Clean up some uses of Failures and MaybeObjects.

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 911 matching lines @@
 #ifdef OBJECT_PRINT
 #define DECLARE_PRINTER(Name) void Name##Print(FILE* out = stdout);
 #else
 #define DECLARE_PRINTER(Name)
 #endif
 
 class MaybeObject BASE_EMBEDDED {
  public:
   inline bool IsFailure();
   inline bool IsRetryAfterGC();
-  inline bool IsException();
   inline bool ToObject(Object** obj) {
     if (IsFailure()) return false;
     *obj = reinterpret_cast<Object*>(this);
     return true;
   }
   inline Object* ToObjectUnchecked() {
     // TODO(jkummerow): Turn this back into an ASSERT when we can be certain
     // that it never fires in Release mode in the wild.
     CHECK(!IsFailure());
     return reinterpret_cast<Object*>(this);
@@ skipping 715 matching lines @@
 
   static const int kMinValue =
       (static_cast<unsigned int>(-1)) << (kSmiValueSize - 1);
   static const int kMaxValue = -(kMinValue + 1);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(Smi);
 };
 
 
-// Failure is used for reporting out of memory situations and
-// propagating exceptions through the runtime system.  Failure objects
-// are transient and cannot occur as part of the object graph.
+// Failure is mainly used for reporting a situation requiring a GC.
+// Failure objects are transient and cannot occur as part of the object graph.
 //
 // Failures are a single word, encoded as follows:
 // +-------------------------+---+--+--+
 // |.........unused..........|sss|tt|11|
 // +-------------------------+---+--+--+
 //                          7 6 4 32 10
 //
 //
 // The low two bits, 0-1, are the failure tag, 11.  The next two bits,
 // 2-3, are a failure type tag 'tt' with possible values:
 //   00 RETRY_AFTER_GC
-//   01 EXCEPTION
-//   10 INTERNAL_ERROR
-//   11 OUT_OF_MEMORY_EXCEPTION
+//   01 NOT_FOUND

[Michael Starzinger, 2014/04/23 14:34:52]

nit: This NOT_FOUND constant doesn't seem to exist, can we drop it from the
comment?

[Yang, 2014/04/23 15:07:55]

This was there in the first patch set. Forgot to remove. Done.

 //
 // The next three bits, 4-6, are an allocation space tag 'sss'.  The
 // allocation space tag is 000 for all failure types except
 // RETRY_AFTER_GC.  For RETRY_AFTER_GC, the possible values are the
 // allocation spaces (the encoding is found in globals.h).
 
 // Failure type tag info.
 const int kFailureTypeTagSize = 2;
 const int kFailureTypeTagMask = (1 << kFailureTypeTagSize) - 1;
 
 class Failure: public MaybeObject {
  public:
-  // RuntimeStubs assumes EXCEPTION = 1 in the compiler-generated code.
   enum Type {
-    RETRY_AFTER_GC = 0,
-    EXCEPTION = 1,       // Returning this marker tells the real exception
-                         // is in Isolate::pending_exception.
-    INTERNAL_ERROR = 2,
-    OUT_OF_MEMORY_EXCEPTION = 3
+    RETRY_AFTER_GC = 0
   };
 
   inline Type type() const;
 
   // Returns the space that needs to be collected for RetryAfterGC failures.
   inline AllocationSpace allocation_space() const;
 
   static inline Failure* RetryAfterGC(AllocationSpace space);
   static inline Failure* RetryAfterGC();  // NEW_SPACE
-  static inline Failure* Exception();
-  static inline Failure* InternalError();
   // Casting.
   static inline Failure* cast(MaybeObject* object);
 
   // Dispatched behavior.
   void FailurePrint(FILE* out = stdout);
   void FailurePrint(StringStream* accumulator);
 
   DECLARE_VERIFIER(Failure)
 
  private:
@@ skipping 9554 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_