Re: [patch/ARM] Add support for single-stepping through IF-THEN blocks

[Joel Brobecker <brobecker@adacore.com>]

> Here's the patch I was ultimately working on that produced the rest of
> today's cleanups.

This is really interesting! Thanks for taking the time to document
the patches - I try to do the same and I think it's really useful
when someone comes back to a piece of code and tries to understand it
(I have trouble rememebering what I did a couple of days ago, so it's
my own notes are very helpful to me too! ;-) ).

There is one thing that I didn't quite get, and the comments in the code
repeat the same thing:

>     cmp     r0, r1 @ Compare r0 and r1
>     ittee   eq     @ If they are equal
>     moveq   r0, #1 @ Then do this
>     moveq   r1, #1 @ And this
>     movne   r0, #2 @ Otherwise this
>     movne   r1, #2 @ And this
[...]
> 1) We use an undefined instruction, rather than the architectural BKPT
> instruction, as the GNU/Linux software breakpoint.  If a hardware
> debugger is connected to the system, BKPT will trigger it.

I don't understand why we cannot use the BKPT insn... Suppose we put
a BKPT at the beginning of each block, what would happen? Would we
get a SIGTRAP even if the insn wasn't supposed to be called?

-- 
Joel