Update mmtk-core.

Author: qinsoon

mmtk/Cargo.toml

@@ -26,7 +26,7 @@ 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 = "722546b37e7579aee9d093f51b97f5a729a553d5" }
+mmtk = { git = "https://github.com/mmtk/mmtk-core.git", rev = "a55db731e38618f2143a14b5152390dcc7ba4faf" }
 # Uncomment the following to build locally
 # mmtk = { path = "../repos/mmtk-core" }
 

openjdk/mmtkUpcalls.cpp

@@ -329,7 +329,6 @@ static void mmtk_enqueue_references(void** objects, size_t len) {
   oop prev = NULL;
   for (size_t i = 0; i < len; i++) {
     oop reff = (oop) objects[i];
-    printf("enqueue: %p\n", reff);
     if (prev != NULL) {
       HeapAccess<AS_NO_KEEPALIVE>::oop_store_at(prev, java_lang_ref_Reference::discovered_offset, reff);
     }