Avoid removing sets of a pseudo PIC register in LRA.

	PR rtl-optimization/69648
	* lra-constraints.c (update_ebb_live_info): Don't remove sets of
	pic_offset_table_rtx.

From-SVN: r233424

gcc/ChangeLog

 2016-02-15  Bernd Schmidt  <bschmidt@redhat.com>
 
+	PR rtl-optimization/69648
+	* lra-constraints.c (update_ebb_live_info): Don't remove sets of
+	pic_offset_table_rtx.
+
 	PR rtl-optimization/69752
 	* ira.c (update_equiv_regs): When looking for more than a single SET,
 	also take other side effects into account.

gcc/lra-constraints.c

@@ -5178,8 +5178,10 @@ update_ebb_live_info (rtx_insn *head, rtx_insn *tail)
       curr_id = lra_get_insn_recog_data (curr_insn);
       curr_static_id = curr_id->insn_static_data;
       remove_p = false;
-      if ((set = single_set (curr_insn)) != NULL_RTX && REG_P (SET_DEST (set))
+      if ((set = single_set (curr_insn)) != NULL_RTX
+	  && REG_P (SET_DEST (set))
 	  && (regno = REGNO (SET_DEST (set))) >= FIRST_PSEUDO_REGISTER
+	  && SET_DEST (set) != pic_offset_table_rtx
 	  && bitmap_bit_p (&check_only_regs, regno)
 	  && ! bitmap_bit_p (&live_regs, regno))
 	remove_p = true;