Allow arbitrary names for weak references in heap snapshots.

src/heap-snapshot-generator.cc

 // Copyright 2013 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 29 matching lines @@
 
 
 HeapGraphEdge::HeapGraphEdge(Type type, const char* name, int from, int to)
     : type_(type),
       from_index_(from),
       to_index_(to),
       name_(name) {
   ASSERT(type == kContextVariable
       || type == kProperty
       || type == kInternal
-      || type == kShortcut);
+      || type == kShortcut
+      || type == kWeak);
 }
 
 
 HeapGraphEdge::HeapGraphEdge(Type type, int index, int from, int to)
     : type_(type),
       from_index_(from),
       to_index_(to),
       index_(index) {
-  ASSERT(type == kElement || type == kHidden || type == kWeak);
+  ASSERT(type == kElement || type == kHidden);
 }
 
 
 void HeapGraphEdge::ReplaceToIndexWithEntry(HeapSnapshot* snapshot) {
   to_entry_ = &snapshot->entries()[to_index_];
 }
 
 
 const int HeapEntry::kNoEntry = -1;
 
@@ skipping 73 matching lines @@
       case HeapGraphEdge::kHidden:
         edge_prefix = "$";
         OS::SNPrintF(index, "%d", edge.index());
         break;
       case HeapGraphEdge::kShortcut:
         edge_prefix = "^";
         edge_name = edge.name();
         break;
       case HeapGraphEdge::kWeak:
         edge_prefix = "w";
-        OS::SNPrintF(index, "%d", edge.index());
+        edge_name = edge.name();
         break;
       default:
         OS::SNPrintF(index, "!!! unknown edge type: %d ", edge.type());
     }
     edge.to()->Print(edge_prefix, edge_name, max_depth, indent + 2);
   }
 }
 
 
 const char* HeapEntry::TypeAsString() {
@@ skipping 943 matching lines @@
                          js_fun->literals_or_bindings(),
                          JSFunction::kLiteralsOffset);
     TagObject(shared_info, "(shared function info)");
     SetInternalReference(js_fun, entry,
                          "shared", shared_info,
                          JSFunction::kSharedFunctionInfoOffset);
     TagObject(js_fun->context(), "(context)");
     SetInternalReference(js_fun, entry,
                          "context", js_fun->context(),
                          JSFunction::kContextOffset);
-    for (int i = JSFunction::kNonWeakFieldsEndOffset;
-         i < JSFunction::kSize;
-         i += kPointerSize) {
-      SetWeakReference(js_fun, entry, i, *HeapObject::RawField(js_fun, i), i);
-    }
+    SetWeakReference(js_fun, entry,
+                     "next_function_link", js_fun->next_function_link(),
+                     JSFunction::kNextFunctionLinkOffset);
+    STATIC_CHECK(JSFunction::kNextFunctionLinkOffset
+                 == JSFunction::kNonWeakFieldsEndOffset);
+    STATIC_CHECK(JSFunction::kNextFunctionLinkOffset + kPointerSize
+                 == JSFunction::kSize);
   } else if (obj->IsGlobalObject()) {
     GlobalObject* global_obj = GlobalObject::cast(obj);
     SetInternalReference(global_obj, entry,
                          "builtins", global_obj->builtins(),
                          GlobalObject::kBuiltinsOffset);
     SetInternalReference(global_obj, entry,
                          "native_context", global_obj->native_context(),
                          GlobalObject::kNativeContextOffset);
     SetInternalReference(global_obj, entry,
                          "global_receiver", global_obj->global_receiver(),
                          GlobalObject::kGlobalReceiverOffset);
   } else if (obj->IsJSArrayBufferView()) {
     JSArrayBufferView* view = JSArrayBufferView::cast(obj);
     SetInternalReference(view, entry, "buffer", view->buffer(),
                          JSArrayBufferView::kBufferOffset);
-    SetWeakReference(view, entry, 1, view->weak_next(),
+    SetWeakReference(view, entry, "weak_next", view->weak_next(),
                      JSArrayBufferView::kWeakNextOffset);
   } else if (obj->IsJSArrayBuffer()) {
     JSArrayBuffer* buffer = JSArrayBuffer::cast(obj);
-    SetWeakReference(buffer, entry, 1, buffer->weak_next(),
+    SetWeakReference(buffer, entry, "weak_next", buffer->weak_next(),
                      JSArrayBuffer::kWeakNextOffset);
-    SetWeakReference(buffer, entry, 2, buffer->weak_first_view(),
+    SetWeakReference(buffer, entry,
+                     "weak_first_view", buffer->weak_first_view(),
                      JSArrayBuffer::kWeakFirstViewOffset);
   }
   TagObject(js_obj->properties(), "(object properties)");
   SetInternalReference(obj, entry,
                        "properties", js_obj->properties(),
                        JSObject::kPropertiesOffset);
   TagObject(js_obj->elements(), "(object elements)");
   SetInternalReference(obj, entry,
                        "elements", js_obj->elements(),
                        JSObject::kElementsOffset);
@@ skipping 31 matching lines @@
       VariableMode mode;
       int idx = scope_info->FunctionContextSlotIndex(name, &mode);
       if (idx >= 0) {
         SetContextReference(context, entry, name, context->get(idx),
                             Context::OffsetOfElementAt(idx));
       }
     }
   }
 
