Uses SNPRINT macro where possible. Otherwise uses #define for format.

runtime/vm/assembler_x64.h

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_ASSEMBLER_X64_H_
 #define VM_ASSEMBLER_X64_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_x64.h directly; use assembler.h instead.
 #endif
@@ skipping 1002 matching lines @@
   void TryAllocateArray(intptr_t cid,
                         intptr_t instance_size,
                         Label* failure,
                         bool near_jump,
                         Register instance,
                         Register end_address,
                         Register temp);
 
   // Debugging and bringup support.
   void Stop(const char* message, bool fixed_length_encoding = false);
-  void Unimplemented(const char* message);
-  void Untested(const char* message);
-  void Unreachable(const char* message);
 
   static void InitializeMemoryWithBreakpoints(uword data, intptr_t length);
 
   static const char* RegisterName(Register reg);
 
   static const char* FpuRegisterName(FpuRegister reg);
 
   static Address ElementAddressForIntIndex(bool is_external,
                                            intptr_t cid,
                                            intptr_t index_scale,
@@ skipping 171 matching lines @@
 }
 
 
 inline void Assembler::EmitOperandSizeOverride() {
   EmitUint8(0x66);
 }
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_X64_H_