[v2] sched: Change no_real_insns_p to no_real_nondebug_insns_p [PR108273]

  Hi,

By addressing Alexander's comments, against v1 this
patch v2 mainly:

  - Rename no_real_insns_p to no_real_nondebug_insns_p;
  - Introduce enum rgn_bb_deps_free_action for three
    kinds of actions to free deps;
  - Change function free_deps_for_bb_no_real_insns_p to
    resolve_forw_deps which only focuses on forward deps;
  - Extend the handlings to cover dbg-cnt sched_block,
    add one test case for it;
  - Move free_trg_info call in schedule_region to an
    appropriate place.

One thing I'm not sure about is the change in function
sched_rgn_local_finish, currently the invocation to
sched_rgn_local_free is guarded with !sel_sched_p (),
so I just follow it, but the initialization of those
structures (in sched_rgn_local_init) isn't guarded
with !sel_sched_p (), it looks odd.

----

As PR108273 shows, when there is one block which only has
NOTE_P and LABEL_P insns at non-debug mode while has some
extra DEBUG_INSN_P insns at debug mode, after scheduling
it, the DFA states would be different between debug mode
and non-debug mode.  Since at non-debug mode, the block
meets no_real_insns_p, it gets skipped; while at debug
mode, it gets scheduled, even it only has NOTE_P, LABEL_P
and DEBUG_INSN_P, the call of function advance_one_cycle
will change the DFA state.  PR108519 also shows this issue
issue can be exposed by some scheduler changes.

This patch is to change function no_real_insns_p to
function no_real_nondebug_insns_p by taking debug insn into
account, which make us not try to schedule for the block
having only NOTE_P, LABEL_P and DEBUG_INSN_P insns,
resulting in consistent DFA states between non-debug and
debug mode.

Changing no_real_insns_p to no_real_nondebug_insns_p caused
ICE when doing free_block_dependencies, the root cause is
that we create dependencies for debug insns, those
dependencies are expected to be resolved during scheduling
insns, but which gets skipped after this change.
By checking the code, it looks it's reasonable to skip to
compute block dependences for no_real_nondebug_insns_p
blocks.  There is also another issue, which gets exposed
in SPEC2017 bmks build at option -O2 -g, is that we could
skip to schedule some block, which already gets dependency
graph built so has dependencies computed and rgn_n_insns
accumulated, then the later verification on if the graph
becomes exhausted by scheduling would fail as follow:

  /* Sanity check: verify that all region insns were
     scheduled.  */
    gcc_assert (sched_rgn_n_insns == rgn_n_insns);

, and also some forward deps aren't resovled.

As Alexander pointed out, the current debug count handling
also suffers the similar issue, so this patch handles these
two cases together: one is for some block gets skipped by
!dbg_cnt (sched_block), the other is for some block which
is not no_real_nondebug_insns_p initially but becomes
no_real_nondebug_insns_p due to speculative scheduling.

This patch can be bootstrapped and regress-tested on
x86_64-redhat-linux, aarch64-linux-gnu and
powerpc64{,le}-linux-gnu.

I also verified this patch can pass SPEC2017 both intrate
and fprate bmks building at -g -O2/-O3.

Any thoughts?

BR,
Kewen
----
	PR rtl-optimization/108273

gcc/ChangeLog:

	* haifa-sched.cc (no_real_insns_p): Rename to ...
	(no_real_nondebug_insns_p): ... this, and consider DEBUG_INSN_P insn.
	* sched-ebb.cc (schedule_ebb): Replace no_real_insns_p with
	no_real_nondebug_insns_p.
	* sched-int.h (no_real_insns_p): Rename to ...
	(no_real_nondebug_insns_p): ... this.
	* sched-rgn.cc (enum rgn_bb_deps_free_action): New enum.
	(bb_deps_free_actions): New static variable.
	(compute_block_dependences): Skip for no_real_nondebug_insns_p.
	(resolve_forw_deps): New function.
	(free_block_dependencies): Check bb_deps_free_actions and call
	function resolve_forw_deps for RGN_BB_DEPS_FREE_ARTICIAL.
	(compute_priorities): Replace no_real_insns_p with
	no_real_nondebug_insns_p.
	(schedule_region): Replace no_real_insns_p with
	no_real_nondebug_insns_p, set RGN_BB_DEPS_FREE_ARTICIAL if the block
	get dependencies computed before but skipped now, fix up count
	sched_rgn_n_insns for it too.  Call free_trg_info when the block
	gets scheduled, and move sched_rgn_local_finish after the loop
	of free_block_dependencies loop.
	(sched_rgn_local_init): Allocate and compute bb_deps_free_actions.
	(sched_rgn_local_finish): Free bb_deps_free_actions.
	* sel-sched.cc (sel_region_target_finish): Replace no_real_insns_p with
	no_real_nondebug_insns_p.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/pr108273.c: New test.
---
 gcc/haifa-sched.cc                          |   9 +-
 gcc/sched-ebb.cc                            |   2 +-
 gcc/sched-int.h                             |   2 +-
 gcc/sched-rgn.cc                            | 148 +++++++++++++++-----
 gcc/sel-sched.cc                            |   3 +-
 gcc/testsuite/gcc.target/powerpc/pr108273.c |  26 ++++
 6 files changed, 150 insertions(+), 40 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/pr108273.c

--
2.25.1
  

Hi,

I'd like to gentle ping this patch:

