Don't duplicate OS::CpuFeaturesImpliedByPlatform for every POSIX platform.

src/platform-posix.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 60 matching lines @@
 #include "codegen.h"
 #include "platform.h"
 
 namespace v8 {
 namespace internal {
 
 // 0 is never a valid thread id.
 static const pthread_t kNoThread = (pthread_t) 0;
 
 
+uint64_t OS::CpuFeaturesImpliedByPlatform() {
+#if defined(__APPLE__)
+  // Mac OS X requires all these to install so we can assume they are present.
+  // These constants are defined by the CPUid instructions.
+  const uint64_t one = 1;
+  return (one << SSE2) | (one << CMOV) | (one << RDTSC) | (one << CPUID);
+#else
+  return 0;  // Nothing special about the other systems.
+#endif
+}
+
+
 // Maximum size of the virtual memory.  0 means there is no artificial
 // limit.
 
 intptr_t OS::MaxVirtualMemory() {
   struct rlimit limit;
   int result = getrlimit(RLIMIT_DATA, &limit);
   if (result != 0) return 0;
   return limit.rlim_cur;
 }
 
@@ skipping 869 matching lines @@
   return ntohl(value);
 }
 
 
 Socket* OS::CreateSocket() {
   return new POSIXSocket();
 }
 
 
 } }  // namespace v8::internal