Reapply "Do not directly load smi constants larger than a 16 bit..."

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
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/constants_x64.h"
 #include "vm/hash_map.h"
+#include "vm/object.h"
 
 namespace dart {
 
 // Forward declarations.
 class RuntimeEntry;
 
 class Immediate : public ValueObject {
  public:
   explicit Immediate(int64_t value) : value_(value) { }
 
@@ skipping 814 matching lines @@
   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);
 
+  // On some other platforms, we draw a distinction between safe and unsafe
+  // smis.
+  static bool IsSafe(const Object& object) { return true; }
+  static bool IsSafeSmi(const Object& object) { return object.IsSmi(); }
+
  private:
   AssemblerBuffer buffer_;
 
   // Objects and jump targets.
   GrowableObjectArray& object_pool_;
 
   // Patchability of pool entries.
   GrowableArray<Patchability> patchable_pool_entries_;
 
   // Pair type parameter for DirectChainedHashMap.
@@ skipping 182 matching lines @@
 }
 
 
 inline void Assembler::EmitOperandSizeOverride() {
   EmitUint8(0x66);
 }
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_X64_H_