From 7cdb73a5889c229f6fc6365cf5e10f7304c23158 Mon Sep 17 00:00:00 2001
From: tonyp <unknown>
Date: Fri, 15 Oct 2010 17:26:56 -0400
Subject: [PATCH] 6992189: G1: inconsistent base used in sparse rem set
 iterator Summary: The remembered set iterator for sparse tables incorrectly
 assumes that index 0 corresponds to the bottom of the heap, not address 0 as
 it is the case. Reviewed-by: ysr, jmasa

---
 .../gc_implementation/g1/heapRegionRemSet.cpp  |  4 +---
 .../vm/gc_implementation/g1/sparsePRT.cpp      |  5 +----
 .../vm/gc_implementation/g1/sparsePRT.hpp      | 18 ++++--------------
 3 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp b/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp
index c4c873274..5d055f655 100644
--- a/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp
+++ b/src/share/vm/gc_implementation/g1/heapRegionRemSet.cpp
@@ -1159,9 +1159,7 @@ HeapRegionRemSetIterator() :
   _hrrs(NULL),
   _g1h(G1CollectedHeap::heap()),
   _bosa(NULL),
-  _sparse_iter(size_t(G1CollectedHeap::heap()->reserved_region().start())
-               >> CardTableModRefBS::card_shift)
-{}
+  _sparse_iter() { }
 
 void HeapRegionRemSetIterator::initialize(const HeapRegionRemSet* hrrs) {
   _hrrs = hrrs;
diff --git a/src/share/vm/gc_implementation/g1/sparsePRT.cpp b/src/share/vm/gc_implementation/g1/sparsePRT.cpp
index 5bc3ab29c..86eaa729d 100644
--- a/src/share/vm/gc_implementation/g1/sparsePRT.cpp
+++ b/src/share/vm/gc_implementation/g1/sparsePRT.cpp
@@ -323,10 +323,7 @@ CardIdx_t /* RSHashTable:: */ RSHashTableIter::find_first_card_in_list() {
 }
 
 size_t /* RSHashTable:: */ RSHashTableIter::compute_card_ind(CardIdx_t ci) {
-  return
-    _heap_bot_card_ind
-    + (_rsht->entry(_bl_ind)->r_ind() * HeapRegion::CardsPerRegion)
-    + ci;
+  return (_rsht->entry(_bl_ind)->r_ind() * HeapRegion::CardsPerRegion) + ci;
 }
 
 bool /* RSHashTable:: */ RSHashTableIter::has_next(size_t& card_index) {
diff --git a/src/share/vm/gc_implementation/g1/sparsePRT.hpp b/src/share/vm/gc_implementation/g1/sparsePRT.hpp
index 7812ac4fb..92a69b4d5 100644
--- a/src/share/vm/gc_implementation/g1/sparsePRT.hpp
+++ b/src/share/vm/gc_implementation/g1/sparsePRT.hpp
@@ -169,7 +169,6 @@ class RSHashTableIter VALUE_OBJ_CLASS_SPEC {
   int _bl_ind;          // [-1, 0.._rsht->_capacity)
   short _card_ind;      // [0..SparsePRTEntry::cards_num())
   RSHashTable* _rsht;
-  size_t _heap_bot_card_ind;
 
   // If the bucket list pointed to by _bl_ind contains a card, sets
   // _bl_ind to the index of that entry, and returns the card.
@@ -183,13 +182,11 @@ class RSHashTableIter VALUE_OBJ_CLASS_SPEC {
   size_t compute_card_ind(CardIdx_t ci);
 
 public:
-  RSHashTableIter(size_t heap_bot_card_ind) :
+  RSHashTableIter() :
     _tbl_ind(RSHashTable::NullEntry),
     _bl_ind(RSHashTable::NullEntry),
     _card_ind((SparsePRTEntry::cards_num() - 1)),
-    _rsht(NULL),
-    _heap_bot_card_ind(heap_bot_card_ind)
-  {}
+    _rsht(NULL) {}
 
   void init(RSHashTable* rsht) {
     _rsht = rsht;
@@ -280,19 +277,12 @@ public:
   bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const {
     return _next->contains_card(region_id, card_index);
   }
-
-#if 0
-  void verify_is_cleared();
-  void print();
-#endif
 };
 
 
-class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
+class SparsePRTIter: public RSHashTableIter {
 public:
-  SparsePRTIter(size_t heap_bot_card_ind) :
-    /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
-  {}
+  SparsePRTIter() : RSHashTableIter() { }
 
   void init(const SparsePRT* sprt) {
     RSHashTableIter::init(sprt->cur());
-- 
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