asm("trap") on 64-bit iOS devices

Question

In my homegrown assert macro, I've been using asm("trap") on iOS devices (or asm("int3") on iOS simulators) to break in the debugger. However, in 64-bit builds for devices, I get an "unrecognized instruction mnemonic" for the trap instruction. Is there an equivalent for arm64?

(Alternatives like __builtin_trap() or raise(SIGINT) do work, but have some behavior I don't like; the former won't let you continue past the break, and the latter is a function so you're always one step below where you need to be in the stack when you break.)

Answer 1

I was able to break into the debugger (and continue afterwards) with asm("svc 0"); . I'm not sure this is the correct way but it seems to do the job.

Answer 2

Haven't tried iOS, but on Linux, the brk instruction causes SIGTRAP to be raised, which traps to the debugger if one is running.

asm("brk #0");