Initial implementation of GetStackSample sampling profiler API.

src/sampler.cc

Index: src/sampler.cc
diff --git a/src/sampler.cc b/src/sampler.cc
index 394efeb7640764870b6f768a9d11a1b879955416..6bd84b75d82142d30e645e087bab1967639e6efb 100644
--- a/src/sampler.cc
+++ b/src/sampler.cc
@@ -226,13 +226,13 @@ class Sampler::PlatformData : public PlatformDataCommon {
 #if defined(USE_SIMULATOR)
 class SimulatorHelper {
  public:
-  inline bool Init(Sampler* sampler, Isolate* isolate) {
+  inline bool Init(Isolate* isolate) {
     simulator_ = isolate->thread_local_top()->simulator_;
     // Check if there is active simulator.
     return simulator_ != NULL;
   }
 
-  inline void FillRegisters(RegisterState* state) {
+  inline void FillRegisters(v8::RegisterState* state) {
 #if V8_TARGET_ARCH_ARM
     state->pc = reinterpret_cast<Address>(simulator_->get_pc());
     state->sp = reinterpret_cast<Address>(simulator_->get_register(
@@ -241,9 +241,9 @@ class SimulatorHelper {
         Simulator::r11));
 #elif V8_TARGET_ARCH_ARM64
     if (simulator_->sp() == 0 || simulator_->fp() == 0) {
-      // It possible that the simulator is interrupted while it is updating
+      // It's possible that the simulator is interrupted while it is updating
       // the sp or fp register. ARM64 simulator does this in two steps:
-      // first setting it to zero and then setting it to the new value.
+      // first setting it to zero and then setting it to a new value.
       // Bailout if sp/fp doesn't contain the new value.
       return;
     }
@@ -353,11 +353,11 @@ void SignalHandler::HandleProfilerSignal(int signal, siginfo_t* info,
   Sampler* sampler = isolate->logger()->sampler();
   if (sampler == NULL) return;
 
-  RegisterState state;
+  v8::RegisterState state;
 
 #if defined(USE_SIMULATOR)
   SimulatorHelper helper;
-  if (!helper.Init(sampler, isolate)) return;
+  if (!helper.Init(isolate)) return;
   helper.FillRegisters(&state);
   // It possible that the simulator is interrupted while it is updating
   // the sp or fp register. ARM64 simulator does this in two steps:
@@ -577,10 +577,10 @@ SamplerThread* SamplerThread::instance_ = NULL;
 // StackTracer implementation
 //
 DISABLE_ASAN void TickSample::Init(Isolate* isolate,
-                                   const RegisterState& regs) {
+                                   const v8::RegisterState& regs) {
   DCHECK(isolate->IsInitialized());
   timestamp = base::TimeTicks::HighResolutionNow();
-  pc = regs.pc;
+  pc = reinterpret_cast<Address>(regs.pc);
   state = isolate->current_vm_state();
 
   // Avoid collecting traces while doing GC.
@@ -603,18 +603,36 @@ DISABLE_ASAN void TickSample::Init(Isolate* isolate,
   } else {
     // Sample potential return address value for frameless invocation of
     // stubs (we'll figure out later, if this value makes sense).
-    tos = Memory::Address_at(regs.sp);
+    tos = Memory::Address_at(reinterpret_cast<Address>(regs.sp));
     has_external_callback = false;
   }
 
-  SafeStackFrameIterator it(isolate, regs.fp, regs.sp, js_entry_sp);
+  SafeStackFrameIterator it(isolate, reinterpret_cast<Address>(regs.fp),
+                            reinterpret_cast<Address>(regs.sp), js_entry_sp);
   top_frame_type = it.top_frame_type();
-  unsigned i = 0;
-  while (!it.done() && i < TickSample::kMaxFramesCount) {
-    stack[i++] = it.frame()->pc();
+
+  frames_count = GetStackSample(
+      isolate, regs, reinterpret_cast<void**>(&stack[0]), kMaxFramesCount);
+}
+
+
+int TickSample::GetStackSample(Isolate* isolate, const v8::RegisterState& regs,

[Benedikt Meurer, 2014/09/23 05:47:48]

Nit: int -> size_t

[alph, 2014/09/23 07:30:46]

Done.

+                               void** frames, int frames_limit) {

[Benedikt Meurer, 2014/09/23 05:47:48]

Nit: int -> size_t

[alph, 2014/09/23 07:30:46]

Done.

+  DCHECK(isolate->IsInitialized());
+  Address js_entry_sp = isolate->js_entry_sp();
+  if (js_entry_sp == 0) {
+    // Not executing JS now.
+    return 0;
+  }
+
+  SafeStackFrameIterator it(isolate, reinterpret_cast<Address>(regs.fp),
+                            reinterpret_cast<Address>(regs.sp), js_entry_sp);
+  int i = 0;

[Benedikt Meurer, 2014/09/23 05:47:48]

Nit: int -> size_t

[alph, 2014/09/23 07:30:46]

Done.

+  while (!it.done() && i < frames_limit) {
+    frames[i++] = it.frame()->pc();
     it.Advance();
   }
-  frames_count = i;
+  return i;
 }
 
 
@@ -682,7 +700,7 @@ void Sampler::DecreaseProfilingDepth() {
 }
 
 
-void Sampler::SampleStack(const RegisterState& state) {
+void Sampler::SampleStack(const v8::RegisterState& state) {
   TickSample* sample = isolate_->cpu_profiler()->StartTickSample();
   TickSample sample_obj;
   if (sample == NULL) sample = &sample_obj;
@@ -714,7 +732,7 @@ void Sampler::DoSample() {
 
 #if defined(USE_SIMULATOR)
   SimulatorHelper helper;
-  if (!helper.Init(this, isolate())) return;
+  if (!helper.Init(isolate())) return;
 #endif
 
   const DWORD kSuspendFailed = static_cast<DWORD>(-1);
@@ -725,7 +743,7 @@ void Sampler::DoSample() {
   memset(&context, 0, sizeof(context));
   context.ContextFlags = CONTEXT_FULL;
   if (GetThreadContext(profiled_thread, &context) != 0) {
-    RegisterState state;
+    v8::RegisterState state;
 #if defined(USE_SIMULATOR)
     helper.FillRegisters(&state);
 #else