Change the way sampler / profiler handle external callbacks.

src/profile-generator.cc

 // Copyright 2010 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 795 matching lines @@
 void ProfileGenerator::RecordTickSample(const TickSample& sample) {
   // Allocate space for stack frames + pc + function + vm-state.
   ScopedVector<CodeEntry*> entries(sample.frames_count + 3);
   // As actual number of decoded code entries may vary, initialize
   // entries vector with NULL values.
   CodeEntry** entry = entries.start();
   memset(entry, 0, entries.length() * sizeof(*entry));
   if (sample.pc != NULL) {
     *entry++ = code_map_.FindEntry(sample.pc);
 
-    if (sample.tos != NULL) {
+    if (sample.has_external_callback) {
+      // Don't use PC when in external callback code, as it can point
+      // inside callback's code, and we will erroneously report
+      // that a callback calls itself.
+      *(entries.start()) = NULL;
+      *entry++ = code_map_.FindEntry(sample.external_callback);
+    } else if (sample.tos != NULL) {
+      // Find out, if top of stack was pointing inside a JS function
+      // meaning that we have encountered a frameless invocation.
       *entry = code_map_.FindEntry(sample.tos);
       if (*entry != NULL && !(*entry)->is_js_function()) {
         *entry = NULL;
       }
       entry++;
     }
 
     for (const Address *stack_pos = sample.stack,
            *stack_end = stack_pos + sample.frames_count;
          stack_pos != stack_end;
@@ skipping 2361 matching lines @@
 
 
 String* GetConstructorNameForHeapProfile(JSObject* object) {
   if (object->IsJSFunction()) return HEAP->closure_symbol();
   return object->constructor_name();
 }
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_LOGGING_AND_PROFILING