9.18.2.2 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’).