Use MMTk's VO bit spec (#200)

This PR updates to mmtk-core:
mmtk/mmtk-core#1248. This allows us to remove
the duplicate code for vo bit.

---------

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

Author: qinsoon

mmtk/Cargo.lock

@@ -40,7 +40,7 @@ memoffset = "*"
 # ykstackmaps = { git = "https://github.com/udesou/ykstackmaps.git", branch = "udesou-master", version = "*" }
 
 [features]
-default = ["mmtk/vm_space", "julia_copy_stack", "object_pinning", "is_mmtk_object"]
+default = ["mmtk/vm_space", "julia_copy_stack", "object_pinning", "is_mmtk_object", "mmtk/vo_bit_access"]
 
 # Plans
 nogc = []

mmtk/Cargo.toml

@@ -406,7 +406,7 @@ fn set_side_vo_bit_for_region(start: Address, size: usize) {
         size
     );
 
-    crate::vo_bit::bulk_update_vo_bit(start, size)
+    mmtk::util::metadata::vo_bit::VO_BIT_SIDE_METADATA_SPEC.bset_metadata(start, size);
 }
 
 #[no_mangle]

mmtk/src/api.rs

@@ -27,7 +27,6 @@ pub mod reference_glue;
 pub mod scanning;
 pub mod slots;
 pub mod util;
-mod vo_bit;
 
 pub mod julia_finalizer;
 pub mod julia_scanning;