I work with the ARM platform and I need to specify AAPCS [1]
calling convention.
Clang and GCC support `__attribute__((__pcs__("aapcs")))` [2].
How to specify this calling convention?
[1] https://developer.arm.com/documentation/ihi0042/latest/
[2]
https://github.com/llvm/llvm-project/blob/master/compiler-rt/lib/builtins/int_lib.h#L27