Cleaned up CpuFeature scope handling.

src/arm/assembler-arm.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 30 matching lines @@
 #define V8_ARM_ASSEMBLER_ARM_H_
 #include <stdio.h>
 #include "assembler.h"
 #include "constants-arm.h"
 #include "serialize.h"
 
 namespace v8 {
 namespace internal {
 
 // CpuFeatures keeps track of which features are supported by the target CPU.
-// Supported features must be enabled by a Scope before use.
+// Supported features must be enabled by a CpuFeatureScope before use.
 class CpuFeatures : public AllStatic {
  public:
   // Detect features of the target CPU. Set safe defaults if the serializer
   // is enabled (snapshots must be portable).
   static void Probe();
 
   // Check whether a feature is supported by the target CPU.
   static bool IsSupported(CpuFeature f) {
     ASSERT(initialized_);
     if (f == VFP3 && !FLAG_enable_vfp3) return false;
     if (f == VFP2 && !FLAG_enable_vfp2) return false;
     if (f == SUDIV && !FLAG_enable_sudiv) return false;
     if (f == UNALIGNED_ACCESSES && !FLAG_enable_unaligned_accesses) {
       return false;
     }
     if (f == VFP32DREGS && !FLAG_enable_32dregs) return false;
     return (supported_ & (1u << f)) != 0;
   }
 
-#ifdef DEBUG
-  // Check whether a feature is currently enabled.
-  static bool IsEnabled(CpuFeature f) {
+  static bool IsFoundByRuntimeProbingOnly(CpuFeature f) {
     ASSERT(initialized_);
-    Isolate* isolate = Isolate::UncheckedCurrent();
-    if (isolate == NULL) {
-      // When no isolate is available, work as if we're running in
-      // release mode.
-      return IsSupported(f);
-    }
-    unsigned enabled = static_cast<unsigned>(isolate->enabled_cpu_features());
-    return (enabled & (1u << f)) != 0;
+    return (found_by_runtime_probing_only_ &
+            (static_cast<uint64_t>(1) << f)) != 0;
   }
-#endif
-
-  // Enable a specified feature within a scope.
-  class Scope BASE_EMBEDDED {
-#ifdef DEBUG
-
-   public:
-    explicit Scope(CpuFeature f) {
-      unsigned mask = 1u << f;
-      // VFP2 and ARMv7 are implied by VFP3.
-      if (f == VFP3) mask |= 1u << VFP2 | 1u << ARMv7;
-      ASSERT(CpuFeatures::IsSupported(f));
-      ASSERT(!Serializer::enabled() ||
-             (CpuFeatures::found_by_runtime_probing_ & mask) == 0);
-      isolate_ = Isolate::UncheckedCurrent();
-      old_enabled_ = 0;
-      if (isolate_ != NULL) {
-        old_enabled_ = static_cast<unsigned>(isolate_->enabled_cpu_features());
-        isolate_->set_enabled_cpu_features(old_enabled_ | mask);
-      }
-    }
-    ~Scope() {
-      ASSERT_EQ(Isolate::UncheckedCurrent(), isolate_);
-      if (isolate_ != NULL) {
-        isolate_->set_enabled_cpu_features(old_enabled_);
-      }
-    }
-
-   private:
-    Isolate* isolate_;
-    unsigned old_enabled_;
-#else
-
-   public:
-    explicit Scope(CpuFeature f) {}
-#endif
-  };
 
   class TryForceFeatureScope BASE_EMBEDDED {
    public:
     explicit TryForceFeatureScope(CpuFeature f)
         : old_supported_(CpuFeatures::supported_) {
       if (CanForce()) {
         CpuFeatures::supported_ |= (1u << f);
       }
     }
 
@@ skipping 12 matching lines @@
     }
 
     const unsigned old_supported_;
   };
 
  private:
 #ifdef DEBUG
   static bool initialized_;
 #endif
   static unsigned supported_;
-  static unsigned found_by_runtime_probing_;
+  static unsigned found_by_runtime_probing_only_;
 
   friend class ExternalReference;
   DISALLOW_COPY_AND_ASSIGN(CpuFeatures);
 };
 
 
 // CPU Registers.
 //
 // 1) We would prefer to use an enum, but enum values are assignment-
 // compatible with int, which has caused code-generation bugs.
@@ skipping 1345 matching lines @@
  public:
   explicit EnsureSpace(Assembler* assembler) {
     assembler->CheckBuffer();
   }
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_ASSEMBLER_ARM_H_