TypedArray constructors/prototypes are currently allocating within their
C++ constructor when trying to access the intrinsic base TypedArray. To
prevent this, construct these objects with an already-allocated base
TypedArray.
We are currently allocating in Set's constructor to create the set's
underlying Map. This can cause GC to occur before the member is actually
initialized, thus we will crash in Set::visit_edges trying to visit a
member that does not exist.
Instead, create the Map in Set::initialize, where we can allocate. Also
change Map to be stored as a normal JS heap-allocated object, rather
than as a stack variable.
The bytecode interpreter can execute generator functions while the AST
interpreter cannot. This simply makes it create a new bytecode
interpreter when one doesn't exist when executing a generator function.
Doing so makes it automatically switch to the bytecode interpreter to
execute any future code until it exits the generator.
Previously, throw and return completions would not be executed inside
the generator. This is incorrect, as throw and return need to perform
unwinds which can potentially execute more code inside the generator,
such as finally blocks.
This is done by also passing the completion type alongside the passed
in value. The continuation block will immediately extract and type and
value and perform the appropriate operation for the given type.
For normal completions, this is continuing as normal.
For throw completions, it will perform `throw <value>`.
For return completions, it will perform `return <value>`, which is a
`Yield return` in this case due to being inside a generator.
This also refactors GeneratorObject to properly send across the
completion type and value to the generator inside of trying to operate
on the completions itself.
This is a prerequisite for yield*, as it performs special iterator
operations when receiving a throw/return completion and does not
complete the generator like the regular yield would.
There's still more work to be done to make GeneratorObject::execute
be closer to the spec. It's mostly a restructuring of the existing
GeneratorObject::next_impl.
For performance, it is desirable to defer evaluation of intrinsics that
are stored on the GlobalObject for every created Realm. To support this,
Object now maintains a global storage map to store lambdas that will
return the associated intrinsic when evaluated. Once accessed, the
instrinsic is moved from this global map to normal Object storage.
To prevent this flow from becoming observable, when a deferred intrinsic
is stored, we still place an empty object in the normal Object storage.
This is so we still create the metadata for the object, and in doing so,
can preserve insertion order of the Object storage. Otherwise, this will
be observable by way of Object.getOwnPropertyDescriptors.
This changes Intrinsics to not initialize most of its constructors and
prototype right away. We still initialize a few that are needed before
some others are created, though we may eventually be able to "link"
dependencies at compile time to avoid this.
This patch does two things:
- We now use u32 instead of size_t for the hops and index fields
in EnvironmentCoordinate. This means we're limited to an environment
nesting level and variable count of 4Gs respectively.
- Instead of wrapping it in an Optional, EnvironmentCoordinate now has
a custom valid/invalid state using a magic marker value.
These two changes reduce the size of Identifier by 16 bytes. :^)
Before this change, each AST node had a 64-byte SourceRange member.
This SourceRange had the following layout:
filename: StringView (16 bytes)
start: Position (24 bytes)
end: Position (24 bytes)
The Position structs have { line, column, offset }, all members size_t.
To reduce memory consumption, AST nodes now only store the following:
source_code: NonnullRefPtr<SourceCode> (8 bytes)
start_offset: u32 (4 bytes)
end_offset: u32 (4 bytes)
SourceCode is a new ref-counted data structure that keeps the filename
and original parsed source code in a single location, and all AST nodes
have a pointer to it.
The start_offset and end_offset can be turned into (line, column) when
necessary by calling SourceCode::range_from_offsets(). This will walk
the source code string and compute line/column numbers on the fly, so
it's not necessarily fast, but it should be rare since this information
is primarily used for diagnostics and exception stack traces.
With this, ASTNode shrinks from 80 bytes to 32 bytes. This gives us a
~23% reduction in memory usage when loading twitter.com/awesomekling
(330 MiB before, 253 MiB after!) :^)
