One Zone per CompilationInfo.

src/zone.cc

 // Copyright 2012 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 49 matching lines @@
   // Computes the address of the nth byte in this segment.
   Address address(int n) const {
     return Address(this) + n;
   }
 
   Segment* next_;
   int size_;
 };
 
 
-Zone::Zone()
+Zone::Zone(Isolate* isolate)
     : zone_excess_limit_(256 * MB),
       segment_bytes_allocated_(0),
       position_(0),
       limit_(0),
       scope_nesting_(0),
-      segment_head_(NULL) {
+      segment_head_(NULL),
+      isolate_(isolate) {
 }
 unsigned Zone::allocation_size_ = 0;
 
 ZoneScope::~ZoneScope() {
-  ASSERT_EQ(Isolate::Current(), isolate_);
-  if (ShouldDeleteOnExit()) isolate_->zone()->DeleteAll();
-  isolate_->zone()->scope_nesting_--;
+  if (ShouldDeleteOnExit()) zone_->Destroy();
+  zone_->scope_nesting_--;
 }
 
 
 // Creates a new segment, sets it size, and pushes it to the front
 // of the segment chain. Returns the new segment.
 Segment* Zone::NewSegment(int size) {
   Segment* result = reinterpret_cast<Segment*>(Malloced::New(size));
   adjust_segment_bytes_allocated(size);
   if (result != NULL) {
     result->Initialize(segment_head_, size);
     segment_head_ = result;
   }
   return result;
 }
 
 
 // Deletes the given segment. Does not touch the segment chain.
 void Zone::DeleteSegment(Segment* segment, int size) {
   adjust_segment_bytes_allocated(-size);
   Malloced::Delete(segment);
 }
 
 
+void Zone::Destroy() {
+  if (isolate_->runtime_zone() == this)

[danno, 2012/06/14 14:22:19]

Yikes! Please move the DeleteAll(DELETE_ALL_BLOCKS) into ~Zone(), and call
DeleteAll(DELETE_ALL_BUT_LAST_BLOCK) where it used to be called.

[sanjoy, 2012/06/15 09:24:31]

Moved deletion to the destructor.

+    DeleteAllButOne();
+  else
+    DeleteAll();
+}
+
+
 void Zone::DeleteAll() {
 #ifdef DEBUG
   // Constant byte value used for zapping dead memory in debug mode.
   static const unsigned char kZapDeadByte = 0xcd;
 #endif
+  Segment* current = segment_head_;
+  while (current != NULL) {
+    Segment* next = current->next();
+    int size = current->size();
+#ifdef DEBUG
+    // Zap the entire current segment (including the header).
+    memset(current, kZapDeadByte, size);
+#endif
+    DeleteSegment(current, size);
+    current = next;
+  }
+}
+
+
+void Zone::DeleteAllButOne() {

[danno, 2012/06/14 14:22:19]

Just add a enum flag to DeleteAll that handles the last block specially.

[sanjoy, 2012/06/15 09:24:31]

Moved deletion to the destructor.

+#ifdef DEBUG
+  // Constant byte value used for zapping dead memory in debug mode.
+  static const unsigned char kZapDeadByte = 0xcd;
+#endif
 
   // Find a segment with a suitable size to keep around.
   Segment* keep = segment_head_;
   while (keep != NULL && keep->size() > kMaximumKeptSegmentSize) {
     keep = keep->next();
   }
 
   // Traverse the chained list of segments, zapping (in debug mode)
   // and freeing every segment except the one we wish to keep.
   Segment* current = segment_head_;
@@ skipping 85 matching lines @@
     V8::FatalProcessOutOfMemory("Zone");
     return NULL;
   }
   limit_ = segment->end();
   ASSERT(position_ <= limit_);
   return result;
 }
 
 
 } }  // namespace v8::internal