feat: 添加 session arena 与逃逸晋升

crates/oxide_vm/src/builtins/array.rs

@@ -127,14 +127,13 @@ pub fn array_is_array(vm: &mut Vm, args: &[u8]) -> NativeResult {
 
 pub fn array_push(vm: &mut Vm, args: &[u8]) -> NativeResult {
     let arr_ptr = array_ptr!(vm, args);
-    let arr = unsafe { &mut *arr_ptr };
-    let mut len = arr.prop_count();
+    let mut len = unsafe { &*arr_ptr }.prop_count();
     for &arg_reg in args.iter().skip(1) {
-        let val = vm.reg(arg_reg);
-        arr.set_prop_at(len, val);
+        let val = vm.promote_if_needed_for_write_ptr(arr_ptr, vm.reg(arg_reg));
+        unsafe { &mut *arr_ptr }.set_prop_at(len, val);
         len += 1;
     }
-    arr.set_prop_count(len);
+    unsafe { &mut *arr_ptr }.set_prop_count(len);
     NativeResult::Ok(JsValue::int(len as i32))
 }
 

crates/oxide_vm/src/dispatch/property.rs

@@ -136,24 +136,25 @@ impl Vm {
 
         let prop_name_si = self.property_key_si(self.regs[b]);
         if self.kernel_core.string_forge().lookup(prop_name_si).as_deref() == Some("__proto__") {
-            let obj = unsafe { &mut *obj_ptr };
-            if self.is_object_prototype(obj_ptr) && !self.regs[a].is_null() {
+            let proto_value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[a]);
+            if self.is_object_prototype(obj_ptr) && !proto_value.is_null() {
                 self.raise_type_error("Object.prototype.__proto__ is immutable")?;
                 self.pc += 3;
                 return Ok(());
             }
-            obj.set_proto(self.regs[a]).map_err(|e| e.to_string())?;
+            let obj = unsafe { &mut *obj_ptr };
+            obj.set_proto(proto_value).map_err(|e| e.to_string())?;
             self.pc += 3;
             return Ok(());
         }
 
-        let obj = unsafe { &mut *obj_ptr };
         let ext0 = self.bytecode[self.pc];
         let ext1 = self.bytecode[self.pc + 1];
         let _ext2 = self.bytecode[self.pc + 2];
         self.pc += 3;
-        let value = self.regs[a];
+        let value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[a]);
         let receiver = self.regs[rd];
+        let obj = unsafe { &mut *obj_ptr };
         if obj.has_prop_meta() {
             self.ordinary_set_dispatch(obj, prop_name_si, value, receiver)?;
             return Ok(());
@@ -209,17 +210,20 @@ impl Vm {
         let Some(obj_ptr) = self.checked_object_ptr(self.regs[rd], "SET_PROP on non-object")? else {
             return Ok(());
         };
-        let obj = unsafe { &mut *obj_ptr };
         let prop_name_si = self.property_key_si(self.regs[b]);
         if self.kernel_core.string_forge().lookup(prop_name_si).as_deref() == Some("__proto__") {
-            if self.is_object_prototype(obj_ptr) && !self.regs[a].is_null() {
+            let proto_value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[a]);
+            if self.is_object_prototype(obj_ptr) && !proto_value.is_null() {
                 self.raise_type_error("Object.prototype.__proto__ is immutable")?;
                 return Ok(());
             }
-            obj.set_proto(self.regs[a]).map_err(|e| e.to_string())?;
+            let obj = unsafe { &mut *obj_ptr };
+            obj.set_proto(proto_value).map_err(|e| e.to_string())?;
             return Ok(());
         }
-        self.ordinary_set_dispatch(obj, prop_name_si, self.regs[a], self.regs[rd])?;
+        let value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[a]);
+        let obj = unsafe { &mut *obj_ptr };
+        self.ordinary_set_dispatch(obj, prop_name_si, value, self.regs[rd])?;
         Ok(())
     }
 
