Re: [PATCH v3 7/8] Improve logging of register data in scheduler dependency analysis

[Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>]

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Dear scheduler maintainers,

Gentle ping.  This patch improves debugging output, it does not touch
scheduling logic.

On Wed, 22 Nov 2023 at 15:15, Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>
wrote:

> Scheduler dependency analysis uses two main data structures:
> 1. reg_pending_* data contains effects of INSN on the register file,
>    which is then incorporated into ...
> 2. deps_desc object, which contains commulative information about all
>    instructions processed from deps_desc object's initialization.
>
> This patch adds debug dumping of (1).
>
> gcc/ChangeLog:
>
>         * sched-deps.cc (print-rtl.h): Include for str_pattern_slim().
>         (dump_reg_pending_data): New function.
>         (sched_analyze_insn): Use it.
> ---
>  gcc/sched-deps.cc | 90 ++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 89 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/sched-deps.cc b/gcc/sched-deps.cc
> index e0d3c97d935..f9290c82fd2 100644
> --- a/gcc/sched-deps.cc
> +++ b/gcc/sched-deps.cc
> @@ -38,6 +38,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "sched-int.h"
>  #include "cselib.h"
>  #include "function-abi.h"
> +#include "print-rtl.h"
>
>  #ifdef INSN_SCHEDULING
>
> @@ -432,10 +433,24 @@ dep_spec_p (dep_t dep)
>    return false;
>  }
>
> +/* These regsets describe how a single instruction affects registers.
> +   Their "life-time" is restricted to a single call of
> sched_analyze_insn().
> +   They are populated by sched_analyze_1() and sched_analyze_2(), and
> +   then sched_analyze_insn() transfers data from these into
> deps->reg_last[i].
> +   Near the end sched_analyze_insn() clears these regsets for the next
> +   insn.  */
>  static regset reg_pending_sets;
>  static regset reg_pending_clobbers;
>  static regset reg_pending_uses;
>  static regset reg_pending_control_uses;
> +
> +/* Similar to reg_pending_* regsets, this variable specifies whether
> +   the current insn analyzed by sched_analyze_insn() is a scheduling
> +   barrier that should "split" dependencies inside a block.  Internally
> +   sched-deps.cc does this by pretending that the barrier insn uses and
> +   sets all registers.
> +   Near the end sched_analyze_insn() transfers barrier info from this
> variable
> +   into deps->last_reg_pending_barrier.  */
>  static enum reg_pending_barrier_mode reg_pending_barrier;
>
>  /* Hard registers implicitly clobbered or used (or may be implicitly
> @@ -2880,7 +2895,77 @@ get_implicit_reg_pending_clobbers (HARD_REG_SET
> *temp, rtx_insn *insn)
>    *temp &= ~ira_no_alloc_regs;
>  }
>
> -/* Analyze an INSN with pattern X to find all dependencies.  */
> +/* Dump state of reg_pending_* data for debug purposes.
> +   Dump only non-empty data to reduce log clobber.  */
> +static void
> +dump_reg_pending_data (FILE *file, rtx_insn *insn)
> +{
> +  fprintf (file, "\n");
> +  fprintf (file, ";; sched_analysis after insn %d: %s\n",
> +          INSN_UID (insn), str_pattern_slim (PATTERN (insn)));
> +
> +  if (!REG_SET_EMPTY_P (reg_pending_sets)
> +      || !REG_SET_EMPTY_P (reg_pending_clobbers)
> +      || !REG_SET_EMPTY_P (reg_pending_uses)
> +      || !REG_SET_EMPTY_P (reg_pending_control_uses))
> +    {
> +      fprintf (file, ";; insn reg");
> +      if (!REG_SET_EMPTY_P (reg_pending_sets))
> +       {
> +         fprintf (file, " sets(");
> +         dump_regset (reg_pending_sets, file);
> +         fprintf (file, ")");
> +       }
> +      if (!REG_SET_EMPTY_P (reg_pending_clobbers))
> +       {
> +         fprintf (file, " clobbers(");
> +         dump_regset (reg_pending_clobbers, file);
> +         fprintf (file, ")");
> +       }
> +      if (!REG_SET_EMPTY_P (reg_pending_uses))
> +       {
> +         fprintf (file, " uses(");
> +         dump_regset (reg_pending_uses, file);
> +         fprintf (file, ")");
> +       }
> +      if (!REG_SET_EMPTY_P (reg_pending_control_uses))
> +       {
> +         fprintf (file, " control(");
> +         dump_regset (reg_pending_control_uses, file);
> +         fprintf (file, ")");
> +       }
> +      fprintf (file, "\n");
> +    }
> +
> +  if (reg_pending_barrier)
> +    fprintf (file, ";; insn reg barrier: %d\n", reg_pending_barrier);
> +
> +  if (!hard_reg_set_empty_p (implicit_reg_pending_clobbers)
> +      || !hard_reg_set_empty_p (implicit_reg_pending_uses))
> +    {
> +      fprintf (file, ";; insn reg");
> +      if (!hard_reg_set_empty_p (implicit_reg_pending_clobbers))
> +       {
> +         print_hard_reg_set (file, implicit_reg_pending_clobbers,
> +                             " implicit clobbers(", false);
> +         fprintf (file, ")");
> +       }
> +      if (!hard_reg_set_empty_p (implicit_reg_pending_uses))
> +       {
> +         print_hard_reg_set (file, implicit_reg_pending_uses,
> +                             " implicit uses(", false);
> +         fprintf (file, ")");
> +       }
> +      fprintf (file, "\n");
> +    }
> +}
> +
> +/* Analyze an INSN with pattern X to find all dependencies.
> +   This analysis uses two main data structures:
> +   1. reg_pending_* data contains effects of INSN on the register file,
> +      which is then incorporated into ...
> +   2. deps_desc object, which contains commulative information about all
> +      instructions processed from deps_desc object's initialization.  */
>  static void
>  sched_analyze_insn (class deps_desc *deps, rtx x, rtx_insn *insn)
>  {
> @@ -3328,6 +3413,9 @@ sched_analyze_insn (class deps_desc *deps, rtx x,
> rtx_insn *insn)
>        deps->last_reg_pending_barrier = reg_pending_barrier;
>      }
>
> +  if (sched_verbose >= 8)
> +    dump_reg_pending_data (sched_dump, insn);
> +
>    CLEAR_REG_SET (reg_pending_uses);
>    CLEAR_REG_SET (reg_pending_clobbers);
>    CLEAR_REG_SET (reg_pending_sets);
> --
> 2.34.1
>
>

-- 
Maxim Kuvyrkov
www.linaro.org