ARM 系列目前支持三大主流的工具鏈，即ARM RealView (armcc), IAR EWARM (iccarm), and GNU Compiler Collection (gcc).
在core_cm3.h中有如下定義：
/* define compiler specific symbols */
#if defined ( __CC_ARM )
#define __ASM __asm /*!< asm keyword for armcc */
#define __INLINE __inline /*!< inline keyword for armcc */
#elif defined ( __ICCARM__ )
#define __ASM __asm /*!< asm keyword for iarcc */
#define __INLINE inline /*!< inline keyword for iarcc. Only
avaiable in High optimization mode! */
#define __nop __no_operation /*!< no operation intrinsic in iarcc */
#elif defined ( __GNUC__ )
#define __ASM asm /*!< asm keyword for gcc */
#define __INLINE inline /*!< inline keyword for gcc
#endif