re PR target/90568 (stack protector should use cmp or sub, not xor, to allow macro-fusion on x86)

	PR target/90568
	* config/i386/i386.md (stack_protect_test_<mode>): Use sub instead
	of xor.

From-SVN: r271552

gcc/ChangeLog

+2019-05-23  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/90568
+	* config/i386/i386.md (stack_protect_test_<mode>): Use sub instead
+	of xor.
+
 2019-05-23  Martin Liska  <mliska@suse.cz>
 
 	PR sanitizer/90570

gcc/config/i386/i386.md

@@ -19521,7 +19521,7 @@
 		    UNSPEC_SP_TEST))
    (clobber (match_scratch:PTR 3 "=&r"))]
   ""
-  "mov{<imodesuffix>}\t{%1, %3|%3, %1}\;xor{<imodesuffix>}\t{%2, %3|%3, %2}"
+  "mov{<imodesuffix>}\t{%1, %3|%3, %1}\;sub{<imodesuffix>}\t{%2, %3|%3, %2}"
   [(set_attr "type" "multi")])
 
 (define_insn "sse4_2_crc32<mode>"