Everywhere: Hoist the Libraries folder to the top-level

Author: https://github.com/trflynn89
Commit: 93712b24bf
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2256
Reviewed-by: https://github.com/sideshowbarker

Libraries/LibJS/Bytecode/BasicBlock.cpp

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/String.h>
+#include <LibJS/Bytecode/BasicBlock.h>
+#include <LibJS/Bytecode/Op.h>
+
+namespace JS::Bytecode {
+
+NonnullOwnPtr<BasicBlock> BasicBlock::create(u32 index, String name)
+{
+    return adopt_own(*new BasicBlock(index, move(name)));
+}
+
+BasicBlock::BasicBlock(u32 index, String name)
+    : m_index(index)
+    , m_name(move(name))
+{
+}
+
+BasicBlock::~BasicBlock()
+{
+    Bytecode::InstructionStreamIterator it(instruction_stream());
+    while (!it.at_end()) {
+        auto& to_destroy = (*it);
+        ++it;
+        Instruction::destroy(const_cast<Instruction&>(to_destroy));
+    }
+}
+
+void BasicBlock::grow(size_t additional_size)
+{
+    m_buffer.grow_capacity(m_buffer.size() + additional_size);
+    m_buffer.resize(m_buffer.size() + additional_size);
+}
+
+}

Libraries/LibJS/Bytecode/BasicBlock.h

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Badge.h>
+#include <AK/String.h>
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Bytecode/ScopedOperand.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Heap/Handle.h>
+
+namespace JS::Bytecode {
+
+struct UnwindInfo {
+    JS::GCPtr<Executable const> executable;
+    JS::GCPtr<Environment> lexical_environment;
+
+    bool handler_called { false };
+};
+
+class BasicBlock {
+    AK_MAKE_NONCOPYABLE(BasicBlock);
+
+public:
+    static NonnullOwnPtr<BasicBlock> create(u32 index, String name);
+    ~BasicBlock();
+
+    u32 index() const { return m_index; }
+
+    ReadonlyBytes instruction_stream() const { return m_buffer.span(); }
+    u8* data() { return m_buffer.data(); }
+    u8 const* data() const { return m_buffer.data(); }
+    size_t size() const { return m_buffer.size(); }
+
+    void rewind()
+    {
+        m_buffer.resize_and_keep_capacity(m_last_instruction_start_offset);
+        m_terminated = false;
+    }
+
+    void grow(size_t additional_size);
+
+    void terminate(Badge<Generator>) { m_terminated = true; }
+    bool is_terminated() const { return m_terminated; }
+
+    String const& name() const { return m_name; }
+
+    void set_handler(BasicBlock const& handler) { m_handler = &handler; }
+    void set_finalizer(BasicBlock const& finalizer) { m_finalizer = &finalizer; }
+
+    BasicBlock const* handler() const { return m_handler; }
+    BasicBlock const* finalizer() const { return m_finalizer; }
+
+    auto const& source_map() const { return m_source_map; }
+    void add_source_map_entry(size_t bytecode_offset, SourceRecord const& source_record) { m_source_map.set(bytecode_offset, source_record); }
+
+    [[nodiscard]] bool has_resolved_this() const { return m_has_resolved_this; }
+    void set_has_resolved_this() { m_has_resolved_this = true; }
+
+    [[nodiscard]] size_t last_instruction_start_offset() const { return m_last_instruction_start_offset; }
+    void set_last_instruction_start_offset(size_t offset) { m_last_instruction_start_offset = offset; }
+
+private:
+    explicit BasicBlock(u32 index, String name);
+
+    u32 m_index { 0 };
+    Vector<u8> m_buffer;
+    BasicBlock const* m_handler { nullptr };
+    BasicBlock const* m_finalizer { nullptr };
+    String m_name;
+    bool m_terminated { false };
+    bool m_has_resolved_this { false };
+
+    HashMap<size_t, SourceRecord> m_source_map;
+
+    size_t m_last_instruction_start_offset { 0 };
+};
+
+}

Libraries/LibJS/Bytecode/Builtins.cpp

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2023, Simon Wanner <simon@skyrising.xyz>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/AST.h>
+#include <LibJS/Bytecode/Builtins.h>
+
+namespace JS::Bytecode {
+
+Optional<Builtin> get_builtin(MemberExpression const& expression)
+{
+    if (expression.is_computed() || !expression.object().is_identifier() || !expression.property().is_identifier())
+        return {};
+    auto base_name = static_cast<Identifier const&>(expression.object()).string();
+    auto property_name = static_cast<Identifier const&>(expression.property()).string();
+#define CHECK_MEMBER_BUILTIN(name, snake_case_name, base, property, ...) \
+    if (base_name == #base##sv && property_name == #property##sv)        \
+        return Builtin::name;
+    JS_ENUMERATE_BUILTINS(CHECK_MEMBER_BUILTIN)
+#undef CHECK_MEMBER_BUILTIN
+    return {};
+}
+
+}

Libraries/LibJS/Bytecode/Builtins.h

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2023, Simon Wanner <simon@skyrising.xyz>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Format.h>
+#include <LibJS/Forward.h>
+
+namespace JS::Bytecode {
+
+// TitleCaseName, snake_case_name, base, property, argument_count
+#define JS_ENUMERATE_BUILTINS(O)             \
+    O(MathAbs, math_abs, Math, abs, 1)       \
+    O(MathLog, math_log, Math, log, 1)       \
+    O(MathPow, math_pow, Math, pow, 2)       \
+    O(MathExp, math_exp, Math, exp, 1)       \
+    O(MathCeil, math_ceil, Math, ceil, 1)    \
+    O(MathFloor, math_floor, Math, floor, 1) \
+    O(MathRound, math_round, Math, round, 1) \
+    O(MathSqrt, math_sqrt, Math, sqrt, 1)
+
+enum class Builtin : u8 {
+#define DEFINE_BUILTIN_ENUM(name, ...) name,
+    JS_ENUMERATE_BUILTINS(DEFINE_BUILTIN_ENUM)
+#undef DEFINE_BUILTIN_ENUM
+        __Count,
+};
+
+static StringView builtin_name(Builtin value)
+{
+    switch (value) {
+#define DEFINE_BUILTIN_CASE(name, snake_case_name, base, property, ...) \
+    case Builtin::name:                                                 \
+        return #base "." #property##sv;
+        JS_ENUMERATE_BUILTINS(DEFINE_BUILTIN_CASE)
+#undef DEFINE_BUILTIN_CASE
+    case Builtin::__Count:
+        VERIFY_NOT_REACHED();
+    }
+    VERIFY_NOT_REACHED();
+}
+
+inline size_t builtin_argument_count(Builtin value)
+{
+    switch (value) {
+#define DEFINE_BUILTIN_CASE(name, snake_case_name, base, property, arg_count, ...) \
+    case Builtin::name:                                                            \
+        return arg_count;
+        JS_ENUMERATE_BUILTINS(DEFINE_BUILTIN_CASE)
+#undef DEFINE_BUILTIN_CASE
+    case Builtin::__Count:
+        VERIFY_NOT_REACHED();
+    }
+    VERIFY_NOT_REACHED();
+}
+
+Optional<Builtin> get_builtin(MemberExpression const& expression);
+
+}
+
+namespace AK {
+
+template<>
+struct Formatter<JS::Bytecode::Builtin> : Formatter<StringView> {
+    ErrorOr<void> format(FormatBuilder& builder, JS::Bytecode::Builtin value)
+    {
+        return Formatter<StringView>::format(builder, builtin_name(value));
+    }
+};
+
+}

