[perf-prof] fix crash when logging.

src/perf-jit.cc

 // Copyright 2016 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 229 matching lines @@
 
   code_index_++;
 
   LogWriteBytes(reinterpret_cast<const char*>(&code_load), sizeof(code_load));
   LogWriteBytes(code_name, length);
   LogWriteBytes(string_terminator, 1);
   LogWriteBytes(reinterpret_cast<const char*>(code_pointer), code_size);
 }
 
 void PerfJitLogger::LogWriteDebugInfo(Code* code, SharedFunctionInfo* shared) {
+  DisallowHeapAllocation no_gc;
   // Compute the entry count and get the name of the script.
   uint32_t entry_count = 0;
   for (SourcePositionTableIterator iterator(code->source_position_table());
        !iterator.done(); iterator.Advance()) {
     entry_count++;
   }
   if (entry_count == 0) return;
-  Handle<Script> script(Script::cast(shared->script()));
-  Handle<Object> name_or_url(Script::GetNameOrSourceURL(script));
+  Script* script = Script::cast(shared->script());
+  Object* name_or_url = script->GetNameOrSourceURL();
 
   int name_length = 0;
   std::unique_ptr<char[]> name_string;
   if (name_or_url->IsString()) {
     name_string =
-        Handle<String>::cast(name_or_url)
+        String::cast(name_or_url)
             ->ToCString(DISALLOW_NULLS, FAST_STRING_TRAVERSAL, &name_length);

[Tobias Tebbi, 2016/12/09 12:53:26]

only ROBUST_STRING_TRAVERSAL seems to guarantee no GC

[Yang, 2016/12/09 14:00:36]

Not sure I understand. I don't think ToCString can trigger GC at all.
ROBUST_STRING_TRAVERSAL merely adds a check that the String is allocate on this
heap.

     DCHECK_EQ(0, name_string.get()[name_length]);
   } else {
     const char unknown[] = "<unknown>";
     name_length = static_cast<int>(strlen(unknown));
     char* buffer = NewArray<char>(name_length);
     base::OS::StrNCpy(buffer, name_length + 1, unknown,
                       static_cast<size_t>(name_length));
     name_string = std::unique_ptr<char[]>(buffer);
   }
   DCHECK_EQ(name_length, static_cast<int>(strlen(name_string.get())));
@@ skipping 11 matching lines @@
   // Add the size of the name after the first entry.
   size += (static_cast<uint32_t>(name_length) + 1) * entry_count;
 
   int padding = ((size + 7) & (~7)) - size;
 
   debug_info.size_ = size + padding;
 
   LogWriteBytes(reinterpret_cast<const char*>(&debug_info), sizeof(debug_info));
 
   int script_line_offset = script->line_offset();
-  Handle<FixedArray> line_ends(FixedArray::cast(script->line_ends()));
+  FixedArray* line_ends = FixedArray::cast(script->line_ends());
   Address code_start = code->instruction_start();
 
   for (SourcePositionTableIterator iterator(code->source_position_table());
        !iterator.done(); iterator.Advance()) {
     int position = iterator.source_position().ScriptOffset();
-    int line_number = Script::GetLineNumber(script, position);
+    int line_number = script->GetLineNumber(position);
     // Compute column.
     int relative_line_number = line_number - script_line_offset;
     int start =
         (relative_line_number == 0)
             ? 0
             : Smi::cast(line_ends->get(relative_line_number - 1))->value() + 1;
     int column_offset = position - start;
     if (relative_line_number == 0) {
       // For the case where the code is on the same line as the script tag.
       column_offset += script->column_offset();
@@ skipping 70 matching lines @@
   header.time_stamp_ =
       static_cast<uint64_t>(base::OS::TimeCurrentMillis() * 1000.0);
   header.flags_ = 0;
 
   LogWriteBytes(reinterpret_cast<const char*>(&header), sizeof(header));
 }
 
 #endif  // V8_OS_LINUX
 }  // namespace internal
 }  // namespace v8