gcc/testsuite/gcc.dg/nop.h - chromiumos/third_party/gcc - Git at Google

 #if defined (__ia64__) || defined (__s390__) || defined (__s390x__)
 #define NOP "nop 0"
 #elif defined (__MMIX__)
 #define NOP "swym 0"
 #else
 #define NOP "nop"
 #endif
	#if defined (__ia64__) \|\| defined (__s390__) \|\| defined (__s390x__)
	#define NOP "nop 0"
	#elif defined (__MMIX__)
	#define NOP "swym 0"
	#else
	#define NOP "nop"
	#endif