https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614818.html

BR,
Kewen

on 2023/3/29 15:18, Kewen.Lin via Gcc-patches wrote:
> Hi,
> 
> By addressing Alexander's comments, against v1 this
> patch v2 mainly:
> 
>   - Rename no_real_insns_p to no_real_nondebug_insns_p;
>   - Introduce enum rgn_bb_deps_free_action for three
>     kinds of actions to free deps;
>   - Change function free_deps_for_bb_no_real_insns_p to
>     resolve_forw_deps which only focuses on forward deps;
>   - Extend the handlings to cover dbg-cnt sched_block,
>     add one test case for it;
>   - Move free_trg_info call in schedule_region to an
>     appropriate place.
> 
> One thing I'm not sure about is the change in function
> sched_rgn_local_finish, currently the invocation to
> sched_rgn_local_free is guarded with !sel_sched_p (),
> so I just follow it, but the initialization of those
> structures (in sched_rgn_local_init) isn't guarded
> with !sel_sched_p (), it looks odd.
> 
> ----
> 
> As PR108273 shows, when there is one block which only has
> NOTE_P and LABEL_P insns at non-debug mode while has some
> extra DEBUG_INSN_P insns at debug mode, after scheduling
> it, the DFA states would be different between debug mode
> and non-debug mode.  Since at non-debug mode, the block
> meets no_real_insns_p, it gets skipped; while at debug
> mode, it gets scheduled, even it only has NOTE_P, LABEL_P
> and DEBUG_INSN_P, the call of function advance_one_cycle
> will change the DFA state.  PR108519 also shows this issue
> issue can be exposed by some scheduler changes.
> 
> This patch is to change function no_real_insns_p to
> function no_real_nondebug_insns_p by taking debug insn into
> account, which make us not try to schedule for the block
> having only NOTE_P, LABEL_P and DEBUG_INSN_P insns,
> resulting in consistent DFA states between non-debug and
> debug mode.
> 
> Changing no_real_insns_p to no_real_nondebug_insns_p caused
> ICE when doing free_block_dependencies, the root cause is
> that we create dependencies for debug insns, those
> dependencies are expected to be resolved during scheduling
> insns, but which gets skipped after this change.
> By checking the code, it looks it's reasonable to skip to
> compute block dependences for no_real_nondebug_insns_p
> blocks.  There is also another issue, which gets exposed
> in SPEC2017 bmks build at option -O2 -g, is that we could
> skip to schedule some block, which already gets dependency
> graph built so has dependencies computed and rgn_n_insns
> accumulated, then the later verification on if the graph
> becomes exhausted by scheduling would fail as follow:
> 
>   /* Sanity check: verify that all region insns were
>      scheduled.  */
>     gcc_assert (sched_rgn_n_insns == rgn_n_insns);
> 
> , and also some forward deps aren't resovled.
> 
> As Alexander pointed out, the current debug count handling
> also suffers the similar issue, so this patch handles these
> two cases together: one is for some block gets skipped by
> !dbg_cnt (sched_block), the other is for some block which
> is not no_real_nondebug_insns_p initially but becomes
> no_real_nondebug_insns_p due to speculative scheduling.
> 
> This patch can be bootstrapped and regress-tested on
> x86_64-redhat-linux, aarch64-linux-gnu and
> powerpc64{,le}-linux-gnu.
> 
> I also verified this patch can pass SPEC2017 both intrate
> and fprate bmks building at -g -O2/-O3.
> 
> Any thoughts?
> 
> BR,
> Kewen
> ----
> 	PR rtl-optimization/108273
> 
> gcc/ChangeLog:
> 
> 	* haifa-sched.cc (no_real_insns_p): Rename to ...
> 	(no_real_nondebug_insns_p): ... this, and consider DEBUG_INSN_P insn.
> 	* sched-ebb.cc (schedule_ebb): Replace no_real_insns_p with
> 	no_real_nondebug_insns_p.
> 	* sched-int.h (no_real_insns_p): Rename to ...
> 	(no_real_nondebug_insns_p): ... this.
> 	* sched-rgn.cc (enum rgn_bb_deps_free_action): New enum.
> 	(bb_deps_free_actions): New static variable.
> 	(compute_block_dependences): Skip for no_real_nondebug_insns_p.
> 	(resolve_forw_deps): New function.
> 	(free_block_dependencies): Check bb_deps_free_actions and call
> 	function resolve_forw_deps for RGN_BB_DEPS_FREE_ARTICIAL.
> 	(compute_priorities): Replace no_real_insns_p with
> 	no_real_nondebug_insns_p.
> 	(schedule_region): Replace no_real_insns_p with
> 	no_real_nondebug_insns_p, set RGN_BB_DEPS_FREE_ARTICIAL if the block
> 	get dependencies computed before but skipped now, fix up count
> 	sched_rgn_n_insns for it too.  Call free_trg_info when the block
> 	gets scheduled, and move sched_rgn_local_finish after the loop
> 	of free_block_dependencies loop.
> 	(sched_rgn_local_init): Allocate and compute bb_deps_free_actions.
> 	(sched_rgn_local_finish): Free bb_deps_free_actions.
> 	* sel-sched.cc (sel_region_target_finish): Replace no_real_insns_p with
> 	no_real_nondebug_insns_p.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.target/powerpc/pr108273.c: New test.
> ---
>  gcc/haifa-sched.cc                          |   9 +-
>  gcc/sched-ebb.cc                            |   2 +-
>  gcc/sched-int.h                             |   2 +-
>  gcc/sched-rgn.cc                            | 148 +++++++++++++++-----
>  gcc/sel-sched.cc                            |   3 +-
>  gcc/testsuite/gcc.target/powerpc/pr108273.c |  26 ++++
>  6 files changed, 150 insertions(+), 40 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr108273.c
> 
> diff --git a/gcc/haifa-sched.cc b/gcc/haifa-sched.cc
> index 48b53776fa9..371de486eb0 100644
> --- a/gcc/haifa-sched.cc
> +++ b/gcc/haifa-sched.cc
> @@ -5033,14 +5033,17 @@ get_ebb_head_tail (basic_block beg, basic_block end,
>    *tailp = end_tail;
>  }
> 
> -/* Return nonzero if there are no real insns in the range [ HEAD, TAIL ].  */
> +/* Return nonzero if there are no real nondebug insns in the range
> +   [ HEAD, TAIL ].  */
> 
>  int
> -no_real_insns_p (const rtx_insn *head, const rtx_insn *tail)
> +no_real_nondebug_insns_p (const rtx_insn *head, const rtx_insn *tail)
>  {
>    while (head != NEXT_INSN (tail))
>      {
> -      if (!NOTE_P (head) && !LABEL_P (head))
> +      if (!NOTE_P (head)
> +	  && !LABEL_P (head)
> +	  && !DEBUG_INSN_P (head))
>  	return 0;
>        head = NEXT_INSN (head);
>      }
> diff --git a/gcc/sched-ebb.cc b/gcc/sched-ebb.cc
> index 3eb6a24f187..e3bb0d57159 100644
> --- a/gcc/sched-ebb.cc
> +++ b/gcc/sched-ebb.cc
> @@ -491,7 +491,7 @@ schedule_ebb (rtx_insn *head, rtx_insn *tail, bool modulo_scheduling)
>    first_bb = BLOCK_FOR_INSN (head);
>    last_bb = BLOCK_FOR_INSN (tail);
> 
> -  if (no_real_insns_p (head, tail))
> +  if (no_real_nondebug_insns_p (head, tail))
>      return BLOCK_FOR_INSN (tail);
> 
>    gcc_assert (INSN_P (head) && INSN_P (tail));
> diff --git a/gcc/sched-int.h b/gcc/sched-int.h
> index 97b7d2d319b..eb4e8acec9f 100644
> --- a/gcc/sched-int.h
> +++ b/gcc/sched-int.h
> @@ -1397,7 +1397,7 @@ extern void free_global_sched_pressure_data (void);
>  extern int haifa_classify_insn (const_rtx);
>  extern void get_ebb_head_tail (basic_block, basic_block,
>  			       rtx_insn **, rtx_insn **);
> -extern int no_real_insns_p (const rtx_insn *, const rtx_insn *);
> +extern int no_real_nondebug_insns_p (const rtx_insn *, const rtx_insn *);
> 
>  extern int insn_sched_cost (rtx_insn *);
>  extern int dep_cost_1 (dep_t, dw_t);
> diff --git a/gcc/sched-rgn.cc b/gcc/sched-rgn.cc
> index f2751f62450..3508a26aeb6 100644
> --- a/gcc/sched-rgn.cc
> +++ b/gcc/sched-rgn.cc
> @@ -213,6 +213,22 @@ static int rgn_nr_edges;
>  /* Array of size rgn_nr_edges.  */
>  static edge *rgn_edges;
> 
> +/* Possible actions for dependencies freeing.  */
> +enum rgn_bb_deps_free_action
> +{
> +  /* This block doesn't get dependencies computed so don't need to free.  */
> +  RGN_BB_DEPS_FREE_NO,
> +  /* This block gets scheduled normally so free dependencies as usual.  */
> +  RGN_BB_DEPS_FREE_NORMAL,
> +  /* This block gets skipped in scheduling but has dependencies computed early,
> +     need to free the forward list articially.  */
> +  RGN_BB_DEPS_FREE_ARTICIAL
> +};
> +
> +/* For basic block i, bb_deps_free_actions[i] indicates which action needs
> +   to be taken for freeing its dependencies.  */
> +static enum rgn_bb_deps_free_action *bb_deps_free_actions;
> +
>  /* Mapping from each edge in the graph to its number in the rgn.  */
