Node: Xtensa Registers, Previous: Xtensa Opcodes, Up: Xtensa Syntax

### Register Names

An initial `$` character is optional in all register names. General purpose registers are named `a0`...`a15`. Additional registers may be added by processor configuration options. In particular, the MAC16 option adds a MR register bank. Its registers are named `m0`...`m3`.

As a special feature, `sp` is also supported as a synonym for `a1`.