Initial implementation of GetStackSample sampling profiler API.

src/sampler.cc

 // Copyright 2013 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/sampler.h"
 
 #if V8_OS_POSIX && !V8_OS_CYGWIN
 
 #define USE_SIGNALS
 
@@ skipping 208 matching lines @@
 
  private:
   HANDLE profiled_thread_;
 };
 #endif
 
 
 #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(
         Simulator::sp));
     state->fp = reinterpret_cast<Address>(simulator_->get_register(
         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;
     }
     state->pc = reinterpret_cast<Address>(simulator_->pc());
     state->sp = reinterpret_cast<Address>(simulator_->sp());
     state->fp = reinterpret_cast<Address>(simulator_->fp());
 #elif V8_TARGET_ARCH_MIPS
     state->pc = reinterpret_cast<Address>(simulator_->get_pc());
     state->sp = reinterpret_cast<Address>(simulator_->get_register(
         Simulator::sp));
@@ skipping 89 matching lines @@
     return;
   }
   if (v8::Locker::IsActive() &&
       !isolate->thread_manager()->IsLockedByCurrentThread()) {
     return;
   }
 
   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:
   // first setting it to zero and then setting it to the new value.
   // Bailout if sp/fp doesn't contain the new value.
   if (state.sp == 0 || state.fp == 0) return;
 #else
   // Extracting the sample from the context is extremely machine dependent.
   ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
 #if !V8_OS_OPENBSD
@@ skipping 199 matching lines @@
 
 
 base::Mutex* SamplerThread::mutex_ = NULL;
 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.
   if (state == GC) return;
 
   Address js_entry_sp = isolate->js_entry_sp();
   if (js_entry_sp == 0) {
     // Not executing JS now.
     return;
   }
 
   ExternalCallbackScope* scope = isolate->external_callback_scope();
   Address handler = Isolate::handler(isolate->thread_local_top());
   // If there is a handler on top of the external callback scope then
   // we have already entrered JavaScript again and the external callback
   // is not the top function.
   if (scope && scope->scope_address() < handler) {
     external_callback = scope->callback();
     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).
-    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();
-    it.Advance();
-  }
-  frames_count = i;
+
+  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();
+  }
+  return i;
+}
+
+
 void Sampler::SetUp() {
 #if defined(USE_SIGNALS)
   SignalHandler::SetUp();
 #endif
   SamplerThread::SetUp();
 }
 
 
 void Sampler::TearDown() {
   SamplerThread::TearDown();
@@ skipping 44 matching lines @@
 
 
 void Sampler::DecreaseProfilingDepth() {
 #if defined(USE_SIGNALS)
   SignalHandler::DecreaseSamplerCount();
 #endif
   base::NoBarrier_AtomicIncrement(&profiling_, -1);
 }
 
 
-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;
   sample->Init(isolate_, state);
   if (is_counting_samples_) {
     if (sample->state == JS || sample->state == EXTERNAL) {
       ++js_and_external_sample_count_;
     }
   }
   Tick(sample);
@@ skipping 11 matching lines @@
 }
 
 #elif V8_OS_WIN || V8_OS_CYGWIN
 
 void Sampler::DoSample() {
   HANDLE profiled_thread = platform_data()->profiled_thread();
   if (profiled_thread == NULL) return;
 
 #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);
   if (SuspendThread(profiled_thread) == kSuspendFailed) return;
 
   // Context used for sampling the register state of the profiled thread.
   CONTEXT context;
   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
 #if V8_HOST_ARCH_X64
     state.pc = reinterpret_cast<Address>(context.Rip);
     state.sp = reinterpret_cast<Address>(context.Rsp);
     state.fp = reinterpret_cast<Address>(context.Rbp);
 #else
     state.pc = reinterpret_cast<Address>(context.Eip);
     state.sp = reinterpret_cast<Address>(context.Esp);
     state.fp = reinterpret_cast<Address>(context.Ebp);
 #endif
 #endif  // USE_SIMULATOR
     SampleStack(state);
   }
   ResumeThread(profiled_thread);
 }
 
 #endif  // USE_SIGNALS
 
 
 } }  // namespace v8::internal