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LibJS+Clients: Add JS::VM object, separate Heap from Interpreter

Taking a big step towards a world of multiple global object, this patch
adds a new JS::VM object that houses the JS::Heap.

This means that the Heap moves out of Interpreter, and the same Heap
can now be used by multiple Interpreters, and can also outlive them.

The VM keeps a stack of Interpreter pointers. We push/pop on this
stack when entering/exiting execution with a given Interpreter.
This allows us to make this change without disturbing too much of
the existing code.

There is still a 1-to-1 relationship between Interpreter and the
global object. This will change in the future.

Ultimately, the goal here is to make Interpreter a transient object
that only needs to exist while you execute some code. Getting there
will take a lot more work though. :^)

Note that in LibWeb, the global JS::VM is called main_thread_vm(),
to distinguish it from future worker VM's.
This commit is contained in:
Andreas Kling 2020-09-20 19:24:44 +02:00
parent c6ae0c41d9
commit 1c43442be4
13 changed files with 218 additions and 27 deletions

View file

@ -34,11 +34,13 @@
#include <LibJS/AST.h>
#include <LibJS/Console.h>
#include <LibJS/Forward.h>
#include <LibJS/Heap/DeferGC.h>
#include <LibJS/Heap/Heap.h>
#include <LibJS/Runtime/ErrorTypes.h>
#include <LibJS/Runtime/Exception.h>
#include <LibJS/Runtime/LexicalEnvironment.h>
#include <LibJS/Runtime/MarkedValueList.h>
#include <LibJS/Runtime/VM.h>
#include <LibJS/Runtime/Value.h>
namespace JS {
@ -75,11 +77,13 @@ typedef Vector<Argument, 8> ArgumentVector;
class Interpreter : public Weakable<Interpreter> {
public:
template<typename GlobalObjectType, typename... Args>
static NonnullOwnPtr<Interpreter> create(Args&&... args)
static NonnullOwnPtr<Interpreter> create(VM& vm, Args&&... args)
{
auto interpreter = adopt_own(*new Interpreter);
interpreter->m_global_object = interpreter->heap().allocate_without_global_object<GlobalObjectType>(forward<Args>(args)...);
static_cast<GlobalObjectType*>(interpreter->m_global_object)->initialize();
DeferGC defer_gc(vm.heap());
auto interpreter = adopt_own(*new Interpreter(vm));
VM::InterpreterScope scope(*interpreter);
interpreter->m_global_object = make_handle(static_cast<Object*>(interpreter->heap().allocate_without_global_object<GlobalObjectType>(forward<Args>(args)...)));
static_cast<GlobalObjectType*>(interpreter->m_global_object.cell())->initialize();
return interpreter;
}
@ -107,7 +111,8 @@ public:
GlobalObject& global_object();
const GlobalObject& global_object() const;
Heap& heap() { return m_heap; }
VM& vm() { return *m_vm; }
Heap& heap() { return vm().heap(); }
void unwind(ScopeType type, FlyString label = {})
{
@ -234,18 +239,18 @@ public:
#undef __JS_ENUMERATE
private:
Interpreter();
explicit Interpreter(VM&);
[[nodiscard]] Value call_internal(Function&, Value this_value, Optional<MarkedValueList>);
Heap m_heap;
NonnullRefPtr<VM> m_vm;
Value m_last_value;
Vector<ScopeFrame> m_scope_stack;
Vector<CallFrame> m_call_stack;
Object* m_global_object { nullptr };
Handle<Object> m_global_object;
Exception* m_exception { nullptr };