are only used in the parameter
code path.
This avoids going through all the shape transitions when setting up the
most common form of ESFO.
This is extremely hot on Uber Eats, and this provides some relief.
Instead of making a copy of the Vector<FunctionParameter> from the AST
every time we instantiate an ECMAScriptFunctionObject, we now keep the
parameters in a ref-counted FunctionParameters object.
This reduces memory usage, and also allows us to cache the bytecode
executables for default parameter expressions without recompiling them
for every instantiation. :^)
The JS runtime is full of checks for is<NumberObject> and friends.
They were showing up in a Speedometer profile as ~1% spent in
dynamic_cast, and this basically chops that down to nothing.
We should always prefer working with String, and Value::to_string() may
even return a cached String if the Value refers to a primitive string,
but no caching occurs for ByteString.
Previously, `String.prototype.split()` caused the construction of a
temporary StringObject when a string primitive was passed as an
argument, solely to perform a Symbol.split lookup. This change allows
skipping that allocation by looking directly into the prototype of
primitive values.
As a result, we can avoid ~200000 StringObject allocations in a single
test from the Speedometer 2 benchmark.
Co-Authored-By: Andreas Kling <andreas@ladybird.org>
Currently, we create `this_argument` with
`ordinary_create_from_constructor`, then we use `arguments_list` to
build the callee_context.
The issue is we don't properly model the side-effects of
`ordinary_create_from_constructor`, if `new_target` is a proxy object
then when we `get` the prototype, arbitrary javascript can run.
This javascript could perform a function call with enough arguments to
reallocate the interpreters m_argument_values_buffer vector. This is
dangerous and leads to a use-after-free, as our stack frame maintains a
pointer to m_argument_values_buffer (`arguments_list`).
This is a normative change in the ECMA-402 spec. See:
7508197
In our implementation, we don't have the affected AOs directly, as we
delegate to ICU. So instead, we must ensure we provide ICU a locale with
the relevant extension keys present.
This is a normative change in the Temporal proposal. See:
bd5ac12
Note: No test added here because this only affects non-ISO-8601
calendars, which we do not yet support.
This is an editorial change in the Temporal proposal. See:
03770bb
Note: We were actually already using the Temporal definition of this AO
in Intl.DurationFormat, so there's no change needed there.
These are going to be included in the ECMA-262 AOs once Temporal reaches
stage 4. There's no need to keep them in the Temporal namespace. Some
upcoming Temporal editorial changes will get awkward without this patch.
If the regex always matches the input, even if it's past the end, then
we need to stop execution of the regex when it's past the end. This
corresponds to step 13.a and prevents it from infinitely looping.
Reduced from: d98672060f/packages/react-i18n/src/utilities/money.ts (L10-L14)
