LibJS/Bytecode: Simplify Bytecode::Interpreter lifetime model

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.)

Meta/Lagom/Wasm/js_repl.cpp

@@ -102,7 +102,6 @@ private:
 };
 
 static bool s_dump_ast = false;
-static bool s_run_bytecode = false;
 static bool s_as_module = false;
 static bool s_print_last_result = false;
 
@@ -119,9 +118,8 @@ static ErrorOr<bool> parse_and_run(JS::Interpreter& interpreter, StringView sour
         if (s_dump_ast)
             script_or_module->parse_node().dump(0);
 
-        if (s_run_bytecode) {
+        if (auto* bytecode_interpreter = g_vm->bytecode_interpreter_if_exists()) {
-            JS::Bytecode::Interpreter bytecode_interpreter(interpreter.realm());
+            result = bytecode_interpreter->run(*script_or_module);
-            result = bytecode_interpreter.run(*script_or_module);
         } else {
             result = interpreter.run(*script_or_module);
         }

Tests/LibJS/test262-runner.cpp

@@ -215,12 +215,10 @@ static Result<void, TestError> run_test(StringView source, StringView filepath,
     if (program_or_error.is_error())
         return program_or_error.release_error();
 
-    OwnPtr<JS::Bytecode::Interpreter> bytecode_interpreter = nullptr;
+    auto* bytecode_interpreter = vm->bytecode_interpreter_if_exists();
-    if (JS::Bytecode::Interpreter::enabled())
-        bytecode_interpreter = make<JS::Bytecode::Interpreter>(realm);
 
     auto run_with_interpreter = [&](ScriptOrModuleProgram& program) {
-        if (JS::Bytecode::Interpreter::enabled())
+        if (bytecode_interpreter)
             return run_program(*bytecode_interpreter, program);
         return run_program(*ast_interpreter, program);
     };

Userland/Libraries/LibJS/Bytecode/Interpreter.cpp

@@ -32,26 +32,15 @@ void Interpreter::set_enabled(bool enabled)
     s_bytecode_interpreter_enabled = enabled;
 }
 
-static Interpreter* s_current;
 bool g_dump_bytecode = false;
 
-Interpreter* Interpreter::current()
+Interpreter::Interpreter(VM& vm)
+    : m_vm(vm)
 {
-    return s_current;
-}
-
-Interpreter::Interpreter(Realm& realm)
-    : m_vm(realm.vm())
-    , m_realm(realm)
-{
-    VERIFY(!s_current);
-    s_current = this;
 }
 
 Interpreter::~Interpreter()
 {
-    VERIFY(s_current == this);
-    s_current = nullptr;
 }
 
 // 16.1.6 ScriptEvaluation ( scriptRecord ), https://tc39.es/ecma262/#sec-runtime-semantics-scriptevaluation
@@ -124,7 +113,7 @@ ThrowCompletionOr<Value> Interpreter::run(Script& script_record, JS::GCPtr<Envir
                 executable->dump();
 
             // a. Set result to the result of evaluating script.
-            auto result_or_error = run_and_return_frame(*executable, nullptr);
+            auto result_or_error = run_and_return_frame(script_record.realm(), *executable, nullptr);
             if (result_or_error.value.is_error())
                 result = result_or_error.value.release_error();
             else
@@ -189,7 +178,7 @@ void Interpreter::set_optimizations_enabled(bool enabled)
     m_optimizations_enabled = enabled;
 }
 
-Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& executable, BasicBlock const* entry_point, RegisterWindow* in_frame)
+Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Realm& realm, Executable const& executable, BasicBlock const* entry_point, RegisterWindow* in_frame)
 {
     dbgln_if(JS_BYTECODE_DEBUG, "Bytecode::Interpreter will run unit {:p}", &executable);
 
