--- gcc/config/xm-i38v4.h	2018/04/24 17:51:35	1.1.1.1
+++ gcc/config/xm-i38v4.h	2018/04/24 18:05:17	1.1.1.2
@@ -2,3 +2,11 @@
 
 #include "xm-i386.h"
 #include "xm-svr4.h"
+
+/* If compiled with GNU C, use the built-in alloca.  */
+#undef alloca
+#ifdef __GNUC__
+#define alloca __builtin_alloca
+#else
+#define USE_C_ALLOCA
+#endif