I
| Register | ABI Name | Description | Saved by Calle- |
|---|---|---|---|
| x0 | zero | hardwired zero | – |
| x1 | ra | return address | -R |
| x2 | sp | stack pointer | -E |
| x3 | gp | global pointer | – |
| x4 | tp | thread pointer | – |
| x5 | t0 | temporary register 0 | -R |
| x6 | t1 | temporary register 1 | -R |
| x7 | t2 | temporary register 2 | -R |
| x8 | s0 / fp | saved register 0 / frame pointer | -E |
| x9 | s1 | saved register 1 | -E |
| x10 | a0 | function argument 0 / return value 0 | -R |
| x11 | a1 | function argument 1 / return value 1 | -R |
| x12 | a2 | function argument 2 | -R |
| x13 | a3 | function argument 3 | -R |
| x14 | a4 | function argument 4 | -R |
| x15 | a5 | function argument 5 | -R |
| x16 | a6 | function argument 6 | -R |
| x17 | a7 | function argument 7 | -R |
| x18 | s2 | saved register 2 | -E |
| x19 | s3 | saved register 3 | -E |
| x20 | s4 | saved register 4 | -E |
| x21 | s5 | saved register 5 | -E |
| x22 | s6 | saved register 6 | -E |
| x23 | s7 | saved register 7 | -E |
| x24 | s8 | saved register 8 | -E |
| x25 | s9 | saved register 9 | -E |
| x26 | s10 | saved register 10 | -E |
| x27 | s11 | saved register 11 | -E |
| x28 | t3 | temporary register 3 | -R |
| x29 | t4 | temporary register 4 | -R |
| x30 | t5 | temporary register 5 | -R |
| x31 | t6 | temporary register 6 | -R |