[gcc r14-6766] sched: Remove debug counter sched_block

[Kewen Lin]

https://gcc.gnu.org/g:ef259ebeb39501bfddcc7c203a9a7a0daefa8ffd

commit r14-6766-gef259ebeb39501bfddcc7c203a9a7a0daefa8ffd
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Wed Dec 20 21:21:54 2023 -0600

    sched: Remove debug counter sched_block
    
    Currently the debug counter sched_block doesn't work well
    since we create dependencies for some insns and those
    dependencies are expected to be resolved during scheduling
    insns but they can get skipped once we are skipping some
    block while respecting sched_block debug counter.
    
    For example, for the below test case:
    --
    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];
    }
    --
    ICE occurs with option "-O2 -fdbg-cnt=sched_block:1".
    
    As the discussion in [1], it seems that we think this debug
    counter is useless and can be removed.  It's also implied
    that if it's useful and used often, the above issue should
    have been cared about and resolved earlier.  So this patch
    is to remove this debug counter.
    
    [1] https://gcc.gnu.org/pipermail/gcc-patches/2023-November/635852.html
    
    gcc/ChangeLog:
    
            * dbgcnt.def (sched_block): Remove.
            * sched-rgn.cc (schedule_region): Remove the support of debug count
            sched_block.

Diff:
---
 gcc/dbgcnt.def   |  1 -
 gcc/sched-rgn.cc | 19 ++++++-------------
 2 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/gcc/dbgcnt.def b/gcc/dbgcnt.def
index 871cbf75d93..a8c4e61e13d 100644
--- a/gcc/dbgcnt.def
+++ b/gcc/dbgcnt.def
@@ -198,7 +198,6 @@ DEBUG_COUNTER (pre_insn)
 DEBUG_COUNTER (prefetch)
 DEBUG_COUNTER (registered_jump_thread)
 DEBUG_COUNTER (sched2_func)
-DEBUG_COUNTER (sched_block)
 DEBUG_COUNTER (sched_breakdep)
 DEBUG_COUNTER (sched_func)
 DEBUG_COUNTER (sched_insn)
diff --git a/gcc/sched-rgn.cc b/gcc/sched-rgn.cc
index e5964f54ead..1c8acf5068a 100644
--- a/gcc/sched-rgn.cc
+++ b/gcc/sched-rgn.cc
@@ -3198,20 +3198,13 @@ schedule_region (int rgn)
       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);
+      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);
-        }
-      else
-        {
-          sched_rgn_n_insns += rgn_n_insns;
-        }
+      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);
 
       /* Clean up.  */
       if (current_nr_blocks > 1)