Re: [PATCH v2] Fix LRA to handle multi-word eliminable registers

[Vladimir Makarov <vmakarov at redhat dot com>]

On 06/23/2018 08:38 AM, Dimitar Dimitrov wrote:
> For some targets, Pmode != UNITS_PER_WORD. Take this into account
> when marking hard registers as being used.
>
> I tested C and C++ testsuits for x86_64 with and without this
> patch. There was no regression, i.e. gcc.sum and g++.sum matched
> exactly.
>
> Changes since patch series v1:
>    - Cleanup to use add_to_hard_reg_set.
>    - Also fix check_pseudos_live_through_calls.
>    - Decouple PRU tests so that LRA patch is now standalone.
>
> gcc/ChangeLog:
>
> 2018-06-23  Dimitar Dimitrov  <dimitar@dinux.eu>
>
> 	* lra-eliminations.c (update_reg_eliminate): Mark all spanning hard
> 	registers for Pmode..
> 	* lra-lives.c (check_pseudos_live_through_calls): Mark all spanning
> 	hard registers for the clobbered pseudo.
I am not sure about necessity of a change in 
check_pseudos_live_through_calls.  But I guess reload treats partially 
clobbered regs in analogous way as the change.  Plus the change makes 
LRA code safer anyway.

So please go ahead and commit the patch into the trunk.

Thank you.
> Cc: Vladimir Makarov <vmakarov@redhat.com>
> Cc: Peter Bergner <bergner@vnet.ibm.com>
> Cc: Kenneth Zadeck <zadeck@naturalbridge.com>
> Cc: Seongbae Park <seongbae.park@gmail.com>
> Cc: Jeff Law <law@redhat.com>
> Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>
> ---
>   gcc/lra-eliminations.c | 4 ++--
>   gcc/lra-lives.c        | 3 ++-
>   2 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/gcc/lra-eliminations.c b/gcc/lra-eliminations.c
> index 21d8d5f8018..f5f104020b3 100644
> --- a/gcc/lra-eliminations.c
> +++ b/gcc/lra-eliminations.c
> @@ -1264,13 +1264,13 @@ update_reg_eliminate (bitmap insns_with_changed_offsets)
>     CLEAR_HARD_REG_SET (temp_hard_reg_set);
>     for (ep = reg_eliminate; ep < &reg_eliminate[NUM_ELIMINABLE_REGS]; ep++)
>       if (elimination_map[ep->from] == NULL)
> -      SET_HARD_REG_BIT (temp_hard_reg_set, ep->from);
> +      add_to_hard_reg_set (&temp_hard_reg_set, Pmode, ep->from);
>       else if (elimination_map[ep->from] == ep)
>         {
>   	/* Prevent the hard register into which we eliminate from
>   	   the usage for pseudos.  */
>           if (ep->from != ep->to)
> -	  SET_HARD_REG_BIT (temp_hard_reg_set, ep->to);
> +	  add_to_hard_reg_set (&temp_hard_reg_set, Pmode, ep->to);
>   	if (maybe_ne (ep->previous_offset, ep->offset))
>   	  {
>   	    bitmap_ior_into (insns_with_changed_offsets,
> diff --git a/gcc/lra-lives.c b/gcc/lra-lives.c
> index 588bc09cb8e..920fd02b997 100644
> --- a/gcc/lra-lives.c
> +++ b/gcc/lra-lives.c
> @@ -581,7 +581,8 @@ check_pseudos_live_through_calls (int regno,
>     for (hr = 0; hr < FIRST_PSEUDO_REGISTER; hr++)
>       if (targetm.hard_regno_call_part_clobbered (hr,
>   						PSEUDO_REGNO_MODE (regno)))
> -      SET_HARD_REG_BIT (lra_reg_info[regno].conflict_hard_regs, hr);
> +      add_to_hard_reg_set (&lra_reg_info[regno].conflict_hard_regs,
> +			   PSEUDO_REGNO_MODE (regno), hr);
>     lra_reg_info[regno].call_p = true;
>     if (! sparseset_bit_p (pseudos_live_through_setjumps, regno))
>       return;