@@ -201,12 +190,12 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable const& e
     ExecutionContext execution_context(vm().heap());
     if (vm().execution_context_stack().is_empty() || !vm().running_execution_context().lexical_environment) {
         // The "normal" interpreter pushes an execution context without environment so in that case we also want to push one.
-        execution_context.this_value = &m_realm->global_object();
+        execution_context.this_value = &realm.global_object();
         static DeprecatedFlyString global_execution_context_name = "(*BC* global execution context)";
         execution_context.function_name = global_execution_context_name;
-        execution_context.lexical_environment = &m_realm->global_environment();
+        execution_context.lexical_environment = &realm.global_environment();
-        execution_context.variable_environment = &m_realm->global_environment();
+        execution_context.variable_environment = &realm.global_environment();
-        execution_context.realm = m_realm;
+        execution_context.realm = realm;
         execution_context.is_strict_mode = executable.is_strict_mode;
         vm().push_execution_context(execution_context);
         pushed_execution_context = true;
@@ -395,10 +384,10 @@ ThrowCompletionOr<void> Interpreter::continue_pending_unwind(Label const& resume
     return {};
 }
 
-VM::InterpreterExecutionScope Interpreter::ast_interpreter_scope()
+VM::InterpreterExecutionScope Interpreter::ast_interpreter_scope(Realm& realm)
 {
     if (!m_ast_interpreter)
-        m_ast_interpreter = JS::Interpreter::create_with_existing_realm(m_realm);
+        m_ast_interpreter = JS::Interpreter::create_with_existing_realm(realm);
 
     return { *m_ast_interpreter };
 }
@@ -449,4 +438,29 @@ DeprecatedString Interpreter::debug_position() const
     return DeprecatedString::formatted("{}:{:2}:{:4x}", m_current_executable->name, m_current_block->name(), pc());
 }
 
+ThrowCompletionOr<NonnullOwnPtr<Bytecode::Executable>> compile(VM& vm, ASTNode const& node, FunctionKind kind, DeprecatedFlyString const& name)
+{
+    auto executable_result = Bytecode::Generator::generate(node, kind);
+    if (executable_result.is_error())
+        return vm.throw_completion<InternalError>(ErrorType::NotImplemented, TRY_OR_THROW_OOM(vm, executable_result.error().to_string()));
+
+    auto bytecode_executable = executable_result.release_value();
+    bytecode_executable->name = name;
+    auto& passes = Bytecode::Interpreter::optimization_pipeline();
+    passes.perform(*bytecode_executable);
+    if constexpr (JS_BYTECODE_DEBUG) {
+        dbgln("Optimisation passes took {}us", passes.elapsed());
+        dbgln("Compiled Bytecode::Block for function '{}':", name);
+    }
+    if (Bytecode::g_dump_bytecode)
+        bytecode_executable->dump();
+
+    return bytecode_executable;
+}
+
+Realm& Interpreter::realm()
+{
+    return *m_vm.current_realm();
+}
+
 }

Userland/Libraries/LibJS/Bytecode/Interpreter.h

@@ -11,6 +11,7 @@
 #include <LibJS/Forward.h>
 #include <LibJS/Heap/Cell.h>
 #include <LibJS/Heap/Handle.h>
+#include <LibJS/Runtime/FunctionKind.h>
 #include <LibJS/Runtime/VM.h>
 #include <LibJS/Runtime/Value.h>
 
@@ -31,13 +32,10 @@ public:
     [[nodiscard]] static bool enabled();
     static void set_enabled(bool);
 
-    explicit Interpreter(Realm&);
+    explicit Interpreter(VM&);
     ~Interpreter();
 
-    // FIXME: Remove this thing once we don't need it anymore!
+    Realm& realm();
-    static Interpreter* current();
-
-    Realm& realm() { return m_realm; }
     VM& vm() { return m_vm; }
 
     void set_optimizations_enabled(bool);
@@ -45,9 +43,9 @@ public:
     ThrowCompletionOr<Value> run(Script&, JS::GCPtr<Environment> lexical_environment_override = nullptr);
     ThrowCompletionOr<Value> run(SourceTextModule&);
 