>  #define EDGE_TO_BIT(edge) ((int)(size_t)(edge)->aux)
>  #define SET_EDGE_TO_BIT(edge,nr) ((edge)->aux = (void *)(size_t)(nr))
> @@ -2730,6 +2746,15 @@ compute_block_dependences (int bb)
>    gcc_assert (EBB_FIRST_BB (bb) == EBB_LAST_BB (bb));
>    get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
> 
> +  /* Don't compute block dependencies if there are no real nondebug insns.  */
> +  if (no_real_nondebug_insns_p (head, tail))
> +    {
> +      if (current_nr_blocks > 1)
> +	propagate_deps (bb, &tmp_deps);
> +      free_deps (&tmp_deps);
> +      return;
> +    }
> +
>    sched_analyze (&tmp_deps, head, tail);
> 
>    add_branch_dependences (head, tail);
> @@ -2744,6 +2769,24 @@ compute_block_dependences (int bb)
>      targetm.sched.dependencies_evaluation_hook (head, tail);
>  }
> 
> +/* Artificially resolve forward dependencies for instructions HEAD to TAIL.  */
> +
> +static void
> +resolve_forw_deps (rtx_insn *head, rtx_insn *tail)
> +{
> +  rtx_insn *insn;
> +  rtx_insn *next_tail = NEXT_INSN (tail);
> +  sd_iterator_def sd_it;
> +  dep_t dep;
> +
> +  /* There could be some insns which get skipped in scheduling but we compute
> +     dependencies for them previously, so make them resolved.  */
> +  for (insn = head; insn != next_tail; insn = NEXT_INSN (insn))
> +    for (sd_it = sd_iterator_start (insn, SD_LIST_FORW);
> +	 sd_iterator_cond (&sd_it, &dep);)
> +      sd_resolve_dep (sd_it);
> +}
> +
>  /* Free dependencies of instructions inside BB.  */
>  static void
>  free_block_dependencies (int bb)
> @@ -2753,9 +2796,12 @@ free_block_dependencies (int bb)
> 
>    get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
> 
> -  if (no_real_insns_p (head, tail))
> +  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_NO)
>      return;
> 
> +  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_ARTICIAL)
> +    resolve_forw_deps (head, tail);
> +
>    sched_free_deps (head, tail, true);
>  }
> 
> @@ -3019,7 +3065,7 @@ compute_priorities (void)
>        gcc_assert (EBB_FIRST_BB (bb) == EBB_LAST_BB (bb));
>        get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
> 
> -      if (no_real_insns_p (head, tail))
> +      if (no_real_nondebug_insns_p (head, tail))
>  	continue;
> 
>        rgn_n_insns += set_priorities (head, tail);
> @@ -3153,7 +3199,7 @@ schedule_region (int rgn)
> 
>  	  get_ebb_head_tail (first_bb, last_bb, &head, &tail);
> 
> -	  if (no_real_insns_p (head, tail))
> +	  if (no_real_nondebug_insns_p (head, tail))
>  	    {
>  	      gcc_assert (first_bb == last_bb);
>  	      continue;
> @@ -3173,44 +3219,62 @@ schedule_region (int rgn)
> 
>        get_ebb_head_tail (first_bb, last_bb, &head, &tail);
> 
> -      if (no_real_insns_p (head, tail))
> +      if (no_real_nondebug_insns_p (head, tail))
>  	{
>  	  gcc_assert (first_bb == last_bb);
>  	  save_state_for_fallthru_edge (last_bb, bb_state[first_bb->index]);
> -	  continue;
> +
> +	  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_NO)
> +	    continue;
> +
> +	  /* As it's not no_real_nondebug_insns_p initially, then it has some
> +	     dependencies computed so free it articially.  */
> +	  bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_ARTICIAL;
>  	}
> +      else
> +	{
> +	  current_sched_info->prev_head = PREV_INSN (head);
> +	  current_sched_info->next_tail = NEXT_INSN (tail);
> 
> -      current_sched_info->prev_head = PREV_INSN (head);
> -      current_sched_info->next_tail = NEXT_INSN (tail);
> +	  remove_notes (head, tail);
> 
> -      remove_notes (head, tail);
> +	  unlink_bb_notes (first_bb, last_bb);
> 
> -      unlink_bb_notes (first_bb, last_bb);
> +	  target_bb = bb;
> 
> -      target_bb = bb;
> +	  gcc_assert (flag_schedule_interblock || current_nr_blocks == 1);
> +	  current_sched_info->queue_must_finish_empty = current_nr_blocks == 1;
> 
> -      gcc_assert (flag_schedule_interblock || current_nr_blocks == 1);
> -      current_sched_info->queue_must_finish_empty = current_nr_blocks == 1;
> +	  curr_bb = first_bb;
> +	  if (dbg_cnt (sched_block))
> +	    {
> +	      int saved_last_basic_block = last_basic_block_for_fn (cfun);
> 
> -      curr_bb = first_bb;
> -      if (dbg_cnt (sched_block))
> -        {
> -	  int saved_last_basic_block = last_basic_block_for_fn (cfun);
> +	      schedule_block (&curr_bb, bb_state[first_bb->index]);
> +	      gcc_assert (EBB_FIRST_BB (bb) == first_bb);
> +	      sched_rgn_n_insns += sched_n_insns;
> +	      realloc_bb_state_array (saved_last_basic_block);
> +	      save_state_for_fallthru_edge (last_bb, curr_state);
> 
> -	  schedule_block (&curr_bb, bb_state[first_bb->index]);
> -	  gcc_assert (EBB_FIRST_BB (bb) == first_bb);
> -	  sched_rgn_n_insns += sched_n_insns;
> -	  realloc_bb_state_array (saved_last_basic_block);
> -	  save_state_for_fallthru_edge (last_bb, curr_state);
> -        }
> -      else
> -        {
> -          sched_rgn_n_insns += rgn_n_insns;
> -        }
> +	      /* Clean up.  */
> +	      if (current_nr_blocks > 1)
> +		free_trg_info ();
> +	    }
> +	  else
> +	    bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_ARTICIAL;
> +	}
> 
> -      /* Clean up.  */
> -      if (current_nr_blocks > 1)
> -	free_trg_info ();
> +      /* We have counted this block when computing rgn_n_insns
> +	 previously, so need to fix up sched_rgn_n_insns now.  */
> +      if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_ARTICIAL)
> +	{
> +	  while (head != NEXT_INSN (tail))
> +	    {
> +	      if (INSN_P (head))
> +		sched_rgn_n_insns++;
> +	      head = NEXT_INSN (head);
> +	    }
> +	}
>      }
> 
>    /* Sanity check: verify that all region insns were scheduled.  */
> @@ -3218,13 +3282,13 @@ schedule_region (int rgn)
> 
>    sched_finish_ready_list ();
> 
> -  /* Done with this region.  */
> -  sched_rgn_local_finish ();
> -
>    /* Free dependencies.  */
>    for (bb = 0; bb < current_nr_blocks; ++bb)
>      free_block_dependencies (bb);
> 
> +  /* Done with this region.  */
> +  sched_rgn_local_finish ();
> +
>    gcc_assert (haifa_recovery_bb_ever_added_p
>  	      || deps_pools_are_empty_p ());
>  }
> @@ -3445,6 +3509,19 @@ sched_rgn_local_init (int rgn)
>  	    e->aux = NULL;
>          }
>      }
> +
> +  /* Initialize bb_deps_free_actions.  */
> +  bb_deps_free_actions
> +    = XNEWVEC (enum rgn_bb_deps_free_action, current_nr_blocks);
> +  for (bb = 0; bb < current_nr_blocks; bb++)
> +    {
> +      rtx_insn *head, *tail;
> +      get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
> +      if (no_real_nondebug_insns_p (head, tail))
> +	bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_NO;
> +      else
> +	bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_NORMAL;
> +    }
>  }
> 
>  /* Free data computed for the finished region.  */
> @@ -3462,9 +3539,12 @@ sched_rgn_local_free (void)
>  void
>  sched_rgn_local_finish (void)
>  {
> -  if (current_nr_blocks > 1 && !sel_sched_p ())
> +  if (!sel_sched_p ())
>      {
> -      sched_rgn_local_free ();
> +      if (current_nr_blocks > 1)
> +	sched_rgn_local_free ();
> +
> +      free (bb_deps_free_actions);
>      }
>  }
> 
> diff --git a/gcc/sel-sched.cc b/gcc/sel-sched.cc
> index cb1cf75bfe4..04415590455 100644
> --- a/gcc/sel-sched.cc
> +++ b/gcc/sel-sched.cc
> @@ -7213,7 +7213,8 @@ sel_region_target_finish (bool reset_sched_cycles_p)
> 
>        find_ebb_boundaries (EBB_FIRST_BB (i), scheduled_blocks);
> 
> -      if (no_real_insns_p (current_sched_info->head, current_sched_info->tail))
> +      if (no_real_nondebug_insns_p (current_sched_info->head,
> +				    current_sched_info->tail))
>  	continue;
> 
>        if (reset_sched_cycles_p)
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr108273.c b/gcc/testsuite/gcc.target/powerpc/pr108273.c
> new file mode 100644
> index 00000000000..937224eaa69
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr108273.c
> @@ -0,0 +1,26 @@
> +/* { dg-options "-O2 -fdbg-cnt=sched_block:1" } */
> +/* { dg-prune-output {\*\*\*dbgcnt:.*limit.*reached} } */
> +
> +/* Verify there is no ICE.  */
> +
> +int a, b, c, e, f;
> +float d;
> +
> +void
> +g ()
> +{
> +  float h, i[1];
> +  for (; f;)
> +    if (c)
> +      {
> +	d *e;
> +	if (b)
> +	  {
> +	    float *j = i;
> +	    j[0] += 0;
> +	  }
> +	h += d;
> +      }
> +  if (h)
> +    a = i[0];
> +}
> --
> 2.25.1
  

