Free memory allocated by backtrace_symbols immediately.

R=petermarshall@chromium.org

Bug: v8:6687
Change-Id: Ic447a6cd5cb8a7a251b4820fc82f1f1d033be355
Reviewed-on: https://chromium-review.googlesource.com/612067Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47340}

src/external-reference-table.cc

@@ -49,14 +49,6 @@ ExternalReferenceTable::ExternalReferenceTable(Isolate* isolate) {
   AddApiReferences(isolate);
 }
 
-ExternalReferenceTable::~ExternalReferenceTable() {
-#ifdef SYMBOLIZE_FUNCTION
-  for (char** table : symbol_tables_) {
-    free(table);
-  }
-#endif
-}
-
 #ifdef DEBUG
 void ExternalReferenceTable::ResetCount() {
   for (ExternalReferenceEntry& entry : refs_) entry.count = 0;
@@ -70,12 +62,14 @@ void ExternalReferenceTable::PrintCount() {
 }
 #endif  // DEBUG
 
-const char* ExternalReferenceTable::ResolveSymbol(void* address,
-                                                  std::vector<char**>* tables) {
+const char* ExternalReferenceTable::ResolveSymbol(void* address) {
 #ifdef SYMBOLIZE_FUNCTION
-  char** table = backtrace_symbols(&address, 1);
-  if (tables) tables->push_back(table);
-  return table[0];
+  char** names = backtrace_symbols(&address, 1);
+  const char* name = names[0];
+  // The array of names is malloc'ed. However, each name string is static
+  // and do not need to be freed.
+  free(names);
+  return name;
 #else
   return "<unresolved>";
 #endif  // SYMBOLIZE_FUNCTION
@@ -468,11 +462,7 @@ void ExternalReferenceTable::AddApiReferences(Isolate* isolate) {
   if (api_external_references != nullptr) {
     while (*api_external_references != 0) {
       Address address = reinterpret_cast<Address>(*api_external_references);
-#ifdef SYMBOLIZE_FUNCTION
-      Add(address, ResolveSymbol(address, &symbol_tables_));
-#else
       Add(address, ResolveSymbol(address));
-#endif
       api_external_references++;
     }
   }

src/external-reference-table.h

@@ -21,7 +21,6 @@ class Isolate;
 class ExternalReferenceTable {
  public:
   static ExternalReferenceTable* instance(Isolate* isolate);
-  ~ExternalReferenceTable();
 
   uint32_t size() const { return static_cast<uint32_t>(refs_.length()); }
   Address address(uint32_t i) { return refs_[i].address; }
@@ -36,8 +35,7 @@ class ExternalReferenceTable {
   void PrintCount();
 #endif  // DEBUG
 
-  static const char* ResolveSymbol(void* address,
-                                   std::vector<char**>* = nullptr);
+  static const char* ResolveSymbol(void* address);
 
  private:
   struct ExternalReferenceEntry {
@@ -68,9 +66,6 @@ class ExternalReferenceTable {
   void AddApiReferences(Isolate* isolate);
 
   List<ExternalReferenceEntry> refs_;
-#ifdef DEBUG
-  std::vector<char**> symbol_tables_;
-#endif
   uint32_t api_refs_start_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalReferenceTable);