[base] Implement CPU time on Windows.

src/base/cpu.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/base/cpu.h"
 
 #if V8_LIBC_MSVCRT
 #include <intrin.h>  // __cpuid()
 #endif
 #if V8_OS_LINUX
@@ skipping 320 matching lines @@
       has_bmi1_(false),
       has_bmi2_(false),
       has_lzcnt_(false),
       has_popcnt_(false),
       has_idiva_(false),
       has_neon_(false),
       has_thumb2_(false),
       has_vfp_(false),
       has_vfp3_(false),
       has_vfp3_d32_(false),
-      is_fp64_mode_(false) {
+      is_fp64_mode_(false),
+      has_non_stop_time_stamp_counter_(false) {
   memcpy(vendor_, "Unknown", 8);
 #if V8_OS_NACL
 // Portable host shouldn't do feature detection.
 // TODO(jfb): Remove the hardcoded ARM simulator flags in the build, and
 // hardcode them here instead.
 #elif V8_HOST_ARCH_IA32 || V8_HOST_ARCH_X64
   int cpu_info[4];
 
   // __cpuid with an InfoType argument of 0 returns the number of
   // valid Ids in CPUInfo[0] and the CPU identification string in
@@ skipping 59 matching lines @@
   __cpuid(cpu_info, 0x80000000);
   unsigned num_ext_ids = cpu_info[0];
 
   // Interpret extended CPU feature information.
   if (num_ext_ids > 0x80000000) {
     __cpuid(cpu_info, 0x80000001);
     has_lzcnt_ = (cpu_info[2] & 0x00000020) != 0;
     // SAHF must be probed in long mode.
     has_sahf_ = (cpu_info[2] & 0x00000001) != 0;
   }
 

[fmeawad, 2016/05/25 23:40:31]

nit: Add a small comment to explain what happens here.

[lpy, 2016/05/26 16:25:22]

Done.

+  const int parameter_containing_non_stop_time_stamp_counter = 0x80000007;
+  if (num_ext_ids >= parameter_containing_non_stop_time_stamp_counter) {
+    __cpuid(cpu_info, parameter_containing_non_stop_time_stamp_counter);
+    has_non_stop_time_stamp_counter_ = (cpu_info[3] & (1 << 8)) != 0;
+  }
+
 #elif V8_HOST_ARCH_ARM
 
 #if V8_OS_LINUX
 
   CPUInfo cpu_info;
 
   // Extract implementor from the "CPU implementer" field.
   char* implementer = cpu_info.ExtractField("CPU implementer");
   if (implementer != NULL) {
     char* end;
@@ skipping 268 matching lines @@
       part_ = PPC_POWER5;
       break;
   }
 #endif  // V8_OS_AIX
 #endif  // !USE_SIMULATOR
 #endif  // V8_HOST_ARCH_PPC
 }
 
 }  // namespace base
 }  // namespace v8