Hi,

I'd like to gentle ping this patch:

https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614818.html

BR,
Kewen

> on 2023/3/29 15:18, Kewen.Lin via Gcc-patches wrote:
>> Hi,
>>
>> By addressing Alexander's comments, against v1 this
>> patch v2 mainly:
>>
>>   - Rename no_real_insns_p to no_real_nondebug_insns_p;
>>   - Introduce enum rgn_bb_deps_free_action for three
>>     kinds of actions to free deps;
>>   - Change function free_deps_for_bb_no_real_insns_p to
>>     resolve_forw_deps which only focuses on forward deps;
>>   - Extend the handlings to cover dbg-cnt sched_block,
>>     add one test case for it;
>>   - Move free_trg_info call in schedule_region to an
>>     appropriate place.
>>
>> One thing I'm not sure about is the change in function
>> sched_rgn_local_finish, currently the invocation to
>> sched_rgn_local_free is guarded with !sel_sched_p (),
>> so I just follow it, but the initialization of those
>> structures (in sched_rgn_local_init) isn't guarded
>> with !sel_sched_p (), it looks odd.
>>
>> ----
>>
>> As PR108273 shows, when there is one block which only has
>> NOTE_P and LABEL_P insns at non-debug mode while has some
>> extra DEBUG_INSN_P insns at debug mode, after scheduling
>> it, the DFA states would be different between debug mode
>> and non-debug mode.  Since at non-debug mode, the block
>> meets no_real_insns_p, it gets skipped; while at debug
>> mode, it gets scheduled, even it only has NOTE_P, LABEL_P
>> and DEBUG_INSN_P, the call of function advance_one_cycle
>> will change the DFA state.  PR108519 also shows this issue
>> issue can be exposed by some scheduler changes.
>>
>> This patch is to change function no_real_insns_p to
>> function no_real_nondebug_insns_p by taking debug insn into
>> account, which make us not try to schedule for the block
>> having only NOTE_P, LABEL_P and DEBUG_INSN_P insns,
>> resulting in consistent DFA states between non-debug and
>> debug mode.
>>
>> Changing no_real_insns_p to no_real_nondebug_insns_p caused
>> ICE when doing free_block_dependencies, the root cause is
>> that we create dependencies for debug insns, those
>> dependencies are expected to be resolved during scheduling
>> insns, but which gets skipped after this change.
>> By checking the code, it looks it's reasonable to skip to
>> compute block dependences for no_real_nondebug_insns_p
>> blocks.  There is also another issue, which gets exposed
>> in SPEC2017 bmks build at option -O2 -g, is that we could
>> skip to schedule some block, which already gets dependency
>> graph built so has dependencies computed and rgn_n_insns
>> accumulated, then the later verification on if the graph
>> becomes exhausted by scheduling would fail as follow:
>>
>>   /* Sanity check: verify that all region insns were
>>      scheduled.  */
>>     gcc_assert (sched_rgn_n_insns == rgn_n_insns);
>>
>> , and also some forward deps aren't resovled.
>>
>> As Alexander pointed out, the current debug count handling
>> also suffers the similar issue, so this patch handles these
>> two cases together: one is for some block gets skipped by
>> !dbg_cnt (sched_block), the other is for some block which
>> is not no_real_nondebug_insns_p initially but becomes
>> no_real_nondebug_insns_p due to speculative scheduling.
>>
>> This patch can be bootstrapped and regress-tested on
>> x86_64-redhat-linux, aarch64-linux-gnu and
>> powerpc64{,le}-linux-gnu.
>>
>> I also verified this patch can pass SPEC2017 both intrate
>> and fprate bmks building at -g -O2/-O3.
>>
>> Any thoughts?
>>
>> BR,
>> Kewen
>> ----
>> 	PR rtl-optimization/108273
>>
>> gcc/ChangeLog:
>>
>> 	* haifa-sched.cc (no_real_insns_p): Rename to ...
>> 	(no_real_nondebug_insns_p): ... this, and consider DEBUG_INSN_P insn.
>> 	* sched-ebb.cc (schedule_ebb): Replace no_real_insns_p with
>> 	no_real_nondebug_insns_p.
>> 	* sched-int.h (no_real_insns_p): Rename to ...
>> 	(no_real_nondebug_insns_p): ... this.
>> 	* sched-rgn.cc (enum rgn_bb_deps_free_action): New enum.
>> 	(bb_deps_free_actions): New static variable.
>> 	(compute_block_dependences): Skip for no_real_nondebug_insns_p.
>> 	(resolve_forw_deps): New function.
>> 	(free_block_dependencies): Check bb_deps_free_actions and call
>> 	function resolve_forw_deps for RGN_BB_DEPS_FREE_ARTICIAL.
>> 	(compute_priorities): Replace no_real_insns_p with
>> 	no_real_nondebug_insns_p.
>> 	(schedule_region): Replace no_real_insns_p with
>> 	no_real_nondebug_insns_p, set RGN_BB_DEPS_FREE_ARTICIAL if the block
>> 	get dependencies computed before but skipped now, fix up count
>> 	sched_rgn_n_insns for it too.  Call free_trg_info when the block
>> 	gets scheduled, and move sched_rgn_local_finish after the loop
>> 	of free_block_dependencies loop.
>> 	(sched_rgn_local_init): Allocate and compute bb_deps_free_actions.
>> 	(sched_rgn_local_finish): Free bb_deps_free_actions.
>> 	* sel-sched.cc (sel_region_target_finish): Replace no_real_insns_p with
>> 	no_real_nondebug_insns_p.
>>
>> gcc/testsuite/ChangeLog:
>>
>> 	* gcc.target/powerpc/pr108273.c: New test.
>> ---
>>  gcc/haifa-sched.cc                          |   9 +-
>>  gcc/sched-ebb.cc                            |   2 +-
>>  gcc/sched-int.h                             |   2 +-
>>  gcc/sched-rgn.cc                            | 148 +++++++++++++++-----
>>  gcc/sel-sched.cc                            |   3 +-
>>  gcc/testsuite/gcc.target/powerpc/pr108273.c |  26 ++++
>>  6 files changed, 150 insertions(+), 40 deletions(-)
>>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr108273.c
>>
>> diff --git a/gcc/haifa-sched.cc b/gcc/haifa-sched.cc
>> index 48b53776fa9..371de486eb0 100644
>> --- a/gcc/haifa-sched.cc
>> +++ b/gcc/haifa-sched.cc
>> @@ -5033,14 +5033,17 @@ get_ebb_head_tail (basic_block beg, basic_block end,
>>    *tailp = end_tail;
>>  }
>>
>> -/* Return nonzero if there are no real insns in the range [ HEAD, TAIL ].  */
>> +/* Return nonzero if there are no real nondebug insns in the range
>> +   [ HEAD, TAIL ].  */
>>
>>  int
>> -no_real_insns_p (const rtx_insn *head, const rtx_insn *tail)
>> +no_real_nondebug_insns_p (const rtx_insn *head, const rtx_insn *tail)
>>  {
>>    while (head != NEXT_INSN (tail))
>>      {
>> -      if (!NOTE_P (head) && !LABEL_P (head))
>> +      if (!NOTE_P (head)
>> +	  && !LABEL_P (head)
>> +	  && !DEBUG_INSN_P (head))
>>  	return 0;
>>        head = NEXT_INSN (head);
>>      }
>> diff --git a/gcc/sched-ebb.cc b/gcc/sched-ebb.cc
>> index 3eb6a24f187..e3bb0d57159 100644
>> --- a/gcc/sched-ebb.cc
>> +++ b/gcc/sched-ebb.cc
>> @@ -491,7 +491,7 @@ schedule_ebb (rtx_insn *head, rtx_insn *tail, bool modulo_scheduling)
>>    first_bb = BLOCK_FOR_INSN (head);
>>    last_bb = BLOCK_FOR_INSN (tail);
>>
>> -  if (no_real_insns_p (head, tail))
>> +  if (no_real_nondebug_insns_p (head, tail))
>>      return BLOCK_FOR_INSN (tail);
>>
>>    gcc_assert (INSN_P (head) && INSN_P (tail));
>> diff --git a/gcc/sched-int.h b/gcc/sched-int.h
>> index 97b7d2d319b..eb4e8acec9f 100644
>> --- a/gcc/sched-int.h
>> +++ b/gcc/sched-int.h
>> @@ -1397,7 +1397,7 @@ extern void free_global_sched_pressure_data (void);
>>  extern int haifa_classify_insn (const_rtx);
>>  extern void get_ebb_head_tail (basic_block, basic_block,
>>  			       rtx_insn **, rtx_insn **);
>> -extern int no_real_insns_p (const rtx_insn *, const rtx_insn *);
>> +extern int no_real_nondebug_insns_p (const rtx_insn *, const rtx_insn *);
>>
>>  extern int insn_sched_cost (rtx_insn *);
>>  extern int dep_cost_1 (dep_t, dw_t);
>> diff --git a/gcc/sched-rgn.cc b/gcc/sched-rgn.cc
>> index f2751f62450..3508a26aeb6 100644
>> --- a/gcc/sched-rgn.cc
>> +++ b/gcc/sched-rgn.cc
>> @@ -213,6 +213,22 @@ static int rgn_nr_edges;
>>  /* Array of size rgn_nr_edges.  */
>>  static edge *rgn_edges;
>>
>> +/* Possible actions for dependencies freeing.  */
>> +enum rgn_bb_deps_free_action
>> +{
>> +  /* This block doesn't get dependencies computed so don't need to free.  */
>> +  RGN_BB_DEPS_FREE_NO,
>> +  /* This block gets scheduled normally so free dependencies as usual.  */
>> +  RGN_BB_DEPS_FREE_NORMAL,
>> +  /* This block gets skipped in scheduling but has dependencies computed early,
>> +     need to free the forward list articially.  */
>> +  RGN_BB_DEPS_FREE_ARTICIAL
>> +};
>> +
>> +/* For basic block i, bb_deps_free_actions[i] indicates which action needs
>> +   to be taken for freeing its dependencies.  */
>> +static enum rgn_bb_deps_free_action *bb_deps_free_actions;
>> +
>>  /* Mapping from each edge in the graph to its number in the rgn.  */
