Add code for CPU feature detection and use it to detect SSE3 and SSE 4.1.

runtime/vm/assembler_x64.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ASSEMBLER_X64_H_
 #define VM_ASSEMBLER_X64_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_x64.h directly; use assembler.h instead.
 #endif
@@ skipping 254 matching lines @@
 
   int position_;
   int unresolved_;
   int unresolved_near_positions_[kMaxUnresolvedBranches];
 
   friend class Assembler;
   DISALLOW_COPY_AND_ASSIGN(Label);
 };
 
 
+class CPUFeatures : public AllStatic {
+ public:
+  static void InitOnce();
+  static bool sse3_supported();
+  static bool sse4_1_supported();
+
+ private:
+  static const uint64_t kSSE3BitMask = static_cast<uint64_t>(1) << 32;
+  static const uint64_t kSSE4_1BitMask = static_cast<uint64_t>(1) << 51;
+
+  static bool sse3_supported_;
+  static bool sse4_1_supported_;
+#ifdef DEBUG
+  static bool initialized_;
+#endif
+};
+
+
 class Assembler : public ValueObject {
  public:
   Assembler() : buffer_(), prolog_offset_(-1), comments_() { }
   ~Assembler() { }
 
   static const bool kNearJump = true;
   static const bool kFarJump = false;
 
   /*
    * Emit Machine Instructions.
@@ skipping 205 matching lines @@
     lock();
     cmpxchgl(address, reg);
   }
 
   void cmpxchgq(const Address& address, Register reg);
   void lock_cmpxchgq(const Address& address, Register reg) {
     lock();
     cmpxchgq(address, reg);
   }
 
+  void cpuid();
+
   // Issue memory to memory move through a TMP register.
   void MoveMemoryToMemory(const Address& dst, const Address& src) {
     movq(TMP, src);
     movq(dst, TMP);
   }
 
   void Exchange(Register reg, const Address& mem) {
     movq(TMP, mem);
     movq(mem, reg);
     movq(reg, TMP);
@@ skipping 197 matching lines @@
 }
 
 
 inline void Assembler::EmitOperandSizeOverride() {
   EmitUint8(0x66);
 }
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_X64_H_