Libraries/LibJS/Bytecode/CodeGenerationError.cpp

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/AST.h>
+#include <LibJS/Bytecode/CodeGenerationError.h>
+
+namespace JS::Bytecode {
+
+ErrorOr<String> CodeGenerationError::to_string() const
+{
+    return String::formatted("CodeGenerationError in {}: {}", failing_node ? failing_node->class_name() : "<unknown node>", reason_literal);
+}
+
+}

Libraries/LibJS/Bytecode/CodeGenerationError.h

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2022, Ali Mohammad Pur <mpfard@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/String.h>
+#include <AK/StringView.h>
+#include <LibJS/Forward.h>
+
+namespace JS::Bytecode {
+
+struct CodeGenerationError {
+    ASTNode const* failing_node { nullptr };
+    StringView reason_literal;
+
+    ErrorOr<String> to_string() const;
+};
+
+template<typename T>
+using CodeGenerationErrorOr = ErrorOr<T, CodeGenerationError>;
+
+}

Libraries/LibJS/Bytecode/Executable.cpp

@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2021-2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/BasicBlock.h>
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Bytecode/Instruction.h>
+#include <LibJS/Bytecode/RegexTable.h>
+#include <LibJS/SourceCode.h>
+
+namespace JS::Bytecode {
+
+JS_DEFINE_ALLOCATOR(Executable);
+
+Executable::Executable(
+    Vector<u8> bytecode,
+    NonnullOwnPtr<IdentifierTable> identifier_table,
+    NonnullOwnPtr<StringTable> string_table,
+    NonnullOwnPtr<RegexTable> regex_table,
+    Vector<Value> constants,
+    NonnullRefPtr<SourceCode const> source_code,
+    size_t number_of_property_lookup_caches,
+    size_t number_of_global_variable_caches,
+    size_t number_of_registers,
+    bool is_strict_mode)
+    : bytecode(move(bytecode))
+    , string_table(move(string_table))
+    , identifier_table(move(identifier_table))
+    , regex_table(move(regex_table))
+    , constants(move(constants))
+    , source_code(move(source_code))
+    , number_of_registers(number_of_registers)
+    , is_strict_mode(is_strict_mode)
+{
+    property_lookup_caches.resize(number_of_property_lookup_caches);
+    global_variable_caches.resize(number_of_global_variable_caches);
+}
+
+Executable::~Executable() = default;
+
+void Executable::dump() const
+{
+    warnln("\033[37;1mJS bytecode executable\033[0m \"{}\"", name);
+    InstructionStreamIterator it(bytecode, this);
+
+    size_t basic_block_offset_index = 0;
+
+    while (!it.at_end()) {
+        bool print_basic_block_marker = false;
+        if (basic_block_offset_index < basic_block_start_offsets.size()
+            && it.offset() == basic_block_start_offsets[basic_block_offset_index]) {
+            ++basic_block_offset_index;
+            print_basic_block_marker = true;
+        }
+
+        StringBuilder builder;
+        builder.appendff("[{:4x}] ", it.offset());
+        if (print_basic_block_marker)
+            builder.appendff("{:4}: ", basic_block_offset_index - 1);
+        else
+            builder.append("      "sv);
+        builder.append((*it).to_byte_string(*this));
+
+        warnln("{}", builder.string_view());
+
+        ++it;
+    }
+
+    if (!exception_handlers.is_empty()) {
+        warnln("");
+        warnln("Exception handlers:");
+        for (auto& handlers : exception_handlers) {
+            warnln("    from {:4x} to {:4x} handler {:4x} finalizer {:4x}",
+                handlers.start_offset,
+                handlers.end_offset,
+                handlers.handler_offset.value_or(0),
+                handlers.finalizer_offset.value_or(0));
+        }
+    }
+
+    warnln("");
+}
+
+void Executable::visit_edges(Visitor& visitor)
+{
+    Base::visit_edges(visitor);
+    visitor.visit(constants);
+}
+
+Optional<Executable::ExceptionHandlers const&> Executable::exception_handlers_for_offset(size_t offset) const
+{
+    for (auto& handlers : exception_handlers) {
+        if (handlers.start_offset <= offset && offset < handlers.end_offset)
+            return handlers;
+    }
+    return {};
+}
+
+UnrealizedSourceRange Executable::source_range_at(size_t offset) const
+{
+    if (offset >= bytecode.size())
+        return {};
+    auto it = InstructionStreamIterator(bytecode.span().slice(offset), this);
+    VERIFY(!it.at_end());
+    auto mapping = source_map.get(offset);
+    if (!mapping.has_value())
+        return {};
+    return UnrealizedSourceRange {
+        .source_code = source_code,
+        .start_offset = mapping->source_start_offset,
+        .end_offset = mapping->source_end_offset,
+    };
+}
+
+}

Libraries/LibJS/Bytecode/Executable.h

@@ -0,0 +1,111 @@
+/*
+ * Copyright (c) 2021-2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/DeprecatedFlyString.h>
+#include <AK/HashMap.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/OwnPtr.h>
+#include <AK/WeakPtr.h>
+#include <LibJS/Bytecode/IdentifierTable.h>
+#include <LibJS/Bytecode/Label.h>
+#include <LibJS/Bytecode/StringTable.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Heap/Cell.h>
+#include <LibJS/Heap/CellAllocator.h>
+#include <LibJS/Runtime/EnvironmentCoordinate.h>
+#include <LibJS/SourceRange.h>
+
+namespace JS::Bytecode {
+
+struct PropertyLookupCache {
+    WeakPtr<Shape> shape;
+    Optional<u32> property_offset;
+    WeakPtr<Object> prototype;
+    WeakPtr<PrototypeChainValidity> prototype_chain_validity;
+};
+
+struct GlobalVariableCache : public PropertyLookupCache {
+    u64 environment_serial_number { 0 };
+    Optional<u32> environment_binding_index;
+};
+
+struct SourceRecord {
+    u32 source_start_offset {};
+    u32 source_end_offset {};
+};
+
+class Executable final : public Cell {
+    JS_CELL(Executable, Cell);
+    JS_DECLARE_ALLOCATOR(Executable);
+
+public:
+    Executable(
+        Vector<u8> bytecode,
+        NonnullOwnPtr<IdentifierTable>,
+        NonnullOwnPtr<StringTable>,
+        NonnullOwnPtr<RegexTable>,
+        Vector<Value> constants,
+        NonnullRefPtr<SourceCode const>,
+        size_t number_of_property_lookup_caches,
+        size_t number_of_global_variable_caches,
+        size_t number_of_registers,
+        bool is_strict_mode);
+
+    virtual ~Executable() override;
+
+    DeprecatedFlyString name;
+    Vector<u8> bytecode;
+    Vector<PropertyLookupCache> property_lookup_caches;
+    Vector<GlobalVariableCache> global_variable_caches;
+    NonnullOwnPtr<StringTable> string_table;
+    NonnullOwnPtr<IdentifierTable> identifier_table;
+    NonnullOwnPtr<RegexTable> regex_table;
+    Vector<Value> constants;
+
+    NonnullRefPtr<SourceCode const> source_code;
+    size_t number_of_registers { 0 };
+    bool is_strict_mode { false };
+
+    struct ExceptionHandlers {
+        size_t start_offset;
+        size_t end_offset;
+        Optional<size_t> handler_offset;
+        Optional<size_t> finalizer_offset;
+    };
+
+    Vector<ExceptionHandlers> exception_handlers;
+    Vector<size_t> basic_block_start_offsets;
+
+    HashMap<size_t, SourceRecord> source_map;
+
+    Vector<DeprecatedFlyString> local_variable_names;
+    size_t local_index_base { 0 };
+
+    Optional<IdentifierTableIndex> length_identifier;
+
+    ByteString const& get_string(StringTableIndex index) const { return string_table->get(index); }
+    DeprecatedFlyString const& get_identifier(IdentifierTableIndex index) const { return identifier_table->get(index); }
+
+    Optional<DeprecatedFlyString const&> get_identifier(Optional<IdentifierTableIndex> const& index) const
+    {
+        if (!index.has_value())
+            return {};
+        return get_identifier(*index);
+    }
+
+    [[nodiscard]] Optional<ExceptionHandlers const&> exception_handlers_for_offset(size_t offset) const;
+
+    [[nodiscard]] UnrealizedSourceRange source_range_at(size_t offset) const;
+
+    void dump() const;
+
+private:
+    virtual void visit_edges(Visitor&) override;
+};
+
+}

