Update to MMTk core PR #643 (#72)

Author: qinsoon

mmtk/Cargo.lock

@@ -27,7 +27,7 @@ log = "*"
 # - change branch
 # - change repo name
 # But other changes including adding/removing whitespaces in commented lines may break the CI.
-mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "69b4fe46ee4353a2fdeb4911ba914b63a7ffa29a" }
+mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "6e1b4df8e6bf41f86c24824b4c664f05b2b9fbfb" }
 # Uncomment the following and fix the path to mmtk-core to build locally
 # mmtk = { path = "../repos/mmtk-core" }
 

mmtk/Cargo.toml

@@ -60,7 +60,9 @@ pub extern "C" fn bind_mutator(
 // It is fine we turn the pointer back to box, as we turned a boxed value to the raw pointer in bind_mutator()
 #[allow(clippy::not_unsafe_ptr_arg_deref)]
 pub extern "C" fn destroy_mutator(mutator: *mut Mutator<V8>) {
-    memory_manager::destroy_mutator(unsafe { Box::from_raw(mutator) })
+    // Turn this back to boxed mutator, and let Rust reclaim it when it goes out of scope
+    let mut boxed_mutator = unsafe { Box::from_raw(mutator) };
+    memory_manager::destroy_mutator(&mut boxed_mutator);
 }
 
 #[no_mangle]

mmtk/src/api.rs

@@ -53,6 +53,9 @@ impl ObjectModel<V8> for VMObjectModel {
         unimplemented!()
     }
 
+    const UNIFIED_OBJECT_REFERENCE_ADDRESS: bool = true;
+    const OBJECT_REF_OFFSET_LOWER_BOUND: isize = 0;
+
     fn ref_to_object_start(object: ObjectReference) -> Address {
         object.to_raw_address()
     }