-    ThrowCompletionOr<Value> run(Bytecode::Executable const& executable, Bytecode::BasicBlock const* entry_point = nullptr)
+    ThrowCompletionOr<Value> run(Realm& realm, Bytecode::Executable const& executable, Bytecode::BasicBlock const* entry_point = nullptr)
     {
-        auto value_and_frame = run_and_return_frame(executable, entry_point);
+        auto value_and_frame = run_and_return_frame(realm, executable, entry_point);
         return move(value_and_frame.value);
     }
 
@@ -55,7 +53,7 @@ public:
         ThrowCompletionOr<Value> value;
         OwnPtr<RegisterWindow> frame;
     };
-    ValueAndFrame run_and_return_frame(Bytecode::Executable const&, Bytecode::BasicBlock const* entry_point, RegisterWindow* = nullptr);
+    ValueAndFrame run_and_return_frame(Realm&, Bytecode::Executable const&, Bytecode::BasicBlock const* entry_point, RegisterWindow* = nullptr);
 
     ALWAYS_INLINE Value& accumulator() { return reg(Register::accumulator()); }
     Value& reg(Register const& r) { return registers()[r.index()]; }
@@ -97,7 +95,7 @@ public:
     };
     static Bytecode::PassManager& optimization_pipeline(OptimizationLevel = OptimizationLevel::Default);
 
-    VM::InterpreterExecutionScope ast_interpreter_scope();
+    VM::InterpreterExecutionScope ast_interpreter_scope(Realm&);
 
 private:
     RegisterWindow& window()
@@ -115,7 +113,6 @@ private:
     static AK::Array<OwnPtr<PassManager>, static_cast<UnderlyingType<Interpreter::OptimizationLevel>>(Interpreter::OptimizationLevel::__Count)> s_optimization_pipelines;
 
     VM& m_vm;
-    NonnullGCPtr<Realm> m_realm;
     Vector<Variant<NonnullOwnPtr<RegisterWindow>, RegisterWindow*>> m_register_windows;
     Optional<BasicBlock const*> m_pending_jump;
     BasicBlock const* m_scheduled_jump { nullptr };
@@ -131,4 +128,6 @@ private:
 
 extern bool g_dump_bytecode;
 
+ThrowCompletionOr<NonnullOwnPtr<Bytecode::Executable>> compile(VM&, ASTNode const& no, JS::FunctionKind kind, DeprecatedFlyString const& name);
+
 }

Userland/Libraries/LibJS/Bytecode/Op.cpp

@@ -1081,7 +1081,7 @@ ThrowCompletionOr<void> IteratorResultValue::execute_impl(Bytecode::Interpreter&
 ThrowCompletionOr<void> NewClass::execute_impl(Bytecode::Interpreter& interpreter) const
 {
     auto name = m_class_expression.name();
-    auto scope = interpreter.ast_interpreter_scope();
+    auto scope = interpreter.ast_interpreter_scope(interpreter.realm());
     auto& ast_interpreter = scope.interpreter();
 
     auto* class_object = TRY(m_class_expression.class_definition_evaluation(ast_interpreter, name, name.is_null() ? ""sv : name));

Userland/Libraries/LibJS/Runtime/AbstractOperations.cpp

@@ -701,7 +701,7 @@ ThrowCompletionOr<Value> perform_eval(VM& vm, Value x, CallerMode strict_caller,
 
