* lcm.c (optimize_mode_switching): Do not rebuild liveness information

	when no changes has been made.

	* gcse.c (reg_set_bitmap): Turn into reg_set.
	(modify_mem_list_set, canon_modify_mem_list_set)
	(clear_modify_mem_tables, free_modify_mem_tables): New.
	(gcse_main); Use free_modify_mem_tables.
	(free_gcse_mem): Likewise; free the bitmaps.
	(alloc_gcse_main): Initialize the bitmaps.
	(canon_list_insert): Set canon_modify_mem_list_set.
	(record_last_mem_set_info): Likewise; set modify_mem_list_set.
	(compute_hash_table): Use clear_modify_mem_tables.
	(reset_opr_set_tables): Likewise.
	(oprs_not_set_p): reg_set_bitmap is regset.
	(mark_set, mark_clobber): Likewise.

	* df.h (DF_EQUIV_NOTES): New constant.
	(df_insn_refs_record): Record uses inside or REG_EQUIV/EQUAL notes
	when asked for.

	* sched-rgn.c (CHECK_DEAD_NOTES): New constant.
	(init_regions, schedule_insns): Conditionalize the checking
	code by CHECK_DEAD_NOTES; avoid multiple calls to update_life_info.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@46634 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/lcm.c b/gcc/lcm.c
index 4f5d6927161..88e58410d81 100644
--- a/gcc/lcm.c
+++ b/gcc/lcm.c
@@ -1029,6 +1029,7 @@ optimize_mode_switching (file)
   int i, j;
   int n_entities;
   int max_num_modes = 0;
+  bool emited = false;
 
 #ifdef NORMAL_MODE
   /* Increment n_basic_blocks before allocating bb_info.  */
@@ -1239,10 +1240,16 @@ optimize_mode_switching (file)
 	      mode_set = gen_sequence ();
 	      end_sequence ();
 
+	      /* Do not bother to insert empty sequence.  */
+	      if (GET_CODE (mode_set) == SEQUENCE
+		  && !XVECLEN (mode_set, 0))
+		continue;
+
 	      /* If this is an abnormal edge, we'll insert at the end
 		 of the previous block.  */
 	      if (eg->flags & EDGE_ABNORMAL)
 		{
+		  emited = true;
 		  if (GET_CODE (src_bb->end) == JUMP_INSN)
 		    emit_insn_before (mode_set, src_bb->end);
 		  /* It doesn't make sense to switch to normal mode
@@ -1313,10 +1320,16 @@ optimize_mode_switching (file)
 	      mode_set = gen_sequence ();
 	      end_sequence ();
 
+	      /* Do not bother to insert empty sequence.  */
+	      if (GET_CODE (mode_set) == SEQUENCE
+		  && !XVECLEN (mode_set, 0))
+		continue;
+
 	      /* If this is an abnormal edge, we'll insert at the end of the
 		 previous block.  */
 	      if (eg->flags & EDGE_ABNORMAL)
 		{
+		  emited = true;
 		  if (GET_CODE (eg->src->end) == JUMP_INSN)
 		    emit_insn_before (mode_set, eg->src->end);
 		  else if (GET_CODE (eg->src->end) == INSN)
@@ -1349,6 +1362,12 @@ optimize_mode_switching (file)
 		  mode_set = gen_sequence ();
 		  end_sequence ();
 
+		  /* Do not bother to insert empty sequence.  */
+		  if (GET_CODE (mode_set) == SEQUENCE
+		      && !XVECLEN (mode_set, 0))
+		    continue;
+
+		  emited = true;
 		  if (GET_CODE (ptr->insn_ptr) == NOTE
 		      && (NOTE_LINE_NUMBER (ptr->insn_ptr)
 			  == NOTE_INSN_BASIC_BLOCK))
@@ -1376,6 +1395,9 @@ optimize_mode_switching (file)
   if (need_commit)
     commit_edge_insertions ();
 
+  if (!need_commit && !emited)
+    return 0;
+
   /* Ideally we'd figure out what blocks were affected and start from
      there, but this is enormously complicated by commit_edge_insertions,
      which would screw up any indicies we'd collected, and also need to