Debugging option while porting GCC

[Kim, Eunchan]

On Thu, Sep 24, 2009 at 3:11 PM, Ian Lance Taylor <iant@google.com> wrote:
> "Kim, Eunchan" <helpbygrace@gmail.com> writes:
>
>> I found reg/f means that it is frame related register. But i didn't
>> understand why my sp, which is elim in this function, is (reg:SI) not
>> (reg/f:SI).
>>
>> does anyone know why this is happened?
>
> Look at your ELIMINABLE_REGS macro.  There is most likely something
> wrong with it.  Or you have defined STACK_POINTER_REGNUM and
> HARD_FRAME_POINTER_REGNUM to have the same value, or something like
> that.
>
> Ian
>

Thank you Ian for replying.

I change ELIMINABLE_REGS to
ARG -> STACK
ARG -> FRAME
FRAME -> STACK

then i could compile with -g option.

But I failed compiling with -O2 and -g. So i printed what is
difference between -O2 -g and only -g.

when i compiled with -g. Before i modify ELIMINABLE_REGS, elim was
(reg/f:SI 10 r10) . which is actually ARG_POINTER_REGNUM. So it seems
to be changed to STACK_POINTER after editing ELIMINABLE_REGS.

But as i mentioned above, when i compiled with '-O2 -g', the elim was
(reg:SI 12 r12) . 12 is STACK_POINTER_REGNUM). I don't know why this
happened. elim should be (reg/f:SI 12 r12).

Eunchan