 #define EXTRACT_CONTEXT_FIELD(index, type, name) \
-  SetInternalReference(context, entry, #name, context->get(Context::index), \
-      FixedArray::OffsetOfElementAt(Context::index));
+  if (Context::index < Context::FIRST_WEAK_SLOT) { \
+    SetInternalReference(context, entry, #name, context->get(Context::index), \
+        FixedArray::OffsetOfElementAt(Context::index)); \
+  } else { \
+    SetWeakReference(context, entry, #name, context->get(Context::index), \
+        FixedArray::OffsetOfElementAt(Context::index)); \
+  }
   EXTRACT_CONTEXT_FIELD(CLOSURE_INDEX, JSFunction, closure);
   EXTRACT_CONTEXT_FIELD(PREVIOUS_INDEX, Context, previous);
   EXTRACT_CONTEXT_FIELD(EXTENSION_INDEX, Object, extension);
   EXTRACT_CONTEXT_FIELD(GLOBAL_OBJECT_INDEX, GlobalObject, global);
   if (context->IsNativeContext()) {
     TagObject(context->jsfunction_result_caches(),
               "(context func. result caches)");
     TagObject(context->normalized_map_cache(), "(context norm. map cache)");
     TagObject(context->runtime_context(), "(runtime context)");
     TagObject(context->embedder_data(), "(context data)");
     NATIVE_CONTEXT_FIELDS(EXTRACT_CONTEXT_FIELD);
+    EXTRACT_CONTEXT_FIELD(OPTIMIZED_FUNCTIONS_LIST, , optimized_functions_list);

[tfarina, 2014/01/27 01:05:29]

looks like this broke the clang build on linux x64:

$ ninja -C out/Debug/ All
....
../../src/heap-snapshot-generator.cc:1217:53: error: empty macro arguments are a
C99 feature [-Werror,-Wc99-extensions]
    EXTRACT_CONTEXT_FIELD(OPTIMIZED_FUNCTIONS_LIST, , optimized_functions_list);
                                                    ^
../../src/heap-snapshot-generator.cc:1218:48: error: empty macro arguments are a
C99 feature [-Werror,-Wc99-extensions]
    EXTRACT_CONTEXT_FIELD(OPTIMIZED_CODE_LIST, , optimized_code_list);
                                               ^
../../src/heap-snapshot-generator.cc:1219:50: error: empty macro arguments are a
C99 feature [-Werror,-Wc99-extensions]
    EXTRACT_CONTEXT_FIELD(DEOPTIMIZED_CODE_LIST, , deoptimized_code_list);
                                                 ^
../../src/heap-snapshot-generator.cc:1220:46: error: empty macro arguments are a
C99 feature [-Werror,-Wc99-extensions]
    EXTRACT_CONTEXT_FIELD(NEXT_CONTEXT_LINK, , next_context_link);
                                             ^
4 errors generated.