     // 29. If result.[[Type]] is normal, then
     //     a. Set result to the result of evaluating body.
-    if (auto* bytecode_interpreter = Bytecode::Interpreter::current()) {
+    if (auto* bytecode_interpreter = vm.bytecode_interpreter_if_exists()) {
         auto executable_result = Bytecode::Generator::generate(program);
         if (executable_result.is_error())
             return vm.throw_completion<InternalError>(ErrorType::NotImplemented, TRY_OR_THROW_OOM(vm, executable_result.error().to_string()));
@@ -710,7 +710,7 @@ ThrowCompletionOr<Value> perform_eval(VM& vm, Value x, CallerMode strict_caller,
         executable->name = "eval"sv;
         if (Bytecode::g_dump_bytecode)
             executable->dump();
-        auto result_or_error = bytecode_interpreter->run_and_return_frame(*executable, nullptr);
+        auto result_or_error = bytecode_interpreter->run_and_return_frame(eval_realm, *executable, nullptr);
         if (result_or_error.value.is_error())
             return result_or_error.value.release_error();
 

Userland/Libraries/LibJS/Runtime/ECMAScriptFunctionObject.cpp

@@ -455,8 +455,8 @@ ThrowCompletionOr<void> ECMAScriptFunctionObject::function_declaration_instantia
                 } else if (i < execution_context_arguments.size() && !execution_context_arguments[i].is_undefined()) {
                     argument_value = execution_context_arguments[i];
                 } else if (parameter.default_value) {
-                    if (auto* bytecode_interpreter = Bytecode::Interpreter::current()) {
+                    if (auto* bytecode_interpreter = vm.bytecode_interpreter_if_exists()) {
-                        auto value_and_frame = bytecode_interpreter->run_and_return_frame(*m_default_parameter_bytecode_executables[default_parameter_index - 1], nullptr);
+                        auto value_and_frame = bytecode_interpreter->run_and_return_frame(realm, *m_default_parameter_bytecode_executables[default_parameter_index - 1], nullptr);
                         if (value_and_frame.value.is_error())
                             return value_and_frame.value.release_error();
                         // Resulting value is in the accumulator.
@@ -751,9 +751,19 @@ void async_block_start(VM& vm, NonnullRefPtr<Statement const> const& async_body,
     auto& running_context = vm.running_execution_context();
 
     // 3. Set the code evaluation state of asyncContext such that when evaluation is resumed for that execution context the following steps will be performed:
-    auto execution_steps = NativeFunction::create(realm, "", [&async_body, &promise_capability, &async_context](auto& vm) -> ThrowCompletionOr<Value> {
+    auto execution_steps = NativeFunction::create(realm, "", [&realm, &async_body, &promise_capability, &async_context](auto& vm) -> ThrowCompletionOr<Value> {
         // a. Let result be the result of evaluating asyncBody.
-        auto result = async_body->execute(vm.interpreter());
+        Completion result;
+        if (auto* bytecode_interpreter = vm.bytecode_interpreter_if_exists()) {
+            // FIXME: Cache this executable somewhere.
+            auto maybe_executable = Bytecode::compile(vm, async_body, FunctionKind::Async, "AsyncBlockStart"sv);
+            if (maybe_executable.is_error())
+                result = maybe_executable.release_error();
+            else
+                result = bytecode_interpreter->run_and_return_frame(realm, *maybe_executable.value(), nullptr).value;
+        } else {
+            result = async_body->execute(vm.interpreter());
+        }
 
         // b. Assert: If we return here, the async function either threw an exception or performed an implicit or explicit return; all awaiting is done.
 
@@ -817,7 +827,7 @@ Completion ECMAScriptFunctionObject::ordinary_call_evaluate_body()
     if (m_kind == FunctionKind::AsyncGenerator)
         return vm.throw_completion<InternalError>(ErrorType::NotImplemented, "Async Generator function execution");
 
-    auto* bytecode_interpreter = Bytecode::Interpreter::current();
+    auto* bytecode_interpreter = vm.bytecode_interpreter_if_exists();
 
