Re: Use cbranch optabs in ifcvt.c

[Jeff Law <law@redhat.com>]

On 08/24/2015 05:20 AM, Richard Sandiford wrote:
> Similarly to the patch for cmpstr(n), this patch uses the optabs
> interface for cbranchcc4 instead of using HAVE_cbranchcc4 directly.
> I've cached the result in a pass-local variable (valid only for
> the duration of the pass).
>
> The references to incscc and decscc are dead.  The only reference
> to them in the documentation is:
>
>      Some machines can also perform @code{and} or @code{plus} operations on
>      condition code values with less instructions than the corresponding
>      @samp{cstore@var{mode}4} insn followed by @code{and} or @code{plus}.  On those
>      machines, define the appropriate patterns.  Use the names @code{incscc}
>      and @code{decscc}, respectively, for the patterns which perform
>      @code{plus} or @code{minus} operations on condition code values.  See
>      @file{rs6000.md} for some examples.  The GNU Superoptimizer can be used to
>      find such instruction sequences on other machines.
>
> which is in tm.texi rather than md.texi.  This seems hopelessly out of
> date, not least because rs6000.md has no incscc or decscc patterns.
> If the "appropriate patterns" are just combine patterns, perhaps we
> should just delete the whole paragraph?
I think the whole paragraph should just go away.  We don't do anything 
with those special patterns anymore.   The PA still defines them, but 
they're just combiner patterns in the end.




>
> Tested on x86_64-linux-gnu.  OK to install?
>
> Thanks,
> Richard
>
> gcc/
> 	* ifcvt.c (HAVE_incscc, HAVE_decscc, HAVE_cbranchcc4): Delete.
> 	(have_cbranchcc4): New variable.
> 	(cc_in_cond, noce_emit_cmove, noce_get_alt_condition)
> 	(noce_get_condition): Use it instead of HAVE_cbranchcc4.
> 	(if_convert): Initialize have_cbranchcc4.
OK.
jeff