From 3befba443e36251cce81cf49a974b9063b36e669 Mon Sep 17 00:00:00 2001
From: Lei Li <lei.l.li@intel.com>
Date: Fri, 23 Jan 2015 16:37:59 +0800
Subject: [PATCH] ART: reduce UpdateModUnionTable time for partial GC

UpdateModUnionTable is to scan objects with dirty cards in the immune
region. The immune region of partial GC are image space and zygote
space. As image space is always immuned for any kind of GC, there is no
need to scan dirty cards of zygote space pointing to image space for
partial GC.

Change-Id: I2e1f61c2b361985c211076a441418797abf324c2
---
 runtime/gc/accounting/mod_union_table.cc | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/runtime/gc/accounting/mod_union_table.cc b/runtime/gc/accounting/mod_union_table.cc
index 0a15e9eb9..b1ccc0bfd 100644
--- a/runtime/gc/accounting/mod_union_table.cc
+++ b/runtime/gc/accounting/mod_union_table.cc
@@ -26,6 +26,7 @@
 #include "gc/collector/mark_sweep-inl.h"
 #include "gc/heap.h"
 #include "gc/space/space.h"
+#include "gc/space/image_space.h"
 #include "mirror/art_field-inl.h"
 #include "mirror/object-inl.h"
 #include "mirror/class-inl.h"
@@ -76,8 +77,9 @@ class ModUnionUpdateObjectReferencesVisitor {
  public:
   ModUnionUpdateObjectReferencesVisitor(MarkHeapReferenceCallback* callback, void* arg,
                                         space::ContinuousSpace* from_space,
+                                        space::ImageSpace* image_space,
                                         bool* contains_reference_to_other_space)
-    : callback_(callback), arg_(arg), from_space_(from_space),
+    : callback_(callback), arg_(arg), from_space_(from_space), image_space_(image_space),
       contains_reference_to_other_space_(contains_reference_to_other_space) {
   }
 
@@ -87,7 +89,7 @@ class ModUnionUpdateObjectReferencesVisitor {
     // Only add the reference if it is non null and fits our criteria.
     mirror::HeapReference<Object>* obj_ptr = obj->GetFieldObjectReferenceAddr(offset);
     mirror::Object* ref = obj_ptr->AsMirrorPtr();
-    if (ref != nullptr && !from_space_->HasAddress(ref)) {
+    if (ref != nullptr && !from_space_->HasAddress(ref) && !image_space_->HasAddress(ref)) {
       *contains_reference_to_other_space_ = true;
       callback_(obj_ptr, arg_);
     }
@@ -98,6 +100,7 @@ class ModUnionUpdateObjectReferencesVisitor {
   void* arg_;
   // Space which we are scanning
   space::ContinuousSpace* const from_space_;
+  space::ImageSpace* const image_space_;
   // Set if we have any references to another space.
   bool* const contains_reference_to_other_space_;
 };
@@ -105,16 +108,16 @@ class ModUnionUpdateObjectReferencesVisitor {
 class ModUnionScanImageRootVisitor {
  public:
   ModUnionScanImageRootVisitor(MarkHeapReferenceCallback* callback, void* arg,
-                               space::ContinuousSpace* from_space,
+                               space::ContinuousSpace* from_space, space::ImageSpace* image_space,
                                bool* contains_reference_to_other_space)
-      : callback_(callback), arg_(arg), from_space_(from_space),
+      : callback_(callback), arg_(arg), from_space_(from_space), image_space_(image_space),
         contains_reference_to_other_space_(contains_reference_to_other_space) {}
 
   void operator()(Object* root) const
       EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
     DCHECK(root != NULL);
-    ModUnionUpdateObjectReferencesVisitor ref_visitor(callback_, arg_, from_space_,
+    ModUnionUpdateObjectReferencesVisitor ref_visitor(callback_, arg_, from_space_, image_space_,
                                                       contains_reference_to_other_space_);
     root->VisitReferences<kMovingClasses>(ref_visitor, VoidFunctor());
   }
@@ -124,6 +127,7 @@ class ModUnionScanImageRootVisitor {
   void* const arg_;
   // Space which we are scanning
   space::ContinuousSpace* const from_space_;
+  space::ImageSpace* const image_space_;
   // Set if we have any references to another space.
   bool* const contains_reference_to_other_space_;
 };
@@ -331,9 +335,11 @@ void ModUnionTableCardCache::ClearCards() {
 void ModUnionTableCardCache::UpdateAndMarkReferences(MarkHeapReferenceCallback* callback,
                                                      void* arg) {
   CardTable* card_table = heap_->GetCardTable();
+  space::ImageSpace* image_space = heap_->GetImageSpace();
   ContinuousSpaceBitmap* bitmap = space_->GetLiveBitmap();
   bool reference_to_other_space = false;
-  ModUnionScanImageRootVisitor scan_visitor(callback, arg, space_, &reference_to_other_space);
+  ModUnionScanImageRootVisitor scan_visitor(callback, arg, space_, image_space,
+                                            &reference_to_other_space);
   for (auto it = cleared_cards_.begin(), end = cleared_cards_.end(); it != end; ) {
     uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(*it));
     DCHECK(space_->HasAddress(reinterpret_cast<Object*>(start)));
-- 
2.11.0