rtl.h (skip_consecutive_labels): Declare.

	* rtl.h (skip_consecutive_labels): Declare.
	* emit-rtl.c (skip_consecutive_labels): New function.
	* reorg.c (relax_delay_slots, dbr_schedule): Use it.
	* jump.c (follow_jumps): Say what null return values mean.

From-SVN: r82357

gcc/ChangeLog

+2004-05-28  Richard Sandiford  <rsandifo@redhat.com>
+
+	* rtl.h (skip_consecutive_labels): Declare.
+	* emit-rtl.c (skip_consecutive_labels): New function.
+	* reorg.c (relax_delay_slots, dbr_schedule): Use it.
+	* jump.c (follow_jumps): Say what null return values mean.
+
 2004-05-28  Kaz Kojima  <kkojima@gcc.gnu.org>
 
 	PR target/13250

gcc/emit-rtl.c

@@ -3110,6 +3110,21 @@ prev_label (rtx insn)
   return insn;
 }
 
+/* Return the last label to mark the same position as LABEL.  Return null
+   if LABEL itself is null.  */
+
+rtx
+skip_consecutive_labels (rtx label)
+{
+  rtx insn;
+
+  for (insn = label; insn != 0 && !INSN_P (insn); insn = NEXT_INSN (insn))
+    if (LABEL_P (insn))
+      label = insn;
+
+  return label;
+}
+
 #ifdef HAVE_cc0
 /* INSN uses CC0 and is being moved into a delay slot.  Set up REG_CC_SETTER
    and REG_CC_USER notes so we can find it.  */

gcc/jump.c

@@ -999,6 +999,7 @@ sets_cc0_p (rtx x)
 
 /* Follow any unconditional jump at LABEL;
    return the ultimate label reached by any such chain of jumps.
+   Return null if the chain ultimately leads to a return instruction.
    If LABEL is not followed by a jump, return LABEL.
    If the chain loops or we can't find end, return LABEL,
    since that tells caller to avoid changing the insn.

gcc/reorg.c

@@ -3079,11 +3079,7 @@ relax_delay_slots (rtx first)
 	  && (condjump_p (insn) || condjump_in_parallel_p (insn))
 	  && (target_label = JUMP_LABEL (insn)) != 0)
 	{
-	  target_label = follow_jumps (target_label);
-	  /* See comment further down why we must use next_real_insn here,
-	     instead of next_active_insn.  */
-	  target_label = prev_label (next_real_insn (target_label));
-
+	  target_label = skip_consecutive_labels (follow_jumps (target_label));
 	  if (target_label == 0)
 	    target_label = find_end_label ();
 
@@ -3231,14 +3227,8 @@ relax_delay_slots (rtx first)
 	{
 	  /* If this jump goes to another unconditional jump, thread it, but
 	     don't convert a jump into a RETURN here.  */
-	  trial = follow_jumps (target_label);
-	  /* We use next_real_insn instead of next_active_insn, so that
-	     the special USE insns emitted by reorg won't be ignored.
-	     If they are ignored, then they will get deleted if target_label
-	     is now unreachable, and that would cause mark_target_live_regs
-	     to fail.  */
-	  trial = prev_label (next_real_insn (trial));
-	  if (trial == 0 && target_label != 0)
+	  trial = skip_consecutive_labels (follow_jumps (target_label));
+	  if (trial == 0)
 	    trial = find_end_label ();
 
 	  if (trial != target_label
@@ -3621,7 +3611,7 @@ dbr_schedule (rtx first, FILE *file)
       if (GET_CODE (insn) == JUMP_INSN
 	  && (condjump_p (insn) || condjump_in_parallel_p (insn))
 	  && JUMP_LABEL (insn) != 0
-	  && ((target = prev_label (next_active_insn (JUMP_LABEL (insn))))
+	  && ((target = skip_consecutive_labels (JUMP_LABEL (insn)))
 	      != JUMP_LABEL (insn)))
 	redirect_jump (insn, target, 1);
     }

gcc/rtl.h

@@ -1695,6 +1695,7 @@ extern rtx next_active_insn (rtx);
 extern int active_insn_p (rtx);
 extern rtx prev_label (rtx);
 extern rtx next_label (rtx);
+extern rtx skip_consecutive_labels (rtx);
 extern rtx next_cc0_user (rtx);
 extern rtx prev_cc0_setter (rtx);