爱特每羊队
129 lines
4.3 KiB
Rust
129 lines
4.3 KiB
Rust
//! inline cache（IC）字节码流辅助函数。
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//!
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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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use crate::vm_trace;
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use oxide_bytecode::opcode::{self, Instr};
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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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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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}
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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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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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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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}
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/// 把流中所有 IC 扩展字清零，使全部缓存 shape 失效。
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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() {
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if 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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}
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i += 4;
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} else {
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i += 1;
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}
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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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#[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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return obj;
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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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if !cursor.is_object() {
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return std::ptr::null();
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}
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let proto_ptr = cursor.as_js_object_ptr();
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if proto_ptr.is_null() {
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return std::ptr::null();
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}
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cursor = unsafe { (*proto_ptr).proto() };
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}
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if cursor.is_object() {
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let ptr = cursor.as_js_object_ptr();
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if !ptr.is_null() {
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return ptr as *const JsObject;
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}
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}
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std::ptr::null()
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}
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#[inline(always)]
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pub(crate) fn ic_get_hit(obj: &JsObject, shape_id: u32, slot_index: u32, proto_depth: u8) -> Option<JsValue> {
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if shape_id == 0 {
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return None;
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}
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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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return None;
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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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return None;
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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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Some(target_ref.get_prop_shape(slot_index))
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} else {
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None
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}
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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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return false;
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}
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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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return false;
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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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return false;
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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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true
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} else {
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false
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}
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}
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