     // 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.
@@ -826,32 +836,11 @@ Completion ECMAScriptFunctionObject::ordinary_call_evaluate_body()
     // However, this does cause an awkward situation with features not supported in bytecode, where features that work outside of generators with AST
     // suddenly stop working inside of generators.
     // This is a stop gap until bytecode mode becomes the default.
-    OwnPtr<Bytecode::Interpreter> temp_bc_interpreter;
     if (m_kind == FunctionKind::Generator && !bytecode_interpreter) {
-        temp_bc_interpreter = make<Bytecode::Interpreter>(realm);
+        bytecode_interpreter = &vm.bytecode_interpreter();
-        bytecode_interpreter = temp_bc_interpreter.ptr();
     }
 
     if (bytecode_interpreter) {
-        auto compile = [&](auto& node, auto kind, auto name) -> ThrowCompletionOr<NonnullOwnPtr<Bytecode::Executable>> {
-            auto executable_result = Bytecode::Generator::generate(node, kind);
-            if (executable_result.is_error())
-                return vm.throw_completion<InternalError>(ErrorType::NotImplemented, TRY_OR_THROW_OOM(vm, executable_result.error().to_string()));
-
-            auto bytecode_executable = executable_result.release_value();
-            bytecode_executable->name = name;
-            auto& passes = Bytecode::Interpreter::optimization_pipeline();
-            passes.perform(*bytecode_executable);
-            if constexpr (JS_BYTECODE_DEBUG) {
-                dbgln("Optimisation passes took {}us", passes.elapsed());
-                dbgln("Compiled Bytecode::Block for function '{}':", m_name);
-            }
-            if (Bytecode::g_dump_bytecode)
-                bytecode_executable->dump();
-
-            return bytecode_executable;
-        };
-
         // NOTE: There's a subtle ordering issue here:
         //       - We have to compile the default parameter values before instantiating the function.
         //       - We have to instantiate the function before compiling the function body.
@@ -864,7 +853,7 @@ Completion ECMAScriptFunctionObject::ordinary_call_evaluate_body()
             for (auto& parameter : m_formal_parameters) {
                 if (!parameter.default_value)
                     continue;
-                auto executable = TRY(compile(*parameter.default_value, FunctionKind::Normal, DeprecatedString::formatted("default parameter #{} for {}", default_parameter_index, m_name)));
+                auto executable = TRY(Bytecode::compile(vm, *parameter.default_value, FunctionKind::Normal, DeprecatedString::formatted("default parameter #{} for {}", default_parameter_index, m_name)));
                 m_default_parameter_bytecode_executables.append(move(executable));
             }
         }
@@ -872,10 +861,10 @@ Completion ECMAScriptFunctionObject::ordinary_call_evaluate_body()
         TRY(function_declaration_instantiation(nullptr));
 
         if (!m_bytecode_executable) {
-            m_bytecode_executable = TRY(compile(*m_ecmascript_code, m_kind, m_name));
+            m_bytecode_executable = TRY(Bytecode::compile(vm, *m_ecmascript_code, m_kind, m_name));
         }
 
-        auto result_and_frame = bytecode_interpreter->run_and_return_frame(*m_bytecode_executable, nullptr);
+        auto result_and_frame = bytecode_interpreter->run_and_return_frame(realm, *m_bytecode_executable, nullptr);
 
         VERIFY(result_and_frame.frame != nullptr);
         if (result_and_frame.value.is_error())

Userland/Libraries/LibJS/Runtime/GeneratorObject.cpp

@@ -104,18 +104,7 @@ ThrowCompletionOr<Value> GeneratorObject::execute(VM& vm, Completion const& comp
     completion_object->define_direct_property(vm.names.type, Value(to_underlying(completion.type())), default_attributes);
     completion_object->define_direct_property(vm.names.value, completion.value().value(), default_attributes);
 