Libraries/LibJS/Bytecode/Generator.h

@@ -0,0 +1,409 @@
+/*
+ * Copyright (c) 2021-2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/OwnPtr.h>
+#include <AK/SinglyLinkedList.h>
+#include <LibJS/AST.h>
+#include <LibJS/Bytecode/BasicBlock.h>
+#include <LibJS/Bytecode/CodeGenerationError.h>
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Bytecode/IdentifierTable.h>
+#include <LibJS/Bytecode/Label.h>
+#include <LibJS/Bytecode/Op.h>
+#include <LibJS/Bytecode/Register.h>
+#include <LibJS/Bytecode/StringTable.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Runtime/FunctionKind.h>
+#include <LibRegex/Regex.h>
+
+namespace JS::Bytecode {
+
+class Generator {
+public:
+    VM& vm() { return m_vm; }
+
+    enum class SurroundingScopeKind {
+        Global,
+        Function,
+        Block,
+    };
+
+    enum class MustPropagateCompletion {
+        No,
+        Yes,
+    };
+
+    static CodeGenerationErrorOr<NonnullGCPtr<Executable>> generate_from_ast_node(VM&, ASTNode const&, FunctionKind = FunctionKind::Normal);
+    static CodeGenerationErrorOr<NonnullGCPtr<Executable>> generate_from_function(VM&, ECMAScriptFunctionObject const& function);
+
+    CodeGenerationErrorOr<void> emit_function_declaration_instantiation(ECMAScriptFunctionObject const& function);
+
+    [[nodiscard]] ScopedOperand allocate_register();
+    [[nodiscard]] ScopedOperand local(u32 local_index);
+    [[nodiscard]] ScopedOperand accumulator();
+    [[nodiscard]] ScopedOperand this_value();
+
+    void free_register(Register);
+
+    void set_local_initialized(u32 local_index);
+    [[nodiscard]] bool is_local_initialized(u32 local_index) const;
+
+    class SourceLocationScope {
+    public:
+        SourceLocationScope(Generator&, ASTNode const& node);
+        ~SourceLocationScope();
+
+    private:
+        Generator& m_generator;
+        ASTNode const* m_previous_node { nullptr };
+    };
+
+    class UnwindContext {
+    public:
+        UnwindContext(Generator&, Optional<Label> finalizer);
+
+        UnwindContext const* previous() const { return m_previous_context; }
+        void set_handler(Label handler) { m_handler = handler; }
+        Optional<Label> handler() const { return m_handler; }
+        Optional<Label> finalizer() const { return m_finalizer; }
+
+        ~UnwindContext();
+
+    private:
+        Generator& m_generator;
+        Optional<Label> m_finalizer;
+        Optional<Label> m_handler {};
+        UnwindContext const* m_previous_context { nullptr };
+    };
+
+    template<typename OpType, typename... Args>
+    requires(requires { OpType(declval<Args>()...); })
+    void emit(Args&&... args)
+    {
+        VERIFY(!is_current_block_terminated());
+        size_t slot_offset = m_current_basic_block->size();
+        m_current_basic_block->set_last_instruction_start_offset(slot_offset);
+        grow(sizeof(OpType));
+        void* slot = m_current_basic_block->data() + slot_offset;
+        new (slot) OpType(forward<Args>(args)...);
+        if constexpr (OpType::IsTerminator)
+            m_current_basic_block->terminate({});
+        m_current_basic_block->add_source_map_entry(slot_offset, { m_current_ast_node->start_offset(), m_current_ast_node->end_offset() });
+    }
+
+    template<typename OpType, typename ExtraSlotType, typename... Args>
+    requires(requires { OpType(declval<Args>()...); })
+    void emit_with_extra_slots(size_t extra_slot_count, Args&&... args)
+    {
+        VERIFY(!is_current_block_terminated());
+
+        size_t size_to_allocate = round_up_to_power_of_two(sizeof(OpType) + extra_slot_count * sizeof(ExtraSlotType), alignof(void*));
+        size_t slot_offset = m_current_basic_block->size();
+        m_current_basic_block->set_last_instruction_start_offset(slot_offset);
+        grow(size_to_allocate);
+        void* slot = m_current_basic_block->data() + slot_offset;
+        new (slot) OpType(forward<Args>(args)...);
+        if constexpr (OpType::IsTerminator)
+            m_current_basic_block->terminate({});
+        m_current_basic_block->add_source_map_entry(slot_offset, { m_current_ast_node->start_offset(), m_current_ast_node->end_offset() });
+    }
+
+    template<typename OpType, typename... Args>
+    requires(requires { OpType(declval<Args>()...); })
+    void emit_with_extra_operand_slots(size_t extra_operand_slots, Args&&... args)
+    {
+        emit_with_extra_slots<OpType, Operand>(extra_operand_slots, forward<Args>(args)...);
+    }
+
+    template<typename OpType, typename... Args>
+    requires(requires { OpType(declval<Args>()...); })
+    void emit_with_extra_value_slots(size_t extra_operand_slots, Args&&... args)
+    {
+        emit_with_extra_slots<OpType, Value>(extra_operand_slots, forward<Args>(args)...);
+    }
+
+    void emit_jump_if(ScopedOperand const& condition, Label true_target, Label false_target);
+
+    struct ReferenceOperands {
+        Optional<ScopedOperand> base {};                                 // [[Base]]
+        Optional<ScopedOperand> referenced_name {};                      // [[ReferencedName]] as an operand
+        Optional<IdentifierTableIndex> referenced_identifier {};         // [[ReferencedName]] as an identifier
+        Optional<IdentifierTableIndex> referenced_private_identifier {}; // [[ReferencedName]] as a private identifier
+        Optional<ScopedOperand> this_value {};                           // [[ThisValue]]
+        Optional<ScopedOperand> loaded_value {};                         // Loaded value, if we've performed a load.
+    };
+
+    CodeGenerationErrorOr<ReferenceOperands> emit_load_from_reference(JS::ASTNode const&, Optional<ScopedOperand> preferred_dst = {});
+    CodeGenerationErrorOr<void> emit_store_to_reference(JS::ASTNode const&, ScopedOperand value);
+    CodeGenerationErrorOr<void> emit_store_to_reference(ReferenceOperands const&, ScopedOperand value);
+    CodeGenerationErrorOr<Optional<ScopedOperand>> emit_delete_reference(JS::ASTNode const&);
+
+    CodeGenerationErrorOr<ReferenceOperands> emit_super_reference(MemberExpression const&);
+
+    void emit_set_variable(JS::Identifier const& identifier, ScopedOperand value, Bytecode::Op::BindingInitializationMode initialization_mode = Bytecode::Op::BindingInitializationMode::Set, Bytecode::Op::EnvironmentMode mode = Bytecode::Op::EnvironmentMode::Lexical);
+
+    void push_home_object(ScopedOperand);
+    void pop_home_object();
+    void emit_new_function(ScopedOperand dst, JS::FunctionExpression const&, Optional<IdentifierTableIndex> lhs_name);
+
+    CodeGenerationErrorOr<Optional<ScopedOperand>> emit_named_evaluation_if_anonymous_function(Expression const&, Optional<IdentifierTableIndex> lhs_name, Optional<ScopedOperand> preferred_dst = {});
+
+    void begin_continuable_scope(Label continue_target, Vector<DeprecatedFlyString> const& language_label_set);
+    void end_continuable_scope();
+    void begin_breakable_scope(Label breakable_target, Vector<DeprecatedFlyString> const& language_label_set);
+    void end_breakable_scope();
+
+    [[nodiscard]] Label nearest_continuable_scope() const;
+    [[nodiscard]] Label nearest_breakable_scope() const;
+
+    void switch_to_basic_block(BasicBlock& block)
+    {
+        m_current_basic_block = &block;
+    }
+
+    [[nodiscard]] BasicBlock& current_block() { return *m_current_basic_block; }
+
+    BasicBlock& make_block(String name = {})
+    {
+        if (name.is_empty())
+            name = String::number(m_next_block++);
+        auto block = BasicBlock::create(m_root_basic_blocks.size(), name);
+        if (auto const* context = m_current_unwind_context) {
+            if (context->handler().has_value())
+                block->set_handler(*m_root_basic_blocks[context->handler().value().basic_block_index()]);
+            if (m_current_unwind_context->finalizer().has_value())
+                block->set_finalizer(*m_root_basic_blocks[context->finalizer().value().basic_block_index()]);
+        }
+        m_root_basic_blocks.append(move(block));
+        return *m_root_basic_blocks.last();
+    }
+
+    bool is_current_block_terminated() const
+    {
+        return m_current_basic_block->is_terminated();
+    }
+
+    StringTableIndex intern_string(ByteString string)
+    {
+        return m_string_table->insert(move(string));
+    }
+
+    RegexTableIndex intern_regex(ParsedRegex regex)
+    {
+        return m_regex_table->insert(move(regex));
