Do not process the linked list in the jl_handler_t object

Author: udesou

mmtk/src/julia_scanning.rs

@@ -649,7 +649,6 @@ pub unsafe fn capture_potential_task(addr: Address, extra_root_tasks: &mut Vec<O
         let vtag_usize = mmtk_jl_typetagof(obj).as_usize();
 
         if vtag_usize == ((jl_small_typeof_tags_jl_task_tag as usize) << 4) {
-            log::info!("Task {} occurs in shadow stack!", objref);
             extra_root_tasks.push(objref);
         }
     }

mmtk/src/julia_types.rs

@@ -1,4 +1,4 @@
-/* automatically generated by rust-bindgen 0.71.1 */
+/* automatically generated by rust-bindgen 0.72.0 */
 
 #[repr(C)]
 #[derive(Copy, Clone, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
@@ -36,7 +36,9 @@ where
     pub unsafe fn raw_get_bit(this: *const Self, index: usize) -> bool {
         debug_assert!(index / 8 < core::mem::size_of::<Storage>());
         let byte_index = index / 8;
-        let byte = *(core::ptr::addr_of!((*this).storage) as *const u8).offset(byte_index as isize);
+        let byte = unsafe {
+            *(core::ptr::addr_of!((*this).storage) as *const u8).offset(byte_index as isize)
+        };
         Self::extract_bit(byte, index)
     }
     #[inline]
@@ -64,9 +66,10 @@ where
     pub unsafe fn raw_set_bit(this: *mut Self, index: usize, val: bool) {
         debug_assert!(index / 8 < core::mem::size_of::<Storage>());
         let byte_index = index / 8;
-        let byte =
-            (core::ptr::addr_of_mut!((*this).storage) as *mut u8).offset(byte_index as isize);
-        *byte = Self::change_bit(*byte, index, val);
+        let byte = unsafe {
+            (core::ptr::addr_of_mut!((*this).storage) as *mut u8).offset(byte_index as isize)
+        };
+        unsafe { *byte = Self::change_bit(*byte, index, val) };
     }
     #[inline]
     pub fn get(&self, bit_offset: usize, bit_width: u8) -> u64 {
@@ -93,7 +96,7 @@ where
         debug_assert!((bit_offset + (bit_width as usize)) / 8 <= core::mem::size_of::<Storage>());
         let mut val = 0;
         for i in 0..(bit_width as usize) {
-            if Self::raw_get_bit(this, i + bit_offset) {
+            if unsafe { Self::raw_get_bit(this, i + bit_offset) } {
                 let index = if cfg!(target_endian = "big") {
                     bit_width as usize - 1 - i
                 } else {
@@ -133,7 +136,7 @@ where
             } else {
                 i
             };
-            Self::raw_set_bit(this, index + bit_offset, val_bit_is_set);
+            unsafe { Self::raw_set_bit(this, index + bit_offset, val_bit_is_set) };
         }
     }
 }
@@ -3520,10 +3523,3 @@ const _: () = {
     ["Align of template specialization: pinned_ref_open0_jl_value_t_close0"]
         [::std::mem::align_of::<pinned_ref<jl_value_t>>() - 8usize];
 };
-#[allow(clippy::unnecessary_operation, clippy::identity_op)]
-const _: () = {
-    ["Size of template specialization: pinned_ref_open0_jl_value_t_close0"]
-        [::std::mem::size_of::<pinned_ref<jl_value_t>>() - 8usize];
-    ["Align of template specialization: pinned_ref_open0_jl_value_t_close0"]
-        [::std::mem::align_of::<pinned_ref<jl_value_t>>() - 8usize];
-};

mmtk/src/scanning.rs

@@ -79,7 +79,7 @@ impl Scanning<JuliaVM> for VMScanning {
                         TASK_ROOTS.lock().unwrap().insert(
                             ObjectReference::from_raw_address_unchecked(Address::from_ptr(task)),
                         );
-                        log::info!(
+                        log::debug!(
                             "Processing root task: {:?}",
                             ObjectReference::from_raw_address_unchecked(Address::from_ptr(task))
                         );
@@ -120,43 +120,33 @@ impl Scanning<JuliaVM> for VMScanning {
                         use crate::conservative::is_potential_mmtk_object;
                         use crate::conservative::CONSERVATIVE_ROOTS;
 
-                        let mut eh = (*task).eh;
-                        loop {
-                            if !eh.is_null() {
-                                // conservatively deal with the scope objects
-                                // FIXME: we could potentially just add them to the node_buffer
-                                let scope_address = Address::from_ptr((*eh).scope);
-                                if let Some(obj) = is_potential_mmtk_object(scope_address) {
-                                    CONSERVATIVE_ROOTS.lock().unwrap().insert(obj);
-                                }
+                        // NB: task.eh has a field `struct _jl_handler_t *prev` but it does not seem
+                        // like we need to traverse the whole list to capture all the handlers.
+                        // We might need to confirm this with the Julia devs.
+                        let eh = (*task).eh;
+
+                        if !eh.is_null() {
+                            // FIXME: we could potentially just add these to the node_buffer
+                            let scope_address = Address::from_ptr((*eh).scope);
+                            if let Some(obj) = is_potential_mmtk_object(scope_address) {
+                                CONSERVATIVE_ROOTS.lock().unwrap().insert(obj);
+                            }
 
-                                // conservatively scan eh_ctx and potentially traverse the list of handlers (_jl_handler_t *prev)
-                                let sigjump_buf = (*eh).eh_ctx[0].__jmpbuf;
-                                for buff in sigjump_buf {
+                            if let Some(jmpbuf) = (*eh).eh_ctx.get(0) {
+                                for buff in jmpbuf.__jmpbuf {
                                     if let Some(obj) =
                                         is_potential_mmtk_object(Address::from_usize(buff as usize))
                                     {
-                                        // println!(
-                                        //     "buf_addr (mmtk object) = {:x} from root task = {:?}, type = {}",
-                                        //     buff,
-                                        //     task,
-                                        //     crate::julia_scanning::get_julia_object_type(
-                                        //         Address::from_usize(buff as usize)
-                                        //     )
-                                        // );
                                         CONSERVATIVE_ROOTS.lock().unwrap().insert(obj);
                                     }
                                 }
+                            };
 
-                                // Another option, call conservative_scan_range on the __jmpbuf array
-                                // use crate::conservative::conservative_scan_range;
-                                // use crate::conservative::get_range;
-                                // let (lo, hi) = get_range(&(*eh).eh_ctx[0].__jmpbuf);
-                                // conservative_scan_range(lo, hi);
-                                eh = (*eh).prev;
-                            } else {
-                                break;
-                            }
+                            // // Another option, call conservative_scan_range on the __jmpbuf array
+                            // use crate::conservative::conservative_scan_range;
+                            // use crate::conservative::get_range;
+                            // let (lo, hi) = get_range(&(*eh).eh_ctx[0].__jmpbuf);
+                            // conservative_scan_range(lo, hi);
                         }
                     }