Intrinsics, i.e. mostly constructor and prototype objects, but also
things like empty and new object shape now live on a new heap-allocated
JS::Intrinsics object, thus completing the long journey of taking all
the magic away from the global object.
This represents the Realm's [[Intrinsics]] slot in the spec and matches
its existing [[GlobalObject]] / [[GlobalEnv]] slots in terms of
architecture.
In the majority of cases it should now be possibly to fully allocate a
regular object without the global object existing, and in fact that's
what we do now - the realm is allocated before the global object, and
the intrinsics between both :^)
The basic idea is that a global object cannot just come out of nowhere,
it must be associated to a realm - so get it from there, if needed.
This is to enforce the changes from all the previous commits by not
handing out global objects unless you actually have an initialized
realm (either stored somewhere, or the VM's current realm).
- Prefer VM::current_realm() over GlobalObject::associated_realm()
- Prefer VM::heap() over GlobalObject::heap()
- Prefer Cell::vm() over Cell::global_object()
- Prefer Wrapper::vm() over Wrapper::global_object()
- Inline Realm::global_object() calls used to access intrinsics as they
will later perform a direct lookup without going through the global
object
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.
This is a continuation of the previous five commits.
A first big step into the direction of no longer having to pass a realm
(or currently, a global object) trough layers upon layers of AOs!
Unlike the create() APIs we can safely assume that this is only ever
called when a running execution context and therefore current realm
exists. If not, you can always manually allocate the Error and put it in
a Completion :^)
In the spec, throw exceptions implicitly use the current realm's
intrinsics as well: https://tc39.es/ecma262/#sec-throw-an-exception
This is a continuation of the previous four commits.
Passing a global object here is largely redundant, we definitely need
the interpreter but can get the VM and (later) current active realm from
there - and also the global object while we still need it, although I'd
like to remove Interpreter::global_object() in the future.
This now matches the bytecode interpreter's execute_impl() functions.
This is a continuation of the previous three commits.
Now that create() receives the allocating realm, we can simply forward
that to allocate(), which accounts for the majority of these changes.
Additionally, we can get rid of the realm_from_global_object() in one
place, with one more remaining in VM::throw_completion().
This is a continuation of the previous two commits.
As allocating a JS cell already primarily involves a realm instead of a
global object, and we'll need to pass one to the allocate() function
itself eventually (it's bridged via the global object right now), the
create() functions need to receive a realm as well.
The plan is for this to be the highest-level function that actually
receives a realm and passes it around, AOs on an even higher level will
use the "current realm" concept via VM::current_realm() as that's what
the spec assumes; passing around realms (or global objects, for that
matter) on higher AO levels is pointless and unlike for allocating
individual objects, which may happen outside of regular JS execution, we
don't need control over the specific realm that is being used there.
This is no longer required, since the variable scope is ended after
switching to the end block, which means that LeaveLexicalEnvironment
will always be generated instead of depending on the unwind mechanism
to handle it for us.
BlockDeclarationInstantiation takes as input the new lexical
environment that was created and checks if there is a binding for the
current name only in this new scope.
This allows shadowing lexical variables and prevents us crashing due to
an already initialized lexical variable in this case:
```js
let x = 1;
{
let x = 1;
}
```
An executable is generated for the top-level script and for each
function. Strict mode can only be changed with the first statement of
the top-level script and each function, which corresponds directly to
Executable.
This prevents us from needing a sv suffix, and potentially reduces the
need to run generic code for a single character (as contains,
starts_with, ends_with etc. for a char will be just a length and
equality check).
No functional changes.
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).
No functional changes.
If the for loop's body is not block terminated, we will generate a Jump
to the end block which will block terminate the body. Then, we ended
the lexical variable scope if needed. However, since the body is now
block terminated, the "LeaveLexicalEnvironment" instruction that is
generated by end_variable_scope is now dropped on the floor.
This fixes this by moving it to the beginning of the end block.
Previously we only did this if the body block was not terminated.
If it was, all future codegen would happen in this block terminated
body block until another switch occurred, dropping all generated
instructions in this time on the floor.
This allows you to recurse into a named function that is stored in a
variable. For example, this would previously print "wrong" instead of
"right":
```js
function g() { console.log("wrong") }
f = function g(i) { if (i !== 1) g(1); else console.log("right"); }
f()
```
Previously it would pass in `is_arrow_function` as
`contains_direct_call_to_eval`, which broke strict mode propagation in
arrow functions. This makes test-js work without falling apart because
`this` is mysteriously undefined because of the use of arrow functions
inside classes, which are strict mode by default.
This is done by keeping track of all the labels that apply to a given
break/continue scope alongside their bytecode target. When a
break/continue with a label is generated, we scan from the most inner
scope to the most outer scope looking for the label, performing any
necessary unwinds on the way. Once the label is found, it is then
jumped to.
`delete` has to operate directly on Reference Records, so this
introduces a new set of operations called DeleteByValue, DeleteVariable
and DeleteById. They operate similarly to their Get counterparts,
except they end in creating a (temporary) Reference and calling delete_
on it.
When calling emit_load_from_reference with a MemberExpression, it is
only necessary to store the result of evaluating MemberExpression's
object when performing computed property lookup.
This allows us to skip unnecessary stores for identifier lookup.
For example, this would generate 3 unnecessary stores:
```
> Temporal.PlainDateTime.prototype.add
JS::Bytecode::Executable (REPL)
1:
[ 0] GetVariable 0 (Temporal)
[ 28] Store $2
[ 30] GetById 1 (PlainDateTime)
[ 40] Store $3
[ 48] GetById 2 (prototype)
[ 58] Store $4
[ 60] GetById 3 (add)
```
With this, it generates:
```
> Temporal.PlainDateTime.prototype.add
JS::Bytecode::Executable (REPL)
1:
[ 0] GetVariable 0 (Temporal)
[ 28] GetById 1 (PlainDateTime)
[ 38] GetById 2 (prototype)
[ 48] GetById 3 (add)
```
The body of for/in/of can contain an unconditional block terminator
(e.g. return, throw), so we have to check for that before generating
the Jump to the loop update block.
NewArray now only contains two elements maximum in `m_elements` to
indicate the range of registers to create the array from.
However, `m_element_count` still contains how many registers are in the
range and the stringifier was not updated to account for this. Thus, if
the range contained more than 2 registers, it would do a read OOB on
`m_elements`.
This makes it now just print the first and second entries in
`m_elements` in the format of `[<reg>-<reg>]`.
