Support profiler stack sampling in any situation. After this change, almost...

Support profiler stack sampling in any situation. After this change, almost all profiler ticks (except GC ones) have a stack sample data associated.

Tested under Linux, OS X, and Windows.

Review URL: http://codereview.chromium.org/50052

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1565 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/frames-arm.h

@@ -154,11 +154,9 @@ class InternalFrameConstants : public AllStatic {
 };
 
 
-inline Object* JavaScriptFrame::function() const {
+inline Object* JavaScriptFrame::function_slot_object() const {
   const int offset = JavaScriptFrameConstants::kFunctionOffset;
-  Object* result = Memory::Object_at(fp() + offset);
-  ASSERT(result->IsJSFunction());
-  return result;
+  return Memory::Object_at(fp() + offset);
 }
 
 

src/frames-ia32.h

@@ -129,11 +129,9 @@ class InternalFrameConstants : public AllStatic {
 };
 
 
-inline Object* JavaScriptFrame::function() const {
+inline Object* JavaScriptFrame::function_slot_object() const {
   const int offset = JavaScriptFrameConstants::kFunctionOffset;
-  Object* result = Memory::Object_at(fp() + offset);
-  ASSERT(result->IsJSFunction());
-  return result;
+  return Memory::Object_at(fp() + offset);
 }
 
 

src/frames-inl.h

@@ -169,6 +169,20 @@ inline bool JavaScriptFrame::has_adapted_arguments() const {
 }
 
 
+inline bool JavaScriptFrame::is_at_function() const {
+  Object* result = function_slot_object();
+  return Heap::Contains(reinterpret_cast<Address>(result)) &&
+      result->IsJSFunction();
+}
+
+
+inline Object* JavaScriptFrame::function() const {
+  Object* result = function_slot_object();
+  ASSERT(result->IsJSFunction());
+  return result;
+}
+
+
 template<typename Iterator>
 inline JavaScriptFrame* JavaScriptFrameIteratorTemp<Iterator>::frame() const {
   // TODO(1233797): The frame hierarchy needs to change. It's

src/frames.cc

@@ -66,23 +66,32 @@ class StackHandlerIterator BASE_EMBEDDED {
 #define INITIALIZE_SINGLETON(type, field) field##_(this),
 StackFrameIterator::StackFrameIterator()
     : STACK_FRAME_TYPE_LIST(INITIALIZE_SINGLETON)
-      frame_(NULL), handler_(NULL), thread_(Top::GetCurrentThread()) {
+      frame_(NULL), handler_(NULL), thread_(Top::GetCurrentThread()),
+      fp_(NULL), sp_(NULL), advance_(&StackFrameIterator::AdvanceWithHandler) {
   Reset();
 }
 StackFrameIterator::StackFrameIterator(ThreadLocalTop* t)
     : STACK_FRAME_TYPE_LIST(INITIALIZE_SINGLETON)
-      frame_(NULL), handler_(NULL), thread_(t) {
+      frame_(NULL), handler_(NULL), thread_(t),
+      fp_(NULL), sp_(NULL), advance_(&StackFrameIterator::AdvanceWithHandler) {
   Reset();
 }
-StackFrameIterator::StackFrameIterator(bool reset)
+StackFrameIterator::StackFrameIterator(bool use_top, Address fp, Address sp)
     : STACK_FRAME_TYPE_LIST(INITIALIZE_SINGLETON)
-      frame_(NULL), handler_(NULL), thread_(Top::GetCurrentThread()) {
-  if (reset) Reset();
+      frame_(NULL), handler_(NULL),
+      thread_(use_top ? Top::GetCurrentThread() : NULL),
+      fp_(use_top ? NULL : fp), sp_(sp),
+      advance_(use_top ? &StackFrameIterator::AdvanceWithHandler :
+               &StackFrameIterator::AdvanceWithoutHandler) {
+  if (use_top || fp != NULL) {
+    Reset();
+  }
 }
+
 #undef INITIALIZE_SINGLETON
 
 
-void StackFrameIterator::Advance() {
+void StackFrameIterator::AdvanceWithHandler() {
   ASSERT(!done());
   // Compute the state of the calling frame before restoring
   // callee-saved registers and unwinding handlers. This allows the
@@ -105,17 +114,45 @@ void StackFrameIterator::Advance() {
 }
 
