[PATCH] [ARC] Restore blink first when optimizing for speed.

Claudiu Zissulescu claziss@gmail.com
Wed Apr 3 10:09:00 GMT 2019


Great, thanks!
Claudiu

On Wed, Apr 3, 2019 at 2:50 AM Andrew Burgess
<andrew.burgess@embecosm.com> wrote:
>
> * Claudiu Zissulescu <claziss@gmail.com> [2019-03-25 11:56:49 +0100]:
>
> > Hi,
> >
> > When not optimizing for size, we can restore first blink, hence the return
> > instruction will be executed faster.
> >
> > OK to apply?
> > Claudiu
> >
> > gcc/
> > xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>
> >
> >       * config/arc/arc.c (GMASK_LEN): Define.
> >       (arc_restore_callee_saves): Restore first blink when
> >       !optimize_size.
>
>
> This looks fine.
>
> Thanks,
> Andrew
>
> > ---
> >  gcc/config/arc/arc.c | 37 +++++++++++++++++++++++++++++++++++--
> >  1 file changed, 35 insertions(+), 2 deletions(-)
> >
> > diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
> > index de2c8d5df9c..9a6920a709f 100644
> > --- a/gcc/config/arc/arc.c
> > +++ b/gcc/config/arc/arc.c
> > @@ -2545,6 +2545,9 @@ struct GTY (()) arc_frame_info
> >    bool save_return_addr;
> >  };
> >
> > +/* GMASK bit length -1.  */
> > +#define GMASK_LEN 31
> > +
> >  /* Defining data structures for per-function information.  */
> >
> >  typedef struct GTY (()) machine_function
> > @@ -3087,6 +3090,8 @@ arc_restore_callee_saves (unsigned int gmask,
> >  {
> >    rtx reg;
> >    int frame_deallocated = 0;
> > +  HOST_WIDE_INT offs = cfun->machine->frame_info.reg_size;
> > +  bool early_blink_restore;
> >
> >    /* Emit mov fp,sp.  */
> >    if (arc_frame_pointer_needed () && offset)
> > @@ -3112,9 +3117,21 @@ arc_restore_callee_saves (unsigned int gmask,
> >        offset = 0;
> >      }
> >
> > +  /* When we do not optimize for size, restore first blink.  */
> > +  early_blink_restore = restore_blink && !optimize_size && offs;
> > +  if (early_blink_restore)
> > +    {
> > +      rtx addr = plus_constant (Pmode, stack_pointer_rtx, offs);
> > +      reg = gen_rtx_REG (Pmode, RETURN_ADDR_REGNUM);
> > +      rtx insn = frame_move_inc (reg, gen_frame_mem (Pmode, addr),
> > +                              stack_pointer_rtx, NULL_RTX);
> > +      add_reg_note (insn, REG_CFA_RESTORE, reg);
> > +      restore_blink = false;
> > +    }
> > +
> >    /* N.B. FRAME_POINTER_MASK and RETURN_ADDR_MASK are cleared in gmask.  */
> >    if (gmask)
> > -    for (int i = 0; i <= 31; i++)
> > +    for (int i = 0; i <= GMASK_LEN; i++)
> >        {
> >       machine_mode restore_mode = SImode;
> >
> > @@ -3127,7 +3144,23 @@ arc_restore_callee_saves (unsigned int gmask,
> >         continue;
> >
> >       reg = gen_rtx_REG (restore_mode, i);
> > -     frame_deallocated += frame_restore_reg (reg, 0);
> > +     offs = 0;
> > +     switch (restore_mode)
> > +       {
> > +       case E_DImode:
> > +         if ((GMASK_LEN - __builtin_clz (gmask)) == (i + 1)
> > +             && early_blink_restore)
> > +           offs = 4;
> > +         break;
> > +       case E_SImode:
> > +         if ((GMASK_LEN - __builtin_clz (gmask)) == i
> > +             && early_blink_restore)
> > +           offs = 4;
> > +         break;
> > +       default:
> > +         offs = 0;
> > +       }
> > +     frame_deallocated += frame_restore_reg (reg, offs);
> >       offset = 0;
> >
> >       if (restore_mode == DImode)
> > --
> > 2.20.1
> >



More information about the Gcc-patches mailing list