-    auto* bytecode_interpreter = Bytecode::Interpreter::current();
+    auto& bytecode_interpreter = vm.bytecode_interpreter();
-
-    // If we're coming from a context which has no bytecode interpreter, e.g. from AST mode calling Generate.prototype.next,
-    // we need to make one to be able to continue, as generators are only supported in bytecode mode.
-    // See also ECMAScriptFunctionObject::ordinary_call_evaluate_body where this is done as well.
-    OwnPtr<Bytecode::Interpreter> temp_bc_interpreter;
-    if (!bytecode_interpreter) {
-        temp_bc_interpreter = make<Bytecode::Interpreter>(realm);
-        bytecode_interpreter = temp_bc_interpreter.ptr();
-    }
-
-    VERIFY(bytecode_interpreter);
 
     auto const* next_block = generated_continuation(m_previous_value);
 
@@ -131,9 +120,9 @@ ThrowCompletionOr<Value> GeneratorObject::execute(VM& vm, Completion const& comp
     if (frame)
         frame->registers[0] = completion_object;
     else
-        bytecode_interpreter->accumulator() = completion_object;
+        bytecode_interpreter.accumulator() = completion_object;
 
-    auto next_result = bytecode_interpreter->run_and_return_frame(*m_generating_function->bytecode_executable(), next_block, frame);
+    auto next_result = bytecode_interpreter.run_and_return_frame(realm, *m_generating_function->bytecode_executable(), next_block, frame);
 
     vm.pop_execution_context();
 

Userland/Libraries/LibJS/Runtime/ShadowRealm.cpp

@@ -4,6 +4,8 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Bytecode/Interpreter.h>
 #include <LibJS/Interpreter.h>
 #include <LibJS/Lexer.h>
 #include <LibJS/Parser.h>

Userland/Libraries/LibJS/Runtime/VM.cpp

@@ -14,6 +14,7 @@
 #include <AK/StringBuilder.h>
 #include <LibFileSystem/FileSystem.h>
 #include <LibJS/AST.h>
+#include <LibJS/Bytecode/Interpreter.h>
 #include <LibJS/Interpreter.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/Array.h>
@@ -65,6 +66,8 @@ VM::VM(OwnPtr<CustomData> custom_data, ErrorMessages error_messages)
     , m_error_messages(move(error_messages))
     , m_custom_data(move(custom_data))
 {
+    m_bytecode_interpreter = make<Bytecode::Interpreter>(*this);
+
     m_empty_string = m_heap.allocate_without_realm<PrimitiveString>(String {});
 
     for (size_t i = 0; i < single_ascii_character_strings.size(); ++i)
@@ -166,6 +169,8 @@ VM::VM(OwnPtr<CustomData> custom_data, ErrorMessages error_messages)
     };
 }
 
+VM::~VM() = default;
+
 String const& VM::error_message(ErrorMessage type) const
 {
     VERIFY(type < ErrorMessage::__Count);
@@ -196,6 +201,18 @@ Interpreter* VM::interpreter_if_exists()
     return m_interpreters.last();
 }
 
+Bytecode::Interpreter& VM::bytecode_interpreter()
+{
+    return *m_bytecode_interpreter;
+}
+
+Bytecode::Interpreter* VM::bytecode_interpreter_if_exists()
+{
+    if (!Bytecode::Interpreter::enabled())
+        return nullptr;
+    return m_bytecode_interpreter;
+}
+
 void VM::push_interpreter(Interpreter& interpreter)
 {
     m_interpreters.append(&interpreter);

Userland/Libraries/LibJS/Runtime/VM.h

@@ -39,11 +39,14 @@ public:
     };
 
     static ErrorOr<NonnullRefPtr<VM>> create(OwnPtr<CustomData> = {});
-    ~VM() = default;
+    ~VM();
 
     Heap& heap() { return m_heap; }
     Heap const& heap() const { return m_heap; }
 
+    Bytecode::Interpreter& bytecode_interpreter();
+    Bytecode::Interpreter* bytecode_interpreter_if_exists();
+
     Interpreter& interpreter();
     Interpreter* interpreter_if_exists();
 
