Adding a high-resolution timer to platform win32.

src/platform-win32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 573 matching lines @@
 
 
 // Returns current time as the number of milliseconds since
 // 00:00:00 UTC, January 1, 1970.
 double OS::TimeCurrentMillis() {
   Time t;
   t.SetToCurrentTime();
   return t.ToJSTime();
 }
 
-// Returns the tickcounter based on timeGetTime.
+
+static LARGE_INTEGER* frequency = NULL;

[caseq, 2012/08/27 09:09:58]

Does this have to be dynamically allocated?

+
+
+// Returns the tickcounter based on QueryPerformanceCounter or timeGetTime.
 int64_t OS::Ticks() {
-  return timeGetTime() * 1000;  // Convert to microseconds.
+  static LARGE_INTEGER tick;
+  if (frequency != NULL && QueryPerformanceCounter(&tick)) {
+    return static_cast<int64_t>(tick.QuadPart * 1000000.0 / frequency->QuadPart);
+  } else {

[caseq, 2012/08/27 09:09:58]

I'd drop the parenthesis and "else".

+    return timeGetTime() * 1000;  // Convert to microseconds.
+  }
 }
 
 
 // Returns a string identifying the current timezone taking into
 // account daylight saving.
 const char* OS::LocalTimezone(double time) {
   return Time(time).LocalTimezone();
 }
 
 
@@ skipping 1473 matching lines @@
 
 
 void OS::SetUp() {
   // Seed the random number generator.
   // Convert the current time to a 64-bit integer first, before converting it
   // to an unsigned. Going directly can cause an overflow and the seed to be
   // set to all ones. The seed will be identical for different instances that
   // call this setup code within the same millisecond.
   uint64_t seed = static_cast<uint64_t>(TimeCurrentMillis());
   srand(static_cast<unsigned int>(seed));
+  // Get the number of ticks per second that is used in OS::Ticks()
+  frequency = new LARGE_INTEGER();
+  if (!QueryPerformanceFrequency(frequency)) {
+    delete frequency;
+    frequency = NULL;
+  }
   limit_mutex = CreateMutex();
   SamplerThread::SetUp();
 }
 
 
 void OS::TearDown() {
+  delete frequency;
+  frequency = NULL;
   SamplerThread::TearDown();
   delete limit_mutex;
 }
 
 
 Sampler::Sampler(Isolate* isolate, int interval)
     : isolate_(isolate),
       interval_(interval),
       profiling_(false),
       active_(false),
@@ skipping 16 matching lines @@
 
 
 void Sampler::Stop() {
   ASSERT(IsActive());
   SamplerThread::RemoveActiveSampler(this);
   SetActive(false);
 }
 
 
 } }  // namespace v8::internal