jump.c (delete_related_insns): Keep (use (insn))s.

gcc/
	* jump.c (delete_related_insns): Keep (use (insn))s.
	* reorg.c (redundant_insn): Check for barriers too.

From-SVN: r206749

gcc/ChangeLog

+2014-01-18  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	* jump.c (delete_related_insns): Keep (use (insn))s.
+	* reorg.c (redundant_insn): Check for barriers too.
+
 2014-01-17  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/i386.c (ix86_split_lea_for_addr): Fix a comment

gcc/jump.c

@@ -1355,6 +1355,13 @@ delete_related_insns (rtx insn)
 	  /* Keep going past other deleted labels to delete what follows.  */
 	  else if (code == CODE_LABEL && INSN_DELETED_P (next))
 	    next = NEXT_INSN (next);
+	  /* Keep the (use (insn))s created by dbr_schedule, which needs
+	     them in order to track liveness relative to a previous
+	     barrier.  */
+	  else if (INSN_P (next)
+		   && GET_CODE (PATTERN (next)) == USE
+		   && INSN_P (XEXP (PATTERN (next), 0)))
+	    next = NEXT_INSN (next);
 	  else if (code == BARRIER || INSN_P (next))
 	    /* Note: if this deletes a jump, it can cause more
 	       deletion of unreachable code, after a different label.

gcc/reorg.c

@@ -1512,7 +1512,10 @@ redundant_insn (rtx insn, rtx target, rtx delay_list)
        trial && insns_to_search > 0;
        trial = PREV_INSN (trial))
     {
-      if (LABEL_P (trial))
+      /* (use (insn))s can come immediately after a barrier if the
+	 label that used to precede them has been deleted as dead.
+	 See delete_related_insns.  */
+      if (LABEL_P (trial) || BARRIER_P (trial))
 	return 0;
 
       if (!INSN_P (trial))