commit bb87e0f1a52de656bc77cb01cb887e51a0e5198b
author Mathieu Chartier <mathieuc@google.com> Fri Apr 03 11:21:55 2015 -0700
committer Mathieu Chartier <mathieuc@google.com> Mon Apr 06 10:44:37 2015 -0700
tree 113f014c6e20fab3e936a3ac05f9f738639541f6
parent e57fc0f0260fcb1d08cbb720ec95c04c0f394b91

Refactor and improve GC root handling

Changed GcRoot to use compressed references. Changed root visiting to
use virtual functions instead of function pointers. Changed root visting
interface to be an array of roots instead of a single root at a time.
Added buffered root marking helper to avoid dispatch overhead.

Root marking seems a bit faster on EvaluateAndApplyChanges due to batch
marking. Pause times unaffected.

Mips64 is untested but might work, maybe.

Before:
MarkConcurrentRoots: Sum: 67.678ms 99% C.I. 2us-664.999us Avg: 161.138us Max: 671us

After:
MarkConcurrentRoots: Sum: 54.806ms 99% C.I. 2us-499.986us Avg: 136.333us Max: 602us

Bug: 19264997

Change-Id: I0a71ebb5928f205b9b3f7945b25db6489d5657ca

runtime/runtime.h

diff --git a/runtime/runtime.h b/runtime/runtime.h
index af6abbd..baa4d18 100644
--- a/runtime/runtime.h
+++ b/runtime/runtime.h
@@ -296,27 +296,27 @@
 
   // Visit all the roots. If only_dirty is true then non-dirty roots won't be visited. If
   // clean_dirty is true then dirty roots will be marked as non-dirty after visiting.
-  void VisitRoots(RootCallback* visitor, void* arg, VisitRootFlags flags = kVisitRootFlagAllRoots)
+  void VisitRoots(RootVisitor* visitor, VisitRootFlags flags = kVisitRootFlagAllRoots)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Visit image roots, only used for hprof since the GC uses the image space mod union table
   // instead.
-  void VisitImageRoots(RootCallback* visitor, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  void VisitImageRoots(RootVisitor* visitor) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Visit all of the roots we can do safely do concurrently.
-  void VisitConcurrentRoots(RootCallback* visitor, void* arg,
+  void VisitConcurrentRoots(RootVisitor* visitor,
                             VisitRootFlags flags = kVisitRootFlagAllRoots)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Visit all of the non thread roots, we can do this with mutators unpaused.
-  void VisitNonThreadRoots(RootCallback* visitor, void* arg)
+  void VisitNonThreadRoots(RootVisitor* visitor)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
-  void VisitTransactionRoots(RootCallback* visitor, void* arg)
+  void VisitTransactionRoots(RootVisitor* visitor)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Visit all of the thread roots.
-  void VisitThreadRoots(RootCallback* visitor, void* arg) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  void VisitThreadRoots(RootVisitor* visitor) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Flip thread roots from from-space refs to to-space refs.
   size_t FlipThreadRoots(Closure* thread_flip_visitor, Closure* flip_callback,
@@ -324,7 +324,7 @@
       LOCKS_EXCLUDED(Locks::mutator_lock_);
 
   // Visit all other roots which must be done with mutators suspended.
-  void VisitNonConcurrentRoots(RootCallback* visitor, void* arg)
+  void VisitNonConcurrentRoots(RootVisitor* visitor)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Sweep system weaks, the system weak is deleted if the visitor return nullptr. Otherwise, the
@@ -334,7 +334,7 @@
 
   // Constant roots are the roots which never change after the runtime is initialized, they only
   // need to be visited once per GC cycle.
-  void VisitConstantRoots(RootCallback* callback, void* arg)
+  void VisitConstantRoots(RootVisitor* visitor)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
 
   // Returns a special method that calls into a trampoline for runtime method resolution