re PR target/66655 (miscompilation due to ipa-ra on MinGW)

	PR target/66655
	* config/i386/cygming.h (MAKE_DECL_ONE_ONLY): Define to use weak
	decls if weak support is available.

From-SVN: r232071

gcc/ChangeLog

+2016-01-05  Nick Clifton  <nickc@redhat.com>
+
+	PR target/66655
+	* config/i386/cygming.h (MAKE_DECL_ONE_ONLY): Define to use weak
+	decls if weak support is available.
+
 2016-01-04  Martin Sebor  <msebor@redhat.com>
 
 	* doc/invoke.texi (Warning Options): Document -Winvalid-memory-model.

gcc/config/i386/cygming.h

@@ -432,6 +432,11 @@ do {						\
       fputc ('\n', (FILE));           \
     }                                 \
   while (0)
+
+/* Use the weak support for ONE_ONLY decls.  */
+#undef  MAKE_DECL_ONE_ONLY
+#define MAKE_DECL_ONE_ONLY(DECL) (DECL_WEAK (DECL) = 1)
+
 #endif /* HAVE_GAS_WEAK */
 
 /* FIXME: SUPPORTS_WEAK && TARGET_HAVE_NAMED_SECTIONS is true,