On Wed, Jul 12, 2017 at 03:30:00PM +0200, Georg-Johann Lay wrote:
> On 12.07.2017 14:11, Segher Boessenkool wrote:
> >On Tue, Jul 11, 2017 at 10:47:27AM +0200, Georg-Johann Lay wrote:
> >>This small addition improves costs of PARALLELs in
> >>rtlanal.c:seq_cost(). Up to now, these costs are
> >>assumed to be 1 which gives gross inexact costs for,
> >>e.g. divmod which is represented as PARALLEL.
> >
> >insn_rtx_cost returns 0 ("unknown") for such a PARALLEL, so your
> >current patch does not change this at all?
>
> Huh? It returns the costs of 1st SET in a PARALLEL (provided it
> has one), no? Or even costs for come compares.
No, it returns 0 if there is more than one normal SET (or more than
one compare).
> >>+ else if (INSN_P (seq)
> >>+ && PARALLEL == GET_CODE (PATTERN (seq)))
> >
> >Yoda conditions have we should not.
>
> hmm, I didn't find something like PARALLEL_P (rtx).
> Is comparing rtx_codes deprecated now?
I meant it should be written
else if (INSN_P (seq) && GET_CODE (PATTERN (seq)) == PARALLEL)
i.e. constant on the right.
> >This whole thing could be something like
> >
> > if (INSN_P (seq))
> > {
> > int t = insn_rtx_cost (PATTERN (seq), speed);
>
> This will behave differently.
Yes, I know, I even said so.
> >(Why do you need a check for INSN_P here? Why does it increment the
>
> >cost for non-insns? So many questions).
>
> Again, you'll have to ask the original author for reasoning.
Since you want to change the code, to make it better, I was hoping
you would dig in a bit. To make it better, not just different :-/
Segher
