as: MMIX-Regs

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1 9.28.3.3 Register names
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1 Local and global registers are specified as '$0' to '$255'.  The
1 recognized special register names are 'rJ', 'rA', 'rB', 'rC', 'rD',
1 'rE', 'rF', 'rG', 'rH', 'rI', 'rK', 'rL', 'rM', 'rN', 'rO', 'rP', 'rQ',
1 'rR', 'rS', 'rT', 'rU', 'rV', 'rW', 'rX', 'rY', 'rZ', 'rBB', 'rTT',
1 'rWW', 'rXX', 'rYY' and 'rZZ'.  A leading ':' is optional for special
1 register names.
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1    Local and global symbols can be equated to register names and used in
1 place of ordinary registers.
1 
1    Similarly for special registers, local and global symbols can be
1 used.  Also, symbols equated from numbers and constant expressions are
1 allowed in place of a special register, except when either of the
1 options '--no-predefined-syms' and '--fixed-special-register-names' are
1 specified.  Then only the special register names above are allowed for
1 the instructions having a special register operand; 'GET' and 'PUT'.
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