+    }
+
+    IdentifierTableIndex intern_identifier(DeprecatedFlyString string)
+    {
+        return m_identifier_table->insert(move(string));
+    }
+
+    Optional<IdentifierTableIndex> intern_identifier_for_expression(Expression const& expression);
+
+    bool is_in_generator_or_async_function() const { return m_enclosing_function_kind == FunctionKind::Async || m_enclosing_function_kind == FunctionKind::Generator || m_enclosing_function_kind == FunctionKind::AsyncGenerator; }
+    bool is_in_generator_function() const { return m_enclosing_function_kind == FunctionKind::Generator || m_enclosing_function_kind == FunctionKind::AsyncGenerator; }
+    bool is_in_async_function() const { return m_enclosing_function_kind == FunctionKind::Async || m_enclosing_function_kind == FunctionKind::AsyncGenerator; }
+    bool is_in_async_generator_function() const { return m_enclosing_function_kind == FunctionKind::AsyncGenerator; }
+
+    enum class BindingMode {
+        Lexical,
+        Var,
+        Global,
+    };
+    struct LexicalScope {
+        SurroundingScopeKind kind;
+    };
+
+    // Returns true if a lexical environment was created.
+    bool emit_block_declaration_instantiation(ScopeNode const&);
+
+    void begin_variable_scope();
+    void end_variable_scope();
+
+    enum class BlockBoundaryType {
+        Break,
+        Continue,
+        Unwind,
+        ReturnToFinally,
+        LeaveFinally,
+        LeaveLexicalEnvironment,
+    };
+    template<typename OpType>
+    void perform_needed_unwinds()
+    requires(OpType::IsTerminator && !IsSame<OpType, Op::Jump>)
+    {
+        for (size_t i = m_boundaries.size(); i > 0; --i) {
+            auto boundary = m_boundaries[i - 1];
+            using enum BlockBoundaryType;
+            switch (boundary) {
+            case Unwind:
+                if constexpr (IsSame<OpType, Bytecode::Op::Throw>)
+                    return;
+                emit<Bytecode::Op::LeaveUnwindContext>();
+                break;
+            case LeaveLexicalEnvironment:
+                emit<Bytecode::Op::LeaveLexicalEnvironment>();
+                break;
+            case Break:
+            case Continue:
+                break;
+            case ReturnToFinally:
+                return;
+            case LeaveFinally:
+                emit<Bytecode::Op::LeaveFinally>();
+                break;
+            };
+        }
+    }
+
+    bool is_in_finalizer() const { return m_boundaries.contains_slow(BlockBoundaryType::LeaveFinally); }
+    bool must_enter_finalizer() const { return m_boundaries.contains_slow(BlockBoundaryType::ReturnToFinally); }
+
+    void generate_break();
+    void generate_break(DeprecatedFlyString const& break_label);
+
+    void generate_continue();
+    void generate_continue(DeprecatedFlyString const& continue_label);
+
+    template<typename OpType>
+    void emit_return(ScopedOperand value)
+    requires(IsOneOf<OpType, Op::Return, Op::Yield>)
+    {
+        // FIXME: Tell the call sites about the `saved_return_value` destination
+        //        And take that into account in the movs below.
+        perform_needed_unwinds<OpType>();
+        if (must_enter_finalizer()) {
+            VERIFY(m_current_basic_block->finalizer() != nullptr);
+            // Compare to:
+            // *  Interpreter::do_return
+            // *  Interpreter::run_bytecode::handle_ContinuePendingUnwind
+            // *  Return::execute_impl
+            // *  Yield::execute_impl
+            if constexpr (IsSame<OpType, Op::Yield>)
+                emit<Bytecode::Op::PrepareYield>(Operand(Register::saved_return_value()), value);
+            else
+                emit<Bytecode::Op::Mov>(Operand(Register::saved_return_value()), value);
+            emit<Bytecode::Op::Mov>(Operand(Register::exception()), add_constant(Value {}));
+            // FIXME: Do we really need to clear the return value register here?
+            emit<Bytecode::Op::Mov>(Operand(Register::return_value()), add_constant(Value {}));
+            emit<Bytecode::Op::Jump>(Label { *m_current_basic_block->finalizer() });
+            return;
+        }
+
+        if constexpr (IsSame<OpType, Op::Return>)
+            emit<Op::Return>(value);
+        else
+            emit<Op::Yield>(nullptr, value);
+    }
+
+    void start_boundary(BlockBoundaryType type) { m_boundaries.append(type); }
+    void end_boundary(BlockBoundaryType type)
+    {
+        VERIFY(m_boundaries.last() == type);
+        m_boundaries.take_last();
+    }
+
+    [[nodiscard]] ScopedOperand copy_if_needed_to_preserve_evaluation_order(ScopedOperand const&);
+
+    [[nodiscard]] ScopedOperand get_this(Optional<ScopedOperand> preferred_dst = {});
+
+    void emit_get_by_id(ScopedOperand dst, ScopedOperand base, IdentifierTableIndex property_identifier, Optional<IdentifierTableIndex> base_identifier = {});
+
+    void emit_get_by_id_with_this(ScopedOperand dst, ScopedOperand base, IdentifierTableIndex, ScopedOperand this_value);
+
+    void emit_iterator_value(ScopedOperand dst, ScopedOperand result);
+    void emit_iterator_complete(ScopedOperand dst, ScopedOperand result);
+
+    [[nodiscard]] size_t next_global_variable_cache() { return m_next_global_variable_cache++; }
+    [[nodiscard]] size_t next_property_lookup_cache() { return m_next_property_lookup_cache++; }
+
+    enum class DeduplicateConstant {
+        Yes,
+        No,
+    };
+    [[nodiscard]] ScopedOperand add_constant(Value);
+
+    [[nodiscard]] Value get_constant(ScopedOperand const& operand) const
+    {
+        VERIFY(operand.operand().is_constant());
+        return m_constants[operand.operand().index()];
+    }
+
+    UnwindContext const* current_unwind_context() const { return m_current_unwind_context; }
+
+    [[nodiscard]] bool is_finished() const { return m_finished; }
+
+    [[nodiscard]] bool must_propagate_completion() const { return m_must_propagate_completion; }
+
+private:
+    VM& m_vm;
+
+    static CodeGenerationErrorOr<NonnullGCPtr<Executable>> compile(VM&, ASTNode const&, FunctionKind, GCPtr<ECMAScriptFunctionObject const>, MustPropagateCompletion, Vector<DeprecatedFlyString> local_variable_names);
+
+    enum class JumpType {
+        Continue,
+        Break,
+    };
+    void generate_scoped_jump(JumpType);
+    void generate_labelled_jump(JumpType, DeprecatedFlyString const& label);
+
+    Generator(VM&, GCPtr<ECMAScriptFunctionObject const>, MustPropagateCompletion);
+    ~Generator() = default;
+
+    void grow(size_t);
+
+    // Returns true if a fused instruction was emitted.
+    [[nodiscard]] bool fuse_compare_and_jump(ScopedOperand const& condition, Label true_target, Label false_target);
+
+    struct LabelableScope {
+        Label bytecode_target;
+        Vector<DeprecatedFlyString> language_label_set;
+    };
+
+    BasicBlock* m_current_basic_block { nullptr };
+    ASTNode const* m_current_ast_node { nullptr };
+    UnwindContext const* m_current_unwind_context { nullptr };
+
+    Vector<NonnullOwnPtr<BasicBlock>> m_root_basic_blocks;
+    NonnullOwnPtr<StringTable> m_string_table;
+    NonnullOwnPtr<IdentifierTable> m_identifier_table;
+    NonnullOwnPtr<RegexTable> m_regex_table;
+    MarkedVector<Value> m_constants;
+
+    mutable Optional<ScopedOperand> m_true_constant;
+    mutable Optional<ScopedOperand> m_false_constant;
+    mutable Optional<ScopedOperand> m_null_constant;
+    mutable Optional<ScopedOperand> m_undefined_constant;
+    mutable Optional<ScopedOperand> m_empty_constant;
+    mutable HashMap<i32, ScopedOperand> m_int32_constants;
+
+    ScopedOperand m_accumulator;
+    ScopedOperand m_this_value;
+    Vector<Register> m_free_registers;
+
+    u32 m_next_register { Register::reserved_register_count };
+    u32 m_next_block { 1 };
+    u32 m_next_property_lookup_cache { 0 };
+    u32 m_next_global_variable_cache { 0 };
+    FunctionKind m_enclosing_function_kind { FunctionKind::Normal };
+    Vector<LabelableScope> m_continuable_scopes;
+    Vector<LabelableScope> m_breakable_scopes;
+    Vector<BlockBoundaryType> m_boundaries;
+    Vector<ScopedOperand> m_home_objects;
+
+    HashTable<u32> m_initialized_locals;
+
+    bool m_finished { false };
+    bool m_must_propagate_completion { true };
+
+    GCPtr<ECMAScriptFunctionObject const> m_function;
+
+    Optional<IdentifierTableIndex> m_length_identifier;
+};
+
+}

