r0-r15 and R0-R15

a1-a4 (argument, result, or scratch registers, synonyms for r0 to r3)

v1-v8 (variable registers, r4 to r11)

sb and SB (static base, r9)

sl and SL (stack limit, r10)

fp and FP (frame pointer, r11)

ip and IP (intra-procedure-call scratch register, r12)

sp and SP (stack pointer, r13)

lr and LR (link register, r14)

pc and PC (program counter, r15).