Fix issue 5275: The VM must always generate the most compact form of an integer (Smi, Mint or Bigin…

runtime/vm/object.h

Index: runtime/vm/object.h
===================================================================
--- runtime/vm/object.h	(revision 22802)
+++ runtime/vm/object.h	(working copy)
@@ -3931,12 +3931,14 @@
 
   // Return the most compact presentation of an integer.
   RawInteger* AsValidInteger() const;
-  // Return an integer in the form of a RawBigint.
-  RawBigint* AsBigint() const;
 
   RawInteger* ArithmeticOp(Token::Kind operation, const Integer& other) const;
   RawInteger* BitOp(Token::Kind operation, const Integer& other) const;
 
+ private:
+  // Return an integer in the form of a RawBigint.
+  RawBigint* AsBigint() const;
+
   OBJECT_IMPLEMENTATION(Integer, Number);
   friend class Class;
 };
@@ -4046,13 +4048,18 @@
 
   virtual int CompareWith(const Integer& other) const;
 
-  static RawMint* New(int64_t value, Heap::Space space = Heap::kNew);
-  static RawMint* NewCanonical(int64_t value);
-
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawMint));
   }
 
+ protected:
+  // Only Integer::NewXXX is allowed to call Mint::NewXXX directly.
+  friend class Integer;
+
+  static RawMint* New(int64_t value, Heap::Space space = Heap::kNew);
+
+  static RawMint* NewCanonical(int64_t value);
+
  private:
   void set_value(int64_t value) const;
 
@@ -4088,13 +4095,17 @@
     return RoundedAllocationSize(sizeof(RawBigint) + (len * kBytesPerElement));
   }
 
+  RawBigint* ArithmeticOp(Token::Kind operation, const Bigint& other) const;
+
+ protected:
+  // Only Integer::NewXXX is allowed to call Bigint::NewXXX directly.
+  friend class Integer;
+
   static RawBigint* New(const String& str, Heap::Space space = Heap::kNew);
 
   // Returns a canonical Bigint object allocated in the old gen space.
   static RawBigint* NewCanonical(const String& str);
 
-  RawBigint* ArithmeticOp(Token::Kind operation, const Bigint& other) const;
-
  private:
   Chunk GetChunkAt(intptr_t i) const {
     return *ChunkAddr(i);