Libraries/LibJS/Bytecode/IdentifierTable.cpp

@@ -0,0 +1,30 @@
+/*
+ * Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/IdentifierTable.h>
+
+namespace JS::Bytecode {
+
+IdentifierTableIndex IdentifierTable::insert(DeprecatedFlyString string)
+{
+    m_identifiers.append(move(string));
+    VERIFY(m_identifiers.size() <= NumericLimits<u32>::max());
+    return { static_cast<u32>(m_identifiers.size() - 1) };
+}
+
+DeprecatedFlyString const& IdentifierTable::get(IdentifierTableIndex index) const
+{
+    return m_identifiers[index.value];
+}
+
+void IdentifierTable::dump() const
+{
+    outln("Identifier Table:");
+    for (size_t i = 0; i < m_identifiers.size(); i++)
+        outln("{}: {}", i, m_identifiers[i]);
+}
+
+}

Libraries/LibJS/Bytecode/IdentifierTable.h

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/DeprecatedFlyString.h>
+#include <AK/DistinctNumeric.h>
+#include <AK/Vector.h>
+
+namespace JS::Bytecode {
+
+struct IdentifierTableIndex {
+    bool is_valid() const { return value != NumericLimits<u32>::max(); }
+    u32 value { 0 };
+};
+
+class IdentifierTable {
+    AK_MAKE_NONMOVABLE(IdentifierTable);
+    AK_MAKE_NONCOPYABLE(IdentifierTable);
+
+public:
+    IdentifierTable() = default;
+
+    IdentifierTableIndex insert(DeprecatedFlyString);
+    DeprecatedFlyString const& get(IdentifierTableIndex) const;
+    void dump() const;
+    bool is_empty() const { return m_identifiers.is_empty(); }
+
+private:
+    Vector<DeprecatedFlyString> m_identifiers;
+};
+
+}

Libraries/LibJS/Bytecode/Instruction.cpp

@@ -0,0 +1,119 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Bytecode/Instruction.h>
+#include <LibJS/Bytecode/Op.h>
+
+namespace JS::Bytecode {
+
+void Instruction::destroy(Instruction& instruction)
+{
+#define __BYTECODE_OP(op)                        \
+    case Type::op:                               \
+        static_cast<Op::op&>(instruction).~op(); \
+        return;
+
+    switch (instruction.type()) {
+        ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+#undef __BYTECODE_OP
+}
+
+void Instruction::visit_labels(Function<void(JS::Bytecode::Label&)> visitor)
+{
+#define __BYTECODE_OP(op)                                             \
+    case Type::op:                                                    \
+        static_cast<Op::op&>(*this).visit_labels_impl(move(visitor)); \
+        return;
+
+    switch (type()) {
+        ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+#undef __BYTECODE_OP
+}
+
+void Instruction::visit_operands(Function<void(JS::Bytecode::Operand&)> visitor)
+{
+#define __BYTECODE_OP(op)                                               \
+    case Type::op:                                                      \
+        static_cast<Op::op&>(*this).visit_operands_impl(move(visitor)); \
+        return;
+
+    switch (type()) {
+        ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+#undef __BYTECODE_OP
+}
+
+template<typename Op>
+concept HasVariableLength = Op::IsVariableLength;
+
+template<typename Op>
+concept HasFixedLength = !Op::IsVariableLength;
+
+template<HasVariableLength Op>
+size_t get_length_impl(Op const& op)
+{
+    return op.length_impl();
+}
+
+// Function template for types without a length_impl method
+template<HasFixedLength Op>
+size_t get_length_impl(Op const&)
+{
+    return sizeof(Op);
+}
+
+size_t Instruction::length() const
+{
+#define __BYTECODE_OP(op)                                   \
+    case Type::op: {                                        \
+        auto& typed_op = static_cast<Op::op const&>(*this); \
+        return get_length_impl(typed_op);                   \
+    }
+
+    switch (type()) {
+        ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
+    default:
+        VERIFY_NOT_REACHED();
+    }
+
+#undef __BYTECODE_OP
+}
+
+UnrealizedSourceRange InstructionStreamIterator::source_range() const
+{
+    VERIFY(m_executable);
+    auto record = m_executable->source_map.get(offset()).value();
+    return {
+        .source_code = m_executable->source_code,
+        .start_offset = record.source_start_offset,
+        .end_offset = record.source_end_offset,
+    };
+}
+
+RefPtr<SourceCode> InstructionStreamIterator::source_code() const
+{
+    return m_executable ? m_executable->source_code.ptr() : nullptr;
+}
+
+Operand::Operand(Register reg)
+    : m_type(Type::Register)
+    , m_index(reg.index())
+{
+}
+
+}