>>  #define EDGE_TO_BIT(edge) ((int)(size_t)(edge)->aux)
>>  #define SET_EDGE_TO_BIT(edge,nr) ((edge)->aux = (void *)(size_t)(nr))
>> @@ -2730,6 +2746,15 @@ compute_block_dependences (int bb)
>>    gcc_assert (EBB_FIRST_BB (bb) == EBB_LAST_BB (bb));
>>    get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>
>> +  /* Don't compute block dependencies if there are no real nondebug insns.  */
>> +  if (no_real_nondebug_insns_p (head, tail))
>> +    {
>> +      if (current_nr_blocks > 1)
>> +	propagate_deps (bb, &tmp_deps);
>> +      free_deps (&tmp_deps);
>> +      return;
>> +    }
>> +
>>    sched_analyze (&tmp_deps, head, tail);
>>
>>    add_branch_dependences (head, tail);
>> @@ -2744,6 +2769,24 @@ compute_block_dependences (int bb)
>>      targetm.sched.dependencies_evaluation_hook (head, tail);
>>  }
>>
>> +/* Artificially resolve forward dependencies for instructions HEAD to TAIL.  */
>> +
>> +static void
>> +resolve_forw_deps (rtx_insn *head, rtx_insn *tail)
>> +{
>> +  rtx_insn *insn;
>> +  rtx_insn *next_tail = NEXT_INSN (tail);
>> +  sd_iterator_def sd_it;
>> +  dep_t dep;
>> +
>> +  /* There could be some insns which get skipped in scheduling but we compute
>> +     dependencies for them previously, so make them resolved.  */
>> +  for (insn = head; insn != next_tail; insn = NEXT_INSN (insn))
>> +    for (sd_it = sd_iterator_start (insn, SD_LIST_FORW);
>> +	 sd_iterator_cond (&sd_it, &dep);)
>> +      sd_resolve_dep (sd_it);
>> +}
>> +
>>  /* Free dependencies of instructions inside BB.  */
>>  static void
>>  free_block_dependencies (int bb)
>> @@ -2753,9 +2796,12 @@ free_block_dependencies (int bb)
>>
>>    get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>
>> -  if (no_real_insns_p (head, tail))
>> +  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_NO)
>>      return;
>>
>> +  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_ARTICIAL)
>> +    resolve_forw_deps (head, tail);
>> +
>>    sched_free_deps (head, tail, true);
>>  }
>>
>> @@ -3019,7 +3065,7 @@ compute_priorities (void)
>>        gcc_assert (EBB_FIRST_BB (bb) == EBB_LAST_BB (bb));
>>        get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>
>> -      if (no_real_insns_p (head, tail))
>> +      if (no_real_nondebug_insns_p (head, tail))
>>  	continue;
>>
>>        rgn_n_insns += set_priorities (head, tail);
>> @@ -3153,7 +3199,7 @@ schedule_region (int rgn)
>>
>>  	  get_ebb_head_tail (first_bb, last_bb, &head, &tail);
>>
>> -	  if (no_real_insns_p (head, tail))
>> +	  if (no_real_nondebug_insns_p (head, tail))
>>  	    {
>>  	      gcc_assert (first_bb == last_bb);
>>  	      continue;
>> @@ -3173,44 +3219,62 @@ schedule_region (int rgn)
>>
>>        get_ebb_head_tail (first_bb, last_bb, &head, &tail);
>>
>> -      if (no_real_insns_p (head, tail))
>> +      if (no_real_nondebug_insns_p (head, tail))
>>  	{
>>  	  gcc_assert (first_bb == last_bb);
>>  	  save_state_for_fallthru_edge (last_bb, bb_state[first_bb->index]);
>> -	  continue;
>> +
>> +	  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_NO)
>> +	    continue;
>> +
>> +	  /* As it's not no_real_nondebug_insns_p initially, then it has some
>> +	     dependencies computed so free it articially.  */
>> +	  bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_ARTICIAL;
>>  	}
>> +      else
>> +	{
>> +	  current_sched_info->prev_head = PREV_INSN (head);
>> +	  current_sched_info->next_tail = NEXT_INSN (tail);
>>
>> -      current_sched_info->prev_head = PREV_INSN (head);
>> -      current_sched_info->next_tail = NEXT_INSN (tail);
>> +	  remove_notes (head, tail);
>>
>> -      remove_notes (head, tail);
>> +	  unlink_bb_notes (first_bb, last_bb);
>>
>> -      unlink_bb_notes (first_bb, last_bb);
>> +	  target_bb = bb;
>>
>> -      target_bb = bb;
>> +	  gcc_assert (flag_schedule_interblock || current_nr_blocks == 1);
>> +	  current_sched_info->queue_must_finish_empty = current_nr_blocks == 1;
>>
>> -      gcc_assert (flag_schedule_interblock || current_nr_blocks == 1);
>> -      current_sched_info->queue_must_finish_empty = current_nr_blocks == 1;
>> +	  curr_bb = first_bb;
>> +	  if (dbg_cnt (sched_block))
>> +	    {
>> +	      int saved_last_basic_block = last_basic_block_for_fn (cfun);
>>
>> -      curr_bb = first_bb;
>> -      if (dbg_cnt (sched_block))
>> -        {
>> -	  int saved_last_basic_block = last_basic_block_for_fn (cfun);
>> +	      schedule_block (&curr_bb, bb_state[first_bb->index]);
>> +	      gcc_assert (EBB_FIRST_BB (bb) == first_bb);
>> +	      sched_rgn_n_insns += sched_n_insns;
>> +	      realloc_bb_state_array (saved_last_basic_block);
>> +	      save_state_for_fallthru_edge (last_bb, curr_state);
>>
>> -	  schedule_block (&curr_bb, bb_state[first_bb->index]);
>> -	  gcc_assert (EBB_FIRST_BB (bb) == first_bb);
>> -	  sched_rgn_n_insns += sched_n_insns;
>> -	  realloc_bb_state_array (saved_last_basic_block);
>> -	  save_state_for_fallthru_edge (last_bb, curr_state);
>> -        }
>> -      else
>> -        {
>> -          sched_rgn_n_insns += rgn_n_insns;
>> -        }
>> +	      /* Clean up.  */
>> +	      if (current_nr_blocks > 1)
>> +		free_trg_info ();
>> +	    }
>> +	  else
>> +	    bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_ARTICIAL;
>> +	}
>>
>> -      /* Clean up.  */
>> -      if (current_nr_blocks > 1)
>> -	free_trg_info ();
>> +      /* We have counted this block when computing rgn_n_insns
>> +	 previously, so need to fix up sched_rgn_n_insns now.  */
>> +      if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_ARTICIAL)
>> +	{
>> +	  while (head != NEXT_INSN (tail))
>> +	    {
>> +	      if (INSN_P (head))
>> +		sched_rgn_n_insns++;
>> +	      head = NEXT_INSN (head);
>> +	    }
>> +	}
>>      }
>>
>>    /* Sanity check: verify that all region insns were scheduled.  */
>> @@ -3218,13 +3282,13 @@ schedule_region (int rgn)
>>
>>    sched_finish_ready_list ();
>>
>> -  /* Done with this region.  */
>> -  sched_rgn_local_finish ();
>> -
>>    /* Free dependencies.  */
>>    for (bb = 0; bb < current_nr_blocks; ++bb)
>>      free_block_dependencies (bb);
>>
>> +  /* Done with this region.  */
>> +  sched_rgn_local_finish ();
>> +
>>    gcc_assert (haifa_recovery_bb_ever_added_p
>>  	      || deps_pools_are_empty_p ());
>>  }
>> @@ -3445,6 +3509,19 @@ sched_rgn_local_init (int rgn)
>>  	    e->aux = NULL;
>>          }
>>      }
>> +
>> +  /* Initialize bb_deps_free_actions.  */
>> +  bb_deps_free_actions
>> +    = XNEWVEC (enum rgn_bb_deps_free_action, current_nr_blocks);
>> +  for (bb = 0; bb < current_nr_blocks; bb++)
>> +    {
>> +      rtx_insn *head, *tail;
>> +      get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>> +      if (no_real_nondebug_insns_p (head, tail))
>> +	bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_NO;
>> +      else
>> +	bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_NORMAL;
>> +    }
>>  }
>>
>>  /* Free data computed for the finished region.  */
>> @@ -3462,9 +3539,12 @@ sched_rgn_local_free (void)
>>  void
>>  sched_rgn_local_finish (void)
>>  {
>> -  if (current_nr_blocks > 1 && !sel_sched_p ())
>> +  if (!sel_sched_p ())
>>      {
>> -      sched_rgn_local_free ();
>> +      if (current_nr_blocks > 1)
>> +	sched_rgn_local_free ();
>> +
>> +      free (bb_deps_free_actions);
>>      }
>>  }
>>
>> diff --git a/gcc/sel-sched.cc b/gcc/sel-sched.cc
>> index cb1cf75bfe4..04415590455 100644
>> --- a/gcc/sel-sched.cc
>> +++ b/gcc/sel-sched.cc
>> @@ -7213,7 +7213,8 @@ sel_region_target_finish (bool reset_sched_cycles_p)
>>
>>        find_ebb_boundaries (EBB_FIRST_BB (i), scheduled_blocks);
>>
>> -      if (no_real_insns_p (current_sched_info->head, current_sched_info->tail))
>> +      if (no_real_nondebug_insns_p (current_sched_info->head,
>> +				    current_sched_info->tail))
>>  	continue;
>>
>>        if (reset_sched_cycles_p)
>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr108273.c b/gcc/testsuite/gcc.target/powerpc/pr108273.c
>> new file mode 100644
>> index 00000000000..937224eaa69
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.target/powerpc/pr108273.c
>> @@ -0,0 +1,26 @@
>> +/* { dg-options "-O2 -fdbg-cnt=sched_block:1" } */
>> +/* { dg-prune-output {\*\*\*dbgcnt:.*limit.*reached} } */
>> +
>> +/* Verify there is no ICE.  */
>> +
>> +int a, b, c, e, f;
>> +float d;
>> +
>> +void
>> +g ()
>> +{
>> +  float h, i[1];
>> +  for (; f;)
>> +    if (c)
>> +      {
>> +	d *e;
>> +	if (b)
>> +	  {
>> +	    float *j = i;
>> +	    j[0] += 0;
>> +	  }
>> +	h += d;
>> +      }
>> +  if (h)
>> +    a = i[0];
>> +}
>> --
>> 2.25.1
>
  

