re PR debug/54551 (DF resets some DEBUG_INSNs unnecessarily)

gcc/ChangeLog:
PR debug/54551
* Makefile.in (VALTRACK_H): Add hash-table.h.
* valtrack.h: Include hash-table.h.
(struct dead_debug_global_entry): New.
(struct dead_debug_hash_descr): New.
(struct dead_debug_global): New.
(struct dead_debug): Rename to...
(struct dead_debug_local): ... this.  Adjust all uses.
(dead_debug_global_init, dead_debug_global_finish): New.
(dead_debug_init): Rename to...
(dead_debug_local_init): ... this.  Adjust all callers.
(dead_debug_finish): Rename to...
(dead_debug_local_finish): ... this.  Adjust all callers.
* valtrack.c (dead_debug_global_init): New.
(dead_debug_init): Rename to...
(dead_debug_local_init): ... this.  Take global parameter.
Save it and initialize used bitmap from it.
(dead_debug_global_find, dead_debug_global_insert): New.
(dead_debug_global_replace_temp): New.
(dead_debug_promote_uses): New.
(dead_debug_finish): Rename to...
(dead_debug_local_finish): ... this.  Promote remaining uses.
(dead_debug_global_finish): New.
(dead_debug_add): Try to replace global temps first.
(dead_debug_insert_temp): Support global replacements.
* dce.c (word_dce_process_block, dce_process_block): Add
global_debug parameter.  Pass it on.
(fast_dce): Initialize, pass on and finalize global_debug.
* df-problems.c (df_set_unused_notes_for_mw): Adjusted.
(df_create_unused_notes, df_note_bb_compute): Likewise.
(df_note_compute): Justify local-only dead debug analysis.
gcc/testsuite/ChangeLog:
PR debug/54551
* gcc.dg/guality/pr54551.c: New.

From-SVN: r192001

1 files changed, 10 insertions, 5 deletions

diff --git a/gcc/df-problems.c b/gcc/df-problems.c
index abeb118..a1a0e71 100644
--- a/gcc/df-problems.c
+++ b/gcc/df-problems.c
@@ -2892,7 +2892,7 @@ static void
 df_set_unused_notes_for_mw (rtx insn, struct df_mw_hardreg *mws,
 			    bitmap live, bitmap do_not_gen,
 			    bitmap artificial_uses,
-			    struct dead_debug *debug)
+			    struct dead_debug_local *debug)
 {
   unsigned int r;
 
@@ -3021,7 +3021,7 @@ df_set_dead_notes_for_mw (rtx insn, struct df_mw_hardreg *mws,
 static void
 df_create_unused_note (rtx insn, df_ref def,
 		       bitmap live, bitmap artificial_uses,
-		       struct dead_debug *debug)
+		       struct dead_debug_local *debug)
 {
   unsigned int dregno = DF_REF_REGNO (def);
 
@@ -3060,9 +3060,9 @@ df_note_bb_compute (unsigned int bb_index,
   rtx insn;
   df_ref *def_rec;
   df_ref *use_rec;
-  struct dead_debug debug;
+  struct dead_debug_local debug;
 
-  dead_debug_init (&debug, NULL);
+  dead_debug_local_init (&debug, NULL, NULL);
 
   bitmap_copy (live, df_get_live_out (bb));
   bitmap_clear (artificial_uses);
@@ -3268,7 +3268,7 @@ df_note_bb_compute (unsigned int bb_index,
 	}
     }
 
-  dead_debug_finish (&debug, NULL);
+  dead_debug_local_finish (&debug, NULL);
 }
 
 
@@ -3286,6 +3286,11 @@ df_note_compute (bitmap all_blocks)
 
   EXECUTE_IF_SET_IN_BITMAP (all_blocks, 0, bb_index, bi)
   {
+    /* ??? Unlike fast DCE, we don't use global_debug for uses of dead
+       pseudos in debug insns because we don't always (re)visit blocks
+       with death points after visiting dead uses.  Even changing this
+       loop to postorder would still leave room for visiting a death
+       point before visiting a subsequent debug use.  */
     df_note_bb_compute (bb_index, &live, &do_not_gen, &artificial_uses);
   }