Libraries/LibJS/Bytecode/Instruction.h

@@ -0,0 +1,219 @@
+/*
+ * Copyright (c) 2021-2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Forward.h>
+#include <AK/Function.h>
+#include <AK/Span.h>
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Forward.h>
+#include <LibJS/SourceRange.h>
+
+#define ENUMERATE_BYTECODE_OPS(O)      \
+    O(Add)                             \
+    O(AddPrivateName)                  \
+    O(ArrayAppend)                     \
+    O(AsyncIteratorClose)              \
+    O(Await)                           \
+    O(BitwiseAnd)                      \
+    O(BitwiseNot)                      \
+    O(BitwiseOr)                       \
+    O(BitwiseXor)                      \
+    O(BlockDeclarationInstantiation)   \
+    O(Call)                            \
+    O(CallBuiltin)                     \
+    O(CallConstruct)                   \
+    O(CallDirectEval)                  \
+    O(CallWithArgumentArray)           \
+    O(Catch)                           \
+    O(ConcatString)                    \
+    O(ContinuePendingUnwind)           \
+    O(CopyObjectExcludingProperties)   \
+    O(CreateArguments)                 \
+    O(CreateLexicalEnvironment)        \
+    O(CreatePrivateEnvironment)        \
+    O(CreateRestParams)                \
+    O(CreateVariable)                  \
+    O(CreateVariableEnvironment)       \
+    O(Decrement)                       \
+    O(DeleteById)                      \
+    O(DeleteByIdWithThis)              \
+    O(DeleteByValue)                   \
+    O(DeleteByValueWithThis)           \
+    O(DeleteVariable)                  \
+    O(Div)                             \
+    O(Dump)                            \
+    O(End)                             \
+    O(EnterObjectEnvironment)          \
+    O(EnterUnwindContext)              \
+    O(Exp)                             \
+    O(GetArgument)                     \
+    O(GetById)                         \
+    O(GetByIdWithThis)                 \
+    O(GetByValue)                      \
+    O(GetByValueWithThis)              \
+    O(GetCalleeAndThisFromEnvironment) \
+    O(GetGlobal)                       \
+    O(GetImportMeta)                   \
+    O(GetIterator)                     \
+    O(GetLength)                       \
+    O(GetLengthWithThis)               \
+    O(GetMethod)                       \
+    O(GetNewTarget)                    \
+    O(GetNextMethodFromIteratorRecord) \
+    O(GetObjectFromIteratorRecord)     \
+    O(GetObjectPropertyIterator)       \
+    O(GetPrivateById)                  \
+    O(GetBinding)                      \
+    O(GreaterThan)                     \
+    O(GreaterThanEquals)               \
+    O(HasPrivateId)                    \
+    O(ImportCall)                      \
+    O(In)                              \
+    O(Increment)                       \
+    O(InitializeLexicalBinding)        \
+    O(InitializeVariableBinding)       \
+    O(InstanceOf)                      \
+    O(IteratorClose)                   \
+    O(IteratorNext)                    \
+    O(IteratorToArray)                 \
+    O(Jump)                            \
+    O(JumpFalse)                       \
+    O(JumpGreaterThan)                 \
+    O(JumpGreaterThanEquals)           \
+    O(JumpIf)                          \
+    O(JumpLessThan)                    \
+    O(JumpLessThanEquals)              \
+    O(JumpLooselyEquals)               \
+    O(JumpLooselyInequals)             \
+    O(JumpNullish)                     \
+    O(JumpStrictlyEquals)              \
+    O(JumpStrictlyInequals)            \
+    O(JumpTrue)                        \
+    O(JumpUndefined)                   \
+    O(LeaveFinally)                    \
+    O(LeaveLexicalEnvironment)         \
+    O(LeavePrivateEnvironment)         \
+    O(LeaveUnwindContext)              \
+    O(LeftShift)                       \
+    O(LessThan)                        \
+    O(LessThanEquals)                  \
+    O(LooselyEquals)                   \
+    O(LooselyInequals)                 \
+    O(Mod)                             \
+    O(Mov)                             \
+    O(Mul)                             \
+    O(NewArray)                        \
+    O(NewClass)                        \
+    O(NewFunction)                     \
+    O(NewObject)                       \
+    O(NewPrimitiveArray)               \
+    O(NewRegExp)                       \
+    O(NewTypeError)                    \
+    O(Not)                             \
+    O(PrepareYield)                    \
+    O(PostfixDecrement)                \
+    O(PostfixIncrement)                \
+    O(PutById)                         \
+    O(PutByIdWithThis)                 \
+    O(PutBySpread)                     \
+    O(PutByValue)                      \
+    O(PutByValueWithThis)              \
+    O(PutPrivateById)                  \
+    O(ResolveSuperBase)                \
+    O(ResolveThisBinding)              \
+    O(RestoreScheduledJump)            \
+    O(Return)                          \
+    O(RightShift)                      \
+    O(ScheduleJump)                    \
+    O(SetArgument)                     \
+    O(SetLexicalBinding)               \
+    O(SetVariableBinding)              \
+    O(StrictlyEquals)                  \
+    O(StrictlyInequals)                \
+    O(Sub)                             \
+    O(SuperCallWithArgumentArray)      \
+    O(Throw)                           \
+    O(ThrowIfNotObject)                \
+    O(ThrowIfNullish)                  \
+    O(ThrowIfTDZ)                      \
+    O(Typeof)                          \
+    O(TypeofBinding)                   \
+    O(UnaryMinus)                      \
+    O(UnaryPlus)                       \
+    O(UnsignedRightShift)              \
+    O(Yield)
+
+namespace JS::Bytecode {
+
+class alignas(void*) Instruction {
+public:
+    constexpr static bool IsTerminator = false;
+    static constexpr bool IsVariableLength = false;
+
+    enum class Type {
+#define __BYTECODE_OP(op) \
+    op,
+        ENUMERATE_BYTECODE_OPS(__BYTECODE_OP)
+#undef __BYTECODE_OP
+    };
+
+    Type type() const { return m_type; }
+    size_t length() const;
+    ByteString to_byte_string(Bytecode::Executable const&) const;
+    void visit_labels(Function<void(Label&)> visitor);
+    void visit_operands(Function<void(Operand&)> visitor);
+    static void destroy(Instruction&);
+
+protected:
+    explicit Instruction(Type type)
+        : m_type(type)
+    {
+    }
+
+    void visit_labels_impl(Function<void(Label&)>) { }
+    void visit_operands_impl(Function<void(Operand&)>) { }
+
+private:
+    Type m_type {};
+};
+
+class InstructionStreamIterator {
+public:
+    InstructionStreamIterator(ReadonlyBytes bytes, Executable const* executable = nullptr, size_t offset = 0)
+        : m_begin(bytes.data())
+        , m_end(bytes.data() + bytes.size())
+        , m_ptr(bytes.data() + offset)
+        , m_executable(executable)
+    {
+    }
+
+    size_t offset() const { return m_ptr - m_begin; }
+    bool at_end() const { return m_ptr >= m_end; }
+
+    Instruction const& operator*() const { return dereference(); }
+
+    ALWAYS_INLINE void operator++()
+    {
+        m_ptr += dereference().length();
+    }
+
+    UnrealizedSourceRange source_range() const;
+    RefPtr<SourceCode> source_code() const;
+
+    Executable const* executable() const { return m_executable; }
+
+private:
+    Instruction const& dereference() const { return *reinterpret_cast<Instruction const*>(m_ptr); }
+
+    u8 const* m_begin { nullptr };
+    u8 const* m_end { nullptr };
+    u8 const* m_ptr { nullptr };
+    GCPtr<Executable const> m_executable;
+};
+
+}

