Cleaned up CpuFeature scope handling.

src/assembler.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 50 matching lines @@
 
   Isolate* isolate() const { return isolate_; }
   int jit_cookie() const { return jit_cookie_; }
 
   bool emit_debug_code() const { return emit_debug_code_; }
   void set_emit_debug_code(bool value) { emit_debug_code_ = value; }
 
   bool predictable_code_size() const { return predictable_code_size_; }
   void set_predictable_code_size(bool value) { predictable_code_size_ = value; }
 
+  uint64_t enabled_cpu_features() const { return enabled_cpu_features_; }
+  void set_enabled_cpu_features(uint64_t features) {
+    enabled_cpu_features_ = features;
+  }
+  bool IsEnabled(CpuFeature f) {
+    return (enabled_cpu_features_ & (static_cast<uint64_t>(1) << f)) != 0;
+  }
+
   // Overwrite a host NaN with a quiet target NaN.  Used by mksnapshot for
   // cross-snapshotting.
   static void QuietNaN(HeapObject* nan) { }
 
   int pc_offset() const { return static_cast<int>(pc_ - buffer_); }
 
   static const int kMinimalBufferSize = 4*KB;
 
  protected:
   // The buffer into which code and relocation info are generated. It could
   // either be owned by the assembler or be provided externally.
   byte* buffer_;
   int buffer_size_;
   bool own_buffer_;
 
   // The program counter, which points into the buffer above and moves forward.
   byte* pc_;
 
  private:
   Isolate* isolate_;
   int jit_cookie_;
+  uint64_t enabled_cpu_features_;
   bool emit_debug_code_;
   bool predictable_code_size_;
 };
 
 
 // Avoids using instructions that vary in size in unpredictable ways between the
 // snapshot and the running VM.
 class PredictableCodeSizeScope {
  public:
   PredictableCodeSizeScope(AssemblerBase* assembler, int expected_size);
   ~PredictableCodeSizeScope();
 
  private:
   AssemblerBase* assembler_;
   int expected_size_;
   int start_offset_;
   bool old_value_;
 };
 
 
+// Enable a specified feature within a scope.
+class CpuFeatureScope BASE_EMBEDDED {
+ public:
+#ifdef DEBUG
+  CpuFeatureScope(AssemblerBase* assembler, CpuFeature f);
+  ~CpuFeatureScope();
+
+ private:
+  AssemblerBase* assembler_;
+  uint64_t old_enabled_;
+#else
+  CpuFeatureScope(AssemblerBase* assembler, CpuFeature f) {}
+#endif
+};
+
+
 // -----------------------------------------------------------------------------
 // Labels represent pc locations; they are typically jump or call targets.
 // After declaration, a label can be freely used to denote known or (yet)
 // unknown pc location. Assembler::bind() is used to bind a label to the
 // current pc. A label can be bound only once.
 
 class Label BASE_EMBEDDED {
  public:
   enum Distance {
     kNear, kFar
@@ skipping 869 matching lines @@
  public:
   NullCallWrapper() { }
   virtual ~NullCallWrapper() { }
   virtual void BeforeCall(int call_size) const { }
   virtual void AfterCall() const { }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_