[PATCH] Remove dead code in df-scan.c (PR tree-optimization/90978).

[Martin Liška]

Hi.

The patch is about removal of an unreachable code. That has been proved
by an accidental gcc_unreachable places 9 year ago.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.

Ready to be installed?
Thanks,
Martin

gcc/ChangeLog:

2019-06-25  Martin Liska  <mli...@suse.cz>

        PR tree-optimization/90978
        * df-scan.c (df_update_entry_block_defs): Remove dead else
        branch.
        (df_update_exit_block_uses): Likewise.
---
 gcc/df-scan.c | 44 ++++++++++++--------------------------------
 1 file changed, 12 insertions(+), 32 deletions(-)



diff --git a/gcc/df-scan.c b/gcc/df-scan.c
index 08d7af33371..2eea149e458 100644
--- a/gcc/df-scan.c
+++ b/gcc/df-scan.c
@@ -3601,23 +3601,13 @@ df_update_entry_block_defs (void)
 
   auto_bitmap refs (&df_bitmap_obstack);
   df_get_entry_block_def_set (refs);
-  if (df->entry_block_defs)
+  gcc_assert (df->entry_block_defs);
+  if (!bitmap_equal_p (df->entry_block_defs, 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;
-	  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);
+      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;
     }
 
@@ -3775,23 +3765,13 @@ df_update_exit_block_uses (void)
 
   auto_bitmap refs (&df_bitmap_obstack);
   df_get_exit_block_use_set (refs);
-  if (df->exit_block_uses)
+  gcc_assert (df->exit_block_uses);
+  if (!bitmap_equal_p (df->exit_block_uses, 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;
-	  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);
+      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;
     }