as: TILEPro Registers
9.47.2.2 Register Names
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General-purpose registers are represented by predefined symbols of the
form 'rN', where N represents a number between '0' and '63'. However,
the following registers have canonical names that must be used instead:
'r54'
sp
'r55'
lr
'r56'
sn
'r57'
idn0
'r58'
idn1
'r59'
udn0
'r60'
udn1
'r61'
udn2
'r62'
udn3
'r63'
zero
The assembler will emit a warning if a numeric name is used instead
of the canonical name. The '.no_require_canonical_reg_names' assembler
pseudo-op turns off this warning. '.require_canonical_reg_names' turns
it back on.