Cleaned up CpuFeature scope handling.

src/ia32/assembler-ia32.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 487 matching lines @@
 
   class TypeField: public BitField<Type, 0, 2> {};
   class NextField: public BitField<int,  2, 32-2> {};
 
   void init(Label* L, Type type);
 };
 
 
 
 // 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.
 // Example:
-//   if (CpuFeatures::IsSupported(SSE2)) {
-//     CpuFeatures::Scope fscope(SSE2);
+//   if (assembler->IsSupported(SSE2)) {
+//     CpuFeatureScope fscope(assembler, SSE2);
 //     // Generate SSE2 floating point code.
 //   } else {
 //     // Generate standard x87 floating point code.
 //   }
 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 == SSE2 && !FLAG_enable_sse2) return false;
     if (f == SSE3 && !FLAG_enable_sse3) return false;
     if (f == SSE4_1 && !FLAG_enable_sse4_1) return false;
     if (f == CMOV && !FLAG_enable_cmov) return false;
     if (f == RDTSC && !FLAG_enable_rdtsc) return false;
     return (supported_ & (static_cast<uint64_t>(1) << 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);
-    }
-    uint64_t enabled = isolate->enabled_cpu_features();
-    return (enabled & (static_cast<uint64_t>(1) << 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) {
-      uint64_t mask = static_cast<uint64_t>(1) << f;
-      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_ = 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_;
-    uint64_t 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_ |= (static_cast<uint64_t>(1) << f);
       }
     }
 
@@ skipping 12 matching lines @@
     }
 
     const uint64_t old_supported_;
   };
 
  private:
 #ifdef DEBUG
   static bool initialized_;
 #endif
   static uint64_t supported_;
-  static uint64_t found_by_runtime_probing_;
+  static uint64_t found_by_runtime_probing_only_;
 
   friend class ExternalReference;
   DISALLOW_COPY_AND_ASSIGN(CpuFeatures);
 };
 
 
 class Assembler : public AssemblerBase {
  private:
   // We check before assembling an instruction that there is sufficient
   // space to write an instruction and its relocation information.
@@ skipping 648 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_ASSEMBLER_IA32_H_