Support weak heap references in the ConstantPool to support IsWeakObjectInOptimizedCode objects.

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 287 matching lines @@
     LAST_REAL_RELOC_MODE = VENEER_POOL,
     FIRST_PSEUDO_RELOC_MODE = CODE_AGE_SEQUENCE,
     LAST_PSEUDO_RELOC_MODE = CODE_AGE_SEQUENCE,
     LAST_CODE_ENUM = DEBUG_BREAK,
     LAST_GCED_ENUM = CELL,
     // Modes <= LAST_COMPACT_ENUM are guaranteed to have compact encoding.
     LAST_COMPACT_ENUM = CODE_TARGET_WITH_ID,
     LAST_STANDARD_NONCOMPACT_ENUM = INTERNAL_REFERENCE
   };
 
+  enum WeakMode {
+    NOT_WEAK,
+    WEAK_IN_OPTIMIZED_CODE
+  };
 
   RelocInfo() {}
 
   RelocInfo(byte* pc, Mode rmode, intptr_t data, Code* host)
       : pc_(pc), rmode_(rmode), data_(data), host_(host) {
   }
+
+  RelocInfo(byte* pc, Mode rmode, WeakMode weak_mode, intptr_t data)
+      : pc_(pc), rmode_(rmode), data_(data), weak_mode_(weak_mode) {
+  }
+
   RelocInfo(byte* pc, double data64)
       : pc_(pc), rmode_(NONE64), data64_(data64), host_(NULL) {
   }
 
   static inline bool IsRealRelocMode(Mode mode) {
     return mode >= FIRST_REAL_RELOC_MODE &&
         mode <= LAST_REAL_RELOC_MODE;
   }
   static inline bool IsPseudoRelocMode(Mode mode) {
     ASSERT(!IsRealRelocMode(mode));
@@ skipping 64 matching lines @@
   byte* pc() const { return pc_; }
   void set_pc(byte* pc) { pc_ = pc; }
   Mode rmode() const {  return rmode_; }
   intptr_t data() const { return data_; }
   double data64() const { return data64_; }
   uint64_t raw_data64() {
     return BitCast<uint64_t>(data64_);
   }
   Code* host() const { return host_; }
   void set_host(Code* host) { host_ = host; }
+  WeakMode weak_mode() const { return weak_mode_; }
 
   // Apply a relocation by delta bytes
   INLINE(void apply(intptr_t delta));
 
   // Is the pointer this relocation info refers to coded like a plain pointer
   // or is it strange in some way (e.g. relative or patched into a series of
   // instructions).
   bool IsCodedSpecially();
 
   // If true, the pointer this relocation info refers to is an entry in the
@@ skipping 104 matching lines @@
   // On ARM, note that pc_ is the address of the constant pool entry
   // to be relocated and not the address of the instruction
   // referencing the constant pool entry (except when rmode_ ==
   // comment).
   byte* pc_;
   Mode rmode_;
   union {
     intptr_t data_;
     double data64_;
   };
-  Code* host_;
+  union {
+    Code* host_;
+    WeakMode weak_mode_;
+  };
   // External-reference pointers are also split across instruction-pairs
   // on some platforms, but are accessed via indirect pointers. This location
   // provides a place for that pointer to exist naturally. Its address
   // is returned by RelocInfo::target_reference_address().
   Address reconstructed_adr_ptr_;
   friend class RelocIterator;
 };
 
 
 // RelocInfoWriter serializes a stream of relocation info. It writes towards
@@ skipping 544 matching lines @@
 
  private:
   int32_t multiplier_;
   int32_t shift_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_