[Tracing] Fix inaccurate time accumulation in runtime statistics.

src/counters.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/counters.h"
 
 #include <iomanip>
 
 #include "src/base/platform/platform.h"
 #include "src/isolate.h"
@@ skipping 283 matching lines @@
 
 // static
 void RuntimeCallStats::Leave(RuntimeCallStats* stats, RuntimeCallTimer* timer) {
   if (stats->current_timer_.Value() == timer) {
     stats->current_timer_.SetValue(timer->Stop());
   } else {
     // Must be a Threading cctest. Walk the chain of Timers to find the
     // buried one that's leaving. We don't care about keeping nested timings
     // accurate, just avoid crashing by keeping the chain intact.
     RuntimeCallTimer* next = stats->current_timer_.Value();
-    while (next->parent() != timer) next = next->parent();
+    while (next && next->parent() != timer) next = next->parent();
+    if (next == nullptr) return;
     next->parent_.SetValue(timer->Stop());
   }
 }
 
 // static
 void RuntimeCallStats::CorrectCurrentCounterId(RuntimeCallStats* stats,
                                                CounterId counter_id) {
   DCHECK_NOT_NULL(stats->current_timer_.Value());
   RuntimeCallCounter* counter = &(stats->*counter_id);
   stats->current_timer_.Value()->counter_ = counter;
@@ skipping 24 matching lines @@
 #define PRINT_COUNTER(name) entries.Add(&this->Handler_##name);
   FOR_EACH_HANDLER_COUNTER(PRINT_COUNTER)
 #undef PRINT_COUNTER
 
   entries.Print(os);
 }
 
 void RuntimeCallStats::Reset() {
   if (V8_LIKELY(FLAG_runtime_stats == 0)) return;
 
+  // In tracing, we only what to trace the time spent on top level trace events,
+  // if runtime counter stack is not empty, we should clear the whole runtime
+  // counter stack, and then reset counters so that we can dump counters into
+  // top level trace events accurately.
+  while (current_timer_.Value()) {
+    current_timer_.SetValue(current_timer_.Value()->Stop());
+  }
+
 #define RESET_COUNTER(name) this->name.Reset();
   FOR_EACH_MANUAL_COUNTER(RESET_COUNTER)
 #undef RESET_COUNTER
 
 #define RESET_COUNTER(name, nargs, result_size) this->Runtime_##name.Reset();
   FOR_EACH_INTRINSIC(RESET_COUNTER)
 #undef RESET_COUNTER
 
 #define RESET_COUNTER(name) this->Builtin_##name.Reset();
   BUILTIN_LIST_C(RESET_COUNTER)
 #undef RESET_COUNTER
 
 #define RESET_COUNTER(name) this->API_##name.Reset();
   FOR_EACH_API_COUNTER(RESET_COUNTER)
 #undef RESET_COUNTER
 
 #define RESET_COUNTER(name) this->Handler_##name.Reset();
   FOR_EACH_HANDLER_COUNTER(RESET_COUNTER)
 #undef RESET_COUNTER
 
   in_use_ = true;
 }
 
 void RuntimeCallStats::Dump(v8::tracing::TracedValue* value) {
-  if (current_timer_.Value() != nullptr) {
-    current_timer_.Value()->Elapsed();
-  }
 #define DUMP_COUNTER(name) \
   if (this->name.count > 0) this->name.Dump(value);
   FOR_EACH_MANUAL_COUNTER(DUMP_COUNTER)
 #undef DUMP_COUNTER
 
 #define DUMP_COUNTER(name, nargs, result_size) \
   if (this->Runtime_##name.count > 0) this->Runtime_##name.Dump(value);
   FOR_EACH_INTRINSIC(DUMP_COUNTER)
 #undef DUMP_COUNTER
 
@@ skipping 10 matching lines @@
 #define DUMP_COUNTER(name) \
   if (this->Handler_##name.count > 0) this->Handler_##name.Dump(value);
   FOR_EACH_HANDLER_COUNTER(DUMP_COUNTER)
 #undef DUMP_COUNTER
 
   in_use_ = false;
 }
 
 }  // namespace internal
 }  // namespace v8