perf: String() 有限 double 转串加 16 槽 last-value 缓存

Cargo.lock

@@ -1095,7 +1095,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_builtins"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "chrono",
  "fast-float",
@@ -1120,7 +1120,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_bytecode"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "num-bigint",
  "oxide_log",
@@ -1128,7 +1128,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cfg"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_emit",
@@ -1139,7 +1139,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_cli"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "ansi_term",
  "bumpalo",
@@ -1159,7 +1159,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_code_cache"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "lru",
  "oxide_bytecode",
@@ -1168,7 +1168,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_compiler"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1187,7 +1187,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_dce"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1201,7 +1201,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_emit"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "num-bigint",
  "oxc_allocator",
@@ -1216,7 +1216,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_ir"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_log",
@@ -1225,7 +1225,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_kernel"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "bumpalo",
  "dashmap",
@@ -1240,7 +1240,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_liveness"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1252,7 +1252,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_log"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "tracing",
  "tracing-appender",
@@ -1261,7 +1261,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_parser"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxc_allocator",
  "oxc_ast",
@@ -1276,7 +1276,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_regalloc"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_cfg",
@@ -1292,7 +1292,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_runtime_api"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "num-bigint",
  "num-traits",
@@ -1304,7 +1304,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_test262"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "oxide_bytecode",
  "oxide_compiler",
@@ -1321,7 +1321,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_types"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "bumpalo",
  "hashbrown 0.14.5",
@@ -1333,7 +1333,7 @@ dependencies = [
 
 [[package]]
 name = "oxide_vm"
-version = "0.8.1"
+version = "0.8.2"
 dependencies = [
  "bumpalo",
  "chrono",

Cargo.toml

@@ -22,7 +22,7 @@ members = [
 ]
 
 [workspace.package]
-version = "0.8.1"
+version = "0.8.2"
 edition = "2021"
 license = "MIT"
 rust-version = "1.80"

crates/oxide_builtins/src/string/basic.rs

@@ -164,8 +164,9 @@ pub fn string_constructor<H: VmHost>(vm: &mut H, args: &[u8]) -> NativeResult {
             } else if d.is_infinite() {
                 JsValue::string(oxide_kernel::string_forge::const_string_ptr(if d > 0.0 { 5 } else { 6 }))
             } else {
-                // 有限 double 走原数值转串链，行为与转换链一致。
+                // 有限 double 走十六槽 last-value 缓存：命中复用已登记串，
-                vm.new_string_owned(oxide_runtime_api::js_number_to_string(d))
+                // miss 走原数值转串链，行为与转换链一致。
+                vm.number_to_string_cached(d)
             }
         } else {
             // BigInt/对象参数走完整转换链（对象可经 valueOf/toString 抛错）；

