Add a flag for printf debugging the compiler dispatcher

src/compiler-dispatcher/compiler-dispatcher-tracer.cc

 // Copyright 2016 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/compiler-dispatcher/compiler-dispatcher-tracer.h"
 
 #include "src/isolate.h"
+#include "src/utils.h"
 
 namespace v8 {
 namespace internal {
 
 namespace {
 
 double MonotonicallyIncreasingTimeInMs() {
   return V8::GetCurrentPlatform()->MonotonicallyIncreasingTime() *
          static_cast<double>(base::Time::kMillisecondsPerSecond);
 }
@@ skipping 118 matching lines @@
     size_t ast_size_in_bytes) const {
   base::LockGuard<base::Mutex> lock(&mutex_);
   return Estimate(compile_events_, ast_size_in_bytes);
 }
 
 double CompilerDispatcherTracer::EstimateFinalizeCompilingInMs() const {
   base::LockGuard<base::Mutex> lock(&mutex_);
   return Average(finalize_compiling_events_);
 }
 
+void CompilerDispatcherTracer::DumpStatistics() const {
+  PrintF(
+      "CompilerDispatcherTracer: "
+      "prepare_parsing=%.2lfms parsing=%.2lfms/kb finalize_parsing=%.2lfms "
+      "prepare_compiling=%.2lfms compiling=%.2lfms/kb "
+      "finalize_compilig=%.2lfms\n",
+      EstimatePrepareToParseInMs(), EstimateParseInMs(1 * KB),
+      EstimateFinalizeParsingInMs(), EstimatePrepareToCompileInMs(),
+      EstimateCompileInMs(1 * KB), EstimateFinalizeCompilingInMs());
+}
+
 double CompilerDispatcherTracer::Average(
     const base::RingBuffer<double>& buffer) {
   if (buffer.Count() == 0) return 0.0;
   double sum = buffer.Sum([](double a, double b) { return a + b; }, 0.0);
   return sum / buffer.Count();
 }
 
 double CompilerDispatcherTracer::Estimate(
     const base::RingBuffer<std::pair<size_t, double>>& buffer, size_t num) {
   if (buffer.Count() == 0) return kEstimatedRuntimeWithoutData;
   std::pair<size_t, double> sum = buffer.Sum(
       [](std::pair<size_t, double> a, std::pair<size_t, double> b) {
         return std::make_pair(a.first + b.first, a.second + b.second);
       },
       std::make_pair(0, 0.0));
   return num * (sum.second / sum.first);
 }
 
 }  // namespace internal
 }  // namespace v8