commit 7048ae42d2b02d62110e297221460cacf1f6db73
author Ian Rogers <irogers@google.com> Mon Jun 02 14:24:56 2014 -0700
committer Vladimir Marko <vmarko@google.com> Mon Jun 16 20:33:27 2014 +0100
tree 84f31e7f7007d7e11698cad020804e39b112ba89
parent 0aa08bb3d443e294f9f99b4fa7572ff4d60e1e39

Make class status volatile.

Discourage loads and stores from reordering around the status being updated.
Bug: 15347354

(cherry-picked from 03dbc04d1d5a3bd62801989b16e994a9ed0dafb5)

Change-Id: I29a4144bd3a145017831540ce1130da5401e39c0

compiler/dex/quick/gen_common.cc

diff --git a/compiler/dex/quick/gen_common.cc b/compiler/dex/quick/gen_common.cc
index 4f2a876..03edf2a 100644
--- a/compiler/dex/quick/gen_common.cc
+++ b/compiler/dex/quick/gen_common.cc
@@ -603,6 +603,8 @@
                                                      field_info.StorageIndex(), r_base));
 
         FreeTemp(r_tmp);
+        // Ensure load of status and load of value don't re-order.
+        GenMemBarrier(kLoadLoad);
       }
       FreeTemp(r_method);
     }
@@ -694,6 +696,8 @@
                                                      field_info.StorageIndex(), r_base));
 
         FreeTemp(r_tmp);
+        // Ensure load of status and load of value don't re-order.
+        GenMemBarrier(kLoadLoad);
       }
       FreeTemp(r_method);
     }

compiler/llvm/gbc_expander.cc

diff --git a/compiler/llvm/gbc_expander.cc b/compiler/llvm/gbc_expander.cc
index 25c9b20..f8dca66 100644
--- a/compiler/llvm/gbc_expander.cc
+++ b/compiler/llvm/gbc_expander.cc
@@ -1868,6 +1868,10 @@
 
   phi->addIncoming(storage_object_addr, block_check_init);
   phi->addIncoming(loaded_storage_object_addr, block_after_load_static);
+
+  // Ensure load of status and load of value don't re-order.
+  irb_.CreateMemoryBarrier(art::kLoadLoad);
+
   return phi;
 }
 

runtime/mirror/class.cc

diff --git a/runtime/mirror/class.cc b/runtime/mirror/class.cc
index 4869b45..4b02c0f 100644
--- a/runtime/mirror/class.cc
+++ b/runtime/mirror/class.cc
@@ -105,11 +105,11 @@
 
     self->SetException(gc_safe_throw_location, old_exception.Get());
   }
-  CHECK(sizeof(Status) == sizeof(uint32_t)) << PrettyClass(this);
+  COMPILE_ASSERT(sizeof(Status) == sizeof(uint32_t), size_of_status_not_uint32);
   if (Runtime::Current()->IsActiveTransaction()) {
-    SetField32<true>(OFFSET_OF_OBJECT_MEMBER(Class, status_), new_status);
+    SetField32Volatile<true>(OFFSET_OF_OBJECT_MEMBER(Class, status_), new_status);
   } else {
-    SetField32<false>(OFFSET_OF_OBJECT_MEMBER(Class, status_), new_status);
+    SetField32Volatile<false>(OFFSET_OF_OBJECT_MEMBER(Class, status_), new_status);
   }
   // Classes that are being resolved or initialized need to notify waiters that the class status
   // changed. See ClassLinker::EnsureResolved and ClassLinker::WaitForInitializeClass.

runtime/mirror/class.h

diff --git a/runtime/mirror/class.h b/runtime/mirror/class.h
index 40c9975..90381a7 100644
--- a/runtime/mirror/class.h
+++ b/runtime/mirror/class.h
@@ -125,7 +125,8 @@
   template<VerifyObjectFlags kVerifyFlags = kDefaultVerifyFlags>
   Status GetStatus() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     COMPILE_ASSERT(sizeof(Status) == sizeof(uint32_t), size_of_status_not_uint32);
-    return static_cast<Status>(GetField32<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, status_)));
+    return static_cast<Status>(
+        GetField32Volatile<kVerifyFlags>(OFFSET_OF_OBJECT_MEMBER(Class, status_)));
   }
 
   void SetStatus(Status new_status, Thread* self) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);