unrelated question: has anyone ever passed a pointer/reference to an asm block only to have the compiler optimize away the variable whose address you passed into the asm block?

in this case, the value passed into write was a reference to some data inside of an option.
```
core::arch::asm!("
mov r12,{read}
movs r3,{write}
svc #114
", read=in(reg) &raw mut read, write=in(reg) write, clobber_abi("C"));
```