More compact string representation on 64 bit.

runtime/vm/raw_object.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 RUNTIME_VM_RAW_OBJECT_H_
 #define RUNTIME_VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/exceptions.h"
@@ skipping 248 matching lines @@
 class RawObject {
  public:
   // The tags field which is a part of the object header uses the following
   // bit fields for storing tags.
   enum TagBits {
     kMarkBit = 0,
     kCanonicalBit = 1,
     kVMHeapObjectBit = 2,
     kRememberedBit = 3,
     kReservedTagPos = 4,  // kReservedBit{100K,1M,10M}
-#if defined(ARCH_IS_32_BIT)
     kReservedTagSize = 4,
     kSizeTagPos = kReservedTagPos + kReservedTagSize,  // = 8
     kSizeTagSize = 8,
     kClassIdTagPos = kSizeTagPos + kSizeTagSize,  // = 16
     kClassIdTagSize = 16,
-#elif defined(ARCH_IS_64_BIT)
-    kReservedTagSize = 12,
-    kSizeTagPos = kReservedTagPos + kReservedTagSize,  // = 16
-    kSizeTagSize = 16,
-    kClassIdTagPos = kSizeTagPos + kSizeTagSize,  // = 32
-    kClassIdTagSize = 32,
-#else
-#error Unexpected architecture word size
-#endif
   };
 
   COMPILE_ASSERT(kClassIdTagSize == (sizeof(classid_t) * kBitsPerByte));
 
   // Encodes the object size in the tag in units of object alignment.
   class SizeTag {
    public:
     static const intptr_t kMaxSizeTag = ((1 << RawObject::kSizeTagSize) - 1)
                                         << kObjectAlignmentLog2;
 
@@ skipping 313 matching lines @@
   friend class ClassStatsVisitor;
   template <bool>
   friend class MarkingVisitorBase;
   friend class Mint;
   friend class Object;
   friend class OneByteString;  // StoreSmi
   friend class RawCode;
   friend class RawExternalTypedData;
   friend class RawInstructions;
   friend class RawInstance;
+  friend class RawString;
   friend class RawTypedData;
   friend class Scavenger;
   friend class ScavengerVisitor;
   friend class SizeExcludingClassVisitor;  // GetClassId
   friend class InstanceAccumulator;        // GetClassId
   friend class RetainingPathVisitor;       // GetClassId
   friend class SkippedCodeFunctions;       // StorePointer
   friend class ImageReader;                // tags_ check
   friend class ImageWriter;
   friend class AssemblyImageWriter;
@@ skipping 1229 matching lines @@
 };
 COMPILE_ASSERT(sizeof(RawDouble) == 16);
 
 
 class RawString : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(String);
 
  protected:
   RawObject** from() { return reinterpret_cast<RawObject**>(&ptr()->length_); }
   RawSmi* length_;
+#if !defined(HASH_IN_OBJECT_HEADER)
   RawSmi* hash_;
   RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->hash_); }
+#else
+  RawObject** to() { return reinterpret_cast<RawObject**>(&ptr()->length_); }
+#endif
 
+ private:
   friend class Library;
+  friend class OneByteStringSerializationCluster;
+  friend class TwoByteStringSerializationCluster;
+  friend class OneByteStringDeserializationCluster;
+  friend class TwoByteStringDeserializationCluster;
+  friend class RODataSerializationCluster;
 };
 
 
 class RawOneByteString : public RawString {
   RAW_HEAP_OBJECT_IMPLEMENTATION(OneByteString);
 
   // Variable length data follows here.
   uint8_t* data() { OPEN_ARRAY_START(uint8_t, uint8_t); }
   const uint8_t* data() const { OPEN_ARRAY_START(uint8_t, uint8_t); }
 
@@ skipping 566 matching lines @@
 inline intptr_t RawObject::NumberOfTypedDataClasses() {
   // Make sure this is updated when new TypedData types are added.
   COMPILE_ASSERT(kTypedDataInt8ArrayViewCid == kTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
+
 }  // namespace dart
 
 #endif  // RUNTIME_VM_RAW_OBJECT_H_