@@ -240,17 +244,20 @@ impl Vm {
         let Some(obj_ptr) = self.checked_object_ptr(self.regs[rd], "SET_PROP_DYNAMIC on non-object")? else {
             return Ok(());
         };
-        let obj = unsafe { &mut *obj_ptr };
         let prop_name_si = self.property_key_si(self.regs[a]);
         if self.kernel_core.string_forge().lookup(prop_name_si).as_deref() == Some("__proto__") {
-            if self.is_object_prototype(obj_ptr) && !self.regs[b].is_null() {
+            let proto_value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[b]);
+            if self.is_object_prototype(obj_ptr) && !proto_value.is_null() {
                 self.raise_type_error("Object.prototype.__proto__ is immutable")?;
                 return Ok(());
             }
-            obj.set_proto(self.regs[b]).map_err(|e| e.to_string())?;
+            let obj = unsafe { &mut *obj_ptr };
+            obj.set_proto(proto_value).map_err(|e| e.to_string())?;
             return Ok(());
         }
-        self.ordinary_set_dispatch(obj, prop_name_si, self.regs[b], self.regs[rd])?;
+        let value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[b]);
+        let obj = unsafe { &mut *obj_ptr };
+        self.ordinary_set_dispatch(obj, prop_name_si, value, self.regs[rd])?;
         Ok(())
     }
 
@@ -265,8 +272,9 @@ impl Vm {
         } else {
             0
         };
+        let value = self.promote_if_needed_for_write_ptr(obj_ptr, self.regs[b]);
         let obj = unsafe { &mut *obj_ptr };
-        obj.set_prop_at(idx, self.regs[b]);
+        obj.set_prop_at(idx, value);
         Ok(())
     }
 }

crates/oxide_vm/src/lib.rs

@@ -5,6 +5,7 @@ pub mod builtins;
 pub mod coercion;
 mod dispatch;
 pub mod native;
+mod session_arena;
 pub mod vm;
 mod vm_dispatch_ctrl;
 mod vm_dispatch_misc;

