Do not store fp and sp values in TickSample

Their values are not used neither by the tick processor nor by CpuProfiler so it is just a waste of space.

TickSample used to be a transport for grabbed register values to TickSample::Trace, now they are passed in a special structure RegisterState which is allocated on the stack for the sampling period.

Some common pieces were moved from platform-dependent code into Sampler::SampleStack and TickSample::Init.

BUG=None
R=jkummerow@chromium.org, loislo@chromium.org

Review URL: https://codereview.chromium.org/18620002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15484 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/frames.cc

@@ -216,10 +216,11 @@ bool StackTraceFrameIterator::IsValidFrame() {
 
 SafeStackFrameIterator::SafeStackFrameIterator(
     Isolate* isolate,
-    Address fp, Address sp, Address low_bound, Address high_bound) :
-    StackFrameIteratorBase(isolate, false),
-    low_bound_(low_bound), high_bound_(high_bound),
-    top_frame_type_(StackFrame::NONE) {
+    Address fp, Address sp, Address js_entry_sp)
+    : StackFrameIteratorBase(isolate, false),
+      low_bound_(sp),
+      high_bound_(js_entry_sp),
+      top_frame_type_(StackFrame::NONE) {
   StackFrame::State state;
   StackFrame::Type type;
   ThreadLocalTop* top = isolate->thread_local_top();

src/frames.h

@@ -881,7 +881,7 @@ class SafeStackFrameIterator: public StackFrameIteratorBase {
  public:
   SafeStackFrameIterator(Isolate* isolate,
                          Address fp, Address sp,
-                         Address low_bound, Address high_bound);
+                         Address js_entry_sp);
 
   inline JavaScriptFrame* frame() const;
   void Advance();

src/log.cc

@@ -1364,8 +1364,6 @@ void Logger::TickEvent(TickSample* sample, bool overflow) {
   LogMessageBuilder msg(this);
   msg.Append("%s,", kLogEventsNames[TICK_EVENT]);
   msg.AppendAddress(sample->pc);
-  msg.Append(',');
-  msg.AppendAddress(sample->sp);
   msg.Append(",%ld", static_cast<int>(OS::Ticks() - epoch_));
   if (sample->has_external_callback) {
     msg.Append(",1,");

src/sampler.h

@@ -44,22 +44,25 @@ class Isolate;
 // (if used for profiling) the program counter and stack pointer for
 // the thread that created it.
 
+struct RegisterState {
+  RegisterState() : pc(NULL), sp(NULL), fp(NULL) {}
+  Address pc;      // Instruction pointer.
+  Address sp;      // Stack pointer.
+  Address fp;      // Frame pointer.
+};
+
 // TickSample captures the information collected for each sample.
 struct TickSample {
   TickSample()
       : state(OTHER),
         pc(NULL),
-        sp(NULL),
-        fp(NULL),
         external_callback(NULL),
         frames_count(0),
         has_external_callback(false),
         top_frame_type(StackFrame::NONE) {}
-  void Trace(Isolate* isolate);
+  void Init(Isolate* isolate, const RegisterState& state);
   StateTag state;  // The state of the VM.
   Address pc;      // Instruction pointer.
-  Address sp;      // Stack pointer.
-  Address fp;      // Frame pointer.
   union {
     Address tos;   // Top stack value (*sp).
     Address external_callback;
@@ -85,11 +88,7 @@ class Sampler {
   int interval() const { return interval_; }
 
   // Performs stack sampling.
-  void SampleStack(TickSample* sample);
-
-  // This method is called for each sampling period with the current
-  // program counter.
-  virtual void Tick(TickSample* sample) = 0;
+  void SampleStack(const RegisterState& regs);
 
   // Start and stop sampler.
   void Start();
@@ -110,6 +109,11 @@ class Sampler {
   class PlatformData;
   PlatformData* platform_data() const { return data_; }
 
+ protected:
+  // This method is called for each sampling period with the current
+  // program counter.
+  virtual void Tick(TickSample* sample) = 0;
+
  private:
   void SetActive(bool value) { NoBarrier_Store(&active_, value); }
 

test/cctest/test-log-stack-tracer.cc

@@ -52,6 +52,7 @@ using v8::internal::Address;
 using v8::internal::Handle;
 using v8::internal::Isolate;
 using v8::internal::JSFunction;
+using v8::internal::RegisterState;
 using v8::internal::TickSample;
 
