Hi Bernd,
> Hi Robert,
> > gcc/
> > * regrename.c (create_new_chain): Initialize terminated_dead,
> > renamed and tied_chain.
> > (find_best_rename_reg): Pick and check register from the tied chain.
> > (regrename_do_replace): Mark head as renamed.
> > (scan_rtx_reg): Tie chains in move insns. Set terminate_dead flag.
> > * regrename.h (struct du_head): Add tied_chain, renamed and
> > terminated_dead members.
>
> Thanks - this looks a lot better already. You didn't say how it was
> bootstrapped and tested; please include this information for future
> submissions. For a patch like this, some data on the improvement you got
> would also be appreciated.
Ah, sorry. I bootstrapped on x86_64-unknown-linux-gnu and ran the Dejagnu
with -frename-registers. All looked fine. As for the data, I'll do
the comparison and will update this thread by next week.
>
> I'd still like to investigate the possibility of further simplification:
>
> > + {
> > + /* Find the input chain. */
> > + for (i = c->id - 1; id_to_chain.iterate (i, &head); i--)
> > + if (head->last && head->last->insn == insn
> > + && head->terminated_dead)
> > + {
> > + gcc_assert (head->regno == REGNO (recog_data.operand[1]));
> > + c->tied_chain = head;
> > + head->tied_chain = c;
> > +
> > + if (dump_file)
> > + fprintf (dump_file, "Tying chain %s (%d) with %s (%d)\n",
> > + reg_names[c->regno], c->id,
> > + reg_names[head->regno], head->id);
> > + /* Once tied, we're done. */
> > + break;
> > + }
> > + }
> > + }
> > +
> This looks like it's a little more complicated than necessary. Couldn't
> you add a static var "terminated_this_insn" which gets initialized to
> NULL and set when a reg dies, and then you check this here rather than
> having a loop? That would also eliminate the new "terminated_dead" field.
That is a good idea. I'll add the changes and update together
with the results.
> Other than that I'm pretty happy with this.
>
>
> Bernd
Regards,
Robert
