[arm] Clean up use of IsSupported and IsEnabled.

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 62 matching lines @@
   bool serializer_enabled() const { return serializer_enabled_; }
   void enable_serializer() { serializer_enabled_ = true; }
 
   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;
   }
+  // Features are usually enabled by CpuFeatureScope, which also asserts that
+  // the features are supported before they are enabled.
   bool IsEnabled(CpuFeature f) {
     return (enabled_cpu_features_ & (static_cast<uint64_t>(1) << f)) != 0;
   }
+  void EnableCpuFeature(CpuFeature f) {
+    enabled_cpu_features_ |= (static_cast<uint64_t>(1) << f);
+  }
 
   bool is_constant_pool_available() const {
     if (FLAG_enable_embedded_constant_pool) {
       return constant_pool_available_;
     } else {
       // Embedded constant pool not supported on this architecture.
       UNREACHABLE();
       return false;
     }
   }
@@ skipping 81 matching lines @@
   AssemblerBase* assembler_;
   int expected_size_;
   int start_offset_;
   bool old_value_;
 };
 
 
 // Enable a specified feature within a scope.
 class CpuFeatureScope BASE_EMBEDDED {
  public:
+  enum CheckPolicy {
+    kCheckSupported,
+    kDontCheckSupported,
+  };
+
 #ifdef DEBUG
-  CpuFeatureScope(AssemblerBase* assembler, CpuFeature f);
+  CpuFeatureScope(AssemblerBase* assembler, CpuFeature f,
+                  CheckPolicy check = kCheckSupported);
   ~CpuFeatureScope();
 
  private:
   AssemblerBase* assembler_;
   uint64_t old_enabled_;
 #else
-  CpuFeatureScope(AssemblerBase* assembler, CpuFeature f) {}
+  CpuFeatureScope(AssemblerBase* assembler, CpuFeature f,
+                  CheckPolicy check = kCheckSupported) {}
 #endif
 };
 
 
 // CpuFeatures keeps track of which features are supported by the target CPU.
 // Supported features must be enabled by a CpuFeatureScope before use.
 // Example:
 //   if (assembler->IsSupported(SSE3)) {
 //     CpuFeatureScope fscope(assembler, SSE3);
 //     // Generate code containing SSE3 instructions.
@@ skipping 1066 matching lines @@
     std::vector<ConstantPoolEntry> shared_entries;
   };
 
   Label emitted_label_;  // Records pc_offset of emitted pool
   PerTypeEntryInfo info_[ConstantPoolEntry::NUMBER_OF_TYPES];
 };
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_ASSEMBLER_H_