Instead of trying to keep a live reference to the bytecode interpreter's
current instruction stream iterator, we now simply copy the current
iterator whenever pushing to the ExecutionContext stack.
This fixes a stack-use-after-return issue reported by ASAN.
This change introduces a very basic GC graph dumper. The `dump_graph()`
function outputs JSON data that contains information about all nodes in
the graph, including their class types and edges.
Root nodes will have a property indicating their root type or source
location if the root is captured by a SafeFunction. It would be useful
to add source location for other types of roots in the future.
Output JSON dump have following format:
```json
"4908721208": {
"class_name": "Accessor",
"edges": [
"4909298232",
"4909297976"
]
},
"4907520440": {
"root": "SafeFunction Optional Optional.h:137",
"class_name": "Realm",
"edges": [
"4908269624",
"4924821560",
"4908409240",
"4908483960",
"4924527672"
]
},
"4908251320": {
"class_name": "CSSStyleRule",
"edges": [
"4908302648",
"4925101656",
"4908251192"
]
},
```
This makes it easy to set up a realm, global object and root execution
context with a single call to LibJS. It will be useful to basically
everyone except LibWeb.
Cell::heap() and Cell::vm() needed to access member functions from
HeapBlock, and wanted to be inline, so they were moved to VM.h.
That approach will no longer work with VM.h not being included in every
file (starting from the next commit), so this commit fixes that circular
import issue by introducing secondary base classes to host the
references to Heap and VM, respectively.
This is in preparation for an upcoming implementation of the Iterator
Helpers proposal. That proposal will require a JS::Object type named
"Iterator", so this rename is to avoid conflicts.
The JS::VM now owns the one Bytecode::Interpreter. We no longer have
multiple bytecode interpreters, and there is no concept of a "current"
bytecode interpreter.
If you ask for VM::bytecode_interpreter_if_exists(), it will return null
if we're not running the program in "bytecode enabled" mode.
If you ask for VM::bytecode_interpreter(), it will return a bytecode
interpreter in all modes. This is used for situations where even the AST
interpreter switches to bytecode mode (generators, etc.)
Don't try to implement this AO in bytecode. Instead, the bytecode
Interpreter class now has a run() API with the same inputs as the AST
interpreter. It sets up the necessary environments etc, including
invoking the GlobalDeclarationInstantiation AO.
This includes an Error::create overload to create an Error from a UTF-8
StringView. If creating a String from that view fails, the factory will
return an OOM InternalError instead. VM::throw_completion can also make
use of this overload via its perfect forwarding.
If we are out of memory, we can't try to allocate a string that could
fail as well. When Error is converted to String, this would result in an
endless OOM-throwing loop. Instead, pre-allocate the string on the VM,
and use it to construct the Error.
Note that as of this commit, the OOM string is still a DeprecatedString.
This is just preporatory for Error's conversion to String.
This will temporarily bloat the size of PrimitiveString as LibJS is
transitioned to use String throughout, but will make doing so piecemeal
much easier.
DeprecatedFlyString relies heavily on DeprecatedString's StringImpl, so
let's rename it to A) match the name of DeprecatedString, B) write a new
FlyString class that is tied to String.
This makes more sense as an Object method rather than living within the
VM class for no good reason. Most of the other 7.3.xx AOs already work
the same way.
Also add spec comments while we're here.
We have a new, improved string type coming up in AK (OOM aware, no null
state), and while it's going to use UTF-8, the name UTF8String is a
mouthful - so let's free up the String name by renaming the existing
class.
Making the old one have an annoying name will hopefully also help with
quick adoption :^)
A struct with three raw pointers to other GC'd types is a pretty big
liability, let's just turn this into a Cell itself.
This comes with the additional benefit of being able to capture it in
a lambda effortlessly, without having to create handles for individual
members.
Instead of calling Core::EventLoop directly, LibJS now has a virtual
function on VM::CustomData for customizing this behavior.
We use this in LibWeb to plumb the spin request through to the
PlatformEventPlugin.
This removes the requirement of having a global object that actually
inherits from JS::GlobalObject, which is now a perfectly valid scenario.
With the upcoming removal of wrapper objects in LibWeb, the HTML::Window
object will inherit from DOM::EventTarget, which means it cannot also
inherit from JS::GlobalObject.
This is a continuation of the previous six commits.
The global object is only needed to return it if the execution context
stack is empty, but that doesn't seem like a useful thing to allow in
the first place - if you're not currently executing JS, and the
execution context stack is empty, there is no this value to retrieve.
