Change the way sampler / profiler handle external callbacks.

src/log.cc

 // Copyright 2009 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 142 matching lines @@
   // Avoid collecting traces while doing GC.
   if (sample->state == GC) return;
 
   const Address js_entry_sp =
       Isolate::js_entry_sp(isolate->thread_local_top());
   if (js_entry_sp == 0) {
     // Not executing JS now.
     return;
   }
 
-  // Sample potential return address value for frameless invocation of
-  // stubs (we'll figure out later, if this value makes sense).
-  sample->tos = Memory::Address_at(sample->sp);
-
-  int i = 0;
   const Address callback = isolate->external_callback();
-  // Surprisingly, PC can point _exactly_ to callback start, with good
-  // probability, and this will result in reporting fake nested
-  // callback call.
-  if (callback != NULL && callback != sample->pc) {
-    sample->stack[i++] = callback;
+  if (callback != NULL) {
+    sample->external_callback = callback;
+    sample->has_external_callback = true;
+  } else {
+    // Sample potential return address value for frameless invocation of
+    // stubs (we'll figure out later, if this value makes sense).
+    sample->tos = Memory::Address_at(sample->sp);
+    sample->has_external_callback = false;
   }
 
   SafeStackTraceFrameIterator it(isolate,
                                  sample->fp, sample->sp,
                                  sample->sp, js_entry_sp);
+  int i = 0;
   while (!it.done() && i < TickSample::kMaxFramesCount) {
     sample->stack[i++] = it.frame()->pc();
     it.Advance();
   }
   sample->frames_count = i;
 }
 
 
 //
 // Ticker used to provide ticks to the profiler and the sliding state
@@ skipping 938 matching lines @@
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
 void Logger::TickEvent(TickSample* sample, bool overflow) {
   if (!log_->IsEnabled() || !FLAG_prof) return;
   LogMessageBuilder msg(this);
   msg.Append("%s,", kLogEventsNames[TICK_EVENT]);
   msg.AppendAddress(sample->pc);
   msg.Append(',');
   msg.AppendAddress(sample->sp);
   msg.Append(',');
-  msg.AppendAddress(sample->tos);
+  if (sample->has_external_callback) {
+    msg.Append(",1,");
+    msg.AppendAddress(sample->external_callback);
+  } else {
+    msg.Append(",0,");
+    msg.AppendAddress(sample->tos);
+  }
   msg.Append(",%d", static_cast<int>(sample->state));
   if (overflow) {
     msg.Append(",overflow");
   }
   for (int i = 0; i < sample->frames_count; ++i) {
     msg.Append(',');
     msg.AppendAddress(sample->stack[i]);
   }
   msg.Append('\n');
   msg.WriteToLogFile();
@@ skipping 501 matching lines @@
 void SamplerRegistry::RemoveActiveSampler(Sampler* sampler) {
   ASSERT(sampler->IsActive());
   ScopedLock lock(mutex_);
   ASSERT(active_samplers_ != NULL);
   bool removed = active_samplers_->RemoveElement(sampler);
   ASSERT(removed);
   USE(removed);
 }
 
 } }  // namespace v8::internal