The compiler for x64-based processors has the following known limitations:

• No support for the /clr switch. The compiler for x64-based processors only generates native code.
• No support for MMX intrinsic functions.
• No support for run-time checks using the /RTC switch.
• No support for security checks using the /GS switch.
• The _frnd function does not work with arguments whose absolute values are greater than MAX_INT.
• Inlining into SEH filters can result in invalid code if you use the GetExceptionCode or GetExceptionInfo functions. The symptom could be an executable file that terminates without a dialog box.

  //Avoid using GetExceptionInfo() for this structure
  __inline void funca(DWORD); 
  __try { 
  ... 
  } except(funca(GetExceptionCode())) 
  { 
  ... 
  } 
  //Instead use the compiler switch /Ob0 to disable inlining or use: 
  __declspec(noinline) 
  // On a class member function if there is a problem 
  

• Two special cases of the va_start usage and one special case of va_arg usage are not currently supported.

  Define class string as follows:

  class String1 {
  public:
  String1 (const String1 &);
  ...
  };
  
  class String2 {
  ...
  };
  

  Note that String1 has a copy constructor, and String2 could be any class. The following two cases of va_start are not supported:

  <any type> foo1(const String1 last_parameter_with_known_type, ...)
  {
  va_list arg_list;
  va_start(arg_list, last_parameter_with_known_type);
  ...
  }
  
  <any type> foo2(const String2 &last_parameter_with_known_type, ...)
  {
  va_list arg_list;
  va_start(arg_list, last_parameter_with_known_type);
  ...
  }
  

  va_start calls are not supported if:

  • Last parameter with known type is an object of class with default copy constructor (the constructor is called to create a copy of object to pass the copy to function foo1).
  • Last parameter with known type is an object passed by reference.

  The following case of va_arg usage is not supported (see the previous String1 definition):

  <any type> foo3(<any type> last_parameter_with_known_type, ...)
  <any type> foo4( )
  {
  String1 q;
  foo3(last_parameter_with_known_type, q);
  }
  

  The passing of an object of class with default copy constructor in the "..." part of parameters is not supported.

  It does not matter in the previous example if q is a local, global, or temporary variable.

  The fourth case is not supported with object passed by reference in "...", because there are no language-supported ways to do that. The only proposed workaround is to change specifications of foo1, foo2, foo3, and so on to those ones that accept pointers to objects instead.

• Fatal error C1128: <func:#> object file format limit exceeded: more than 64-KB sections can occur if a file contains many functions. Remove -Gy or split up the file so it contains fewer functions. Removing -Zi or -Z7 also removes a lot of sections, because if -Gy is applied, -Zi forces emission of a .debug$S section for each .text section included.
• _asm is not supported for x64-based compilers. All assembly code must be written in a separate file, or intrinsic functions must be used.