9.16.2.2 Register Names

The 128 integer registers are referred to as `rn'. The 128 floating-point registers are referred to as `fn'. The 128 application registers are referred to as `arn'. The 128 control registers are referred to as `crn'. The 64 one-bit predicate registers are referred to as `pn'. The 8 branch registers are referred to as `bn'. In addition, the assembler defines a number of aliases: `gp' (`r1'), `sp' (`r12'), `rp' (`b0'), `ret0' (`r8'), `ret1' (`r9'), `ret2' (`r10'), `ret3' (`r9'), `fargn' (`f8+n'), and `fretn' (`f8+n').

For convenience, the assembler also defines aliases for all named application and control registers. For example, `ar.bsp' refers to the register backing store pointer (`ar17'). Similarly, `cr.eoi' refers to the end-of-interrupt register (`cr67').