 
-void StackFrameIterator::Reset() {
-  Address fp = Top::c_entry_fp(thread_);
+void StackFrameIterator::AdvanceWithoutHandler() {
+  // A simpler version of Advance which doesn't care about handler.
+  ASSERT(!done());
   StackFrame::State state;
-  StackFrame::Type type = ExitFrame::GetStateForFramePointer(fp, &state);
+  StackFrame::Type type = frame_->GetCallerState(&state);
   frame_ = SingletonFor(type, &state);
+}
+
+
+void StackFrameIterator::Reset() {
+  StackFrame::State state;
+  StackFrame::Type type;
+  if (thread_ != NULL) {
+    type = ExitFrame::GetStateForFramePointer(Top::c_entry_fp(thread_), &state);
     handler_ = StackHandler::FromAddress(Top::handler(thread_));
+  } else {
+    ASSERT(fp_ != NULL);
+    state.fp = fp_;
+    state.sp = sp_;
+    state.pc_address =
+        reinterpret_cast<Address*>(StandardFrame::ComputePCAddress(fp_));
+    type = StackFrame::ComputeType(&state);
+    if (SingletonFor(type) == NULL) return;
+  }
+  frame_ = SingletonFor(type, &state);
 }
 
 
 StackFrame* StackFrameIterator::SingletonFor(StackFrame::Type type,
                                              StackFrame::State* state) {
+  if (type == StackFrame::NONE) return NULL;
+  StackFrame* result = SingletonFor(type);
+  ASSERT(result != NULL);
+  result->state_ = *state;
+  return result;
+}
+
+
+StackFrame* StackFrameIterator::SingletonFor(StackFrame::Type type) {
 #define FRAME_TYPE_CASE(type, field) \
   case StackFrame::type: result = &field##_; break;
 
@@ -125,8 +162,6 @@ StackFrame* StackFrameIterator::SingletonFor(StackFrame::Type type,
     STACK_FRAME_TYPE_LIST(FRAME_TYPE_CASE)
     default: break;
   }
-  ASSERT(result != NULL);
-  result->state_ = *state;
   return result;
 
 #undef FRAME_TYPE_CASE
@@ -154,29 +189,50 @@ void StackTraceFrameIterator::Advance() {
 
 
 SafeStackFrameIterator::SafeStackFrameIterator(
-    Address low_bound, Address high_bound) :
+    Address fp, Address sp, Address low_bound, Address high_bound) :
     low_bound_(low_bound), high_bound_(high_bound),
-    is_working_iterator_(IsInBounds(low_bound, high_bound,
-                                    Top::c_entry_fp(Top::GetCurrentThread()))),
-    iteration_done_(!is_working_iterator_), iterator_(is_working_iterator_) {
+    is_valid_top_(
+        IsWithinBounds(low_bound, high_bound,
+                       Top::c_entry_fp(Top::GetCurrentThread())) &&
+        Top::handler(Top::GetCurrentThread()) != NULL),
+    is_valid_fp_(IsWithinBounds(low_bound, high_bound, fp)),
+    is_working_iterator_(is_valid_top_ || is_valid_fp_),
+    iteration_done_(!is_working_iterator_),
+    iterator_(is_valid_top_, is_valid_fp_ ? fp : NULL, sp) {
 }
 
 
 void SafeStackFrameIterator::Advance() {
   ASSERT(is_working_iterator_);
   ASSERT(!done());
-  StackFrame* frame = iterator_.frame();
-  iteration_done_ =
-      !IsGoodStackAddress(frame->sp()) || !IsGoodStackAddress(frame->fp());
-  if (!iteration_done_) {
+  StackFrame* last_frame = iterator_.frame();
+  Address last_sp = last_frame->sp(), last_fp = last_frame->fp();
+  // Before advancing to the next stack frame, perform pointer validity tests
+  iteration_done_ = !IsValidFrame(last_frame) || !IsValidCaller(last_frame);
+  if (iteration_done_) return;
+
   iterator_.Advance();
-    if (!iterator_.done()) {
+  if (iterator_.done()) return;
   // Check that we have actually moved to the previous frame in the stack
   StackFrame* prev_frame = iterator_.frame();
-      iteration_done_ =
-          prev_frame->sp() < frame->sp() || prev_frame->fp() < frame->fp();
-    }
-  }
+  iteration_done_ = prev_frame->sp() < last_sp || prev_frame->fp() < last_fp;
+}
+
+
+bool SafeStackFrameIterator::IsValidFrame(StackFrame* frame) const {
+  return IsValidStackAddress(frame->sp()) && IsValidStackAddress(frame->fp()) &&
+      // JavaScriptFrame uses function shared info to advance, hence it must
+      // point to a valid function object.
+      (!frame->is_java_script() ||
+       reinterpret_cast<JavaScriptFrame*>(frame)->is_at_function());
+}
+
+
+bool SafeStackFrameIterator::IsValidCaller(StackFrame* frame) {
+  StackFrame::State state;
+  frame->ComputeCallerState(&state);
+  return IsValidStackAddress(state.sp) && IsValidStackAddress(state.fp) &&
+      iterator_.SingletonFor(frame->GetCallerState(&state)) != NULL;
 }
 
