* alloc.c (mark_stack): Move local variables into the #ifdef region where

they're used.

src/ChangeLog

@@ -3,6 +3,8 @@
 	* alloc.c (check_cons_list): Do not define unless GC_CHECK_CONS_LIST.
 	(Fmake_vector, Fvector, Fmake_byte_code, Fgarbage_collect):
 	Rename locals to avoid shadowing.
+	(mark_stack): Move local variables into the #ifdef region where
+	they're used.
 	* lisp.h (check_cons_list): Declare if GC_CHECK_CONS_LIST; this
 	avoids undefined behavior in theory.

src/alloc.c

@@ -4312,12 +4312,6 @@ static void
 mark_stack (void)
 {
   int i;
-  /* jmp_buf may not be aligned enough on darwin-ppc64 */
-  union aligned_jmpbuf {
-    Lisp_Object o;
-    jmp_buf j;
-  } j;
-  volatile int stack_grows_down_p = (char *) &j > (char *) stack_base;
   void *end;
 
 #ifdef HAVE___BUILTIN_UNWIND_INIT
@@ -4327,6 +4321,14 @@ mark_stack (void)
   __builtin_unwind_init ();
   end = &end;
 #else /* not HAVE___BUILTIN_UNWIND_INIT */
+#ifndef GC_SAVE_REGISTERS_ON_STACK
+  /* jmp_buf may not be aligned enough on darwin-ppc64 */
+  union aligned_jmpbuf {
+    Lisp_Object o;
+    jmp_buf j;
+  } j;
+  volatile int stack_grows_down_p = (char *) &j > (char *) stack_base;
+#endif
   /* This trick flushes the register windows so that all the state of
      the process is contained in the stack.  */
   /* Fixme: Code in the Boehm GC suggests flushing (with `flushrs') is