Hi,

I'd like to gentle ping this patch:

https://gcc.gnu.org/pipermail/gcc-patches/2023-March/614818.html

BR,
Kewen

>> on 2023/3/29 15:18, Kewen.Lin via Gcc-patches wrote:
>>> Hi,
>>>
>>> By addressing Alexander's comments, against v1 this
>>> patch v2 mainly:
>>>
>>>   - Rename no_real_insns_p to no_real_nondebug_insns_p;
>>>   - Introduce enum rgn_bb_deps_free_action for three
>>>     kinds of actions to free deps;
>>>   - Change function free_deps_for_bb_no_real_insns_p to
>>>     resolve_forw_deps which only focuses on forward deps;
>>>   - Extend the handlings to cover dbg-cnt sched_block,
>>>     add one test case for it;
>>>   - Move free_trg_info call in schedule_region to an
>>>     appropriate place.
>>>
>>> One thing I'm not sure about is the change in function
>>> sched_rgn_local_finish, currently the invocation to
>>> sched_rgn_local_free is guarded with !sel_sched_p (),
>>> so I just follow it, but the initialization of those
>>> structures (in sched_rgn_local_init) isn't guarded
>>> with !sel_sched_p (), it looks odd.
>>>
>>> ----
>>>
>>> As PR108273 shows, when there is one block which only has
>>> NOTE_P and LABEL_P insns at non-debug mode while has some
>>> extra DEBUG_INSN_P insns at debug mode, after scheduling
>>> it, the DFA states would be different between debug mode
>>> and non-debug mode.  Since at non-debug mode, the block
>>> meets no_real_insns_p, it gets skipped; while at debug
>>> mode, it gets scheduled, even it only has NOTE_P, LABEL_P
>>> and DEBUG_INSN_P, the call of function advance_one_cycle
>>> will change the DFA state.  PR108519 also shows this issue
>>> issue can be exposed by some scheduler changes.
>>>
>>> This patch is to change function no_real_insns_p to
>>> function no_real_nondebug_insns_p by taking debug insn into
>>> account, which make us not try to schedule for the block
>>> having only NOTE_P, LABEL_P and DEBUG_INSN_P insns,
>>> resulting in consistent DFA states between non-debug and
>>> debug mode.
>>>
>>> Changing no_real_insns_p to no_real_nondebug_insns_p caused
>>> ICE when doing free_block_dependencies, the root cause is
>>> that we create dependencies for debug insns, those
>>> dependencies are expected to be resolved during scheduling
>>> insns, but which gets skipped after this change.
>>> By checking the code, it looks it's reasonable to skip to
>>> compute block dependences for no_real_nondebug_insns_p
>>> blocks.  There is also another issue, which gets exposed
>>> in SPEC2017 bmks build at option -O2 -g, is that we could
>>> skip to schedule some block, which already gets dependency
>>> graph built so has dependencies computed and rgn_n_insns
>>> accumulated, then the later verification on if the graph
>>> becomes exhausted by scheduling would fail as follow:
>>>
>>>   /* Sanity check: verify that all region insns were
>>>      scheduled.  */
>>>     gcc_assert (sched_rgn_n_insns == rgn_n_insns);
>>>
>>> , and also some forward deps aren't resovled.
>>>
>>> As Alexander pointed out, the current debug count handling
>>> also suffers the similar issue, so this patch handles these
>>> two cases together: one is for some block gets skipped by
>>> !dbg_cnt (sched_block), the other is for some block which
>>> is not no_real_nondebug_insns_p initially but becomes
>>> no_real_nondebug_insns_p due to speculative scheduling.
>>>
>>> This patch can be bootstrapped and regress-tested on
>>> x86_64-redhat-linux, aarch64-linux-gnu and
>>> powerpc64{,le}-linux-gnu.
>>>
>>> I also verified this patch can pass SPEC2017 both intrate
>>> and fprate bmks building at -g -O2/-O3.
>>>
>>> Any thoughts?
>>>
>>> BR,
>>> Kewen
>>> ----
>>> 	PR rtl-optimization/108273
>>>
>>> gcc/ChangeLog:
>>>
>>> 	* haifa-sched.cc (no_real_insns_p): Rename to ...
>>> 	(no_real_nondebug_insns_p): ... this, and consider DEBUG_INSN_P insn.
>>> 	* sched-ebb.cc (schedule_ebb): Replace no_real_insns_p with
>>> 	no_real_nondebug_insns_p.
>>> 	* sched-int.h (no_real_insns_p): Rename to ...
>>> 	(no_real_nondebug_insns_p): ... this.
>>> 	* sched-rgn.cc (enum rgn_bb_deps_free_action): New enum.
>>> 	(bb_deps_free_actions): New static variable.
>>> 	(compute_block_dependences): Skip for no_real_nondebug_insns_p.
>>> 	(resolve_forw_deps): New function.
>>> 	(free_block_dependencies): Check bb_deps_free_actions and call
>>> 	function resolve_forw_deps for RGN_BB_DEPS_FREE_ARTICIAL.
>>> 	(compute_priorities): Replace no_real_insns_p with
>>> 	no_real_nondebug_insns_p.
>>> 	(schedule_region): Replace no_real_insns_p with
>>> 	no_real_nondebug_insns_p, set RGN_BB_DEPS_FREE_ARTICIAL if the block
>>> 	get dependencies computed before but skipped now, fix up count
>>> 	sched_rgn_n_insns for it too.  Call free_trg_info when the block
>>> 	gets scheduled, and move sched_rgn_local_finish after the loop
>>> 	of free_block_dependencies loop.
>>> 	(sched_rgn_local_init): Allocate and compute bb_deps_free_actions.
>>> 	(sched_rgn_local_finish): Free bb_deps_free_actions.
>>> 	* sel-sched.cc (sel_region_target_finish): Replace no_real_insns_p with
>>> 	no_real_nondebug_insns_p.
>>>
>>> gcc/testsuite/ChangeLog:
>>>
>>> 	* gcc.target/powerpc/pr108273.c: New test.
>>> ---
>>>  gcc/haifa-sched.cc                          |   9 +-
>>>  gcc/sched-ebb.cc                            |   2 +-
>>>  gcc/sched-int.h                             |   2 +-
>>>  gcc/sched-rgn.cc                            | 148 +++++++++++++++-----
>>>  gcc/sel-sched.cc                            |   3 +-
>>>  gcc/testsuite/gcc.target/powerpc/pr108273.c |  26 ++++
>>>  6 files changed, 150 insertions(+), 40 deletions(-)
>>>  create mode 100644 gcc/testsuite/gcc.target/powerpc/pr108273.c
>>>
>>> diff --git a/gcc/haifa-sched.cc b/gcc/haifa-sched.cc
>>> index 48b53776fa9..371de486eb0 100644
>>> --- a/gcc/haifa-sched.cc
>>> +++ b/gcc/haifa-sched.cc
