Ensure that store buffer filtering hash sets are cleared after StoreBuffer::Filter.

src/store-buffer.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 31 matching lines @@
       old_limit_(NULL),
       old_top_(NULL),
       old_reserved_limit_(NULL),
       old_buffer_is_sorted_(false),
       old_buffer_is_filtered_(false),
       during_gc_(false),
       store_buffer_rebuilding_enabled_(false),
       callback_(NULL),
       may_move_store_buffer_entries_(true),
       virtual_memory_(NULL),
-      hash_map_1_(NULL),
-      hash_map_2_(NULL) {
+      hash_set_1_(NULL),
+      hash_set_2_(NULL),
+      hash_sets_are_empty_(true) {
 }
 
 
 void StoreBuffer::Setup() {
   virtual_memory_ = new VirtualMemory(kStoreBufferSize * 3);
   uintptr_t start_as_int =
       reinterpret_cast<uintptr_t>(virtual_memory_->address());
   start_ =
       reinterpret_cast<Address*>(RoundUp(start_as_int, kStoreBufferSize * 2));
   limit_ = start_ + (kStoreBufferSize / kPointerSize);
@@ skipping 26 matching lines @@
   USE(vm_limit);
   ASSERT((reinterpret_cast<uintptr_t>(limit_) & kStoreBufferOverflowBit) != 0);
   ASSERT((reinterpret_cast<uintptr_t>(limit_ - 1) & kStoreBufferOverflowBit) ==
          0);
 
   CHECK(virtual_memory_->Commit(reinterpret_cast<Address>(start_),
                                 kStoreBufferSize,
                                 false));  // Not executable.
   heap_->public_set_store_buffer_top(start_);
 
-  hash_map_1_ = new uintptr_t[kHashMapLength];
-  hash_map_2_ = new uintptr_t[kHashMapLength];
+  hash_set_1_ = new uintptr_t[kHashSetLength];
+  hash_set_2_ = new uintptr_t[kHashSetLength];
+  hash_sets_are_empty_ = false;
 
-  ZapHashTables();
+  ClearFilteringHashSets();
 }
 
 
 void StoreBuffer::TearDown() {
   delete virtual_memory_;
   delete old_virtual_memory_;
-  delete[] hash_map_1_;
-  delete[] hash_map_2_;
+  delete[] hash_set_1_;
+  delete[] hash_set_2_;
   old_start_ = old_top_ = old_limit_ = old_reserved_limit_ = NULL;
   start_ = limit_ = NULL;
   heap_->public_set_store_buffer_top(start_);
 }
 
 
 void StoreBuffer::StoreBufferOverflow(Isolate* isolate) {
   isolate->heap()->store_buffer()->Compact();
 }
 
@@ skipping 19 matching lines @@
   intptr_t b =
       reinterpret_cast<intptr_t>(*reinterpret_cast<const Address*>(void_b));
   ASSERT(sizeof(1) == sizeof(a));
   // Shift down to avoid wraparound.
   return (a >> kPointerSizeLog2) - (b >> kPointerSizeLog2);
 }
 #endif
 
 
 void StoreBuffer::Uniq() {
-  ASSERT(HashTablesAreZapped());
   // Remove adjacent duplicates and cells that do not point at new space.
   Address previous = NULL;
   Address* write = old_start_;
   ASSERT(may_move_store_buffer_entries_);
   for (Address* read = old_start_; read < old_top_; read++) {
     Address current = *read;
     if (current != previous) {
       if (heap_->InNewSpace(*reinterpret_cast<Object**>(current))) {
         *write++ = current;
       }
@@ skipping 103 matching lines @@
       containing_chunk = previous_chunk;
     } else {
       containing_chunk = MemoryChunk::FromAnyPointerAddress(addr);
       previous_chunk = containing_chunk;
     }
     if (!containing_chunk->IsFlagSet(flag)) {
       *new_top++ = addr;
     }
   }
   old_top_ = new_top;
+
+  // Hash tables are inconsistent with the store buffer after this operation.
+  ClearFilteringHashSets();
 }
 
 
 void StoreBuffer::SortUniq() {
   Compact();
   if (old_buffer_is_sorted_) return;
-  ZapHashTables();
   qsort(reinterpret_cast<void*>(old_start_),
         old_top_ - old_start_,
         sizeof(*old_top_),
         &CompareAddresses);
   Uniq();
 
   old_buffer_is_sorted_ = true;
+
+  // Hash tables are inconsistent with the store buffer after this operation.
+  ClearFilteringHashSets();
 }
 
 
 bool StoreBuffer::PrepareForIteration() {
   Compact();
   PointerChunkIterator it(heap_);
   MemoryChunk* chunk;
   bool page_has_scan_on_scavenge_flag = false;
   while ((chunk = it.next()) != NULL) {
     if (chunk->scan_on_scavenge()) page_has_scan_on_scavenge_flag = true;
   }
 
   if (page_has_scan_on_scavenge_flag) {
     Filter(MemoryChunk::SCAN_ON_SCAVENGE);
   }
-  ZapHashTables();
+
+  // Hash tables are inconsistent with the store buffer after iteration.
+  ClearFilteringHashSets();
+
   return page_has_scan_on_scavenge_flag;
 }
 
 
 #ifdef DEBUG
 void StoreBuffer::Clean() {
-  ZapHashTables();
+  ClearFilteringHashSets();
   Uniq();  // Also removes things that no longer point to new space.
   CheckForFullBuffer();
 }
 
