Age code to allow reclaiming old unexecuted functions

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 193 matching lines @@
     INTERNAL_REFERENCE,  // An address inside the same function.
 
     // Marks a constant pool. Only used on ARM.
     // It uses a custom noncompact encoding.
     CONST_POOL,
 
     // add more as needed
     // Pseudo-types
     NUMBER_OF_MODES,  // There are at most 15 modes with noncompact encoding.
     NONE,  // never recorded
+    CODE_AGE_SEQUENCE,  // Not stored in RelocInfo array, used explictly by
+                        // code aging.
+    FIRST_REAL_RELOC_MODE = CODE_TARGET,
+    LAST_REAL_RELOC_MODE = CONST_POOL,
+    FIRST_PSEUDO_RELOC_MODE = CODE_AGE_SEQUENCE,
+    LAST_PSEUDO_RELOC_MODE = CODE_AGE_SEQUENCE,
     LAST_CODE_ENUM = DEBUG_BREAK,
     LAST_GCED_ENUM = GLOBAL_PROPERTY_CELL,
     // Modes <= LAST_COMPACT_ENUM are guaranteed to have compact encoding.
     LAST_COMPACT_ENUM = CODE_TARGET_WITH_ID,
     LAST_STANDARD_NONCOMPACT_ENUM = INTERNAL_REFERENCE
   };
 
 
   RelocInfo() {}
 
   RelocInfo(byte* pc, Mode rmode, intptr_t data, Code* host)
       : pc_(pc), rmode_(rmode), data_(data), host_(host) {
   }
 
+  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));
+    return mode >= FIRST_PSEUDO_RELOC_MODE &&
+        mode <= LAST_PSEUDO_RELOC_MODE;
+  }
   static inline bool IsConstructCall(Mode mode) {
     return mode == CONSTRUCT_CALL;
   }
   static inline bool IsCodeTarget(Mode mode) {
     return mode <= LAST_CODE_ENUM;
   }
   static inline bool IsEmbeddedObject(Mode mode) {
     return mode == EMBEDDED_OBJECT;
   }
   // Is the relocation mode affected by GC?
@@ skipping 17 matching lines @@
   }
   static inline bool IsExternalReference(Mode mode) {
     return mode == EXTERNAL_REFERENCE;
   }
   static inline bool IsInternalReference(Mode mode) {
     return mode == INTERNAL_REFERENCE;
   }
   static inline bool IsDebugBreakSlot(Mode mode) {
     return mode == DEBUG_BREAK_SLOT;
   }
+  static inline bool IsCodeAgeSequence(Mode mode) {
+    return mode == CODE_AGE_SEQUENCE;
+  }
   static inline int ModeMask(Mode mode) { return 1 << mode; }
 
   // Accessors
   byte* pc() const { return pc_; }
   void set_pc(byte* pc) { pc_ = pc; }
   Mode rmode() const {  return rmode_; }
   intptr_t data() const { return data_; }
   Code* host() const { return host_; }
 
   // Apply a relocation by delta bytes
@@ skipping 12 matching lines @@
                                  WriteBarrierMode mode = UPDATE_WRITE_BARRIER));
   INLINE(Object* target_object());
   INLINE(Handle<Object> target_object_handle(Assembler* origin));
   INLINE(Object** target_object_address());
   INLINE(void set_target_object(Object* target,
                                 WriteBarrierMode mode = UPDATE_WRITE_BARRIER));
   INLINE(JSGlobalPropertyCell* target_cell());
   INLINE(Handle<JSGlobalPropertyCell> target_cell_handle());
   INLINE(void set_target_cell(JSGlobalPropertyCell* cell,
                               WriteBarrierMode mode = UPDATE_WRITE_BARRIER));
-
+  INLINE(Code* code_age_stub());
+  INLINE(void set_code_age_stub(Code* stub));
 
   // Read the address of the word containing the target_address in an
   // instruction stream.  What this means exactly is architecture-independent.
   // The only architecture-independent user of this function is the serializer.
   // The serializer uses it to find out how many raw bytes of instruction to
   // output before the next target.  Architecture-independent code shouldn't
   // dereference the pointer it gets back from this.
   INLINE(Address target_address_address());
   // This indicates how much space a target takes up when deserializing a code
   // stream.  For most architectures this is just the size of a pointer.  For
@@ skipping 175 matching lines @@
   void ReadTaggedPosition();
 
   // If the given mode is wanted, set it in rinfo_ and return true.
   // Else return false. Used for efficiently skipping unwanted modes.
   bool SetMode(RelocInfo::Mode mode) {
     return (mode_mask_ & (1 << mode)) ? (rinfo_.rmode_ = mode, true) : false;
   }
 
   byte* pos_;
   byte* end_;
+  byte* code_age_sequence_;
   RelocInfo rinfo_;
   bool done_;
   int mode_mask_;
   int last_id_;
   int last_position_;
   DISALLOW_COPY_AND_ASSIGN(RelocIterator);
 };
 
 
 //------------------------------------------------------------------------------
@@ skipping 88 matching lines @@
   static ExternalReference perform_gc_function(Isolate* isolate);
   static ExternalReference fill_heap_number_with_random_function(
       Isolate* isolate);
   static ExternalReference random_uint32_function(Isolate* isolate);
   static ExternalReference transcendental_cache_array_address(Isolate* isolate);
   static ExternalReference delete_handle_scope_extensions(Isolate* isolate);
 
   static ExternalReference get_date_field_function(Isolate* isolate);
   static ExternalReference date_cache_stamp(Isolate* isolate);
 
+  static ExternalReference get_make_code_young_function(Isolate* isolate);
+
   // Deoptimization support.
   static ExternalReference new_deoptimizer_function(Isolate* isolate);
   static ExternalReference compute_output_frames_function(Isolate* isolate);
 
   // Static data in the keyed lookup cache.
   static ExternalReference keyed_lookup_cache_keys(Isolate* isolate);
   static ExternalReference keyed_lookup_cache_field_offsets(Isolate* isolate);
 
   // Static variable Heap::roots_array_start()
   static ExternalReference roots_array_start(Isolate* isolate);
@@ skipping 279 matching lines @@
  public:
   NullCallWrapper() { }
   virtual ~NullCallWrapper() { }
   virtual void BeforeCall(int call_size) const { }
   virtual void AfterCall() const { }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_ASSEMBLER_H_