crates/oxide_builtins/tests/string_constructor_tests.rs

@@ -90,3 +90,62 @@ fn string_constructor_fallback_paths() {
     let (_vm, len) = eval("new String(\"ab\").length").unwrap();
     assert_eq!(len.as_int(), 2);
 }
+
+// 位模式低 4 位互异的十六个有限 double（槽位互不冲突的测试前提）。
+const CACHE_TEST_VALUES: [f64; 16] = [
+    0.119, 0.103, 0.087, 0.071, 0.063, 0.207, 0.175, 0.143, 0.015, 0.007, 0.003, 0.005, 0.001, 0.205, 0.173, 0.141,
+];
+
+#[test]
+fn number_to_string_cache_slot_correctness() {
+    // 十六个槽位互异的值两轮各调一次：命中须键全等才返回，
+    // 钉住槽位碰撞不得错返。
+    let mut vm = Vm::new();
+    let mut seen = [false; 16];
+    for &d in &CACHE_TEST_VALUES {
+        let slot = (d.to_bits() as usize) & 15;
+        assert!(!seen[slot], "槽位冲突：{d}");
+        seen[slot] = true;
+    }
+    for _round in 0..2 {
+        for &d in &CACHE_TEST_VALUES {
+            let v = vm.number_to_string_cached(d);
+            assert!(v.is_string());
+            let expected = oxide_runtime_api::js_number_to_string(d);
+            assert_eq!(unsafe { &*v.as_string_ptr() }.as_str(), expected.as_str(), "值 {d} 应与原转换链一致");
+        }
+    }
+}
+
+#[test]
+fn number_to_string_cache_survives_session_gc() {
+    // 填满十六槽后强制完整 session 收集：缓存串已登记为 GC 根，
+    // 收集后读回仍为原内容（漏根登记此测必挂）。
+    let mut vm = Vm::new();
+    for &d in &CACHE_TEST_VALUES {
+        vm.number_to_string_cached(d);
+    }
+    vm.collect_session_gc();
+    for &d in &CACHE_TEST_VALUES {
+        let v = vm.number_to_string_cached(d);
+        assert!(v.is_string());
+        let expected = oxide_runtime_api::js_number_to_string(d);
+        assert_eq!(unsafe { &*v.as_string_ptr() }.as_str(), expected.as_str(), "收集后值 {d} 应可读回");
+    }
+    // 2.5 挤占槽 0 后写新串：新串同样须存活后续收集。
+    let v = vm.number_to_string_cached(2.5);
+    vm.collect_session_gc();
+    let v2 = vm.number_to_string_cached(2.5);
+    assert_eq!(unsafe { &*v2.as_string_ptr() }.as_str(), "2.5");
+    assert_eq!(v.as_string_ptr(), v2.as_string_ptr());
+}
+
+#[test]
+fn number_to_string_cache_identity() {
+    // 同值两次调用命中同槽：返回指针相等（命中复用 session 串）。
+    let mut vm = Vm::new();
+    let a = vm.number_to_string_cached(2.5);
+    let b = vm.number_to_string_cached(2.5);
+    assert!(a.is_string() && b.is_string());
+    assert_eq!(a.as_string_ptr(), b.as_string_ptr());
+}

crates/oxide_runtime_api/src/host.rs

@@ -58,6 +58,14 @@ pub trait VmHost {
     fn new_string(&mut self, s: &str) -> JsValue;
     /// move 接收 `String` 创建会话字符串，避免一次整串克隆。
     fn new_string_owned(&mut self, s: String) -> JsValue;
+    /// 有限 double 转串，带十六槽 last-value 缓存：命中返回已登记为 GC 根的
+    /// session 串，miss 走原数值转串链并写槽。
+    ///
+    /// # 注意事项
+    /// - 非有限值（NaN/±Infinity）走永久常量表，不进槽。
+    /// - `full_reset` 在 session 串释放前清空槽；轻量 `reset` 保留槽
+    ///   （session 串跨 eval 存活，缓存串仍有效）。
+    fn number_to_string_cached(&mut self, d: f64) -> JsValue;
     /// 取 ASCII 单字符的永久字符串值：命中返回共享 perm 串（零分配、可指针
     /// 短路比较），非 ASCII 返回 `None` 由调用方回落普通字符串创建。
     ///

crates/oxide_vm/src/vm/gc_hooks.rs

@@ -76,6 +76,12 @@ impl Vm {
         for &cached in self.template_objects.values() {
             f(cached);
         }
+        // f64→string 缓存槽值是 session 串，是 GC 根（漏根 → 串清扫释放 → 命中悬垂）。
+        for &v in &self.number_to_string_cache_vals {
+            if v.is_string() {
+                f(v);
+            }
+        }
         for &entry in &self.iters.for_of_iters {
             f(entry.iterator);
             f(entry.last_result);

crates/oxide_vm/src/vm/mod.rs

@@ -183,6 +183,12 @@ pub struct Vm {
     /// （发射层字符串常量统一经 perm_string 物化），指针相等即键为 "length"，
     /// 入口快判只比指针免键解析。PermInterner 追加式、指针唯一，永不失效。
     pub(crate) length_perm_ptr: *const JsString,
+    /// f64→string 十六槽 last-value 缓存的键（double 位模式）。空槽判定用
+    /// 对应值非字符串：键 0 是 +0.0 的合法位模式，不得作空标记。
+    pub(crate) number_to_string_cache_keys: [u64; 16],
+    /// f64→string 十六槽 last-value 缓存的值（session 串，经 `for_each_value`
+    /// 登记为 GC 根；`full_reset` 在 session 串释放前清空）。
+    pub(crate) number_to_string_cache_vals: [JsValue; 16],
     pub object_prototype: P<JsObject>,
     /// `%GeneratorPrototype%`：生成器实例的原型（next/return/throw 方法挂此）。
     pub generator_proto: P<JsObject>,

