Re: [testsuite/alpha] Add test for step over fbne instruction

Daniel Jacobowitz
2005-05-26T03:14:51Z

On Wed, May 25, 2005 at 08:11:28PM -0700, Richard Henderson wrote:
> On Thu, May 26, 2005 at 12:35:39PM +1000, Joel Brobecker wrote:
> > " cpys $f31,$f31,$f0\n"
> > " fbgt $f16,$gt_1\n" /* stop at this instruction. */
> > " cpysn $f16,$f16,$f0\n"
> > "$gt_1:\n"
> > " ret $31,($26),1\n"
>
> Hmm, now that I think about it, one potential problem with this form
> is that we're not correctly testing for branch taken. The scenerio
> is that we expect taken, set the bp on the ret, the branch *isn't*
> taken, but we fall through to the ret anyway.
>
> We'd do better to write this
>
> " fbgt $f16,$gt_1\n" /* stop at this instruction. */
> " cpysn $f16,$f16,$f0\n"
> " ret $31,($26),1\n"
> "$gt_1:\n"
> " ret $31,($26),1\n"
>
> so that if we choose wrong, we will in fact lose control.

Then the testsuite is likely to get out of sync - either way, we need
to do a little dance to recover. Joel, how about checking to see that
the instruction we've stopped on is the correct one - how much would
that complicate the test?

--
Daniel Jacobowitz
CodeSourcery, LLC