Libraries/LibJS/Bytecode/Interpreter.h

@@ -0,0 +1,115 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <LibJS/Bytecode/Executable.h>
+#include <LibJS/Bytecode/Label.h>
+#include <LibJS/Bytecode/Register.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Heap/Cell.h>
+#include <LibJS/Runtime/FunctionKind.h>
+#include <LibJS/Runtime/VM.h>
+#include <LibJS/Runtime/Value.h>
+
+namespace JS::Bytecode {
+
+class InstructionStreamIterator;
+
+class Interpreter {
+public:
+    explicit Interpreter(VM&);
+    ~Interpreter();
+
+    [[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; }
+
+    ThrowCompletionOr<Value> run(Script&, JS::GCPtr<Environment> lexical_environment_override = nullptr);
+    ThrowCompletionOr<Value> run(SourceTextModule&);
+
+    ThrowCompletionOr<Value> run(Bytecode::Executable& executable, Optional<size_t> entry_point = {}, Value initial_accumulator_value = {})
+    {
+        auto result_and_return_register = run_executable(executable, entry_point, initial_accumulator_value);
+        return move(result_and_return_register.value);
+    }
+
+    struct ResultAndReturnRegister {
+        ThrowCompletionOr<Value> value;
+        Value return_register_value;
+    };
+    ResultAndReturnRegister run_executable(Bytecode::Executable&, Optional<size_t> entry_point, Value initial_accumulator_value = {});
+
+    ALWAYS_INLINE Value& accumulator() { return reg(Register::accumulator()); }
+    ALWAYS_INLINE Value& saved_return_value() { return reg(Register::saved_return_value()); }
+    Value& reg(Register const& r)
+    {
+        return m_registers_and_constants_and_locals.data()[r.index()];
+    }
+    Value reg(Register const& r) const
+    {
+        return m_registers_and_constants_and_locals.data()[r.index()];
+    }
+
+    [[nodiscard]] Value get(Operand) const;
+    void set(Operand, Value);
+
+    Value do_yield(Value value, Optional<Label> continuation);
+    void do_return(Value value)
+    {
+        reg(Register::return_value()) = value;
+        reg(Register::exception()) = {};
+    }
+
+    void enter_unwind_context();
+    void leave_unwind_context();
+    void catch_exception(Operand dst);
+    void restore_scheduled_jump();
+    void leave_finally();
+
+    void enter_object_environment(Object&);
+
+    Executable& current_executable() { return *m_current_executable; }
+    Executable const& current_executable() const { return *m_current_executable; }
+    Optional<size_t> program_counter() const { return m_program_counter; }
+    Span<Value> allocate_argument_values(size_t argument_count)
+    {
+        m_argument_values_buffer.resize_and_keep_capacity(argument_count);
+        return m_argument_values_buffer.span();
+    }
+
+    ExecutionContext& running_execution_context() { return *m_running_execution_context; }
+
+private:
+    void run_bytecode(size_t entry_point);
+
+    enum class HandleExceptionResponse {
+        ExitFromExecutable,
+        ContinueInThisExecutable,
+    };
+    [[nodiscard]] HandleExceptionResponse handle_exception(size_t& program_counter, Value exception);
+
+    VM& m_vm;
+    Optional<size_t> m_scheduled_jump;
+    GCPtr<Executable> m_current_executable { nullptr };
+    GCPtr<Realm> m_realm { nullptr };
+    GCPtr<Object> m_global_object { nullptr };
+    GCPtr<DeclarativeEnvironment> m_global_declarative_environment { nullptr };
+    Optional<size_t&> m_program_counter;
+    Span<Value> m_arguments;
+    Span<Value> m_registers_and_constants_and_locals;
+    Vector<Value> m_argument_values_buffer;
+    ExecutionContext* m_running_execution_context { nullptr };
+};
+
+extern bool g_dump_bytecode;
+
+ThrowCompletionOr<NonnullGCPtr<Bytecode::Executable>> compile(VM&, ASTNode const&, JS::FunctionKind kind, DeprecatedFlyString const& name);
+ThrowCompletionOr<NonnullGCPtr<Bytecode::Executable>> compile(VM&, ECMAScriptFunctionObject const&);
+
+}

Libraries/LibJS/Bytecode/Label.cpp

@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/BasicBlock.h>
+#include <LibJS/Bytecode/Label.h>
+
+namespace JS::Bytecode {
+
+Label::Label(Bytecode::BasicBlock const& basic_block)
+    : m_address_or_basic_block_index(basic_block.index())
+{
+}
+
+}

Libraries/LibJS/Bytecode/Label.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Format.h>
+
+namespace JS::Bytecode {
+
+class BasicBlock;
+
+class Label {
+public:
+    explicit Label(BasicBlock const&);
+
+    explicit Label(u32 basic_block_index)
+        : m_address_or_basic_block_index(basic_block_index)
+    {
+    }
+
+    // Used while compiling.
+    size_t basic_block_index() const { return m_address_or_basic_block_index; }
+
+    // Used after compiling.
+    size_t address() const { return m_address_or_basic_block_index; }
+
+    void set_address(size_t address) { m_address_or_basic_block_index = address; }
+
+private:
+    u32 m_address_or_basic_block_index { 0 };
+};
+
+}
+
+template<>
+struct AK::Formatter<JS::Bytecode::Label> : AK::Formatter<FormatString> {
+    ErrorOr<void> format(FormatBuilder& builder, JS::Bytecode::Label const& label)
+    {
+        return AK::Formatter<FormatString>::format(builder, "@{:x}"sv, label.address());
+    }
+};

Libraries/LibJS/Bytecode/Operand.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <LibJS/Forward.h>
+
+namespace JS::Bytecode {
+
+class Operand {
+public:
+    enum class Type {
+        Register,
+        Local,
+        Constant,
+    };
+
+    [[nodiscard]] bool operator==(Operand const&) const = default;
+
+    explicit Operand(Type type, u32 index)
+        : m_type(type)
+        , m_index(index)
+    {
+    }
+
+    explicit Operand(Register);
+
+    [[nodiscard]] bool is_register() const { return m_type == Type::Register; }
+    [[nodiscard]] bool is_local() const { return m_type == Type::Local; }
+    [[nodiscard]] bool is_constant() const { return m_type == Type::Constant; }
+
+    [[nodiscard]] Type type() const { return m_type; }
+    [[nodiscard]] u32 index() const { return m_index; }
+
+    [[nodiscard]] Register as_register() const;
+
+    void offset_index_by(u32 offset) { m_index += offset; }
+
+private:
+    Type m_type {};
+    u32 m_index { 0 };
+};
+
+}