crates/oxide_vm/src/vm/vmhost.rs

@@ -33,6 +33,9 @@ impl oxide_runtime_api::VmHost for Vm {
     fn new_string_owned(&mut self, s: String) -> JsValue {
         Vm::new_string_owned(self, s)
     }
+    fn number_to_string_cached(&mut self, d: f64) -> JsValue {
+        Vm::number_to_string_cached(self, d)
+    }
     fn new_bigint(&mut self, v: num_bigint::BigInt) -> JsValue {
         Vm::new_bigint(self, v)
     }

crates/oxide_vm/src/vm_support.rs

@@ -57,6 +57,8 @@ impl Vm {
             session,
             length_si,
             length_perm_ptr,
+            number_to_string_cache_keys: [0u64; 16],
+            number_to_string_cache_vals: [JsValue::undefined(); 16],
             object_prototype: obj_proto,
             generator_proto: P::new(JsObject::new_empty(EMPTY_SHAPE_ID, JsValue::null())),
             generator_function_proto: P::new(JsObject::new_empty(EMPTY_SHAPE_ID, JsValue::null())),
@@ -198,6 +200,8 @@ impl Vm {
             session,
             length_si,
             length_perm_ptr,
+            number_to_string_cache_keys: [0u64; 16],
+            number_to_string_cache_vals: [JsValue::undefined(); 16],
             object_prototype: obj_proto,
             generator_proto: P::new(JsObject::new_empty(EMPTY_SHAPE_ID, JsValue::null())),
             generator_function_proto: P::new(JsObject::new_empty(EMPTY_SHAPE_ID, JsValue::null())),
@@ -409,6 +413,10 @@ impl Vm {
             }),
         );
         self.active_immutables = std::ptr::slice_from_raw_parts(std::ptr::null(), 0);
+        // f64→string 缓存槽指向即将释放的 session 串：须在 teardown 之前清空，
+        // 否则下次命中返回悬垂指针。
+        self.number_to_string_cache_keys = [0u64; 16];
+        self.number_to_string_cache_vals = [JsValue::undefined(); 16];
         self.teardown_session_heap_data();
         self.gc_state.session_bytes_allocated = 0;
         self.gc_state.session_bytes_peak = 0;
@@ -595,6 +603,39 @@ impl Vm {
         self.register_session_string(ptr, len)
     }
 
+    /// 有限 double 转串，带十六槽 last-value 缓存：命中返回已登记的 session 串，
+    /// miss 走原数值转串链并写槽。
+    ///
+    /// # 步骤
+    /// 1. 非有限值（NaN/±Infinity）返回对应永久常量串，不进槽。
+    /// 2. 槽位取位模式低 4 位；槽值为字符串且键全等时返回槽值。
+    /// 3. miss 走原数值转串链新建 session 串，写键与值后返回。
+    ///
+    /// # 副作用
+    /// - 槽值经 `for_each_value` 登记为 GC 根，strings-only 收集不释放；
+    ///   `full_reset` 在 session 串释放前清空槽。
+    ///
+    /// # 注意事项
+    /// - 空槽判定用值非字符串：+0.0 的位模式是 0，键不得作空标记。
+    /// - direct-mapped last-value：异值撞槽即覆盖，返回前键须 64 位全等。
+    pub fn number_to_string_cached(&mut self, d: f64) -> JsValue {
+        if d.is_nan() {
+            return JsValue::string(oxide_kernel::string_forge::const_string_ptr(4));
+        }
+        if d.is_infinite() {
+            return JsValue::string(oxide_kernel::string_forge::const_string_ptr(if d > 0.0 { 5 } else { 6 }));
+        }
+        let bits = d.to_bits();
+        let slot = (bits as usize) & 15;
+        if self.number_to_string_cache_vals[slot].is_string() && self.number_to_string_cache_keys[slot] == bits {
+            return self.number_to_string_cache_vals[slot];
+        }
+        let v = self.new_string_owned(oxide_runtime_api::js_number_to_string(d));
+        self.number_to_string_cache_keys[slot] = bits;
+        self.number_to_string_cache_vals[slot] = v;
+        v
+    }
+
     /// 登记一个 session 字符串并记账（`new_string_owned` 与 `new_cons_string`
     /// 共用），返回字符串值。
     ///