 
@@ -193,9 +249,9 @@ void SafeStackFrameIterator::Reset() {
 
 #ifdef ENABLE_LOGGING_AND_PROFILING
 SafeStackTraceFrameIterator::SafeStackTraceFrameIterator(
-    Address low_bound, Address high_bound) :
-    SafeJavaScriptFrameIterator(low_bound, high_bound) {
-  if (!done() && !frame()->function()->IsJSFunction()) Advance();
+    Address fp, Address sp, Address low_bound, Address high_bound) :
+    SafeJavaScriptFrameIterator(fp, sp, low_bound, high_bound) {
+  if (!done() && !frame()->is_at_function()) Advance();
 }
 
 
@@ -203,7 +259,7 @@ void SafeStackTraceFrameIterator::Advance() {
   while (true) {
     SafeJavaScriptFrameIterator::Advance();
     if (done()) return;
-    if (frame()->function()->IsJSFunction()) return;
+    if (frame()->is_at_function()) return;
   }
 }
 #endif
@@ -279,11 +335,22 @@ void StackFrame::Uncook() {
 }
 
 
+StackFrame::Type StackFrame::GetCallerState(State* state) const {
+  ComputeCallerState(state);
+  return ComputeType(state);
+}
+
+
 Code* EntryFrame::code() const {
   return Heap::js_entry_code();
 }
 
 
+void EntryFrame::ComputeCallerState(State* state) const {
+  GetCallerState(state);
+}
+
+
 StackFrame::Type EntryFrame::GetCallerState(State* state) const {
   const int offset = EntryFrameConstants::kCallerFPOffset;
   Address fp = Memory::Address_at(this->fp() + offset);
@@ -301,13 +368,12 @@ Code* ExitFrame::code() const {
 }
 
 
-StackFrame::Type ExitFrame::GetCallerState(State* state) const {
+void ExitFrame::ComputeCallerState(State* state) const {
   // Setup the caller state.
   state->sp = pp();
   state->fp = Memory::Address_at(fp() + ExitFrameConstants::kCallerFPOffset);
   state->pc_address
       = reinterpret_cast<Address*>(fp() + ExitFrameConstants::kCallerPCOffset);
-  return ComputeType(state);
 }
 
 
@@ -338,11 +404,10 @@ int StandardFrame::ComputeExpressionsCount() const {
 }
 
 
-StackFrame::Type StandardFrame::GetCallerState(State* state) const {
+void StandardFrame::ComputeCallerState(State* state) const {
   state->sp = caller_sp();
   state->fp = caller_fp();
   state->pc_address = reinterpret_cast<Address*>(ComputePCAddress(fp()));
-  return ComputeType(state);
 }
 
 

src/frames.h

@@ -190,8 +190,11 @@ class StackFrame BASE_EMBEDDED {
   const StackFrameIterator* iterator_;
   State state_;
 
+  // Fill in the state of the calling frame.
+  virtual void ComputeCallerState(State* state) const = 0;
+
   // Get the type and the state of the calling frame.
-  virtual Type GetCallerState(State* state) const = 0;
+  virtual Type GetCallerState(State* state) const;
 