 
@@ -66,11 +67,12 @@ static void InitTraceEnv(TickSample* sample) {
 
 
 static void DoTrace(Address fp) {
-  trace_env.sample->fp = fp;
+  RegisterState regs;
+  regs.fp = fp;
   // sp is only used to define stack high bound
-  trace_env.sample->sp =
+  regs.sp =
       reinterpret_cast<Address>(trace_env.sample) - 10240;
-  trace_env.sample->Trace(Isolate::Current());
+  trace_env.sample->Init(Isolate::Current(), regs);
 }
 
 

test/mjsunit/tools/tickprocessor-test-func-info.log

@@ -5,7 +5,7 @@ profiler,"begin",1
 code-creation,Stub,0,0x424260,348,"CompareStub_GE"
 code-creation,LazyCompile,0,0x2a8100,18535,"DrawQube 3d-cube.js:188",0xf43abcac,
 code-creation,LazyCompile,0,0x480100,3908,"DrawLine 3d-cube.js:17",0xf43abc50,
-tick,0x424284,0xbfffeea0,0,0,0x480600,0,0x2aaaa5
-tick,0x42429f,0xbfffed88,0,0,0x480600,0,0x2aacb4
-tick,0x48063d,0xbfffec7c,0,0,0x2d0f7c,0,0x2aaec6
+tick,0x424284,0,0,0x480600,0,0x2aaaa5
+tick,0x42429f,0,0,0x480600,0,0x2aacb4
+tick,0x48063d,0,0,0x2d0f7c,0,0x2aaec6
 profiler,"end"

test/mjsunit/tools/tickprocessor-test.log

@@ -9,17 +9,17 @@ code-creation,LazyCompile,0,0xf541d120,145,"exp native math.js:41"
 function-creation,0xf441d280,0xf541d120
 code-creation,LoadIC,0,0xf541d280,117,"j"
 code-creation,LoadIC,0,0xf541d360,63,"i"
-tick,0x80f82d1,0xffdfe880,0,0,0,0,0xf541ce5c
-tick,0x80f89a1,0xffdfecf0,0,0,0,0,0xf541ce5c
-tick,0x8123b5c,0xffdff1a0,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0x8123b65,0xffdff1a0,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0xf541d2be,0xffdff1e4,0,0,0,0
-tick,0xf541d320,0xffdff1dc,0,0,0,0
-tick,0xf541d384,0xffdff1d8,0,0,0,0
-tick,0xf7db94da,0xffdff0ec,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0xf7db951c,0xffdff0f0,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0xf7dbc508,0xffdff14c,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0xf7dbff21,0xffdff198,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0xf7edec90,0xffdff0ec,0,0,0,0,0xf541d1a1,0xf541ceea
-tick,0xffffe402,0xffdff488,0,0,0,0
+tick,0x80f82d1,0,0,0,0,0xf541ce5c
+tick,0x80f89a1,0,0,0,0,0xf541ce5c
+tick,0x8123b5c,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0x8123b65,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0xf541d2be,0,0,0,0
+tick,0xf541d320,0,0,0,0
+tick,0xf541d384,0,0,0,0
+tick,0xf7db94da,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0xf7db951c,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0xf7dbc508,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0xf7dbff21,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0xf7edec90,0,0,0,0,0xf541d1a1,0xf541ceea
+tick,0xffffe402,0,0,0,0
 profiler,"end"

tools/tickprocessor.js

@@ -169,7 +169,7 @@ function TickProcessor(
       'snapshot-pos': { parsers: [parseInt, parseInt],
           processor: this.processSnapshotPosition },
       'tick': {
-          parsers: [parseInt, parseInt, parseInt, parseInt,
+          parsers: [parseInt, parseInt, parseInt,
                     parseInt, parseInt, 'var-args'],
           processor: this.processTick },
       'heap-sample-begin': { parsers: [null, null, parseInt],
@@ -365,7 +365,6 @@ TickProcessor.prototype.includeTick = function(vmState) {
 };
 
 TickProcessor.prototype.processTick = function(pc,
-                                               sp,
                                                ns_since_start,
                                                is_external_callback,
                                                tos_or_external_callback,