* regcprop.c (copyprop_hardreg_forward_1): Remove noop moves.

From-SVN: r240365

gcc/ChangeLog

+2016-09-22  Jan Hubicka  <hubicka@ucw.cz>
+
+	* regcprop.c (copyprop_hardreg_forward_1): Remove noop moves.
+
 2016-09-22  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>
 
 	* emit-rtl.c (next_cc0_user): Make argument type rtx_insn *.

gcc/regcprop.c

@@ -771,6 +771,26 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
 	}
 
       set = single_set (insn);
+
+      /* Detect noop sets and remove them before processing side effects.  */
+      if (set && REG_P (SET_DEST (set)) && REG_P (SET_SRC (set)))
+	{
+	  unsigned int regno = REGNO (SET_SRC (set));
+	  rtx r1 = find_oldest_value_reg (REGNO_REG_CLASS (regno),
+					  SET_DEST (set), vd);
+	  rtx r2 = find_oldest_value_reg (REGNO_REG_CLASS (regno),
+					  SET_SRC (set), vd);
+	  if (rtx_equal_p (r1 ? r1 : SET_DEST (set), r2 ? r2 : SET_SRC (set)))
+	    {
+	      bool last = insn == BB_END (bb);
+	      fprintf (stderr, "Bingo\n");
+	      delete_insn (insn);
+	      if (last)
+		break;
+	      continue;
+	    }
+	}
+
       extract_constrain_insn (insn);
       preprocess_constraints (insn);
       const operand_alternative *op_alt = which_op_alt ();
@@ -860,7 +880,9 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
 	     register in the same class.  */
 	  if (REG_P (SET_DEST (set)))
 	    {
-	      new_rtx = find_oldest_value_reg (REGNO_REG_CLASS (regno), src, vd);
+	      new_rtx = find_oldest_value_reg (REGNO_REG_CLASS (regno),
+					       src, vd);
+
 	      if (new_rtx && validate_change (insn, &SET_SRC (set), new_rtx, 0))
 		{
 		  if (dump_file)