RE: [PATCH] Disable -mbranch-likely for -Os when targetting generic architecture

[Robert Suchanek <Robert.Suchanek@imgtec.com>]

Hi Catherine,

Apologies for the (very) late reply.
It appears that I never replied to the last message.

> > gcc/
> > 	* config/mips/mips-cpus.def: Replace PTF_AVOID_BRANCHLIKELY
> > with
> > 	PTF_AVOID_BRANCHLIKELY_ALWAYS for generic architecture and
> > with
> > 	PTF_AVOID_BRANCHLIKELY_SPEED for others.
> > 	(mips2, mips3, mips4): Add PTF_AVOID_BRANCHLIKELY_SIZE to tune
> > flags.
> > 	* config/mips/mips.c (mips_option_override): Enable the branch
> > likely
> > 	depending on the tune flags and optimization level.
> > 	* config/mips/mips.h (PTF_AVOID_BRANCHLIKELY): Remove.
> > 	(PTF_AVOID_BRANCHLIKELY_SPEED): Define.
> > 	(PTF_AVOID_BRANCHLIKELY_SIZE): Likewise.
> > 	(PTF_AVOID_BRANCHLIKELY_ALWAYS): Likewise.
> > ---
> >  gcc/config/mips/mips-cpus.def | 56 +++++++++++++++++++++---------------
> > -------
> >  gcc/config/mips/mips.c        |  6 +++--
> >  gcc/config/mips/mips.h        | 20 ++++++++++++----
> >  3 files changed, 47 insertions(+), 35 deletions(-)
> >
> > a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c index 0e0ecf2..f8775c4
> > 100644
> > --- a/gcc/config/mips/mips.c
> > +++ b/gcc/config/mips/mips.c
> > @@ -17916,8 +17916,10 @@ mips_option_override (void)
> >    if ((target_flags_explicit & MASK_BRANCHLIKELY) == 0)
> >      {
> >        if (ISA_HAS_BRANCHLIKELY
> > -	  && (optimize_size
> > -	      || (mips_tune_info->tune_flags & PTF_AVOID_BRANCHLIKELY)
> > == 0))
> > +	  && ((optimize_size && (mips_tune_info->tune_flags
> > +				 & PTF_AVOID_BRANCHLIKELY_SIZE) == 0)
> > +	       || (!optimize_size && (mips_tune_info->tune_flags
> > +				      & PTF_AVOID_BRANCHLIKELY_SPEED) ==
> > 0)))
> >  	target_flags |= MASK_BRANCHLIKELY;
> >        else
> >  	target_flags &= ~MASK_BRANCHLIKELY;
> 
> Should this check be:
> Index: mips.c
> ===================================================================
> --- mips.c      (revision 229138)
> +++ mips.c      (working copy)
> @@ -17758,8 +17758,15 @@
>    if ((target_flags_explicit & MASK_BRANCHLIKELY) == 0)
>      {
>        if (ISA_HAS_BRANCHLIKELY
> -         && (optimize_size
> -             || (mips_tune_info->tune_flags & PTF_AVOID_BRANCHLIKELY) == 0))
> +         && ((optimize_size
> +              && (mips_tune_info->tune_flags
> +                  & PTF_AVOID_BRANCHLIKELY_SIZE) == 0)
> +             || (!optimize_size
> +                && optimize > 0
> +                && ((mips_tune_info->tune_flags
> +                     & PTF_AVOID_BRANCHLIKELY_SPEED) == 0))
> +            || (mips_tune_info->tune_flags
> +                 & PTF_AVOID_BRANCHLIKELY_ALWAYS) == 0))
>         target_flags |= MASK_BRANCHLIKELY;
>        else
>         target_flags &= ~MASK_BRANCHLIKELY;
> 
> Instead?  I don't see a use of PTF_AVOID_BRANCH_ALWAYS in your patch, but it
> seems like it should be checked.
> 

I did that on purpose at the time as the check looked redundant as it will be one
or the other.  However, for easier reading and a potential redefinition of *_ALWAYS
e.g. to a unique value then the extra check is a must.

I'm happy to include this.  Ok to commit with this change?

Regards,
Robert