Fire 'stack' getter of error objects after GC.

src/heap.cc

Index: src/heap.cc
diff --git a/src/heap.cc b/src/heap.cc
index e1090176c9709d9815a3e1c1fdca4f758eeeab84..a0cd930095e7a5f68418d71b89c4da4aecbb1b2d 100644
--- a/src/heap.cc
+++ b/src/heap.cc
@@ -550,6 +550,8 @@ void Heap::GarbageCollectionEpilogue() {
 #ifdef ENABLE_DEBUGGER_SUPPORT
   isolate_->debug()->AfterGarbageCollection();
 #endif  // ENABLE_DEBUGGER_SUPPORT
+
+  error_object_list_.DeferredFormatStackTrace(isolate());
 }
 
 
@@ -1348,6 +1350,8 @@ void Heap::Scavenge() {
   UpdateNewSpaceReferencesInExternalStringTable(
       &UpdateNewSpaceReferenceInExternalStringTableEntry);
 
+  error_object_list_.UpdateReferencesInNewSpace();
+
   promotion_queue_.Destroy();
 
   LiveObjectList::UpdateReferencesForScavengeGC();
@@ -5913,6 +5917,7 @@ void Heap::IterateWeakRoots(ObjectVisitor* v, VisitMode mode) {
       mode != VISIT_ALL_IN_SWEEP_NEWSPACE) {
     // Scavenge collections have special processing for this.
     external_string_table_.Iterate(v);
+    error_object_list_.Iterate(v);
   }
   v->Synchronize(VisitorSynchronization::kExternalStringsTable);
 }
@@ -6453,6 +6458,8 @@ void Heap::TearDown() {
 
   external_string_table_.TearDown();
 
+  error_object_list_.TearDown();
+
   new_space_.TearDown();
 
   if (old_pointer_space_ != NULL) {
@@ -7358,6 +7365,8 @@ void ExternalStringTable::CleanUp() {
     }
   }
   new_space_strings_.Rewind(last);
+  new_space_strings_.Trim();
+
   last = 0;
   for (int i = 0; i < old_space_strings_.length(); ++i) {
     if (old_space_strings_[i] == heap_->the_hole_value()) {
@@ -7367,6 +7376,7 @@ void ExternalStringTable::CleanUp() {
     old_space_strings_[last++] = old_space_strings_[i];
   }
   old_space_strings_.Rewind(last);
+  old_space_strings_.Trim();
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     Verify();
@@ -7381,6 +7391,81 @@ void ExternalStringTable::TearDown() {
 }
 
 
+// Update all references.
+void ErrorObjectList::UpdateReferences() {
+  for (int i = 0; i < list_.length(); i++) {
+    HeapObject* object = HeapObject::cast(list_[i]);
+    MapWord first_word = object->map_word();
+    if (first_word.IsForwardingAddress()) {
+      list_[i] = first_word.ToForwardingAddress();
+    }
+  }
+}
+
+
+// Unforwarded objects in new space are dead and removed from the list.
+void ErrorObjectList::UpdateReferencesInNewSpace() {
+  int write_index = 0;
+  for (int i = 0; i < list_.length(); i++) {
+    HeapObject* object = HeapObject::cast(list_[i]);
+    MapWord first_word = object->map_word();
+    if (first_word.IsForwardingAddress()) {
+      list_[write_index++] = first_word.ToForwardingAddress();
+    }
+  }
+  list_.Rewind(write_index);
+}
+
+
+void ErrorObjectList::DeferredFormatStackTrace(Isolate* isolate) {
+  // If formatting the stack trace causes a GC, this method will be
+  // recursively called.  In that case, skip the recursive call, since
+  // the loop modifies the list while iterating over it.
+  if (nested_) return;
+  nested_ = true;
+  HandleScope scope(isolate);
+  Handle<String> stack_key = isolate->factory()->stack_symbol();
+  int write_index = 0;
+  int budget = kBudgetPerGC;
+  for (int i = 0; i < list_.length(); i++) {
+    Object* object = list_[i];
+    // Skip possible holes in the list.
+    if (object->IsTheHole()) continue;
+    if (isolate->heap()->InNewSpace(object) || budget == 0) {
+      list_[write_index++] = object;
+      continue;
+    }
+    Handle<JSObject> js_object(JSObject::cast(object), isolate);
+    // Fire the stack property getter.
+    LookupResult lookup(isolate);
+    js_object->LocalLookupRealNamedProperty(*stack_key, &lookup);
+    if (lookup.IsFound() && lookup.type() == CALLBACKS) {
+      PropertyAttributes attr;
+      Object::GetProperty(js_object, js_object, &lookup, stack_key, &attr);

[Vyacheslav Egorov (Google), 2012/11/16 01:09:57]

here is two interesting questions:

1) what if somebody _replaces_ the .stack getter? can they do it? then they can
observe GC.

2) what if scavenge happens here? scavenges move things down in this array so
our write index might start pointing to something that we did not process and we
end up overwriting it. this does not matter much (there are no correctness
concerns it seems). but it might be worth a comment

+      budget--;
+    }
+  }
+  list_.Rewind(write_index);
+  list_.Trim();
+  nested_ = false;
+}
+
+
+void ErrorObjectList::RemoveUnmarked(Heap* heap) {
+  for (int i = 0; i < list_.length(); i++) {
+    HeapObject* object = HeapObject::cast(list_[i]);
+    if (!Marking::MarkBitFrom(object).Get()) {
+      list_[i] = heap->the_hole_value();
+    }
+  }
+}
+
+
+void ErrorObjectList::TearDown() {
+  list_.Free();
+}
+
+
 void Heap::QueueMemoryChunkForFree(MemoryChunk* chunk) {
   chunk->set_next_chunk(chunks_queued_for_free_);
   chunks_queued_for_free_ = chunk;