Make maps in monomorphic IC stubs weak.

src/objects.h

 // Copyright 2012 the V8 project authors. 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.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5296 matching lines @@
   inline bool is_load_stub() { return kind() == LOAD_IC; }
   inline bool is_keyed_load_stub() { return kind() == KEYED_LOAD_IC; }
   inline bool is_store_stub() { return kind() == STORE_IC; }
   inline bool is_keyed_store_stub() { return kind() == KEYED_STORE_IC; }
   inline bool is_binary_op_stub() { return kind() == BINARY_OP_IC; }
   inline bool is_compare_ic_stub() { return kind() == COMPARE_IC; }
   inline bool is_compare_nil_ic_stub() { return kind() == COMPARE_NIL_IC; }
   inline bool is_to_boolean_ic_stub() { return kind() == TO_BOOLEAN_IC; }
   inline bool is_keyed_stub();
   inline bool is_optimized_code() { return kind() == OPTIMIZED_FUNCTION; }
+  inline bool is_weak_stub() {
+    Kind k = kind();
+    return (k == LOAD_IC || k == STORE_IC || k == KEYED_LOAD_IC ||
+            k == KEYED_STORE_IC || k == COMPARE_NIL_IC) &&
+           ic_state() == MONOMORPHIC;
+  }
 
   inline void set_raw_kind_specific_flags1(int value);
   inline void set_raw_kind_specific_flags2(int value);
 
   // [major_key]: For kind STUB or BINARY_OP_IC, the major key.
   inline int major_key();
   inline void set_major_key(int value);
   inline bool has_major_key();
 
   // For kind STUB or ICs, tells whether or not a code object was generated by
@@ skipping 237 matching lines @@
     return GetCodeAgeStub(isolate, kNotExecutedCodeAge, NO_MARKING_PARITY);
   }
 
   void PrintDeoptLocation(FILE* out, int bailout_id);
   bool CanDeoptAt(Address pc);
 
 #ifdef VERIFY_HEAP
   void VerifyEmbeddedObjectsDependency();
 #endif
 
+  inline bool CanContainWeakObjects() {
+    return is_optimized_code() || is_weak_stub();
+  }
+
   inline bool IsWeakObject(Object* object) {
-    return is_optimized_code() && IsWeakObjectInOptimizedCode(object);
+    return (is_optimized_code() && IsWeakObjectInOptimizedCode(object)) ||
+           (is_weak_stub() && IsWeakObjectInIC(object));
   }
 
   inline bool IsWeakObjectInOptimizedCode(Object* object);
+  inline bool IsWeakObjectInIC(Object* object);
 
   // Max loop nesting marker used to postpose OSR. We don't take loop
   // nesting that is deeper than 5 levels into account.
   static const int kMaxLoopNestingMarker = 6;
 
   // Layout description.
   static const int kInstructionSizeOffset = HeapObject::kHeaderSize;
   static const int kRelocationInfoOffset = kInstructionSizeOffset + kIntSize;
   static const int kHandlerTableOffset = kRelocationInfoOffset + kPointerSize;
   static const int kDeoptimizationDataOffset =
@@ skipping 5238 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_