Re: [PATCH] S/390: Allow to use r2 to r4 as literal pool base.

[Jakub Jelinek]

On Fri, Dec 18, 2015 at 11:21:38AM +0100, Dominik Vogt wrote:
> Latest patch for r2 to r4, including a test case.
> diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
> index ed684af..cba88bb 100644
> --- a/gcc/config/s390/s390.c
> +++ b/gcc/config/s390/s390.c
> @@ -9584,10 +9584,17 @@ s390_init_frame_layout (void)
>        as base register to avoid save/restore overhead.  */
>        if (!base_used)
>       cfun->machine->base_reg = NULL_RTX;
> -      else if (crtl->is_leaf && !df_regs_ever_live_p (5))
> -     cfun->machine->base_reg = gen_rtx_REG (Pmode, 5);
>        else
> -     cfun->machine->base_reg = gen_rtx_REG (Pmode, BASE_REGNUM);
> +     {
> +       int br = 0;
> +
> +       if (crtl->is_leaf)
> +         /* Prefer r5 (most likely to be free).  */
> +         for (br = 5; br >= 2 && df_regs_ever_live_p (br); br--)
> +           ;
> +       cfun->machine->base_reg =
> +         gen_rtx_REG (Pmode, (br > 0) ? br : BASE_REGNUM);

Note the formatting is wrong.  It should be:
          cfun->machine->base_reg
            = gen_rtx_REG (Pmode, (br > 0) ? br : BASE_REGNUM);

        Jakub