Hardcoded Breakpoint Preventing Program From Running

There is an issue (it's not a bug because of reasons) where if you use armclang at -O0 optimisation with no parameters specified in the main function, the initialisation code contains a coded breakpoint. This will stop the code from running before main is reached.

There are multiple work arounds including:

1) Using MicroLib

2) Disabling semihosting manually:

__asm(".global __use_no_semihosting\n\t");


Note that the following funcitons will need to be retargeted:

extern "C" void _sys_exit(int ch) { }
extern "C" void _sys_command_string(int ch) { }
extern "C" void _ttywrch(int ch) { }

3) Use the following, which apparently is used automatically by armclang on higher optimisation levels:

__asm(".global __ARM_use_no_argv");

Apparently the coming fix "will be a better documentation about the symbol __ARM_use_no_argv and why it is needed when using -O0."

Just wanted to let people know in case it happens to them.

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