perf: JsString 缓存 UTF-16 length，字符串 length 访问改 O(1)

2026-08-10 16:13:24 +08:00
parent f284f74cb1
commit cd96fa6fcb
2 changed files with 27 additions and 3 deletions
@@ -47,8 +47,8 @@ impl Vm {
        if val.is_string() {
            let length_si = self.kernel_core.perm_interner().intern("length").0;
            if prop_name_si == length_si {
-                // SAFETY: val 是字符串值。
-                let len = unsafe { (*val.as_string_ptr()).data.encode_utf16().count() };
+                // SAFETY: val 是字符串值。utf16_len 构造时缓存，O(1) 读取。
+                let len = unsafe { (*val.as_string_ptr()).utf16_len() };
                return Ok(Some(JsValue::int(len as i32)));
            }
            let proto_ptr = self.session.builtin_world().string_proto.as_ptr() as *mut JsObject;