rtl.h (cleanup_barriers): Declare.

	* rtl.h (cleanup_barriers): Declare.
	* jump.c (cleanup_barriers): New function.
	* toplev.c (rest_of_compilation): Call cleanup_barriers
	before loop optimizer and after bb_reorder.

	* flow.c (back_edge_of_syntactic_loop_p): New.
	(split_edge): Use it.

From-SVN: r44409

5 files changed, 68 insertions, 1 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 0ab4a10..fddead1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+Thu Jul 26 22:30:22 CEST 2001  Jan Hubicka  <jh@suse.cz>
+
+	* rtl.h (cleanup_barriers): Declare.
+	* jump.c (cleanup_barriers): New function.
+	* toplev.c (rest_of_compilation): Call cleanup_barriers
+	before loop optimizer and after bb_reorder.
+
+	* flow.c (back_edge_of_syntactic_loop_p): New.
+	(split_edge): Use it.
+
 2001-07-26  Rainer Orth  <ro@TechFak.Uni-Bielefeld.DE>
 
 	* glimits.h (_MACH_MACHLIMITS_H_): Delete.
diff --git a/gcc/flow.c b/gcc/flow.c
index cd33dec..248d429 100644
--- a/gcc/flow.c
+++ b/gcc/flow.c
@@ -482,6 +482,7 @@ static void flow_loops_tree_build	PARAMS ((struct loops *));
 static int flow_loop_level_compute	PARAMS ((struct loop *, int));
 static int flow_loops_level_compute	PARAMS ((struct loops *));
 static void delete_dead_jumptables	PARAMS ((void));
+static bool back_edge_of_syntactic_loop_p PARAMS ((basic_block, basic_block));
 
 /* Find basic blocks of the current function.
    F is the first insn of the function and NREGS the number of register
@@ -1968,6 +1969,30 @@ redirect_edge_and_branch_force (e, target)
   return new_bb;
 }
 
+/* Helper function for split_edge.  Return true in case edge BB2 to BB1
+   is back edge of syntactic loop.  */
+static bool
+back_edge_of_syntactic_loop_p (bb1, bb2)
+	basic_block bb1, bb2;
+{
+  rtx insn;
+  int count;
+  if (bb1->index > bb2->index)
+    return false;
+  if (bb1->index == bb2->index)
+    return true;
+  for (insn = bb1->end; insn != bb2->head && count >= 0;
+       insn = NEXT_INSN (insn))
+    if (GET_CODE (insn) == NOTE)
+      {
+	if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
+	  count++;
+	if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
+	  count--;
+      }
+  return count >= 0;
+}
+
 /* Split a (typically critical) edge.  Return the new block.
    Abort on abnormal edges.
 
@@ -2115,7 +2140,8 @@ split_edge (edge_in)
   if (old_succ != EXIT_BLOCK_PTR
       && PREV_INSN (old_succ->head)
       && GET_CODE (PREV_INSN (old_succ->head)) == NOTE
-      && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG)
+      && NOTE_LINE_NUMBER (PREV_INSN (old_succ->head)) == NOTE_INSN_LOOP_BEG
+      && !back_edge_of_syntactic_loop_p (old_succ, old_pred))
     bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK,
 				PREV_INSN (old_succ->head));
   else if (old_succ != EXIT_BLOCK_PTR)
diff --git a/gcc/jump.c b/gcc/jump.c
index 01fc741..e77ba56 100644
--- a/gcc/jump.c
+++ b/gcc/jump.c
@@ -100,6 +100,32 @@ rebuild_jump_labels (f)
       LABEL_NUSES (XEXP (insn, 0))++;
 }
 
+/* Some old code expects exactly one BARRIER as the NEXT_INSN of a
+   non-fallthru insn.  This is not generally true, as multiple barriers
+   may have crept in, or the BARRIER may be separated from the last
+   real insn by one or more NOTEs.
+
+   This simple pass moves barriers and removes duplicates so that the
+   old code is happy.
+ */
+void
+cleanup_barriers ()
+{
+  rtx insn, next, prev;
+  for (insn = get_insns (); insn; insn = next)
+    {
+      next = NEXT_INSN (insn);
+      if (GET_CODE (insn) == BARRIER)
+	{
+	  prev = prev_nonnote_insn (insn);
+	  if (GET_CODE (prev) == BARRIER)
+	    delete_barrier (insn);
+	  else if (prev != PREV_INSN (insn))
+	    reorder_insns (insn, insn, prev);
+	}
+    }
+}
+
 void
 copy_loop_headers (f)
      rtx f;
diff --git a/gcc/rtl.h b/gcc/rtl.h
index 1fbc9da..7cacfab 100644
--- a/gcc/rtl.h
+++ b/gcc/rtl.h
@@ -1286,6 +1286,7 @@ extern enum rtx_code swap_condition	PARAMS ((enum rtx_code));
 extern enum rtx_code unsigned_condition	PARAMS ((enum rtx_code));
 extern enum rtx_code signed_condition	PARAMS ((enum rtx_code));
 extern void mark_jump_label		PARAMS ((rtx, rtx, int));
+extern void cleanup_barriers		PARAMS ((void));
 
 /* In jump.c */
 extern rtx squeeze_notes		PARAMS ((rtx, rtx));
diff --git a/gcc/toplev.c b/gcc/toplev.c
index a28b38e..21d4fbb 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -3096,6 +3096,8 @@ rest_of_compilation (decl)
 
       if (flag_rerun_loop_opt)
 	{
+	  cleanup_barriers ();
+
 	  /* We only want to perform unrolling once.  */
 
 	  loop_optimize (insns, rtl_dump_file, 0);
@@ -3110,6 +3112,7 @@ rest_of_compilation (decl)
 		  analysis code depends on this information.  */
 	  reg_scan (insns, max_reg_num (), 1);
 	}
+      cleanup_barriers ();
       loop_optimize (insns, rtl_dump_file,
 		     (flag_unroll_loops ? LOOP_UNROLL : 0) | LOOP_BCT);
 
@@ -3614,6 +3617,7 @@ rest_of_compilation (decl)
   /* CFG no longer kept up to date.  */
 
   purge_line_number_notes (insns);
+  cleanup_barriers ();
 
   /* If a scheduling pass for delayed branches is to be done,
      call the scheduling code.  */