Re: [Patch] Teach genrecog/genoutput that scratch registers require write constraint modifiers

gcc/

	* genrecog.c (validate_pattern): Allow empty constraints in
	a match_scratch.

From-SVN: r215397

gcc/ChangeLog

+2014-09-19  James Greenhalgh  <james.greenhalgh@arm.com>
+
+	* genrecog.c (validate_pattern): Allow empty constraints in
+	a match_scratch.
+
 2014-09-19  Aldy Hernandez  <aldyh@redhat.com>
 
 	* dwarf2out.c (decl_ultimate_origin): Update comment.

gcc/genrecog.c

@@ -461,6 +461,7 @@ validate_pattern (rtx pattern, rtx insn, rtx set, int set_code)
 	/* If a MATCH_SCRATCH is used in a context requiring an write-only
 	   or read/write register, validate that.  */
 	if (set_code == '='
+	    && constraints0
 	    && constraints0 != '='
 	    && constraints0 != '+')
 	  {