>>> @@ -5033,14 +5033,17 @@ get_ebb_head_tail (basic_block beg, basic_block end,
>>>    *tailp = end_tail;
>>>  }
>>>
>>> -/* Return nonzero if there are no real insns in the range [ HEAD, TAIL ].  */
>>> +/* Return nonzero if there are no real nondebug insns in the range
>>> +   [ HEAD, TAIL ].  */
>>>
>>>  int
>>> -no_real_insns_p (const rtx_insn *head, const rtx_insn *tail)
>>> +no_real_nondebug_insns_p (const rtx_insn *head, const rtx_insn *tail)
>>>  {
>>>    while (head != NEXT_INSN (tail))
>>>      {
>>> -      if (!NOTE_P (head) && !LABEL_P (head))
>>> +      if (!NOTE_P (head)
>>> +	  && !LABEL_P (head)
>>> +	  && !DEBUG_INSN_P (head))
>>>  	return 0;
>>>        head = NEXT_INSN (head);
>>>      }
>>> diff --git a/gcc/sched-ebb.cc b/gcc/sched-ebb.cc
>>> index 3eb6a24f187..e3bb0d57159 100644
>>> --- a/gcc/sched-ebb.cc
>>> +++ b/gcc/sched-ebb.cc
>>> @@ -491,7 +491,7 @@ schedule_ebb (rtx_insn *head, rtx_insn *tail, bool modulo_scheduling)
>>>    first_bb = BLOCK_FOR_INSN (head);
>>>    last_bb = BLOCK_FOR_INSN (tail);
>>>
>>> -  if (no_real_insns_p (head, tail))
>>> +  if (no_real_nondebug_insns_p (head, tail))
>>>      return BLOCK_FOR_INSN (tail);
>>>
>>>    gcc_assert (INSN_P (head) && INSN_P (tail));
>>> diff --git a/gcc/sched-int.h b/gcc/sched-int.h
>>> index 97b7d2d319b..eb4e8acec9f 100644
>>> --- a/gcc/sched-int.h
>>> +++ b/gcc/sched-int.h
>>> @@ -1397,7 +1397,7 @@ extern void free_global_sched_pressure_data (void);
>>>  extern int haifa_classify_insn (const_rtx);
>>>  extern void get_ebb_head_tail (basic_block, basic_block,
>>>  			       rtx_insn **, rtx_insn **);
>>> -extern int no_real_insns_p (const rtx_insn *, const rtx_insn *);
>>> +extern int no_real_nondebug_insns_p (const rtx_insn *, const rtx_insn *);
>>>
>>>  extern int insn_sched_cost (rtx_insn *);
>>>  extern int dep_cost_1 (dep_t, dw_t);
>>> diff --git a/gcc/sched-rgn.cc b/gcc/sched-rgn.cc
>>> index f2751f62450..3508a26aeb6 100644
>>> --- a/gcc/sched-rgn.cc
>>> +++ b/gcc/sched-rgn.cc
>>> @@ -213,6 +213,22 @@ static int rgn_nr_edges;
>>>  /* Array of size rgn_nr_edges.  */
>>>  static edge *rgn_edges;
>>>
>>> +/* Possible actions for dependencies freeing.  */
>>> +enum rgn_bb_deps_free_action
>>> +{
>>> +  /* This block doesn't get dependencies computed so don't need to free.  */
>>> +  RGN_BB_DEPS_FREE_NO,
>>> +  /* This block gets scheduled normally so free dependencies as usual.  */
>>> +  RGN_BB_DEPS_FREE_NORMAL,
>>> +  /* This block gets skipped in scheduling but has dependencies computed early,
>>> +     need to free the forward list articially.  */
>>> +  RGN_BB_DEPS_FREE_ARTICIAL
>>> +};
>>> +
>>> +/* For basic block i, bb_deps_free_actions[i] indicates which action needs
>>> +   to be taken for freeing its dependencies.  */
>>> +static enum rgn_bb_deps_free_action *bb_deps_free_actions;
>>> +
>>>  /* Mapping from each edge in the graph to its number in the rgn.  */
>>>  #define EDGE_TO_BIT(edge) ((int)(size_t)(edge)->aux)
>>>  #define SET_EDGE_TO_BIT(edge,nr) ((edge)->aux = (void *)(size_t)(nr))
>>> @@ -2730,6 +2746,15 @@ compute_block_dependences (int bb)
>>>    gcc_assert (EBB_FIRST_BB (bb) == EBB_LAST_BB (bb));
>>>    get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>>
>>> +  /* Don't compute block dependencies if there are no real nondebug insns.  */
>>> +  if (no_real_nondebug_insns_p (head, tail))
>>> +    {
>>> +      if (current_nr_blocks > 1)
>>> +	propagate_deps (bb, &tmp_deps);
>>> +      free_deps (&tmp_deps);
>>> +      return;
>>> +    }
>>> +
>>>    sched_analyze (&tmp_deps, head, tail);
>>>
>>>    add_branch_dependences (head, tail);
>>> @@ -2744,6 +2769,24 @@ compute_block_dependences (int bb)
>>>      targetm.sched.dependencies_evaluation_hook (head, tail);
>>>  }
>>>
>>> +/* Artificially resolve forward dependencies for instructions HEAD to TAIL.  */
>>> +
>>> +static void
>>> +resolve_forw_deps (rtx_insn *head, rtx_insn *tail)
>>> +{
>>> +  rtx_insn *insn;
>>> +  rtx_insn *next_tail = NEXT_INSN (tail);
>>> +  sd_iterator_def sd_it;
>>> +  dep_t dep;
>>> +
>>> +  /* There could be some insns which get skipped in scheduling but we compute
>>> +     dependencies for them previously, so make them resolved.  */
>>> +  for (insn = head; insn != next_tail; insn = NEXT_INSN (insn))
>>> +    for (sd_it = sd_iterator_start (insn, SD_LIST_FORW);
>>> +	 sd_iterator_cond (&sd_it, &dep);)
>>> +      sd_resolve_dep (sd_it);
>>> +}
>>> +
>>>  /* Free dependencies of instructions inside BB.  */
>>>  static void
>>>  free_block_dependencies (int bb)
>>> @@ -2753,9 +2796,12 @@ free_block_dependencies (int bb)
>>>
>>>    get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>>
>>> -  if (no_real_insns_p (head, tail))
>>> +  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_NO)
>>>      return;
>>>
>>> +  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_ARTICIAL)
>>> +    resolve_forw_deps (head, tail);
>>> +
>>>    sched_free_deps (head, tail, true);
>>>  }
>>>
>>> @@ -3019,7 +3065,7 @@ compute_priorities (void)
>>>        gcc_assert (EBB_FIRST_BB (bb) == EBB_LAST_BB (bb));
>>>        get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>>
>>> -      if (no_real_insns_p (head, tail))
>>> +      if (no_real_nondebug_insns_p (head, tail))
>>>  	continue;
>>>
>>>        rgn_n_insns += set_priorities (head, tail);
>>> @@ -3153,7 +3199,7 @@ schedule_region (int rgn)
>>>
>>>  	  get_ebb_head_tail (first_bb, last_bb, &head, &tail);
>>>
>>> -	  if (no_real_insns_p (head, tail))
>>> +	  if (no_real_nondebug_insns_p (head, tail))
>>>  	    {
>>>  	      gcc_assert (first_bb == last_bb);
>>>  	      continue;
>>> @@ -3173,44 +3219,62 @@ schedule_region (int rgn)
>>>
>>>        get_ebb_head_tail (first_bb, last_bb, &head, &tail);
>>>
>>> -      if (no_real_insns_p (head, tail))
>>> +      if (no_real_nondebug_insns_p (head, tail))
>>>  	{
>>>  	  gcc_assert (first_bb == last_bb);
