9.18.2.2 Register Names

The 128 integer registers are referred to as ‘ r n ’. The 128 floating-point registers are referred to as ‘ f n ’. The 128 application registers are referred to as ‘ ar n ’. The 128 control registers are referred to as ‘ cr n ’. The 64 one-bit predicate registers are referred to as ‘ p n ’. The 8 branch registers are referred to as ‘ b n ’. In addition, the assembler defines a number of aliases: ‘ gp ’ (‘ r1 ’), ‘ sp ’ (‘ r12 ’), ‘ rp ’ (‘ b0 ’), ‘ ret0 ’ (‘ r8 ’), ‘ ret1 ’ (‘ r9 ’), ‘ ret2 ’ (‘ r10 ’), ‘ ret3 ’ (‘ r9 ’), ‘ farg n ’ (‘ f8+ n ’), and ‘ fret n ’ (‘ 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 ’).