[RS6000] Don't expand strcmp and strncmp inline when -Os

	* config/rs6000/rs6000.md (cmpstrnsi, cmpstrsi): Fail if
	optimizing for size.

From-SVN: r244660

gcc/ChangeLog

 2017-01-20  Alan Modra  <amodra@gmail.com>
 
+	* config/rs6000/rs6000.md (cmpstrnsi, cmpstrsi): Fail if
+	optimizing for size.
+
+2017-01-20  Alan Modra  <amodra@gmail.com>
+
 	PR target/79144
 	* config/rs6000/rs6000.c (expand_strn_compare): Get the asm name
 	for strcmp and strncmp from corresponding builtin decl.

gcc/config/rs6000/rs6000.md

@@ -9102,6 +9102,9 @@
 	      (use (match_operand:SI 4))])]
   "TARGET_CMPB && (BYTES_BIG_ENDIAN || TARGET_LDBRX)"
 {
+  if (optimize_insn_for_size_p ())
+    FAIL;
+
   if (expand_strn_compare (operands, 0))
     DONE;
   else	
@@ -9121,6 +9124,9 @@
 	      (use (match_operand:SI 3))])]
   "TARGET_CMPB && (BYTES_BIG_ENDIAN || TARGET_LDBRX)"
 {
+  if (optimize_insn_for_size_p ())
+    FAIL;
+
   if (expand_strn_compare (operands, 1))
     DONE;
   else