Re: [PATCH] rs6000 branch probability changes

[Segher Boessenkool <segher@kernel.crashing.org>]

On Fri, Jun 30, 2017 at 10:36:27PM +0100, Ramana Radhakrishnan wrote:
> On Fri, Jun 30, 2017 at 2:36 PM, David Edelsohn <dje.gcc@gmail.com> wrote:
> > Convert the rs6000 port to use the new API for branch probabilities.
> >
> > Okay?
> >
> > Thanks, David
> >
> > * config/rs6000/rs6000.c (emit_unlikely_jump): Adjust to new branch
> > probability data type.
> >
> > Index: rs6000.c
> > ===================================================================
> > --- rs6000.c (revision 249839)
> > +++ rs6000.c (working copy)
> > @@ -23514,10 +23514,9 @@
> >  static void
> >  emit_unlikely_jump (rtx cond, rtx label)
> >  {
> > -  int very_unlikely = REG_BR_PROB_BASE / 100 - 1;
> >    rtx x = gen_rtx_IF_THEN_ELSE (VOIDmode, cond, label, pc_rtx);
> >    rtx_insn *insn = emit_jump_insn (gen_rtx_SET (pc_rtx, x));
> > -  add_int_reg_note (insn, REG_BR_PROB, very_unlikely);
> > +  add_int_reg_note (insn, REG_BR_PROB, profile_probability::very_unlikely ());
> 
> Hmmm isn't this very unlikely to work :) ?
> 
> I used this as inspiration to do this for the arm ports but
> add_int_reg_note expects an integer but very_unlikely returns
> profile_probability  ...

It probably should be converted using to_reg_br_prob_base ?


Segher