   // Cooking/uncooking support.
   void Cook();
@@ -199,6 +202,7 @@ class StackFrame BASE_EMBEDDED {
 
   friend class StackFrameIterator;
   friend class StackHandlerIterator;
+  friend class SafeStackFrameIterator;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(StackFrame);
 };
@@ -228,6 +232,7 @@ class EntryFrame: public StackFrame {
   virtual Address GetCallerStackPointer() const { return 0; }
 
  private:
+  virtual void ComputeCallerState(State* state) const;
   virtual Type GetCallerState(State* state) const;
 
   friend class StackFrameIterator;
@@ -280,7 +285,7 @@ class ExitFrame: public StackFrame {
   virtual Address GetCallerStackPointer() const;
 
  private:
-  virtual Type GetCallerState(State* state) const;
+  virtual void ComputeCallerState(State* state) const;
 
   friend class StackFrameIterator;
 };
@@ -328,7 +333,7 @@ class StandardFrame: public StackFrame {
   explicit StandardFrame(StackFrameIterator* iterator)
       : StackFrame(iterator) { }
 
-  virtual Type GetCallerState(State* state) const;
+  virtual void ComputeCallerState(State* state) const;
 
   // Accessors.
   inline Address caller_sp() const;
@@ -368,6 +373,7 @@ class JavaScriptFrame: public StandardFrame {
   virtual Type type() const { return JAVA_SCRIPT; }
 
   // Accessors.
+  inline bool is_at_function() const;
   inline Object* function() const;
   inline Object* receiver() const;
   inline void set_receiver(Object* value);
@@ -413,6 +419,8 @@ class JavaScriptFrame: public StandardFrame {
   virtual Address GetCallerStackPointer() const;
 
  private:
+  inline Object* function_slot_object() const;
+
   friend class StackFrameIterator;
 };
 
@@ -509,8 +517,10 @@ class StackFrameIterator BASE_EMBEDDED {
   // An iterator that iterates over a given thread's stack.
   explicit StackFrameIterator(ThreadLocalTop* thread);
 
-  // An iterator that conditionally resets itself on init.
-  explicit StackFrameIterator(bool reset);
+  // An iterator that can start from a given FP address.
+  // If use_top, then work as usual, if fp isn't NULL, use it,
+  // otherwise, do nothing.
+  StackFrameIterator(bool use_top, Address fp, Address sp);
 
   StackFrame* frame() const {
     ASSERT(!done());
@@ -518,7 +528,7 @@ class StackFrameIterator BASE_EMBEDDED {
   }
 
   bool done() const { return frame_ == NULL; }
-  void Advance();
+  void Advance() { (this->*advance_)(); }
 
   // Go back to the first frame.
   void Reset();
@@ -530,6 +540,9 @@ class StackFrameIterator BASE_EMBEDDED {
   StackFrame* frame_;
   StackHandler* handler_;
   ThreadLocalTop* thread_;
+  Address fp_;
+  Address sp_;
+  void (StackFrameIterator::*advance_)();
 
   StackHandler* handler() const {
     ASSERT(!done());
@@ -538,8 +551,14 @@ class StackFrameIterator BASE_EMBEDDED {
 
   // Get the type-specific frame singleton in a given state.
   StackFrame* SingletonFor(StackFrame::Type type, StackFrame::State* state);
+  // A helper function, can return a NULL pointer.
+  StackFrame* SingletonFor(StackFrame::Type type);
+
+  void AdvanceWithHandler();
+  void AdvanceWithoutHandler();
 
   friend class StackFrame;
+  friend class SafeStackFrameIterator;
   DISALLOW_COPY_AND_ASSIGN(StackFrameIterator);
 };
 
@@ -558,8 +577,11 @@ class JavaScriptFrameIteratorTemp BASE_EMBEDDED {
   // Skip frames until the frame with the given id is reached.
   explicit JavaScriptFrameIteratorTemp(StackFrame::Id id);
 
-  explicit JavaScriptFrameIteratorTemp(Address low_bound, Address high_bound) :
-      iterator_(low_bound, high_bound) { if (!done()) Advance(); }
+  JavaScriptFrameIteratorTemp(Address fp, Address sp,
+                              Address low_bound, Address high_bound) :
+      iterator_(fp, sp, low_bound, high_bound) {
+    if (!done()) Advance();
+  }
 
   inline JavaScriptFrame* frame() const;
 
@@ -595,7 +617,8 @@ class StackTraceFrameIterator: public JavaScriptFrameIterator {
 
 class SafeStackFrameIterator BASE_EMBEDDED {
  public:
-  explicit SafeStackFrameIterator(Address low_bound, Address high_bound);
+  SafeStackFrameIterator(Address fp, Address sp,
+                         Address low_bound, Address high_bound);
 
