LibJS: Introduce Builtins

Builtins are functions that can be detected during bytecode generation
and enable fast-paths in the JIT.

Userland/Libraries/LibJS/Bytecode/Builtins.h

@@ -0,0 +1,66 @@
+/*
+ * 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)
+
+enum class Builtin {
+#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));
+    }
+};
+
+}