爱特每羊队
68 lines
2.4 KiB
Rust
68 lines
2.4 KiB
Rust
//! Inline-cache (IC) bytecode-stream helpers.
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//!
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//! Contains ALL IC read/write/clear logic — property dispatch and member
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//! update handlers route through here, so IC format changes (like the future
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//! side-table migration) require editing only this file.
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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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/// Read the three IC extension words at `pc` (the bytes following an
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/// IC-bearing opcode), advance `pc` past them, and return the decoded
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/// `(shape_id, slot)`.
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pub(crate) fn read_ic_entry(bytecode: &[Instr], pc: &mut usize) -> (u32, u32) {
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let ext0 = bytecode[*pc];
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let ext1 = bytecode[*pc + 1];
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*pc += 3;
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(ext0 & 0x00FF_FFFF, ext1)
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}
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/// Write a resolved `(shape_id, slot)` back into the three IC extension words
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/// at `pc - 3` (they precede the current instruction). Called on an IC miss
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/// after resolving a property, so the next execution of this site hits the cache.
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pub(crate) fn write_ic_back(bytecode: &mut [Instr], pc: usize, shape_id: u32, slot_index: u32) {
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debug_assert!(pc >= 3, "IC write-back requires 3 extension words before pc");
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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] = 0;
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}
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/// Zero every IC extension word in the stream, invalidating all cached shapes.
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/// Used on `rerun()` so re-execution never derefs a stale cached pointer.
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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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#[inline(always)]
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pub(crate) fn ic_get_hit(obj: &JsObject, shape_id: u32, slot_index: u32) -> Option<JsValue> {
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if shape_id != 0 && obj.shape_id() == shape_id && slot_index < obj.prop_vec_len() as u32 {
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Some(obj.get_prop_at(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, value: JsValue) -> bool {
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if shape_id != 0 && obj.shape_id() == shape_id && slot_index < obj.prop_vec_len() as u32 {
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obj.set_prop_at(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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