as: MMIX-Regs
9.27.3.3 Register names
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Local and global registers are specified as '$0' to '$255'. The
recognized special register names are 'rJ', 'rA', 'rB', 'rC', 'rD',
'rE', 'rF', 'rG', 'rH', 'rI', 'rK', 'rL', 'rM', 'rN', 'rO', 'rP', 'rQ',
'rR', 'rS', 'rT', 'rU', 'rV', 'rW', 'rX', 'rY', 'rZ', 'rBB', 'rTT',
'rWW', 'rXX', 'rYY' and 'rZZ'. A leading ':' is optional for special
register names.
Local and global symbols can be equated to register names and used in
place of ordinary registers.
Similarly for special registers, local and global symbols can be
used. Also, symbols equated from numbers and constant expressions are
allowed in place of a special register, except when either of the
options '--no-predefined-syms' and '--fixed-special-register-names' are
specified. Then only the special register names above are allowed for
the instructions having a special register operand; 'GET' and 'PUT'.
Info Catalog
as: MMIX-Symbols
as: MMIX-Syntax
as: MMIX-Pseudos