   StackFrame* frame() const {
     ASSERT(is_working_iterator_);
@@ -608,16 +631,20 @@ class SafeStackFrameIterator BASE_EMBEDDED {
   void Reset();
 
  private:
-  static bool IsInBounds(
+  static bool IsWithinBounds(
       Address low_bound, Address high_bound, Address addr) {
     return low_bound <= addr && addr <= high_bound;
   }
-  bool IsGoodStackAddress(Address addr) const {
-    return IsInBounds(low_bound_, high_bound_, addr);
+  bool IsValidStackAddress(Address addr) const {
+    return IsWithinBounds(low_bound_, high_bound_, addr);
   }
+  bool IsValidFrame(StackFrame* frame) const;
+  bool IsValidCaller(StackFrame* frame);
 
   Address low_bound_;
   Address high_bound_;
+  const bool is_valid_top_;
+  const bool is_valid_fp_;
   const bool is_working_iterator_;
   bool iteration_done_;
   StackFrameIterator iterator_;
@@ -631,7 +658,8 @@ typedef JavaScriptFrameIteratorTemp<SafeStackFrameIterator>
 
 class SafeStackTraceFrameIterator: public SafeJavaScriptFrameIterator {
  public:
-  explicit SafeStackTraceFrameIterator(Address low_bound, Address high_bound);
+  explicit SafeStackTraceFrameIterator(Address fp, Address sp,
+                                       Address low_bound, Address high_bound);
   void Advance();
 };
 #endif

src/log.cc

@@ -142,10 +142,9 @@ void StackTracer::Trace(TickSample* sample) {
     return;
   }
 
-  // If c_entry_fp is available, this means that we are inside a C++
-  // function and sample->fp value isn't reliable due to FPO.
-  if (Top::c_entry_fp(Top::GetCurrentThread()) != NULL) {
   SafeStackTraceFrameIterator it(
+      reinterpret_cast<Address>(sample->fp),
+      reinterpret_cast<Address>(sample->sp),
       reinterpret_cast<Address>(sample->sp),
       reinterpret_cast<Address>(low_stack_bound_));
   int i = 0;
@@ -154,16 +153,6 @@ void StackTracer::Trace(TickSample* sample) {
     it.Advance();
   }
   sample->frames_count = i;
-  } else if (sample->sp < sample->fp && sample->fp < low_stack_bound_) {
-    // The check assumes that stack grows from lower addresses.
-    sample->stack[0] = Memory::Address_at(
-        (Address)(sample->fp + StandardFrameConstants::kCallerPCOffset));
-    sample->frames_count = 1;
-  } else {
-    // FP seems to be in some intermediate state,
-    // better discard this sample
-    sample->frames_count = 0;
-  }
 }
 
 
@@ -936,7 +925,7 @@ void Logger::TickEvent(TickSample* sample, bool overflow) {
     msg.Append(",overflow");
   }
   for (int i = 0; i < sample->frames_count; ++i) {
-    msg.Append(",%p", sample->stack[i]);
+    msg.Append(",0x%x", reinterpret_cast<uint32_t>(sample->stack[i]));
   }
   msg.Append('\n');
   msg.WriteToLogFile();

src/log.h

@@ -270,7 +270,7 @@ class Logger {
 };
 
 
-// Class that extracts stack trace, used for profiling
+// Class that extracts stack trace, used for profiling.
 class StackTracer BASE_EMBEDDED {
  public:
   explicit StackTracer(unsigned int low_stack_bound)

src/platform-win32.cc

@@ -1750,7 +1750,6 @@ class Sampler::PlatformData : public Malloced {
         SuspendThread(profiled_thread_);
         context.ContextFlags = CONTEXT_FULL;
         GetThreadContext(profiled_thread_, &context);
-        ResumeThread(profiled_thread_);
         // Invoke tick handler with program counter and stack pointer.
         sample.pc = context.Eip;
         sample.sp = context.Esp;
@@ -1761,6 +1760,10 @@ class Sampler::PlatformData : public Malloced {
       sample.state = Logger::state();
       sampler_->Tick(&sample);
 
+      if (sampler_->IsProfiling()) {
+        ResumeThread(profiled_thread_);
+      }
+
       // Wait until next sampling.
       Sleep(sampler_->interval_);
     }