[cpu-profiler] Add more logging to find flaky failure

There is a flaky 5x failure in the tree which I can't reproduce locally.
This extra logging will help flush out what the problem is.

Bug: v8:8649

Change-Id: If36d2ce0f4feb398d7d746d69b417bb55a714422
Reviewed-on: https://chromium-review.googlesource.com/c/1402787
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58796}

src/libsampler/DEPS

 include_rules = [
   "+include",
   "-src",
+  "+src/flags.h",
   "+src/base",
   "+src/libsampler",
 ]
\ No newline at end of file

src/libsampler/sampler.cc

@@ -63,6 +63,8 @@ typedef zx_arm64_general_regs_t zx_thread_state_general_regs_t;
 #include "src/base/atomic-utils.h"
 #include "src/base/hashmap.h"
 #include "src/base/platform/platform.h"
+// TODO(petermarshall): Remove when cpu profiler logging is no longer needed
+#include "src/flags.h"
 
 #if V8_OS_ANDROID && !defined(__BIONIC_HAVE_UCONTEXT_T)
 
@@ -391,6 +393,9 @@ class SignalHandler {
 
   static void DecreaseSamplerCount() {
     base::MutexGuard lock_guard(mutex_);
+    if (i::FLAG_cpu_profiler_logging) {
+      printf("SignalHandler DecreaseSamplerCount: signals: %d\n", signals_);
+    }
     if (--client_count_ == 0) Restore();
   }
 
@@ -428,13 +433,14 @@ class SignalHandler {
   static int client_count_;
   static bool signal_handler_installed_;
   static struct sigaction old_signal_handler_;
+  static int signals_;
 };
 
 base::Mutex* SignalHandler::mutex_ = nullptr;
 int SignalHandler::client_count_ = 0;
 struct sigaction SignalHandler::old_signal_handler_;
 bool SignalHandler::signal_handler_installed_ = false;
-
+int SignalHandler::signals_ = 0;
 
 void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
                                          void* context) {
@@ -442,6 +448,7 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   if (signal != SIGPROF) return;
   v8::RegisterState state;
   FillRegisterState(context, &state);
+  signals_++;
   SamplerManager::instance()->DoSample(state);
 }
 
@@ -627,6 +634,9 @@ void Sampler::UnregisterIfRegistered() {
 Sampler::~Sampler() {
   DCHECK(!IsActive());
   DCHECK(!IsRegistered());
+  if (i::FLAG_cpu_profiler_logging) {
+    printf("~Sampler: samples = %d\n", samples_);
+  }
   delete data_;
 }
 
@@ -668,6 +678,7 @@ void Sampler::DecreaseProfilingDepth() {
 #if defined(USE_SIGNALS)
 
 void Sampler::DoSample() {
+  samples_++;
   if (!SignalHandler::Installed()) return;
   if (!IsActive() && !IsRegistered()) {
     SamplerManager::instance()->AddSampler(this);

src/libsampler/sampler.h

@@ -100,6 +100,7 @@ class Sampler {
   base::Atomic32 active_;
   base::Atomic32 registered_;
   PlatformData* data_;  // Platform specific data.
+  int samples_ = 0;
   DISALLOW_IMPLICIT_CONSTRUCTORS(Sampler);
 };
 

src/profiler/cpu-profiler.cc

@@ -406,6 +406,9 @@ void CpuProfiler::StartProcessorIfNotStarted() {
 
 CpuProfile* CpuProfiler::StopProfiling(const char* title) {
   if (!is_profiling_) return nullptr;
+  if (i::FLAG_cpu_profiler_logging) {
+    PrintF("StopProfiling: samples = %d\n", generator_->samples_);
+  }
   StopProcessorIfLastProfile(title);
   return profiles_->StopProfiling(title);
 }

src/profiler/profile-generator.cc

@@ -783,6 +783,7 @@ void ProfileGenerator::RecordTickSample(const TickSample& sample) {
   if (FLAG_cpu_profiler_logging) {
     PrintF("RecordTickSample: ");
     sample.print();
+    samples_++;
   }
 
   if (sample.pc != nullptr) {

src/profiler/profile-generator.h

@@ -463,10 +463,16 @@ class CpuProfilesCollection {
 class ProfileGenerator {
  public:
   explicit ProfileGenerator(CpuProfilesCollection* profiles);
+  ~ProfileGenerator() {
+    if (FLAG_cpu_profiler_logging) {
+      PrintF("~ProfileGenerator: samples = %d\n", samples_);
+    }
+  }
 
   void RecordTickSample(const TickSample& sample);
 
   CodeMap* code_map() { return &code_map_; }
+  int samples_ = 0;
 
  private:
   CodeEntry* FindEntry(Address address);