crates/oxide_vm/src/session_arena.rs

@@ -0,0 +1,213 @@
+use std::collections::HashMap;
+
+use oxide_types::object::JsObject;
+use oxide_types::value::JsValue;
+
+use crate::vm::Vm;
+
+impl Vm {
+    pub(crate) fn is_session_escape_root_ptr(&self, target_ptr: *mut JsObject) -> bool {
+        if target_ptr.is_null() {
+            return false;
+        }
+        let global_ptr = self.session.global_object().as_ptr() as *mut JsObject;
+        std::ptr::eq(target_ptr, global_ptr) || unsafe { (&*target_ptr).is_session_epoch() }
+    }
+
+    pub(crate) fn promote_object(&mut self, src: *mut JsObject) -> *mut JsObject {
+        let mut forwarding = HashMap::new();
+        self.promote_object_inner(src, &mut forwarding)
+    }
+
+    pub(crate) fn promote_object_inner(
+        &mut self, src: *mut JsObject, forwarding: &mut HashMap<*mut JsObject, *mut JsObject>,
+    ) -> *mut JsObject {
+        if src.is_null() {
+            return src;
+        }
+        let src_ref = unsafe { &*src };
+        if src_ref.is_session_epoch() || !self.epoch.is_epoch_ptr(src.cast::<u8>()) {
+            return src;
+        }
+        if let Some(dst) = forwarding.get(&src).copied() {
+            return dst;
+        }
+
+        let clone = src_ref.clone_for_session_epoch();
+        let dst = self.session_epoch.alloc(clone) as *mut JsObject;
+        forwarding.insert(src, dst);
+
+        let dst_ref = unsafe { &mut *dst };
+        dst_ref.rewrite_object_values(|value| self.promote_value_if_epoch_object(value, forwarding));
+        dst
+    }
+
+    pub(crate) fn promote_value_if_epoch_object(
+        &mut self, value: JsValue, forwarding: &mut HashMap<*mut JsObject, *mut JsObject>,
+    ) -> JsValue {
+        if !value.is_object() {
+            return value;
+        }
+        let ptr = value.as_js_object_ptr();
+        if ptr.is_null() || !self.epoch.is_epoch_ptr(ptr.cast::<u8>()) {
+            return value;
+        }
+        JsValue::from_js_object(self.promote_object_inner(ptr, forwarding))
+    }
+
+    pub(crate) fn promote_if_needed_for_write_ptr(&mut self, target_ptr: *mut JsObject, value: JsValue) -> JsValue {
+        if !value.is_object() || !self.is_session_escape_root_ptr(target_ptr) {
+            return value;
+        }
+        let value_ptr = value.as_js_object_ptr();
+        if value_ptr.is_null() || !self.epoch.is_epoch_ptr(value_ptr.cast::<u8>()) {
+            return value;
+        }
+        JsValue::from_js_object(self.promote_object(value_ptr))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use oxide_kernel::shape_forge::EMPTY_SHAPE_ID;
+    use oxide_types::object::{PropAttributes, PropMetaEntry};
+
+    fn plain_object(vm: &mut Vm) -> *mut JsObject {
+        let proto = vm.session.builtin_world().object_proto.as_ptr() as *mut JsObject;
+        vm.epoch
+            .alloc(JsObject::new_empty(EMPTY_SHAPE_ID, JsValue::from_js_object(proto)))
+    }
+
+    fn is_epoch_object(vm: &Vm, value: JsValue) -> bool {
+        value.is_object() && vm.epoch.is_epoch_ptr(value.as_js_object_ptr().cast::<u8>())
+    }
+
+    #[test]
+    fn session_arena_promotion_preserves_cycle_identity() {
+        let mut vm = Vm::new();
+        let root = plain_object(&mut vm);
+        unsafe {
+            (*root).set_prop_at(0, JsValue::from_js_object(root));
+        }
+
+        let promoted = vm.promote_object(root);
+        let promoted_obj = unsafe { &*promoted };
+
+        assert!(promoted_obj.is_session_epoch());
+        assert!(std::ptr::eq(promoted_obj.get_prop_at(0).as_js_object_ptr(), promoted));
+    }
+
+    #[test]
+    fn session_arena_promotion_preserves_duplicate_child_reference() {
+        let mut vm = Vm::new();
+        let root = plain_object(&mut vm);
+        let child = plain_object(&mut vm);
+        unsafe {
+            (*root).set_prop_at(0, JsValue::from_js_object(child));
+            (*root).set_prop_at(1, JsValue::from_js_object(child));
+        }
+
