Fix write barrier parameter type (mmtk#148)

Upstream PR: mmtk/mmtk-core#1130

---------

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

Author: wks

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="a02803b4104519ff2289234101a2dd8ceedd1bc7" }
+mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "fea59e4f5cc6176093da1d8efa7d7b3b4b8d0fa7" }
 # 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

@@ -12,6 +12,7 @@ use libc::c_char;
 use log::*;
 use mmtk::memory_manager;
 use mmtk::scheduler::GCWorker;
+use mmtk::util::api_util::NullableObjectReference;
 use mmtk::util::opaque_pointer::*;
 use mmtk::util::{Address, ObjectReference, OpaquePointer};
 use mmtk::AllocationSemantics;
@@ -395,7 +396,7 @@ fn set_side_log_bit_for_region(start: Address, size: usize) {
 pub extern "C" fn mmtk_object_reference_write_post(
     mutator: *mut Mutator<JuliaVM>,
     src: ObjectReference,
-    target: ObjectReference,
+    target: NullableObjectReference,
 ) {
     let mutator = unsafe { &mut *mutator };
     memory_manager::object_reference_write_post(
@@ -404,23 +405,23 @@ pub extern "C" fn mmtk_object_reference_write_post(
         crate::edges::JuliaVMEdge::Simple(mmtk::vm::edge_shape::SimpleEdge::from_address(
             Address::ZERO,
         )),
-        target,
+        target.into(),
     )
 }
 
 #[no_mangle]
 pub extern "C" fn mmtk_object_reference_write_slow(
     mutator: &'static mut Mutator<JuliaVM>,
     src: ObjectReference,
-    target: ObjectReference,
+    target: NullableObjectReference,
 ) {
     use mmtk::MutatorContext;
     mutator.barrier().object_reference_write_slow(
         src,
         crate::edges::JuliaVMEdge::Simple(mmtk::vm::edge_shape::SimpleEdge::from_address(
             Address::ZERO,
         )),
-        target,
+        target.into(),
     );
 }