 
-static bool Zapped(char* start, int size) {
-  for (int i = 0; i < size; i++) {
-    if (start[i] != 0) return false;
-  }
-  return true;
-}
-
-
-bool StoreBuffer::HashTablesAreZapped() {
-  return Zapped(reinterpret_cast<char*>(hash_map_1_),
-                sizeof(uintptr_t) * kHashMapLength) &&
-      Zapped(reinterpret_cast<char*>(hash_map_2_),
-             sizeof(uintptr_t) * kHashMapLength);
-}
-
-
 static Address* in_store_buffer_1_element_cache = NULL;
 
 
 bool StoreBuffer::CellIsInStoreBuffer(Address cell_address) {
   if (!FLAG_enable_slow_asserts) return true;
   if (in_store_buffer_1_element_cache != NULL &&
       *in_store_buffer_1_element_cache == cell_address) {
     return true;
   }
   Address* top = reinterpret_cast<Address*>(heap_->store_buffer_top());
   for (Address* current = top - 1; current >= start_; current--) {
     if (*current == cell_address) {
       in_store_buffer_1_element_cache = current;
       return true;
     }
   }
   for (Address* current = old_top_ - 1; current >= old_start_; current--) {
     if (*current == cell_address) {
       in_store_buffer_1_element_cache = current;
       return true;
     }
   }
   return false;
 }
 #endif
 
 
-void StoreBuffer::ZapHashTables() {
-  memset(reinterpret_cast<void*>(hash_map_1_),
-         0,
-         sizeof(uintptr_t) * kHashMapLength);
-  memset(reinterpret_cast<void*>(hash_map_2_),
-         0,
-         sizeof(uintptr_t) * kHashMapLength);
+void StoreBuffer::ClearFilteringHashSets() {
+  if (!hash_sets_are_empty_) {
+    memset(reinterpret_cast<void*>(hash_set_1_),
+           0,
+           sizeof(uintptr_t) * kHashSetLength);
+    memset(reinterpret_cast<void*>(hash_set_2_),
+           0,
+           sizeof(uintptr_t) * kHashSetLength);
+    hash_sets_are_empty_ = true;
+  }
 }
 
 
 void StoreBuffer::GCPrologue() {
-  ZapHashTables();
+  ClearFilteringHashSets();
   during_gc_ = true;
 }
 
 
 #ifdef DEBUG
 static void DummyScavengePointer(HeapObject** p, HeapObject* o) {
   // Do nothing.
 }
 
 
@@ skipping 287 matching lines @@
   if (top == start_) return;
 
   // There's no check of the limit in the loop below so we check here for
   // the worst case (compaction doesn't eliminate any pointers).
   ASSERT(top <= limit_);
   heap_->public_set_store_buffer_top(start_);
   EnsureSpace(top - start_);
   ASSERT(may_move_store_buffer_entries_);
   // Goes through the addresses in the store buffer attempting to remove
   // duplicates.  In the interest of speed this is a lossy operation.  Some
-  // duplicates will remain.  We have two hash tables with different hash
+  // duplicates will remain.  We have two hash sets with different hash
   // functions to reduce the number of unnecessary clashes.
+  hash_sets_are_empty_ = false;  // Hash sets are in use.
   for (Address* current = start_; current < top; current++) {
     ASSERT(!heap_->cell_space()->Contains(*current));
     ASSERT(!heap_->code_space()->Contains(*current));
     ASSERT(!heap_->old_data_space()->Contains(*current));
     uintptr_t int_addr = reinterpret_cast<uintptr_t>(*current);
     // Shift out the last bits including any tags.
     int_addr >>= kPointerSizeLog2;
     int hash1 =
-        ((int_addr ^ (int_addr >> kHashMapLengthLog2)) & (kHashMapLength - 1));
-    if (hash_map_1_[hash1] == int_addr) continue;
+        ((int_addr ^ (int_addr >> kHashSetLengthLog2)) & (kHashSetLength - 1));
+    if (hash_set_1_[hash1] == int_addr) continue;
     int hash2 =
-        ((int_addr - (int_addr >> kHashMapLengthLog2)) & (kHashMapLength - 1));
-    hash2 ^= hash2 >> (kHashMapLengthLog2 * 2);
-    if (hash_map_2_[hash2] == int_addr) continue;
-    if (hash_map_1_[hash1] == 0) {
-      hash_map_1_[hash1] = int_addr;
-    } else if (hash_map_2_[hash2] == 0) {
-      hash_map_2_[hash2] = int_addr;
+        ((int_addr - (int_addr >> kHashSetLengthLog2)) & (kHashSetLength - 1));
+    hash2 ^= hash2 >> (kHashSetLengthLog2 * 2);
+    if (hash_set_2_[hash2] == int_addr) continue;
+    if (hash_set_1_[hash1] == 0) {
+      hash_set_1_[hash1] = int_addr;
+    } else if (hash_set_2_[hash2] == 0) {
+      hash_set_2_[hash2] = int_addr;
     } else {
       // Rather than slowing down we just throw away some entries.  This will
       // cause some duplicates to remain undetected.
-      hash_map_1_[hash1] = int_addr;
-      hash_map_2_[hash2] = 0;
+      hash_set_1_[hash1] = int_addr;
+      hash_set_2_[hash2] = 0;
     }
     old_buffer_is_sorted_ = false;
     old_buffer_is_filtered_ = false;
     *old_top_++ = reinterpret_cast<Address>(int_addr << kPointerSizeLog2);
     ASSERT(old_top_ <= old_limit_);
   }
   heap_->isolate()->counters()->store_buffer_compactions()->Increment();
   CheckForFullBuffer();
 }
 
 
 void StoreBuffer::CheckForFullBuffer() {
   EnsureSpace(kStoreBufferSize * 2);
 }
 
 } }  // namespace v8::internal