$ clang++ --version
clang version 3.5 (trunk 198389)
Target: x86_64-unknown-linux-gnu
Thread model: posix

[alph, 2014/01/27 09:09:21]

Strange, I also use clang and it compiles just fine for me:
$ ninja -j 1000 -C out/Debug chrome 
ninja: Entering directory `out/Debug'
[13749/13749] LINK chrome
$ clang++ --version
clang version 3.5 (trunk 198389)
Target: x86_64-unknown-linux-gnu
Thread model: posix

Nevertheless, I'll add a dummy argument.

+    EXTRACT_CONTEXT_FIELD(OPTIMIZED_CODE_LIST, , optimized_code_list);
+    EXTRACT_CONTEXT_FIELD(DEOPTIMIZED_CODE_LIST, , deoptimized_code_list);
+    EXTRACT_CONTEXT_FIELD(NEXT_CONTEXT_LINK, , next_context_link);
 #undef EXTRACT_CONTEXT_FIELD
-    for (int i = Context::FIRST_WEAK_SLOT;
-         i < Context::NATIVE_CONTEXT_SLOTS;
-         ++i) {
-      SetWeakReference(context, entry, i, context->get(i),
-          FixedArray::OffsetOfElementAt(i));
-    }
+    STATIC_CHECK(Context::OPTIMIZED_FUNCTIONS_LIST == Context::FIRST_WEAK_SLOT);
+    STATIC_CHECK(Context::NEXT_CONTEXT_LINK + 1
+                 == Context::NATIVE_CONTEXT_SLOTS);
+    STATIC_CHECK(Context::FIRST_WEAK_SLOT + 5 == Context::NATIVE_CONTEXT_SLOTS);
   }
 }
 
 
 void V8HeapExplorer::ExtractMapReferences(int entry, Map* map) {
   if (map->HasTransitionArray()) {
     TransitionArray* transitions = map->transitions();
     int transitions_entry = GetEntry(transitions)->index();
     Object* back_pointer = transitions->back_pointer_storage();
     TagObject(back_pointer, "(back pointer)");
@@ skipping 73 matching lines @@
   SetInternalReference(obj, entry,
                        "debug_info", shared->debug_info(),
                        SharedFunctionInfo::kDebugInfoOffset);
   SetInternalReference(obj, entry,
                        "inferred_name", shared->inferred_name(),
                        SharedFunctionInfo::kInferredNameOffset);
   SetInternalReference(obj, entry,
                        "optimized_code_map", shared->optimized_code_map(),
                        SharedFunctionInfo::kOptimizedCodeMapOffset);
   SetWeakReference(obj, entry,
-                   1, shared->initial_map(),
+                   "initial_map", shared->initial_map(),
                    SharedFunctionInfo::kInitialMapOffset);
 }
 
 
 void V8HeapExplorer::ExtractScriptReferences(int entry, Script* script) {
   HeapObject* obj = script;
   SetInternalReference(obj, entry,
                        "source", script->source(),
                        Script::kSourceOffset);
   SetInternalReference(obj, entry,
@@ skipping 509 matching lines @@
     filler_->SetIndexedReference(HeapGraphEdge::kHidden,
                                  parent_entry,
                                  index,
                                  child_entry);
   }
 }
 
