Revert "Revert "Change dex caches to be weak roots""

This reverts commit 81a9087f0df0518c39405b7d18ba5858a6d8b77b.

Boot.oat creation time goes from 4.7s to 4.9s on host due to extra
locking. Will try to improve this in another CL.

Bug: 23602225
Bug: 22720414

Change-Id: I7e25b75cfb63faa196c7b0f60e46cce50bf12021

1 files changed, 8 insertions, 1 deletions

diff --git a/runtime/java_vm_ext.cc b/runtime/java_vm_ext.cc
index 9d41018c1b..ef7a924c63 100644
--- a/runtime/java_vm_ext.cc
+++ b/runtime/java_vm_ext.cc
@@ -373,7 +373,7 @@ JavaVMExt::JavaVMExt(Runtime* runtime, const RuntimeArgumentMap& runtime_options
       globals_(gGlobalsInitial, gGlobalsMax, kGlobal),
       libraries_(new Libraries),
       unchecked_functions_(&gJniInvokeInterface),
-      weak_globals_lock_("JNI weak global reference table lock"),
+      weak_globals_lock_("JNI weak global reference table lock", kJniWeakGlobalsLock),
       weak_globals_(kWeakGlobalsInitial, kWeakGlobalsMax, kWeakGlobal),
       allow_new_weak_globals_(true),
       weak_globals_add_condition_("weak globals add condition", weak_globals_lock_) {
@@ -578,6 +578,13 @@ void JavaVMExt::UpdateGlobal(Thread* self, IndirectRef ref, mirror::Object* resu
 
 mirror::Object* JavaVMExt::DecodeWeakGlobal(Thread* self, IndirectRef ref) {
   MutexLock mu(self, weak_globals_lock_);
+  return DecodeWeakGlobalLocked(self, ref);
+}
+
+mirror::Object* JavaVMExt::DecodeWeakGlobalLocked(Thread* self, IndirectRef ref) {
+  if (kDebugLocking) {
+    weak_globals_lock_.AssertHeld(self);
+  }
   while (UNLIKELY((!kUseReadBarrier && !allow_new_weak_globals_) ||
                   (kUseReadBarrier && !self->GetWeakRefAccessEnabled()))) {
     weak_globals_add_condition_.WaitHoldingLocks(self);