[obvious] remove some dead df-scan code

[Michael Matz]

Hi,

jimis noticed this on IRC.  Since r160348 there's some dead code in 
df_update_entry_block_defs and df_update_exit_block_uses.  I'm currently 
regstrapping this together with the pointer alignment merging patch on 
x86_64-linux, and am going to commit it as obvious when that works.


Ciao,
Michael.

        * df-scan.c (df_update_entry_block_defs, df_update_exit_block_uses):
        Remove dead code.

Index: df-scan.c
===================================================================
*** df-scan.c   (revision 176790)
--- df-scan.c   (working copy)
*************** void
*** 3849,3884 ****
  df_update_entry_block_defs (void)
  {
    bitmap_head refs;
-   bool changed = false;
  
    bitmap_initialize (&refs, &df_bitmap_obstack);
    df_get_entry_block_def_set (&refs);
!   if (df->entry_block_defs)
!     {
!       if (!bitmap_equal_p (df->entry_block_defs, &refs))
!       {
!         struct df_scan_bb_info *bb_info = df_scan_get_bb_info (ENTRY_BLOCK);
!         df_ref_chain_delete_du_chain (bb_info->artificial_defs);
!         df_ref_chain_delete (bb_info->artificial_defs);
!         bb_info->artificial_defs = NULL;
!         changed = true;
!       }
!     }
!   else
!     {
!       struct df_scan_problem_data *problem_data
!       = (struct df_scan_problem_data *) df_scan->problem_data;
!       gcc_unreachable ();
!       df->entry_block_defs = BITMAP_ALLOC (&problem_data->reg_bitmaps);
!       changed = true;
!     }
! 
!   if (changed)
      {
        df_record_entry_block_defs (&refs);
        bitmap_copy (df->entry_block_defs, &refs);
        df_set_bb_dirty (BASIC_BLOCK (ENTRY_BLOCK));
      }
    bitmap_clear (&refs);
  }
  
--- 3849,3868 ----
  df_update_entry_block_defs (void)
  {
    bitmap_head refs;
  
    bitmap_initialize (&refs, &df_bitmap_obstack);
    df_get_entry_block_def_set (&refs);
!   if (!bitmap_equal_p (df->entry_block_defs, &refs))
      {
+       struct df_scan_bb_info *bb_info = df_scan_get_bb_info (ENTRY_BLOCK);
+       df_ref_chain_delete_du_chain (bb_info->artificial_defs);
+       df_ref_chain_delete (bb_info->artificial_defs);
+       bb_info->artificial_defs = NULL;
        df_record_entry_block_defs (&refs);
        bitmap_copy (df->entry_block_defs, &refs);
        df_set_bb_dirty (BASIC_BLOCK (ENTRY_BLOCK));
      }
+ 
    bitmap_clear (&refs);
  }
  
*************** void
*** 4023,4058 ****
  df_update_exit_block_uses (void)
  {
    bitmap_head refs;
-   bool changed = false;
  
    bitmap_initialize (&refs, &df_bitmap_obstack);
    df_get_exit_block_use_set (&refs);
!   if (df->exit_block_uses)
!     {
!       if (!bitmap_equal_p (df->exit_block_uses, &refs))
!       {
!         struct df_scan_bb_info *bb_info = df_scan_get_bb_info (EXIT_BLOCK);
!         df_ref_chain_delete_du_chain (bb_info->artificial_uses);
!         df_ref_chain_delete (bb_info->artificial_uses);
!         bb_info->artificial_uses = NULL;
!         changed = true;
!       }
!     }
!   else
!     {
!       struct df_scan_problem_data *problem_data
!       = (struct df_scan_problem_data *) df_scan->problem_data;
!       gcc_unreachable ();
!       df->exit_block_uses = BITMAP_ALLOC (&problem_data->reg_bitmaps);
!       changed = true;
!     }
! 
!   if (changed)
      {
        df_record_exit_block_uses (&refs);
        bitmap_copy (df->exit_block_uses,& refs);
        df_set_bb_dirty (BASIC_BLOCK (EXIT_BLOCK));
      }
    bitmap_clear (&refs);
  }
  
--- 4007,4026 ----
  df_update_exit_block_uses (void)
  {
    bitmap_head refs;
  
    bitmap_initialize (&refs, &df_bitmap_obstack);
    df_get_exit_block_use_set (&refs);
!   if (!bitmap_equal_p (df->exit_block_uses, &refs))
      {
+       struct df_scan_bb_info *bb_info = df_scan_get_bb_info (EXIT_BLOCK);
+       df_ref_chain_delete_du_chain (bb_info->artificial_uses);
+       df_ref_chain_delete (bb_info->artificial_uses);
+       bb_info->artificial_uses = NULL;
        df_record_exit_block_uses (&refs);
        bitmap_copy (df->exit_block_uses,& refs);
        df_set_bb_dirty (BASIC_BLOCK (EXIT_BLOCK));
      }
+ 
    bitmap_clear (&refs);
  }