[profiler] Use description for Symbols in Heap snapshots.

Previously we'd report all property edges with symbol names as <symbol>,
which was not very useful, especially with private class fields now
seeing more adoption.

Fixed: chromium:1232467
Change-Id: I53cf0811c4b83d016b988b687c6decbddd3c2fdd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3055309
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75962}

src/profiler/strings-storage.cc

@@ -74,6 +74,23 @@ const char* StringsStorage::GetVFormatted(const char* format, va_list args) {
   return AddOrDisposeString(str.begin(), len);
 }
 
+const char* StringsStorage::GetSymbol(Symbol sym) {
+  if (!sym.description().IsString()) {
+    return "<symbol>";
+  }
+  String description = String::cast(sym.description());
+  int length = std::min(FLAG_heap_snapshot_string_limit, description.length());
+  auto data = description.ToCString(DISALLOW_NULLS, ROBUST_STRING_TRAVERSAL, 0,
+                                    length, &length);
+  if (sym.is_private_name()) {
+    return AddOrDisposeString(data.release(), length);
+  }
+  auto str_length = 8 + length + 1 + 1;
+  auto str_result = NewArray<char>(str_length);
+  snprintf(str_result, str_length, "<symbol %s>", data.get());
+  return AddOrDisposeString(str_result, str_length - 1);
+}
+
 const char* StringsStorage::GetName(Name name) {
   if (name.IsString()) {
     String str = String::cast(name);
@@ -83,7 +100,7 @@ const char* StringsStorage::GetName(Name name) {
         DISALLOW_NULLS, ROBUST_STRING_TRAVERSAL, 0, length, &actual_length);
     return AddOrDisposeString(data.release(), actual_length);
   } else if (name.IsSymbol()) {
-    return "<symbol>";
+    return GetSymbol(Symbol::cast(name));
   }
   return "";
 }
@@ -106,7 +123,7 @@ const char* StringsStorage::GetConsName(const char* prefix, Name name) {
 
     return AddOrDisposeString(cons_result, cons_length - 1);
   } else if (name.IsSymbol()) {
-    return "<symbol>";
+    return GetSymbol(Symbol::cast(name));
   }
   return "";
 }

src/profiler/strings-storage.h

@@ -16,6 +16,7 @@ namespace v8 {
 namespace internal {
 
 class Name;
+class Symbol;
 
 // Provides a storage of strings allocated in C++ heap, to hold them
 // forever, even if they disappear from JS heap or external storage.
@@ -57,6 +58,7 @@ class V8_EXPORT_PRIVATE StringsStorage {
   base::CustomMatcherHashMap::Entry* GetEntry(const char* str, int len);
   PRINTF_FORMAT(2, 0)
   const char* GetVFormatted(const char* format, va_list args);
+  const char* GetSymbol(Symbol sym);
 
   base::CustomMatcherHashMap names_;
   base::Mutex mutex_;

test/cctest/test-heap-profiler.cc

@@ -2358,7 +2358,7 @@ TEST(HiddenPropertiesFastCase) {
       GetProperty(isolate, global, v8::HeapGraphEdge::kProperty, "c");
   CHECK(c);
   const v8::HeapGraphNode* hidden_props =
-      GetProperty(isolate, global, v8::HeapGraphEdge::kProperty, "<symbol>");
+      GetProperty(isolate, c, v8::HeapGraphEdge::kProperty, "<symbol key>");
   CHECK(!hidden_props);
 
   v8::Local<v8::Value> cHandle =
@@ -2377,10 +2377,32 @@ TEST(HiddenPropertiesFastCase) {
   c = GetProperty(isolate, global, v8::HeapGraphEdge::kProperty, "c");
   CHECK(c);
   hidden_props =
-      GetProperty(isolate, c, v8::HeapGraphEdge::kProperty, "<symbol>");
+      GetProperty(isolate, c, v8::HeapGraphEdge::kProperty, "<symbol key>");
   CHECK(hidden_props);
 }
 
+TEST(SymbolsAndPrivateClassFields) {
+  v8::Isolate* isolate = CcTest::isolate();
+  LocalContext env;
+  v8::HandleScope scope(isolate);
+  v8::HeapProfiler* heap_profiler = isolate->GetHeapProfiler();
+
+  CompileRun(
+      "class C { #private = this; [Symbol('MySymbol')] = this; };\n"
+      "c = new C;\n");
+  const v8::HeapSnapshot* snapshot = heap_profiler->TakeHeapSnapshot();
+  CHECK(ValidateSnapshot(snapshot));
+  const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
+  const v8::HeapGraphNode* c =
+      GetProperty(isolate, global, v8::HeapGraphEdge::kProperty, "c");
+  CHECK(c);
+  const v8::HeapGraphNode* prop;
+  prop = GetProperty(isolate, c, v8::HeapGraphEdge::kProperty, "#private");
+  CHECK(prop);
+  prop = GetProperty(isolate, c, v8::HeapGraphEdge::kProperty,
+                     "<symbol MySymbol>");
+  CHECK(prop);
+}
 
 TEST(AccessorInfo) {
   LocalContext env;