Update to MMTK core PR #1159 (mmtk#160)

Co-authored-by: mmtkgc-bot <mmtkgc.bot@gmail.com>

Author: qinsoon

mmtk/Cargo.lock

@@ -31,7 +31,7 @@ lazy_static = "1.1"
 # - 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 = "56b2521d2b99848ee0613a0a5288fe6d81b754ba" }
+mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "a3a72f8e5795678eff06fdc1524f0b429a62ccc0" }
 # Uncomment the following to build locally
 # mmtk = { path = "../repos/mmtk-core" }
 log = {version = "0.4", features = ["max_level_trace", "release_max_level_off"] }

mmtk/Cargo.toml

@@ -156,23 +156,13 @@ impl ObjectModel<JuliaVM> for VMObjectModel {
         res
     }
 
-    #[inline(always)]
-    fn ref_to_address(object: ObjectReference) -> Address {
-        object.to_raw_address()
-    }
-
-    #[inline(always)]
-    fn address_to_ref(address: Address) -> ObjectReference {
-        // `address` is a result of `ref_to_address(object)`, where `object` cannot be NULL.
-        debug_assert!(!address.is_zero());
-        unsafe { ObjectReference::from_raw_address_unchecked(address) }
-    }
-
     #[inline(always)]
     fn ref_to_header(object: ObjectReference) -> Address {
         object.to_raw_address()
     }
 
+    const IN_OBJECT_ADDRESS_OFFSET: isize = 0;
+
     fn dump_object(_object: ObjectReference) {
         unimplemented!()
     }