+        let promoted = vm.promote_object(root);
+        let promoted_obj = unsafe { &*promoted };
+        let left = promoted_obj.get_prop_at(0).as_js_object_ptr();
+        let right = promoted_obj.get_prop_at(1).as_js_object_ptr();
+
+        assert!(std::ptr::eq(left, right));
+        assert!(!std::ptr::eq(left, child));
+        assert!(unsafe { (&*left).is_session_epoch() });
+    }
+
+    #[test]
+    fn session_arena_captured_and_home_object_links_promote() {
+        let mut vm = Vm::new();
+        let root = plain_object(&mut vm);
+        let proto = plain_object(&mut vm);
+        let captured = plain_object(&mut vm);
+        let home = plain_object(&mut vm);
+        let getter = plain_object(&mut vm);
+        let setter = plain_object(&mut vm);
+        unsafe {
+            (*root).set_proto(JsValue::from_js_object(proto)).expect("proto");
+            (*root).set_captured_this(JsValue::from_js_object(captured));
+            (*root).set_home_object(JsValue::from_js_object(home));
+            (*root).set_prop_at(0, JsValue::undefined());
+            (*root).set_accessor_meta(
+                0,
+                JsValue::from_js_object(getter),
+                JsValue::from_js_object(setter),
+                PropAttributes::DEFAULT_DATA,
+            );
+        }
+
+        let promoted = vm.promote_object(root);
+        let promoted_obj = unsafe { &*promoted };
+        let meta = promoted_obj.prop_meta_at(0).expect("meta");
+
+        assert!(!is_epoch_object(&vm, promoted_obj.proto()));
+        assert!(!is_epoch_object(&vm, promoted_obj.captured_this()));
+        assert!(!is_epoch_object(&vm, promoted_obj.home_object()));
+        assert!(!is_epoch_object(&vm, meta.get));
+        assert!(!is_epoch_object(&vm, meta.set));
+    }
+
+    #[test]
+    fn session_arena_barrier_promotes_global_root_write() {
+        let mut vm = Vm::new();
+        let value = JsValue::from_js_object(plain_object(&mut vm));
+        let global_ptr = vm.session.global_object().as_ptr() as *mut JsObject;
+
+        let promoted = vm.promote_if_needed_for_write_ptr(global_ptr, value);
+
+        assert!(promoted.is_object());
+        assert!(!is_epoch_object(&vm, promoted));
+        assert!(unsafe { (&*promoted.as_js_object_ptr()).is_session_epoch() });
+    }
+
+    #[test]
+    fn session_arena_barrier_promotes_already_session_target_write() {
+        let mut vm = Vm::new();
+        let target_epoch = plain_object(&mut vm);
+        let target = vm.promote_object(target_epoch);
+        let value = JsValue::from_js_object(plain_object(&mut vm));
+
+        let promoted = vm.promote_if_needed_for_write_ptr(target, value);
+
+        assert!(!is_epoch_object(&vm, promoted));
+        assert!(unsafe { (&*promoted.as_js_object_ptr()).is_session_epoch() });
+    }
+
+    #[test]
+    fn session_arena_barrier_leaves_non_escape_target_write_unchanged() {
+        let mut vm = Vm::new();
+        let target = plain_object(&mut vm);
+        let value = JsValue::from_js_object(plain_object(&mut vm));
+
+        let unchanged = vm.promote_if_needed_for_write_ptr(target, value);
+
+        assert_eq!(unchanged, value);
+    }
+
+    #[test]
+    fn session_arena_promotion_rewrites_accessor_metadata_values() {
+        let mut vm = Vm::new();
+        let root = plain_object(&mut vm);
+        let getter = plain_object(&mut vm);
+        let setter = plain_object(&mut vm);
+        unsafe {
+            (*root).set_prop_at(0, JsValue::undefined());
+            (*root).set_accessor_meta(
+                0,
+                JsValue::from_js_object(getter),
+                JsValue::from_js_object(setter),
+                PropAttributes::DEFAULT_DATA,
+            );
+        }
+
+        let promoted = vm.promote_object(root);
+        let meta: PropMetaEntry = unsafe { &*promoted }.prop_meta_at(0).expect("meta");
+
+        assert!(!is_epoch_object(&vm, meta.get));
+        assert!(!is_epoch_object(&vm, meta.set));
+    }
+}

