Re: [PATCH 0/7] ira/lra: Support subreg coalesce

[Lehua Ding <lehua.ding@rivai.ai>]

On 2023/11/13 9:11, juzhe.zhong@rivai.ai wrote:
>>> Ah, nice!  How configurable are the bit ranges?
> I think Lehua's patch is configurable for bit ranges.
> Since his patch allow target flexible tracking subreg livenesss 
> according to REGMODE_NATURAL_SIZE
> 
> +/* Return true if REGNO is a pseudo and MODE is a multil regs size.  */
> +bool
> +need_track_subreg (int regno, machine_mode reg_mode)
> +{
> +  poly_int64 total_size = GET_MODE_SIZE (reg_mode);
> +  poly_int64 natural_size = REGMODE_NATURAL_SIZE (reg_mode);
> +  return maybe_gt (total_size, natural_size)
> +	 && multiple_p (total_size, natural_size)
> +	 && regno >= FIRST_PSEUDO_REGISTER;
> +}
> 
> It depends on how targets configure REGMODE_NATURAL_SIZE target hook.
> 
> If we return QImode size, his patch is enable tracking bit ranges 7 bits 
> subreg.

Yes, the current subreg_ranges class provides 
remove_range/add_range/remove_ranges/add_ranges interfaces to modify 
ranges. Each subreg_range contains start and end fields representing the 
range [start, end). For live_subreg problem, the value returned by 
REGMODE_NATURAL_SIZE is used as the unit, for bit track like Jeff's 
side, it can be used bit as the unit.

-- 
Best,
Lehua (RiVAI)
lehua.ding@rivai.ai