>>>  	  save_state_for_fallthru_edge (last_bb, bb_state[first_bb->index]);
>>> -	  continue;
>>> +
>>> +	  if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_NO)
>>> +	    continue;
>>> +
>>> +	  /* As it's not no_real_nondebug_insns_p initially, then it has some
>>> +	     dependencies computed so free it articially.  */
>>> +	  bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_ARTICIAL;
>>>  	}
>>> +      else
>>> +	{
>>> +	  current_sched_info->prev_head = PREV_INSN (head);
>>> +	  current_sched_info->next_tail = NEXT_INSN (tail);
>>>
>>> -      current_sched_info->prev_head = PREV_INSN (head);
>>> -      current_sched_info->next_tail = NEXT_INSN (tail);
>>> +	  remove_notes (head, tail);
>>>
>>> -      remove_notes (head, tail);
>>> +	  unlink_bb_notes (first_bb, last_bb);
>>>
>>> -      unlink_bb_notes (first_bb, last_bb);
>>> +	  target_bb = bb;
>>>
>>> -      target_bb = bb;
>>> +	  gcc_assert (flag_schedule_interblock || current_nr_blocks == 1);
>>> +	  current_sched_info->queue_must_finish_empty = current_nr_blocks == 1;
>>>
>>> -      gcc_assert (flag_schedule_interblock || current_nr_blocks == 1);
>>> -      current_sched_info->queue_must_finish_empty = current_nr_blocks == 1;
>>> +	  curr_bb = first_bb;
>>> +	  if (dbg_cnt (sched_block))
>>> +	    {
>>> +	      int saved_last_basic_block = last_basic_block_for_fn (cfun);
>>>
>>> -      curr_bb = first_bb;
>>> -      if (dbg_cnt (sched_block))
>>> -        {
>>> -	  int saved_last_basic_block = last_basic_block_for_fn (cfun);
>>> +	      schedule_block (&curr_bb, bb_state[first_bb->index]);
>>> +	      gcc_assert (EBB_FIRST_BB (bb) == first_bb);
>>> +	      sched_rgn_n_insns += sched_n_insns;
>>> +	      realloc_bb_state_array (saved_last_basic_block);
>>> +	      save_state_for_fallthru_edge (last_bb, curr_state);
>>>
>>> -	  schedule_block (&curr_bb, bb_state[first_bb->index]);
>>> -	  gcc_assert (EBB_FIRST_BB (bb) == first_bb);
>>> -	  sched_rgn_n_insns += sched_n_insns;
>>> -	  realloc_bb_state_array (saved_last_basic_block);
>>> -	  save_state_for_fallthru_edge (last_bb, curr_state);
>>> -        }
>>> -      else
>>> -        {
>>> -          sched_rgn_n_insns += rgn_n_insns;
>>> -        }
>>> +	      /* Clean up.  */
>>> +	      if (current_nr_blocks > 1)
>>> +		free_trg_info ();
>>> +	    }
>>> +	  else
>>> +	    bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_ARTICIAL;
>>> +	}
>>>
>>> -      /* Clean up.  */
>>> -      if (current_nr_blocks > 1)
>>> -	free_trg_info ();
>>> +      /* We have counted this block when computing rgn_n_insns
>>> +	 previously, so need to fix up sched_rgn_n_insns now.  */
>>> +      if (bb_deps_free_actions[bb] == RGN_BB_DEPS_FREE_ARTICIAL)
>>> +	{
>>> +	  while (head != NEXT_INSN (tail))
>>> +	    {
>>> +	      if (INSN_P (head))
>>> +		sched_rgn_n_insns++;
>>> +	      head = NEXT_INSN (head);
>>> +	    }
>>> +	}
>>>      }
>>>
>>>    /* Sanity check: verify that all region insns were scheduled.  */
>>> @@ -3218,13 +3282,13 @@ schedule_region (int rgn)
>>>
>>>    sched_finish_ready_list ();
>>>
>>> -  /* Done with this region.  */
>>> -  sched_rgn_local_finish ();
>>> -
>>>    /* Free dependencies.  */
>>>    for (bb = 0; bb < current_nr_blocks; ++bb)
>>>      free_block_dependencies (bb);
>>>
>>> +  /* Done with this region.  */
>>> +  sched_rgn_local_finish ();
>>> +
>>>    gcc_assert (haifa_recovery_bb_ever_added_p
>>>  	      || deps_pools_are_empty_p ());
>>>  }
>>> @@ -3445,6 +3509,19 @@ sched_rgn_local_init (int rgn)
>>>  	    e->aux = NULL;
>>>          }
>>>      }
>>> +
>>> +  /* Initialize bb_deps_free_actions.  */
>>> +  bb_deps_free_actions
>>> +    = XNEWVEC (enum rgn_bb_deps_free_action, current_nr_blocks);
>>> +  for (bb = 0; bb < current_nr_blocks; bb++)
>>> +    {
>>> +      rtx_insn *head, *tail;
>>> +      get_ebb_head_tail (EBB_FIRST_BB (bb), EBB_LAST_BB (bb), &head, &tail);
>>> +      if (no_real_nondebug_insns_p (head, tail))
>>> +	bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_NO;
>>> +      else
>>> +	bb_deps_free_actions[bb] = RGN_BB_DEPS_FREE_NORMAL;
>>> +    }
>>>  }
>>>
>>>  /* Free data computed for the finished region.  */
>>> @@ -3462,9 +3539,12 @@ sched_rgn_local_free (void)
>>>  void
>>>  sched_rgn_local_finish (void)
>>>  {
>>> -  if (current_nr_blocks > 1 && !sel_sched_p ())
>>> +  if (!sel_sched_p ())
>>>      {
>>> -      sched_rgn_local_free ();
>>> +      if (current_nr_blocks > 1)
>>> +	sched_rgn_local_free ();
>>> +
>>> +      free (bb_deps_free_actions);
>>>      }
>>>  }
>>>
>>> diff --git a/gcc/sel-sched.cc b/gcc/sel-sched.cc
>>> index cb1cf75bfe4..04415590455 100644
>>> --- a/gcc/sel-sched.cc
>>> +++ b/gcc/sel-sched.cc
>>> @@ -7213,7 +7213,8 @@ sel_region_target_finish (bool reset_sched_cycles_p)
>>>
>>>        find_ebb_boundaries (EBB_FIRST_BB (i), scheduled_blocks);
>>>
>>> -      if (no_real_insns_p (current_sched_info->head, current_sched_info->tail))
>>> +      if (no_real_nondebug_insns_p (current_sched_info->head,
>>> +				    current_sched_info->tail))
>>>  	continue;
>>>
>>>        if (reset_sched_cycles_p)
>>> diff --git a/gcc/testsuite/gcc.target/powerpc/pr108273.c b/gcc/testsuite/gcc.target/powerpc/pr108273.c
>>> new file mode 100644
>>> index 00000000000..937224eaa69
>>> --- /dev/null
>>> +++ b/gcc/testsuite/gcc.target/powerpc/pr108273.c
>>> @@ -0,0 +1,26 @@
>>> +/* { dg-options "-O2 -fdbg-cnt=sched_block:1" } */
>>> +/* { dg-prune-output {\*\*\*dbgcnt:.*limit.*reached} } */
>>> +
>>> +/* Verify there is no ICE.  */
>>> +
>>> +int a, b, c, e, f;
>>> +float d;
>>> +
>>> +void
>>> +g ()
>>> +{
>>> +  float h, i[1];
>>> +  for (; f;)
>>> +    if (c)
>>> +      {
>>> +	d *e;
>>> +	if (b)
>>> +	  {
>>> +	    float *j = i;
>>> +	    j[0] += 0;
>>> +	  }
>>> +	h += d;
>>> +      }
>>> +  if (h)
>>> +    a = i[0];
>>> +}
>>> --
>>> 2.25.1
>>


BR,
Kewen