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AAPCS64

The standard rulebook for function calls on 64-bit ARM - arguments in x0 to x7, result in x0, x19 to x28 kept safe across calls.

The Procedure Call Standard for the Arm 64-bit Architecture passes up to eight integer arguments in x0-x7, returns in x0 (x0:x1 for 16 bytes), uses x8 for an indirect result address, x9-x15 as temporaries, x16-x17 as intra-procedure-call scratch, x18 as the platform register, x19-x28 callee-saved, x29 frame pointer and x30 link register.

Examples

  • Integer arguments go in x0 to x7, the result in x0, and x19 to x28 are callee-saved.

See also

platform register variadic function callee-saved frame pointer
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