* bytecode.c (unmark_byte_stack, exec_byte_code): use ptrdiff_t, not int.

(exec_byte_code): Use tighter memory-full test, one that checks
for alloca overflow.  Do not compute the address of the object
just before an array.

src/ChangeLog

@@ -53,10 +53,12 @@
 	(struct buffer_text, struct buffer):
 	Use ptrdiff_t, not EMACS_INT, where ptrdiff_t is wide enough.
 	Use EMACS_INT, not int, where int might not be wide enough.
-	* bytecode.c (exec_byte_code): Use ptrdiff_t, not int, to avoid
-	needless 32-bit limit on 64-bit hosts.  Remove unnecessary
-	memory-full test.  Use EMACS_INT, not ptrdiff_t or int, where
-	ptrdiff_t or int might not be wide enough.
+	* bytecode.c (unmark_byte_stack, exec_byte_code): Use ptrdiff_t,
+	not int, to avoid needless 32-bit limit on 64-bit hosts.
+	(exec_byte_code): Use tighter memory-full test, one that checks
+	for alloca overflow.  Don't compute the address of the object just
+	before an array, as that's not portable.  Use EMACS_INT, not
+	ptrdiff_t or int, where ptrdiff_t or int might not be wide enough.
 	* callint.c (Fcall_interactively):
 	Use ptrdiff_t, not int, to avoid needless 32-bit limit on 64-bit hosts.
 	* callproc.c (call_process_kill, Fcall_process):

src/bytecode.c

@@ -318,7 +318,7 @@ unmark_byte_stack (void)
     {
       if (stack->byte_string_start != SDATA (stack->byte_string))
 	{
-	  int offset = stack->pc - stack->byte_string_start;
+	  ptrdiff_t offset = stack->pc - stack->byte_string_start;
 	  stack->byte_string_start = SDATA (stack->byte_string);
 	  stack->pc = stack->byte_string_start + offset;
 	}
@@ -446,7 +446,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
 #ifdef BYTE_CODE_SAFE
   ptrdiff_t const_length;
   Lisp_Object *stacke;
-  int bytestr_length;
+  ptrdiff_t bytestr_length;
 #endif
   struct byte_stack stack;
   Lisp_Object *top;
@@ -486,13 +486,14 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
   stack.byte_string = bytestr;
   stack.pc = stack.byte_string_start = SDATA (bytestr);
   stack.constants = vector;
-  top = (Lisp_Object *) alloca (XFASTINT (maxdepth)
+  if (MAX_ALLOCA / sizeof (Lisp_Object) <= XFASTINT (maxdepth))
+    memory_full (SIZE_MAX);
+  top = (Lisp_Object *) alloca ((XFASTINT (maxdepth) + 1)
                                          * sizeof (Lisp_Object));
 #if BYTE_MAINTAIN_TOP
-  stack.bottom = top;
+  stack.bottom = top + 1;
   stack.top = NULL;
 #endif
-  top -= 1;
   stack.next = byte_stack_list;
   byte_stack_list = &stack;