Re: [PATCH, PR rtl-optimization/71148] Avoid cleanup_cfg called with invalidated dominance info

[Richard Biener <richard dot guenther at gmail dot com>]

On Thu, May 19, 2016 at 12:34 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
> On 19 May 09:57, Richard Biener wrote:
>> On Wed, May 18, 2016 at 6:17 PM, Ilya Enkovich <enkovich.gnu@gmail.com> wrote:
>> > Hi,
>> >
>> > This patch resolves PR71148 by releasing dominance info before
>> > cleanup_cfg calls to avoid attempts to fixup invalid dominance
>> > info.
>> >
>> > Dominance info handling in cleanup_cfg looks weird though.  It
>> > tries to fix it but can invalidate it at the same time (PR71084).
>> > We should probably do something with that.
>> >
>> > Tracker is P1 and this patch may be OK solution for now.
>> >
>> > Bootstrapped and regtested on x86_64-pc-linux-gnu.  Ok for trunk?
>>
>> Hum... all this dancing with CSE looks bogus to me.  Does CSE itself
>> need dominance info?  If not then unconditionally free it at its start.
>>
>> Richard.
>>
>
> Here it is.  OK if testing pass?
>
> Thanks,
> Ilya
> --
> gcc/
>
> 2016-05-19  Ilya Enkovich  <ilya.enkovich@intel.com>
>
>         * cse.c (cse_main): Free dominance info.
>         (rest_of_handle_cse): Don't free dominance info.
>         (rest_of_handle_cse2): Likewise.
>         (rest_of_handle_cse_after_global_opts): Likewise.
>
> gcc/testsuite/
>
> 2016-05-19  Ilya Enkovich  <ilya.enkovich@intel.com>
>
>         * gcc.dg/pr71148.c: New test.
>
>
> diff --git a/gcc/cse.c b/gcc/cse.c
> index 322e352..84082fb 100644
> --- a/gcc/cse.c
> +++ b/gcc/cse.c
> @@ -6669,6 +6669,11 @@ cse_main (rtx_insn *f ATTRIBUTE_UNUSED, int nregs)
>    int *rc_order = XNEWVEC (int, last_basic_block_for_fn (cfun));
>    int i, n_blocks;
>
> +  /* CSE doesn't use dominance info but can invalidate it in different ways.
> +     For simplicity free dominance info here.  */
> +  if (dom_info_available_p (CDI_DOMINATORS))
> +    free_dominance_info (CDI_DOMINATORS);

Just call free_dominance_info unconditionally.

Ok with that change (if it passes testing).

Richard.

> +
>    df_set_flags (DF_LR_RUN_DCE);
>    df_note_add_problem ();
>    df_analyze ();
> @@ -7568,9 +7573,6 @@ rest_of_handle_cse (void)
>    else if (tem == 1 || optimize > 1)
>      cse_cfg_altered |= cleanup_cfg (0);
>
> -  if (cse_cfg_altered && dom_info_available_p (CDI_DOMINATORS))
> -    free_dominance_info (CDI_DOMINATORS);
> -
>    return 0;
>  }
>
> @@ -7640,9 +7642,6 @@ rest_of_handle_cse2 (void)
>    else if (tem == 1)
>      cse_cfg_altered |= cleanup_cfg (0);
>
> -  if (cse_cfg_altered && dom_info_available_p (CDI_DOMINATORS))
> -    free_dominance_info (CDI_DOMINATORS);
> -
>    cse_not_expected = 1;
>    return 0;
>  }
> @@ -7717,9 +7716,6 @@ rest_of_handle_cse_after_global_opts (void)
>    else if (tem == 1)
>      cse_cfg_altered |= cleanup_cfg (0);
>
> -  if (cse_cfg_altered && dom_info_available_p (CDI_DOMINATORS))
> -    free_dominance_info (CDI_DOMINATORS);
> -
>    flag_cse_follow_jumps = save_cfj;
>    return 0;
>  }
> diff --git a/gcc/testsuite/gcc.dg/pr71148.c b/gcc/testsuite/gcc.dg/pr71148.c
> new file mode 100644
> index 0000000..6aa4920
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr71148.c
> @@ -0,0 +1,46 @@
> +/* PR rtl-optimization/71148 */
> +/* { dg-do compile } */
> +/* { dg-options "-O3 -funroll-loops" } */
> +
> +int rh, ok, kq, fu;
> +
> +void
> +js (int cs)
> +{
> +  rh = fu;
> +  if (fu != 0)
> +    {
> +      cs /= 3;
> +      if (cs <= 0)
> +        {
> +          int z9;
> +          for (z9 = 0; z9 < 2; ++z9)
> +            {
> +              z9 += cs;
> +              ok += z9;
> +              fu += ok;
> +            }
> +        }
> +    }
> +}
> +
> +void
> +vy (int s3)
> +{
> +  int yo, g2 = 0;
> + sd:
> +  js (g2);
> +  for (yo = 0; yo < 2; ++yo)
> +    {
> +      if (fu != 0)
> +        goto sd;
> +      kq += (s3 != (g2 ? s3 : 0));
> +      for (s3 = 0; s3 < 72; ++s3)
> +        g2 *= (~0 - 1);
> +      g2 -= yo;
> +    }
> +  for (fu = 0; fu < 18; ++fu)
> +    for (yo = 0; yo < 17; ++yo)
> +      if (g2 < 0)
> +        goto sd;
> +}