- Removed the kWatchedBit and the associated weak property handling

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 VM_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/atomic.h"
 #include "vm/globals.h"
@@ skipping 238 matching lines @@
     HEAP_PROFILER_SUPPORT()                                                    \
 
 // RawObject is the base class of all raw objects, even though it carries the
 // class_ field not all raw objects are allocated in the heap and thus cannot
 // be dereferenced (e.g. RawSmi).
 class RawObject {
  public:
   // The tags field which is a part of the object header uses the following
   // bit fields for storing tags.
   enum TagBits {
-    kWatchedBit = 0,
-    kMarkBit = 1,
-    kCanonicalBit = 2,
-    kVMHeapObjectBit = 3,
-    kRememberedBit = 4,
+    kMarkBit = 0,
+    kCanonicalBit = 1,
+    kVMHeapObjectBit = 2,
+    kRememberedBit = 3,
+    kReservedTagPos = 4,  // kReservedBit{100K,1M,10M}
 #if defined(ARCH_IS_32_BIT)
-    kReservedTagPos = 5,  // kReservedBit{100K,1M,10M}
     kReservedTagSize = 3,

[rmacnak, 2016/05/24 20:58:42]

= 4

     kSizeTagPos = kReservedTagPos + kReservedTagSize,  // = 8
     kSizeTagSize = 8,
     kClassIdTagPos = kSizeTagPos + kSizeTagSize,  // = 16
     kClassIdTagSize = 16,
 #elif defined(ARCH_IS_64_BIT)
-    kReservedTagPos = 5,  // kReservedBit{100K,1M,10M}
-    kReservedTagSize = 11,
+    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));
@@ skipping 83 matching lines @@
   void ClearMarkBit() {
     ASSERT(IsMarked());
     UpdateTagBit<MarkBit>(false);
   }
   // Returns false if the bit was already set.
   // TODO(koda): Add "must use result" annotation here, after we add support.
   bool TryAcquireMarkBit() {
     return TryAcquireTagBit<MarkBit>();
   }
 
-  // Support for GC watched bit.
-  // TODO(iposva): Get rid of this.
-  bool IsWatched() const {
-    return WatchedBit::decode(ptr()->tags_);
-  }
-  void SetWatchedBitUnsynchronized() {
-    ASSERT(!IsWatched());
-    uword tags = ptr()->tags_;
-    ptr()->tags_ = WatchedBit::update(true, tags);
-  }
-  void ClearWatchedBitUnsynchronized() {
-    uword tags = ptr()->tags_;
-    ptr()->tags_ = WatchedBit::update(false, tags);
-  }
-
   // Support for object tags.
   bool IsCanonical() const {
     return CanonicalObjectTag::decode(ptr()->tags_);
   }
   void SetCanonical() {
     UpdateTagBit<CanonicalObjectTag>(true);
   }
   void ClearCanonical() {
     UpdateTagBit<CanonicalObjectTag>(false);
   }
@@ skipping 112 matching lines @@
   static bool IsExternalTypedDataClassId(intptr_t index);
   static bool IsInternalVMdefinedClassId(intptr_t index);
   static bool IsVariableSizeClassId(intptr_t index);
   static bool IsImplicitFieldClassId(intptr_t index);
 
   static intptr_t NumberOfTypedDataClasses();
 
  private:
   uword tags_;  // Various object tags (bits).
 
-  class WatchedBit : public BitField<uword, bool, kWatchedBit, 1> {};
-
   class MarkBit : public BitField<uword, bool, kMarkBit, 1> {};
 
   class RememberedBit : public BitField<uword, bool, kRememberedBit, 1> {};
 
   class CanonicalObjectTag : public BitField<uword, bool, kCanonicalBit, 1> {};
 
   class VMHeapObjectTag : public BitField<uword, bool, kVMHeapObjectBit, 1> {};
 
   class ReservedBits : public
       BitField<uword, intptr_t, kReservedTagPos, kReservedTagSize> {};
@@ skipping 1640 matching lines @@
 
   RawObject** from() {
     return reinterpret_cast<RawObject**>(&ptr()->key_);
   }
   RawObject* key_;
   RawObject* value_;
   RawObject** to() {
     return reinterpret_cast<RawObject**>(&ptr()->value_);
   }
 
-  friend class DelaySet;
+  // Linked list is chaining all pending weak properties.
+  // Untyped to make it clear that it is not to be visited by GC.
+  uword next_;
+
   friend class GCMarker;
   template<bool> friend class MarkingVisitorBase;
   friend class Scavenger;
   friend class ScavengerVisitor;
 };
 
 // MirrorReferences are used by mirrors to hold reflectees that are VM
 // internal objects, such as libraries, classes, functions or types.
 class RawMirrorReference : public RawInstance {
   RAW_HEAP_OBJECT_IMPLEMENTATION(MirrorReference);
@@ skipping 243 matching lines @@
   COMPILE_ASSERT(kExternalTypedDataInt8ArrayCid ==
                  kTypedDataInt8ArrayViewCid + 15);
   COMPILE_ASSERT(kByteBufferCid == kExternalTypedDataInt8ArrayCid + 14);
   COMPILE_ASSERT(kNullCid == kByteBufferCid + 1);
   return (kNullCid - kTypedDataInt8ArrayCid);
 }
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_