Allow a platform to indicate that some CPU features are always...

src/platform-linux.cc

 // Copyright 2006-2008 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 66 matching lines @@
   // 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());
   srandom(static_cast<unsigned int>(seed));
 }
 
 
+uint64_t OS::CpuFeaturesImpliedByPlatform() {
+#if (defined(__VFP_FP__) && !defined(__SOFTFP__))
+  // Here gcc is telling us that we are on an ARM and gcc is assuming that we
+  // have VFP3 instructions.  If gcc can assume it then so can we.
+  return 1u << VFP3;
+#else
+  return 0;  // Linux runs on anything.
+#endif
+}
+
+
 double OS::nan_value() {
   return NAN;
 }
 
 
-bool OS::ArmCpuHasFeature(OS::CpuFeature feature) {
+#ifdef __arm__
+bool OS::ArmCpuHasFeature(CpuFeature feature) {
   const char* search_string = NULL;
   const char* file_name = "/proc/cpuinfo";
   // Simple detection of VFP at runtime for Linux.
   // It is based on /proc/cpuinfo, which reveals hardware configuration
   // to user-space applications.  According to ARM (mid 2009), no similar
   // facility is universally available on the ARM architectures,
   // so it's up to individual OSes to provide such.
   //
   // This is written as a straight shot one pass parser
   // and not using STL string and ifstream because,
   // on Linux, it's reading from a (non-mmap-able)
   // character special device.
   switch (feature) {
-    case VFP:
+    case VFP3:
       search_string = "vfp";
       break;
     default:
       UNREACHABLE();
   }
 
   FILE* f = NULL;
   const char* what = search_string;
 
   if (NULL == (f = fopen(file_name, "r")))
@@ skipping 12 matching lines @@
       } else {
         what = search_string;
       }
     }
   }
   fclose(f);
 
   // Did not find string in the proc file.
   return false;
 }
+#endif  // def __arm__
 
 
 int OS::ActivationFrameAlignment() {
 #ifdef V8_TARGET_ARCH_ARM
   // On EABI ARM targets this is required for fp correctness in the
   // runtime system.
   return 8;
 #else
   // With gcc 4.4 the tree vectorization optimiser can generate code
   // that requires 16 byte alignment such as movdqa on x86.
@@ skipping 642 matching lines @@
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal