From 953573565cd4d7b73dfae6baad10ed0a3fd52dc8 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Wed, 28 Feb 2024 18:49:52 +0100
Subject: [PATCH] LibJS/Bytecode: Cache realm, global object, and more in
 interpreter

Instead of looking these up in the VM execution context stack whenever
we need them, we now just cache them in the interpreter when entering
a new call frame.
---
 Userland/Libraries/LibJS/Bytecode/CommonImplementations.h | 6 ++----
 Userland/Libraries/LibJS/Bytecode/Interpreter.cpp         | 8 +++-----
 Userland/Libraries/LibJS/Bytecode/Interpreter.h           | 7 ++++++-
 3 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h b/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h
index 17a0a4a509..1396ee0c31 100644
--- a/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h
+++ b/Userland/Libraries/LibJS/Bytecode/CommonImplementations.h
@@ -183,10 +183,8 @@ inline ThrowCompletionOr<Value> get_by_value(VM& vm, Value base_value, Value pro
 inline ThrowCompletionOr<Value> get_global(Bytecode::Interpreter& interpreter, DeprecatedFlyString const& identifier, GlobalVariableCache& cache)
 {
     auto& vm = interpreter.vm();
-    auto& realm = *vm.current_realm();
-
-    auto& binding_object = realm.global_environment().object_record().binding_object();
-    auto& declarative_record = realm.global_environment().declarative_record();
+    auto& binding_object = interpreter.global_object();
+    auto& declarative_record = interpreter.global_declarative_environment();
 
     // OPTIMIZATION: If the shape of the object hasn't changed, we can use the cached property offset.
     auto& shape = binding_object.shape();
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
index facfb4299e..1ba9065af3 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.cpp
@@ -426,6 +426,9 @@ Interpreter::ValueAndFrame Interpreter::run_and_return_frame(Executable& executa
 
     TemporaryChange restore_executable { m_current_executable, &executable };
     TemporaryChange restore_saved_jump { m_scheduled_jump, static_cast<BasicBlock const*>(nullptr) };
+    TemporaryChange restore_realm { m_realm, vm().current_realm() };
+    TemporaryChange restore_global_object { m_global_object, &m_realm->global_object() };
+    TemporaryChange restore_global_declarative_environment { m_global_declarative_environment, &m_realm->global_environment().declarative_record() };
 
     VERIFY(!vm().execution_context_stack().is_empty());
 
@@ -530,11 +533,6 @@ ThrowCompletionOr<NonnullGCPtr<Bytecode::Executable>> compile(VM& vm, ASTNode co
     return bytecode_executable;
 }
 
-Realm& Interpreter::realm()
-{
-    return *m_vm.current_realm();
-}
-
 void Interpreter::push_call_frame(Variant<NonnullOwnPtr<CallFrame>, CallFrame*> frame)
 {
     m_call_frames.append(move(frame));
diff --git a/Userland/Libraries/LibJS/Bytecode/Interpreter.h b/Userland/Libraries/LibJS/Bytecode/Interpreter.h
index 0ef2185eaf..ae9f91c5be 100644
--- a/Userland/Libraries/LibJS/Bytecode/Interpreter.h
+++ b/Userland/Libraries/LibJS/Bytecode/Interpreter.h
@@ -51,7 +51,9 @@ public:
     explicit Interpreter(VM&);
     ~Interpreter();
 
-    Realm& realm();
+    [[nodiscard]] Realm& realm() { return *m_realm; }
+    [[nodiscard]] Object& global_object() { return *m_global_object; }
+    [[nodiscard]] DeclarativeEnvironment& global_declarative_environment() { return *m_global_declarative_environment; }
     VM& vm() { return m_vm; }
     VM const& vm() const { return m_vm; }
 
@@ -125,6 +127,9 @@ private:
     BasicBlock const* m_scheduled_jump { nullptr };
     Executable* m_current_executable { nullptr };
     BasicBlock const* m_current_block { nullptr };
+    Realm* m_realm { nullptr };
+    Object* m_global_object { nullptr };
+    DeclarativeEnvironment* m_global_declarative_environment { nullptr };
     Optional<InstructionStreamIterator&> m_pc {};
 };