Re: [PATCH 4/8] Force to insert software single step breakpoint

[Yao Qi <qiyaoltc@gmail.com>]

Pedro Alves <palves@redhat.com> writes:

> Hmm, I think we might need to do something else.
>
> If you put a breakpoint there, then the instruction under
> the breakpoint won't execute at all.

That is intended, because if the instruction is executed, it can't be
stopped.

>
> If it's a conditional branch, and the condition is false,
> we will fail to ever advance past the instruction.
>
> Similarly if the branch instruction happens to have important
> side effects (flags? counters?).

We can switch to displaced stepping if we find the instruction may
branch to itself.  Say, we can change gdbarch software_single_step to
return a vector of dest addresses of current pc and caller inserts
software single step breakpoints to these dest addresses.  If any
element of vector equals to the current pc, switch to displaced
stepping if supported.  What do you think?

-- 
Yao (齐尧)