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##### 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`’).