--- gcc/config/pa/xm-pa.h	2018/04/24 18:10:27	1.1.1.1
+++ gcc/config/pa/xm-pa.h	2018/04/24 18:23:38	1.1.1.2
@@ -51,3 +51,8 @@ extern int errno;
 
 /* HP's compiler has problems with enum bitfields.  */
 #define ONLY_INT_FIELDS
+
+/* If not compiled with GNU C, use C alloca.  */
+#ifndef __GNUC__
+#define USE_C_ALLOCA
+#endif