Properly limit backwards label scanning in reorg.

	* reorg.c (label_before_next_insn): New function.
	(relax_delay_slots): Use it instead of prev_label.
	* rtl.h (prev_label): Delete declaration.
	* emit-rtl.c (prev_label): Remove.

From-SVN: r180674

gcc/ChangeLog

+2011-10-30  David S. Miller  <davem@davemloft.net>
+
+	* reorg.c (label_before_next_insn): New function.
+	(relax_delay_slots): Use it instead of prev_label.
+	* rtl.h (prev_label): Delete declaration.
+	* emit-rtl.c (prev_label): Remove.
+
 2011-10-30  Revital Eres  <revital.eres@linaro.org>
 
 	* modulo-sched.c (generate_prolog_epilog): Mark prolog and epilog

gcc/emit-rtl.c

@@ -3330,21 +3330,6 @@ next_label (rtx insn)
   return insn;
 }
 
-/* Return the last CODE_LABEL before the insn INSN, or 0 if there is none.  */
-
-rtx
-prev_label (rtx insn)
-{
-  while (insn)
-    {
-      insn = PREV_INSN (insn);
-      if (insn == 0 || LABEL_P (insn))
-	break;
-    }
-
-  return insn;
-}
-
 /* Return the last label to mark the same position as LABEL.  Return LABEL
    itself if it is null or any return rtx.  */
 

gcc/reorg.c

@@ -3349,6 +3349,21 @@ delete_jump (rtx insn)
     delete_computation (insn);
 }
 
+static rtx
+label_before_next_insn (rtx x, rtx scan_limit)
+{
+  rtx insn = next_active_insn (x);
+  while (insn)
+    {
+      insn = PREV_INSN (insn);
+      if (insn == scan_limit || insn == NULL_RTX)
+	return NULL_RTX;
+      if (LABEL_P (insn))
+	break;
+    }
+  return insn;
+}
+
 
 /* Once we have tried two ways to fill a delay slot, make a pass over the
    code to try to improve the results and to do such things as more jump
@@ -3634,7 +3649,7 @@ relax_delay_slots (rtx first)
 	 identical to the one in its delay slot.  In this case, we can just
 	 delete the branch and the insn in its delay slot.  */
       if (next && NONJUMP_INSN_P (next)
-	  && prev_label (next_active_insn (next)) == target_label
+	  && label_before_next_insn (next, insn) == target_label
 	  && simplejump_p (insn)
 	  && XVECLEN (pat, 0) == 2
 	  && rtx_equal_p (PATTERN (next), PATTERN (XVECEXP (pat, 0, 1))))

gcc/rtl.h

@@ -1812,7 +1812,6 @@ extern rtx next_real_insn (rtx);
 extern rtx prev_active_insn (rtx);
 extern rtx next_active_insn (rtx);
 extern int active_insn_p (const_rtx);
-extern rtx prev_label (rtx);
 extern rtx next_label (rtx);
 extern rtx skip_consecutive_labels (rtx);
 extern rtx next_cc0_user (rtx);