@@ -332,6 +335,8 @@ private:
     u32 m_execution_generation { 0 };
 
     OwnPtr<CustomData> m_custom_data;
+
+    OwnPtr<Bytecode::Interpreter> m_bytecode_interpreter;
 };
 
 ALWAYS_INLINE Heap& Cell::heap() const

Userland/Libraries/LibTest/JavaScriptTestRunner.h

@@ -126,7 +126,6 @@ static consteval size_t __testjs_last()
 static constexpr auto TOP_LEVEL_TEST_NAME = "__$$TOP_LEVEL$$__";
 extern RefPtr<JS::VM> g_vm;
 extern bool g_collect_on_every_allocation;
-extern bool g_run_bytecode;
 extern DeprecatedString g_currently_running_test;
 struct FunctionWithLength {
     JS::ThrowCompletionOr<JS::Value> (*function)(JS::VM&);
@@ -360,10 +359,9 @@ inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
     }
     auto test_script = result.release_value();
 
-    if (g_run_bytecode) {
+    if (auto* bytecode_interpreter = g_vm->bytecode_interpreter_if_exists()) {
         g_vm->push_execution_context(global_execution_context);
-        JS::Bytecode::Interpreter bytecode_interpreter(interpreter->realm());
+        MUST(bytecode_interpreter->run(*test_script));
-        MUST(bytecode_interpreter.run(*test_script));
         g_vm->pop_execution_context();
     } else {
         g_vm->push_execution_context(global_execution_context);
@@ -376,9 +374,8 @@ inline JSFileResult TestRunner::run_file_test(DeprecatedString const& test_path)
     if (file_script.is_error())
         return { test_path, file_script.error() };
     g_vm->push_execution_context(global_execution_context);
-    if (g_run_bytecode) {
+    if (auto* bytecode_interpreter = g_vm->bytecode_interpreter_if_exists()) {
-        JS::Bytecode::Interpreter bytecode_interpreter(interpreter->realm());
+        top_level_result = bytecode_interpreter->run(file_script.value());
-        top_level_result = bytecode_interpreter.run(file_script.value());
     } else {
         top_level_result = interpreter->run(file_script.value());
     }

Userland/Libraries/LibTest/JavaScriptTestRunnerMain.cpp

@@ -20,7 +20,6 @@ namespace JS {
 
 RefPtr<::JS::VM> g_vm;
 bool g_collect_on_every_allocation = false;
-bool g_run_bytecode = false;
 DeprecatedString g_currently_running_test;
 HashMap<DeprecatedString, FunctionWithLength> s_exposed_global_functions;
 Function<void()> g_main_hook;
@@ -94,6 +93,7 @@ int main(int argc, char** argv)
 #endif
     bool print_json = false;
     bool per_file = false;
+    bool use_bytecode = false;
     StringView specified_test_root;
     DeprecatedString common_path;
     DeprecatedString test_glob;
@@ -115,10 +115,11 @@ int main(int argc, char** argv)
             return true;
         },
     });
+
     args_parser.add_option(print_json, "Show results as JSON", "json", 'j');
     args_parser.add_option(per_file, "Show detailed per-file results as JSON (implies -j)", "per-file", 0);
     args_parser.add_option(g_collect_on_every_allocation, "Collect garbage after every allocation", "collect-often", 'g');
-    args_parser.add_option(g_run_bytecode, "Use the bytecode interpreter", "run-bytecode", 'b');
+    args_parser.add_option(use_bytecode, "Use the bytecode interpreter", "run-bytecode", 'b');
     args_parser.add_option(JS::Bytecode::g_dump_bytecode, "Dump the bytecode", "dump-bytecode", 'd');
     args_parser.add_option(test_glob, "Only run tests matching the given glob", "filter", 'f', "glob");
     for (auto& entry : g_extra_args)
@@ -136,11 +137,13 @@ int main(int argc, char** argv)
         AK::set_debug_enabled(false);
     }
 
