rs6000: Don't use REGNO in the add<mode>3 expander

The argument could be a subreg of reg instead, which means we have to
use reg_or_subregno instead of REGNO.


	* config/rs6000/rs6000.md (add<mode>3): Use reg_or_subregno instead
	of REGNO.

From-SVN: r249213

gcc/ChangeLog

+2017-06-15  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	* config/rs6000/rs6000.md (add<mode>3): Use reg_or_subregno instead
+	of REGNO.
+
 2017-06-14  Maciej W. Rozycki  <macro@imgtec.com>
 
 	* config/mips/mips.md (MIPS16_T_REGNUM): Remove constant.

gcc/config/rs6000/rs6000.md

@@ -1631,7 +1631,7 @@
 
       /* Adding a constant to r0 is not a valid insn, so use a different
 	 strategy in that case.  */
-      if (REGNO (operands[1]) == 0 || REGNO (tmp) == 0)
+      if (reg_or_subregno (operands[1]) == 0 || reg_or_subregno (tmp) == 0)
 	{
 	  if (operands[0] == operands[1])
 	    FAIL;