crates/oxide_vm/src/vm.rs

@@ -142,6 +142,7 @@ pub struct Vm {
     pub(crate) session: KernelSession,
     pub(crate) interned_strings: Vec<u32>,
     pub epoch: Epoch,
+    pub(crate) session_epoch: bumpalo::Bump,
     pub object_prototype: P<JsObject>,
     pub math_rng_state: u64,
     pub(crate) sub_modules: Vec<CompiledModule>,
@@ -835,6 +836,7 @@ impl Vm {
                     if !func_val.is_object() || !home_val.is_object() {
                         throw_err!(self, TypeError, "SET_HOME_OBJECT expects function and object");
                     }
+                    let home_val = self.promote_if_needed_for_write_ptr(func_val.as_js_object_ptr(), home_val);
                     let func_obj = unsafe { &mut *func_val.as_js_object_ptr() };
                     if !func_obj.is_function() {
                         throw_err!(self, TypeError, "SET_HOME_OBJECT target is not a function");

crates/oxide_vm/src/vm_props.rs

@@ -114,6 +114,7 @@ impl Vm {
     fn ordinary_set_inner(
         &mut self, obj: &mut JsObject, prop_name_si: u32, val: JsValue, receiver: JsValue, use_frame_push: bool,
     ) -> Result<(), String> {
+        let val = self.promote_if_needed_for_write_ptr(obj as *mut JsObject, val);
         if let Some(pos) = self.get_own_property_slot(obj, prop_name_si) {
             if let Some(meta) = obj.prop_meta_at(pos) {
                 if meta.is_accessor {
@@ -216,6 +217,7 @@ impl Vm {
     pub(crate) fn set_member_prop(
         &mut self, obj: &mut JsObject, prop_name_si: u32, val: JsValue, receiver: JsValue,
     ) -> Result<(), String> {
+        let val = self.promote_if_needed_for_write_ptr(obj as *mut JsObject, val);
         if let Some(pos) = self.kernel_core.shape_forge().lookup_position(obj.shape_id(), prop_name_si) {
             if obj.has_prop_meta() {
                 self.ordinary_set(obj, prop_name_si, val, receiver)?;
@@ -230,6 +232,7 @@ impl Vm {
     }
 
     pub(crate) fn set_or_create_prop_value(&mut self, obj: &mut JsObject, prop_name_si: u32, val: JsValue) {
+        let val = self.promote_if_needed_for_write_ptr(obj as *mut JsObject, val);
         if let Some(pos) = self.kernel_core.shape_forge().lookup_position(obj.shape_id(), prop_name_si) {
             obj.set_prop_at(pos, val);
         } else {
@@ -243,6 +246,7 @@ impl Vm {
     pub(crate) fn define_data_property(
         &mut self, obj: &mut JsObject, prop_name_si: u32, val: JsValue, attributes: PropAttributes,
     ) -> Result<(), String> {
+        let val = self.promote_if_needed_for_write_ptr(obj as *mut JsObject, val);
         let pos = if let Some(pos) = self.kernel_core.shape_forge().lookup_position(obj.shape_id(), prop_name_si) {
             pos
         } else {
@@ -277,6 +281,9 @@ impl Vm {
     pub(crate) fn define_accessor_property(
         &mut self, obj: &mut JsObject, prop_name_si: u32, get: JsValue, set: JsValue, attributes: PropAttributes,
     ) -> Result<(), String> {
+        let target_ptr = obj as *mut JsObject;
+        let get = self.promote_if_needed_for_write_ptr(target_ptr, get);
+        let set = self.promote_if_needed_for_write_ptr(target_ptr, set);
         let pos = if let Some(pos) = self.kernel_core.shape_forge().lookup_position(obj.shape_id(), prop_name_si) {
             pos
         } else {

crates/oxide_vm/src/vm_support.rs

@@ -30,6 +30,7 @@ impl Vm {
             session,
             interned_strings: Vec::new(),
             epoch: Epoch::new(),
+            session_epoch: bumpalo::Bump::new(),
             object_prototype: obj_proto,
             math_rng_state: 0,
             sub_modules: Vec::new(),
@@ -67,6 +68,7 @@ impl Vm {
             session,
             interned_strings: Vec::new(),
             epoch: Epoch::new(),
+            session_epoch: bumpalo::Bump::new(),
             object_prototype: obj_proto,
             math_rng_state: 0,
             sub_modules: Vec::new(),
@@ -117,6 +119,7 @@ impl Vm {
         self.bytecode.clear();
         self.constants.clear();
         self.epoch.reset();
+        self.session_epoch.reset();
         self.interned_strings.clear();
         self.symbol_counter = 0;
         self.symbol_descriptions.clear();
@@ -404,6 +407,25 @@ mod tests {
         assert!(!vm.session.is_dirty_since_snapshot());
     }
 
+    #[test]
+    fn session_epoch_survives_reset() {
+        let mut vm = Vm::new();
+        let session_ptr = vm.session_epoch.alloc(123i32) as *mut i32;
+
+        vm.reset();
+
+        assert!(unsafe { *session_ptr } == 123);
+    }
+
+    #[test]
+    fn session_epoch_reset_is_only_in_full_reset_state_clear() {
+        let src = include_str!("vm_support.rs");
+        let production = src.split("#[cfg(test)]").next().expect("production source");
+        assert_eq!(production.matches("self.session_epoch.reset()").count(), 1);
+        assert!(production.contains("fn clear_full_reset_state(&mut self)"));
+        assert!(production.contains("self.session_epoch.reset();"));
+    }
+
     #[test]
     fn full_reset_refreshes_object_prototype_after_object_dirty() {
         let mut vm = Vm::new();