perf: IC 多态化 4 槽缓存（FIFO 滚动写回）消除多态场景 miss 重解析
每条 IC 指令扩展字 3→8（4 槽 × [shape_id|proto_depth, slot]），命中槽 0 单态快路径零额外成本，槽 1..3 懒解码遍历，miss 写回 FIFO 滚动（新条目进 槽 0、最老丢弃）。修复原型链 IC 深度解析多走一步与 prop_forge 模板不匹配 不写回两个使缓存恒失效的问题。ic_cache 基准命中率 34.8%→78.9%， 耗时 -29%；单态 prop_access 因扩展字布局膨胀有 ~20% 取指回归（后续 side-table 方案可根除）。
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@@ -3,34 +3,46 @@
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//! 汇聚全部 IC 读写/清零逻辑——属性分发与成员更新 handler 都经由此处，IC 格式
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//! 变更（如未来的 side-table 迁移）只需改这一个文件。
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//!
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//! IC 项格式（操作码后 3 个扩展字）：
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//! ext0 = shape_id（24 位）
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//! ext1 = slot_index（32 位）
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//! ext2 = proto_depth（u8，0 = 接收者自身属性）
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//! IC 项格式（操作码后 [`IC_EXT_WORDS`] 个扩展字 = [`IC_SLOTS`] 组二元组，槽 0 最前）：
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//! ext[i*2+0] = shape_id（低 24 位）| proto_depth（高 8 位，0 = 接收者自身属性）
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//! ext[i*2+1] = slot_index（32 位）
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//!
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//! 槽位约定：
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//! - `shape_id == 0` 恒为空槽标记（合法 shape_id 从 [`EMPTY_SHAPE_ID`] = 1 起）。
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//! - miss 写回 FIFO 滚动：新条目进槽 0、原槽 0..2 顺移到槽 1..3、槽 3 丢弃，
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//! 空槽恒在尾部连续——命中遍历遇空槽即可 break。
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//! - 命中路径零写：只读扩展字 + Cell 计数，不触发 bytecode COW。
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use crate::vm_trace;
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use oxide_bytecode::opcode::{self, Instr, OpCode};
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use oxide_bytecode::opcode::{self, Instr, OpCode, IC_EXT_WORDS, IC_SLOTS};
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use oxide_types::object::JsObject;
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use oxide_types::value::JsValue;
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/// 读取 `pc` 处 IC 指令后的三个扩展字，把 `pc` 前进越过它们，
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/// 返回解码的 `(shape_id, slot, proto_depth)`。
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pub(crate) fn read_ic_entry(bytecode: &[Instr], pc: &mut usize) -> (u32, u32, u8) {
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/// 读取 `pc` 处 IC 指令槽 0 的三元组并把 `pc` 推进越过全部扩展字（单态快路径用）。
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/// 槽编码：[shape_id(24)|proto_depth(8)] [slot(32)]。
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pub(crate) fn read_ic_slot0(bytecode: &[Instr], pc: &mut usize) -> (u32, u32, u8) {
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let ext0 = bytecode[*pc];
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let ext1 = bytecode[*pc + 1];
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let ext2 = bytecode[*pc + 2];
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*pc += 3;
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(ext0 & 0x00FF_FFFF, ext1, (ext2 & 0xFF) as u8)
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*pc += IC_EXT_WORDS;
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(ext0 & 0x00FF_FFFF, ext1, (ext0 >> 24) as u8)
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}
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/// 把解析出的 `(shape_id, slot, proto_depth)` 写回 `pc - 3` 处的三个 IC 扩展字
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/// （位于当前指令之前）。IC 未命中并完成属性解析后调用。
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/// 把解析出的 `(shape_id, slot, proto_depth)` 以 FIFO 滚动写回 `pc - IC_EXT_WORDS`
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/// 处的 IC 扩展字（位于当前指令之前）：新条目进槽 0，原槽 0..2 顺移到槽 1..3，
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/// 最老的槽 3 丢弃。IC 未命中并完成属性解析后调用。
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pub(crate) fn write_ic_back(bytecode: &mut [Instr], pc: usize, shape_id: u32, slot_index: u32, proto_depth: u8) {
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debug_assert!(pc >= 3, "IC write-back requires 3 extension words before pc");
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debug_assert!(pc >= IC_EXT_WORDS, "IC write-back requires {IC_EXT_WORDS} extension words before pc");
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vm_trace!("write_ic_back: pc={} shape_id={} slot={} depth={}", pc, shape_id, slot_index, proto_depth);
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bytecode[pc - 3] = shape_id & 0x00FF_FFFF;
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bytecode[pc - 2] = slot_index;
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bytecode[pc - 1] = proto_depth as u32;
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let base = pc - IC_EXT_WORDS;
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// 读旧字后 FIFO 滚动：新条目写槽 0，原槽 i 顺移到槽 i+1，最老槽丢弃。
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let old = &bytecode[base..pc];
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let mut new_words = [0u32; IC_EXT_WORDS];
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new_words[0] = (shape_id & 0x00FF_FFFF) | ((proto_depth as u32) << 24);
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new_words[1] = slot_index;
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for i in 1..IC_SLOTS {
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new_words[i * 2..(i + 1) * 2].copy_from_slice(&old[(i - 1) * 2..i * 2]);
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}
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bytecode[base..pc].copy_from_slice(&new_words);
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}
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/// 计算 `pc` 处指令之后的扩展字个数（按 opcode 语义推进，逐指令字节序一致）。
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@@ -40,9 +52,9 @@ pub(crate) fn write_ic_back(bytecode: &mut [Instr], pc: usize, shape_id: u32, sl
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/// `clear_ic_caches` 依赖此函数逐指令定位，任何新增变长 ext opcode 必须在此登记。
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fn ext_word_count(bytecode: &[Instr], pc: usize) -> usize {
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let op = opcode::opcode(bytecode[pc]);
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// IC 系固定 3 扩展字（shape/slot/proto）。
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// IC 系固定 IC_EXT_WORDS 扩展字（多态槽组）。
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if op.has_ic_ext_words() {
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return 3;
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return IC_EXT_WORDS;
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}
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match op {
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OpCode::SPILL
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@@ -79,16 +91,17 @@ pub(crate) fn clear_ic_caches(bytecode: &mut [Instr]) {
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let mut i = 0;
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while i < bytecode.len() {
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let op = opcode::opcode(bytecode[i]);
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if op.has_ic_ext_words() && i + 3 < bytecode.len() {
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bytecode[i + 1] = 0;
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bytecode[i + 2] = 0;
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bytecode[i + 3] = 0;
