WN and XN
XN directives define names for registers in A64 code.
WN directive defines a name for a
specified 32-bit register.
XN directive defines a name for a
specified 64-bit register.
- is the name to be assigned to the register.
namecannot be the same as any of the predefined names.
- evaluates to a register number from 0 to 30.
allocate convenient names to registers in A64 code, to help you
to remember what you use each register for. Be careful to avoid
conflicting uses of the same register under different names.
sqr4 WN w16 ; defines sqr4 for register w16 regname XN 21 ; defines regname for register x21