re PR rtl-optimization/59278 (combine does not replace matched insn)

	PR rtl-optimization/59278
	combine (reg_dead_at_p): Consider REG_UNUSED notes.

From-SVN: r218250

gcc/ChangeLog

 2014-12-01  Segher Boessenkool  <segher@kernel.crashing.org>
 
+	PR rtl-optimization/59278
+	combine (reg_dead_at_p): Consider REG_UNUSED notes.
+
+2014-12-01  Segher Boessenkool  <segher@kernel.crashing.org>
+
 	* combine.c (try_combine): Use is_parallel_of_n_reg_sets some more.
 
 2014-12-01  Segher Boessenkool  <segher@kernel.crashing.org>

gcc/combine.c

@@ -12990,6 +12990,9 @@ reg_dead_at_p (rtx reg, rtx_insn *insn)
     {
       if (INSN_P (insn))
         {
+	  if (find_regno_note (insn, REG_UNUSED, reg_dead_regno))
+	    return 1;
+
 	  note_stores (PATTERN (insn), reg_dead_at_p_1, NULL);
 	  if (reg_dead_flag)
 	    return reg_dead_flag == 1 ? 1 : 0;