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if op.has_ic_ext_words() && i + IC_EXT_WORDS < bytecode.len() {
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for word in &mut bytecode[i + 1..=i + IC_EXT_WORDS] {
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*word = 0;
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}
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}
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i += 1 + ext_word_count(bytecode, i);
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}
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}
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/// 沿原型链上溯 `proto_depth` 步，返回目标对象的裸指针（链不足时返回 null）。
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/// `proto_depth` 与 IC 写回语义一致：1 = 接收者的直接原型（`obj.proto()`）。
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#[inline(always)]
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fn resolve_proto_target_raw(obj: *const JsObject, proto_depth: u8) -> *const JsObject {
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if proto_depth == 0 {
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@@ -96,7 +109,7 @@ fn resolve_proto_target_raw(obj: *const JsObject, proto_depth: u8) -> *const JsO
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}
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let obj_ref = unsafe { &*obj };
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let mut cursor = obj_ref.proto();
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for _ in 0..proto_depth {
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for _ in 1..proto_depth {
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if !cursor.is_object() {
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return std::ptr::null();
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}
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@@ -139,6 +152,37 @@ pub(crate) fn ic_get_hit(obj: &JsObject, shape_id: u32, slot_index: u32, proto_d
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}
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}
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/// 多态遍历判定：调用方槽 0 单态判定失败后，顺序检查槽 1..3。
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/// 空槽（shape_id==0）恒在尾部（FIFO 滚动保证），遇空即停。
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#[inline(never)]
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pub(crate) fn ic_get_hit_poly(obj: &JsObject, bytecode: &[Instr], ext_pc: usize) -> Option<JsValue> {
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for i in 1..IC_SLOTS {
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let base = ext_pc + i * 2;
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let shape_id = bytecode[base] & 0x00FF_FFFF;
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if shape_id == 0 {
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break;
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}
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let slot_index = bytecode[base + 1];
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let proto_depth = (bytecode[base] >> 24) as u8;
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if proto_depth == 0 {
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if obj.shape_id() == shape_id && slot_index < obj.prop_vec_len() as u32 {
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let v = obj.get_prop_shape(slot_index);
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return Some(v);
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}
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continue;
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}
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let target = resolve_proto_target_raw(obj as *const JsObject, proto_depth);
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if target.is_null() {
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continue;
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}
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let target_ref = unsafe { &*target };
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if target_ref.shape_id() == shape_id && slot_index < target_ref.prop_vec_len() as u32 {
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return Some(target_ref.get_prop_shape(slot_index));
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}
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}
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None
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}
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#[inline(always)]
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pub(crate) fn ic_set_hit(obj: &mut JsObject, shape_id: u32, slot_index: u32, proto_depth: u8, value: JsValue) -> bool {
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if shape_id == 0 {
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@@ -163,3 +207,35 @@ pub(crate) fn ic_set_hit(obj: &mut JsObject, shape_id: u32, slot_index: u32, pro
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false
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}
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}
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/// 多态遍历判定：调用方槽 0 单态判定失败后，顺序检查槽 1..3。
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/// 空槽（shape_id==0）恒在尾部（FIFO 滚动保证），遇空即停。
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#[inline(never)]
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pub(crate) fn ic_set_hit_poly(obj: &mut JsObject, bytecode: &[Instr], ext_pc: usize, value: JsValue) -> bool {
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for i in 1..IC_SLOTS {
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let base = ext_pc + i * 2;
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let shape_id = bytecode[base] & 0x00FF_FFFF;
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if shape_id == 0 {
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break;
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}
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let slot_index = bytecode[base + 1];
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let proto_depth = (bytecode[base] >> 24) as u8;
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if proto_depth == 0 {
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if obj.shape_id() == shape_id && slot_index < obj.prop_vec_len() as u32 {
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obj.set_prop_shape(slot_index, value);
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return true;
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}
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continue;
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}
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let target = resolve_proto_target_raw(obj as *const JsObject, proto_depth);
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if target.is_null() {
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continue;
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}
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let target_ref = unsafe { &*target };
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if target_ref.shape_id() == shape_id && slot_index < target_ref.prop_vec_len() as u32 {
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unsafe { &mut *(target as *mut JsObject) }.set_prop_shape(slot_index, value);
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return true;
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}
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}
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false
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}
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