 
 void V8HeapExplorer::SetWeakReference(HeapObject* parent_obj,
                                       int parent_entry,
-                                      int index,
+                                      const char* reference_name,
                                       Object* child_obj,
                                       int field_offset) {
   ASSERT(parent_entry == GetEntry(parent_obj)->index());
   HeapEntry* child_entry = GetEntry(child_obj);
   if (child_entry == NULL) return;
   if (IsEssentialObject(child_obj)) {
-    filler_->SetIndexedReference(HeapGraphEdge::kWeak,
-                                 parent_entry,
-                                 index,
-                                 child_entry);
+    filler_->SetNamedReference(HeapGraphEdge::kWeak,
+                               parent_entry,
+                               reference_name,
+                               child_entry);
   }
   IndexedReferencesExtractor::MarkVisitedField(parent_obj, field_offset);
 }
 
 
 void V8HeapExplorer::SetPropertyReference(HeapObject* parent_obj,
                                           int parent_entry,
                                           Name* reference_name,
                                           Object* child_obj,
                                           const char* name_format_string,
@@ skipping 51 matching lines @@
   HeapEntry* child_entry = GetEntry(child_obj);
   if (child_entry != NULL) {
     const char* name = GetStrongGcSubrootName(child_obj);
     if (name != NULL) {
       filler_->SetNamedReference(
           HeapGraphEdge::kInternal,
           snapshot_->gc_subroot(tag)->index(),
           name,
           child_entry);
     } else {
-      filler_->SetIndexedAutoIndexReference(
-          is_weak ? HeapGraphEdge::kWeak : HeapGraphEdge::kElement,
-          snapshot_->gc_subroot(tag)->index(),
-          child_entry);
+      if (is_weak) {
+        filler_->SetNamedAutoIndexReference(
+            HeapGraphEdge::kWeak,
+            snapshot_->gc_subroot(tag)->index(),
+            child_entry);
+      } else {
+        filler_->SetIndexedAutoIndexReference(
+            HeapGraphEdge::kElement,
+            snapshot_->gc_subroot(tag)->index(),
+            child_entry);
+      }
     }
 
     // Add a shortcut to JS global object reference at snapshot root.
     if (child_obj->IsNativeContext()) {
       Context* context = Context::cast(child_obj);
       GlobalObject* global = context->global_object();
       if (global->IsJSGlobalObject()) {
         bool is_debug_object = false;
 #ifdef ENABLE_DEBUGGER_SUPPORT
         is_debug_object = heap_->isolate()->debug()->IsDebugGlobal(global);
@@ skipping 713 matching lines @@
 
 
 void HeapSnapshotJSONSerializer::SerializeEdge(HeapGraphEdge* edge,
                                                bool first_edge) {
   // The buffer needs space for 3 unsigned ints, 3 commas, \n and \0
   static const int kBufferSize =
       MaxDecimalDigitsIn<sizeof(unsigned)>::kUnsigned * 3 + 3 + 2;  // NOLINT
   EmbeddedVector<char, kBufferSize> buffer;
   int edge_name_or_index = edge->type() == HeapGraphEdge::kElement
       || edge->type() == HeapGraphEdge::kHidden
-      || edge->type() == HeapGraphEdge::kWeak
       ? edge->index() : GetStringId(edge->name());
   int buffer_pos = 0;
   if (!first_edge) {
     buffer[buffer_pos++] = ',';
   }
   buffer_pos = utoa(edge->type(), buffer, buffer_pos);
   buffer[buffer_pos++] = ',';
   buffer_pos = utoa(edge_name_or_index, buffer, buffer_pos);
   buffer[buffer_pos++] = ',';
   buffer_pos = utoa(entry_index(edge->to()), buffer, buffer_pos);
@@ skipping 298 matching lines @@
   writer_->AddString("\"<dummy>\"");
   for (int i = 1; i < sorted_strings.length(); ++i) {
     writer_->AddCharacter(',');
     SerializeString(sorted_strings[i]);
     if (writer_->aborted()) return;
   }
 }
 
 
 } }  // namespace v8::internal