Libraries/LibJS/Bytecode/RegexTable.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2023, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/RegexTable.h>
+
+namespace JS::Bytecode {
+
+RegexTableIndex RegexTable::insert(ParsedRegex regex)
+{
+    m_regexes.append(move(regex));
+    return m_regexes.size() - 1;
+}
+
+ParsedRegex const& RegexTable::get(RegexTableIndex index) const
+{
+    return m_regexes[index.value()];
+}
+
+void RegexTable::dump() const
+{
+    outln("Regex Table:");
+    for (size_t i = 0; i < m_regexes.size(); i++)
+        outln("{}: {}", i, m_regexes[i].pattern);
+}
+
+}

Libraries/LibJS/Bytecode/RegexTable.h

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2023, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/ByteString.h>
+#include <AK/DistinctNumeric.h>
+#include <AK/Vector.h>
+#include <LibRegex/RegexParser.h>
+
+namespace JS::Bytecode {
+
+AK_TYPEDEF_DISTINCT_NUMERIC_GENERAL(size_t, RegexTableIndex, Comparison);
+
+struct ParsedRegex {
+    regex::Parser::Result regex;
+    ByteString pattern;
+    regex::RegexOptions<ECMAScriptFlags> flags;
+};
+
+class RegexTable {
+    AK_MAKE_NONMOVABLE(RegexTable);
+    AK_MAKE_NONCOPYABLE(RegexTable);
+
+public:
+    RegexTable() = default;
+
+    RegexTableIndex insert(ParsedRegex);
+    ParsedRegex const& get(RegexTableIndex) const;
+    void dump() const;
+    bool is_empty() const { return m_regexes.is_empty(); }
+
+private:
+    Vector<ParsedRegex> m_regexes;
+};
+
+}

Libraries/LibJS/Bytecode/Register.h

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2021, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Format.h>
+
+namespace JS::Bytecode {
+
+class Register {
+public:
+    constexpr static u32 accumulator_index = 0;
+
+    static constexpr Register accumulator()
+    {
+        return Register(accumulator_index);
+    }
+
+    constexpr static u32 saved_return_value_index = 1;
+
+    static constexpr Register saved_return_value()
+    {
+        return Register(saved_return_value_index);
+    }
+
+    static constexpr u32 exception_index = 2;
+
+    static constexpr Register exception()
+    {
+        return Register(exception_index);
+    }
+
+    static constexpr Register this_value()
+    {
+        constexpr u32 this_value_index = 3;
+        return Register(this_value_index);
+    }
+
+    static constexpr Register return_value()
+    {
+        constexpr u32 return_value_index = 4;
+        return Register(return_value_index);
+    }
+
+    static constexpr Register saved_exception()
+    {
+        constexpr u32 saved_exception_index = 5;
+        return Register(saved_exception_index);
+    }
+
+    static constexpr u32 reserved_register_count = 6;
+
+    constexpr explicit Register(u32 index)
+        : m_index(index)
+    {
+    }
+
+    constexpr bool operator==(Register reg) const { return m_index == reg.index(); }
+
+    constexpr u32 index() const { return m_index; }
+
+private:
+    u32 m_index;
+};
+
+}
+
+template<>
+struct AK::Formatter<JS::Bytecode::Register> : AK::Formatter<FormatString> {
+    ErrorOr<void> format(FormatBuilder& builder, JS::Bytecode::Register const& value)
+    {
+        if (value.index() == JS::Bytecode::Register::accumulator_index)
+            return builder.put_string("acc"sv);
+        return AK::Formatter<FormatString>::format(builder, "${}"sv, value.index());
+    }
+};

Libraries/LibJS/Bytecode/ScopedOperand.cpp

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/Generator.h>
+#include <LibJS/Bytecode/ScopedOperand.h>
+
+namespace JS::Bytecode {
+
+ScopedOperandImpl::~ScopedOperandImpl()
+{
+    if (!m_generator.is_finished() && m_operand.is_register() && m_operand.as_register().index() >= Register::reserved_register_count)
+        m_generator.free_register(m_operand.as_register());
+}
+
+Register Operand::as_register() const
+{
+    return Register { m_index };
+}
+
+}

Libraries/LibJS/Bytecode/ScopedOperand.h

@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2024, Andreas Kling <andreas@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/RefCounted.h>
+#include <LibJS/Bytecode/Operand.h>
+
+namespace JS::Bytecode {
+
+class ScopedOperandImpl : public RefCounted<ScopedOperandImpl> {
+public:
+    ScopedOperandImpl(Generator& generator, Operand operand)
+        : m_generator(generator)
+        , m_operand(operand)
+    {
+    }
+
+    ~ScopedOperandImpl();
+
+    [[nodiscard]] Operand const& operand() const { return m_operand; }
+    [[nodiscard]] Operand& operand() { return m_operand; }
+
+private:
+    Generator& m_generator;
+    Operand m_operand;
+};
+
+class ScopedOperand {
+public:
+    explicit ScopedOperand(Generator& generator, Operand operand)
+        : m_impl(adopt_ref(*new ScopedOperandImpl(generator, operand)))
+    {
+    }
+
+    [[nodiscard]] Operand const& operand() const { return m_impl->operand(); }
+    [[nodiscard]] Operand& operand() { return m_impl->operand(); }
+    operator Operand() const { return operand(); }
+
+    [[nodiscard]] bool operator==(ScopedOperand const& other) const { return operand() == other.operand(); }
+
+    [[nodiscard]] size_t ref_count() const { return m_impl->ref_count(); }
+
+private:
+    NonnullRefPtr<ScopedOperandImpl> m_impl;
+};
+
+}

Libraries/LibJS/Bytecode/StringTable.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibJS/Bytecode/StringTable.h>
+
+namespace JS::Bytecode {
+
+StringTableIndex StringTable::insert(ByteString string)
+{
+    m_strings.append(move(string));
+    return m_strings.size() - 1;
+}
+
+ByteString const& StringTable::get(StringTableIndex index) const
+{
+    return m_strings[index.value()];
+}
+
+void StringTable::dump() const
+{
+    outln("String Table:");
+    for (size_t i = 0; i < m_strings.size(); i++)
+        outln("{}: {}", i, m_strings[i]);
+}
+
+}

Libraries/LibJS/Bytecode/StringTable.h

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/ByteString.h>
+#include <AK/DistinctNumeric.h>
+#include <AK/Vector.h>
+
+namespace JS::Bytecode {
+
+AK_TYPEDEF_DISTINCT_NUMERIC_GENERAL(u32, StringTableIndex, Comparison);
+
+class StringTable {
+    AK_MAKE_NONMOVABLE(StringTable);
+    AK_MAKE_NONCOPYABLE(StringTable);
+
+public:
+    StringTable() = default;
+
+    StringTableIndex insert(ByteString);
+    ByteString const& get(StringTableIndex) const;
+    void dump() const;
+    bool is_empty() const { return m_strings.is_empty(); }
+
+private:
+    Vector<ByteString> m_strings;
+};
+
+}