-    if (JS::Bytecode::g_dump_bytecode && !g_run_bytecode) {
+    if (JS::Bytecode::g_dump_bytecode && !use_bytecode) {
         warnln("--dump-bytecode can only be used when --run-bytecode is specified.");
         return 1;
     }
 
+    JS::Bytecode::Interpreter::set_enabled(use_bytecode);
+
     DeprecatedString test_root;
 
     if (!specified_test_root.is_empty()) {

Userland/Libraries/LibWeb/HTML/Scripting/ClassicScript.cpp

@@ -95,9 +95,8 @@ JS::Completion ClassicScript::run(RethrowErrors rethrow_errors, JS::GCPtr<JS::En
         auto timer = Core::ElapsedTimer::start_new();
 
         // 6. Otherwise, set evaluationStatus to ScriptEvaluation(script's record).
-        if (JS::Bytecode::Interpreter::enabled()) {
+        if (auto* bytecode_interpreter = vm().bytecode_interpreter_if_exists()) {
-            auto interpreter = JS::Bytecode::Interpreter(m_script_record->realm());
+            evaluation_status = bytecode_interpreter->run(*m_script_record, lexical_environment_override);
-            evaluation_status = interpreter.run(*m_script_record, lexical_environment_override);
         } else {
             auto interpreter = JS::Interpreter::create_with_existing_realm(m_script_record->realm());
             evaluation_status = interpreter->run(*m_script_record, lexical_environment_override);

Userland/Utilities/js.cpp

@@ -71,7 +71,6 @@ private:
 };
 
 static bool s_dump_ast = false;
-static bool s_run_bytecode = false;
 static bool s_opt_bytecode = false;
 static bool s_as_module = false;
 static bool s_print_last_result = false;
@@ -212,10 +211,9 @@ static ErrorOr<bool> parse_and_run(JS::Interpreter& interpreter, StringView sour
         if (s_dump_ast)
             script_or_module->parse_node().dump(0);
 
-        if (s_run_bytecode) {
+        if (auto* bytecode_interpreter = g_vm->bytecode_interpreter_if_exists()) {
-            JS::Bytecode::Interpreter bytecode_interpreter(interpreter.realm());
+            bytecode_interpreter->set_optimizations_enabled(s_opt_bytecode);
-            bytecode_interpreter.set_optimizations_enabled(s_opt_bytecode);
+            result = bytecode_interpreter->run(*script_or_module);
-            result = bytecode_interpreter.run(*script_or_module);
         } else {
             result = interpreter.run(*script_or_module);
         }
@@ -579,12 +577,13 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     bool use_test262_global = false;
     StringView evaluate_script;
     Vector<StringView> script_paths;
+    bool use_bytecode = false;
 
     Core::ArgsParser args_parser;
     args_parser.set_general_help("This is a JavaScript interpreter.");
     args_parser.add_option(s_dump_ast, "Dump the AST", "dump-ast", 'A');
     args_parser.add_option(JS::Bytecode::g_dump_bytecode, "Dump the bytecode", "dump-bytecode", 'd');
-    args_parser.add_option(s_run_bytecode, "Run the bytecode", "run-bytecode", 'b');
+    args_parser.add_option(use_bytecode, "Run the bytecode", "run-bytecode", 'b');
     args_parser.add_option(s_opt_bytecode, "Optimize the bytecode", "optimize-bytecode", 'p');
     args_parser.add_option(s_as_module, "Treat as module", "as-module", 'm');
     args_parser.add_option(s_print_last_result, "Print last result", "print-last-result", 'l');
@@ -598,6 +597,8 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_positional_argument(script_paths, "Path to script files", "scripts", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
 
+    JS::Bytecode::Interpreter::set_enabled(use_bytecode);
+
     bool syntax_highlight = !disable_syntax_highlight;
 
     AK::set_debug_enabled(!disable_debug_printing);