* src/bytecode.c (struct byte_stack): Remove `constants' when unused.

src/bytecode.c

@@ -313,9 +313,11 @@ struct byte_stack
   Lisp_Object byte_string;
   const unsigned char *byte_string_start;
 
+#if BYTE_MARK_STACK
   /* The vector of constants used during byte-code execution.  Storing
      this here protects it from GC because mark_byte_stack marks it.  */
   Lisp_Object constants;
+#endif
 
   /* Next entry in byte_stack_list.  */
   struct byte_stack *next;
@@ -379,12 +381,12 @@ unmark_byte_stack (void)
 }
 
 
-/* Fetch the next byte from the bytecode stream */
+/* Fetch the next byte from the bytecode stream.  */
 
 #define FETCH *stack.pc++
 
 /* Fetch two bytes from the bytecode stream and make a 16-bit number
-   out of them */
+   out of them.  */
 
 #define FETCH2 (op = FETCH, op + (FETCH << 8))
 
@@ -404,7 +406,7 @@ unmark_byte_stack (void)
 #define DISCARD(n) (top -= (n))
 
 /* Get the value which is at the top of the execution stack, but don't
-   pop it. */
+   pop it.  */
 
 #define TOP (*top)
 
@@ -535,7 +537,9 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
 
   stack.byte_string = bytestr;
   stack.pc = stack.byte_string_start = SDATA (bytestr);
+#if BYTE_MARK_STACK
   stack.constants = vector;
+#endif
   if (MAX_ALLOCA / word_size <= XFASTINT (maxdepth))
     memory_full (SIZE_MAX);
   top = alloca ((XFASTINT (maxdepth) + 1) * sizeof *top);