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Simplify BYTE_CODE_SAFE checking

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* src/bytecode.c (BYTE_CODE_SAFE): Default to false, so that it
can be used outside #if.  All uses of ‘defined BYTE_CODE_SAFE’
changed to ‘BYTE_CODE_SAFE’.  Use BYTE_CODE_SAFE in plain
expressions instead of #if expressions when this is easy.
(struct byte_stack) [BYTE_CODE_SAFE]: Remove member ‘bottom’,
as it is no longer needed.
(exec_byte_code): Omit #if BYTE_CODE_SAFE when this is easy.
Simplify stack-overflow checking when BYTE_CODE_SAFE.
This commit is contained in:
Paul Eggert 2016-08-09 00:37:38 -07:00
parent 846e88eb99
commit 4d07064a43
1 changed files with 21 additions and 58 deletions
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79
src/bytecode.c
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@ -32,13 +32,14 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
# pragma GCC diagnostic ignored "-Wclobbered"
#endif
/*
* define BYTE_CODE_SAFE to enable some minor sanity checking (useful for
* debugging the byte compiler...)
*
* define BYTE_CODE_METER to enable generation of a byte-op usage histogram.
*/
/* #define BYTE_CODE_SAFE */
/* Define BYTE_CODE_SAFE true to enable some minor sanity checking,
useful for debugging the byte compiler. It defaults to false. */
#ifndef BYTE_CODE_SAFE
# define BYTE_CODE_SAFE false
#endif
/* Define BYTE_CODE_METER to generate a byte-op usage histogram. */
/* #define BYTE_CODE_METER */
/* If BYTE_CODE_THREADED is defined, then the interpreter will be
@ -46,7 +47,7 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
as currently implemented, is incompatible with BYTE_CODE_SAFE and
BYTE_CODE_METER. */
#if (defined __GNUC__ && !defined __STRICT_ANSI__ \
&& !defined BYTE_CODE_SAFE && !defined BYTE_CODE_METER)
&& !BYTE_CODE_SAFE && !defined BYTE_CODE_METER)
#define BYTE_CODE_THREADED
#endif
@ -274,7 +275,7 @@ enum byte_code_op
BYTE_CODES
#undef DEFINE
#ifdef BYTE_CODE_SAFE
#if BYTE_CODE_SAFE
Bscan_buffer = 0153, /* No longer generated as of v18. */
Bset_mark = 0163, /* this loser is no longer generated as of v18 */
#endif
@ -289,12 +290,6 @@ struct byte_stack
and is relocated when that string is relocated. */
const unsigned char *pc;
/* bottom of stack. The bottom points to an area of memory
allocated with alloca in Fbyte_code. */
#ifdef BYTE_CODE_SAFE
Lisp_Object *bottom;
#endif
/* The string containing the byte-code, and its current address.
Storing this here protects it from GC. */
Lisp_Object byte_string;
@ -334,7 +329,7 @@ relocate_byte_stack (void)
/* Fetch the next byte from the bytecode stream. */
#ifdef BYTE_CODE_SAFE
#if BYTE_CODE_SAFE
#define FETCH (eassert (stack.byte_string_start == SDATA (stack.byte_string)), *stack.pc++)
#else
#define FETCH *stack.pc++
@ -365,16 +360,8 @@ relocate_byte_stack (void)
/* Check for jumping out of range. */
#ifdef BYTE_CODE_SAFE
#define CHECK_RANGE(ARG) \
if (ARG >= bytestr_length) emacs_abort ()
#else /* not BYTE_CODE_SAFE */
#define CHECK_RANGE(ARG)
#endif /* not BYTE_CODE_SAFE */
(BYTE_CODE_SAFE && bytestr_length <= (ARG) ? emacs_abort () : (void) 0)
/* A version of the QUIT macro which makes sure that the stack top is
set before signaling `quit'. */
@ -431,11 +418,8 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
int op;
/* Lisp_Object v1, v2; */
Lisp_Object *vectorp;
#ifdef BYTE_CODE_SAFE
ptrdiff_t const_length;
Lisp_Object *stacke;
ptrdiff_t bytestr_length;
#endif
struct byte_stack stack;
Lisp_Object *top;
Lisp_Object result;
@ -445,9 +429,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
CHECK_VECTOR (vector);
CHECK_NATNUM (maxdepth);
#ifdef BYTE_CODE_SAFE
const_length = ASIZE (vector);
#endif
if (STRING_MULTIBYTE (bytestr))
/* BYTESTR must have been produced by Emacs 20.2 or the earlier
@ -457,26 +439,20 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
convert them back to the originally intended unibyte form. */
bytestr = Fstring_as_unibyte (bytestr);
#ifdef BYTE_CODE_SAFE
bytestr_length = SBYTES (bytestr);
#endif
vectorp = XVECTOR (vector)->contents;
stack.byte_string = bytestr;
stack.pc = stack.byte_string_start = SDATA (bytestr);
if (MAX_ALLOCA / word_size <= XFASTINT (maxdepth))
memory_full (SIZE_MAX);
top = alloca ((XFASTINT (maxdepth) + 1) * sizeof *top);
#ifdef BYTE_CODE_SAFE
stack.bottom = top + 1;
#endif
int stack_items = XFASTINT (maxdepth) + 1;
Lisp_Object *stack_base = alloca (stack_items * sizeof *top);
Lisp_Object *stack_lim = stack_base + stack_items;
top = stack_base;
stack.next = byte_stack_list;
byte_stack_list = &stack;
#ifdef BYTE_CODE_SAFE
stacke = stack.bottom - 1 + XFASTINT (maxdepth);
#endif
if (!NILP (args_template))
{
eassert (INTEGERP (args_template));
@ -501,12 +477,8 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
while (1)
{
#ifdef BYTE_CODE_SAFE
if (top > stacke)
if (BYTE_CODE_SAFE && ! (stack_base <= top && top < stack_lim))
emacs_abort ();
else if (top < stack.bottom - 1)
emacs_abort ();
#endif
#ifdef BYTE_CODE_METER
prev_op = this_op;
@ -1643,7 +1615,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
TOP = INTEGERP (TOP) ? Qt : Qnil;
NEXT;
#ifdef BYTE_CODE_SAFE
#if BYTE_CODE_SAFE
/* These are intentionally written using 'case' syntax,
because they are incompatible with the threaded
interpreter. */
@ -1713,19 +1685,10 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
CASE_DEFAULT
CASE (Bconstant):
#ifdef BYTE_CODE_SAFE
if (op < Bconstant)
{
emacs_abort ();
}
if ((op -= Bconstant) >= const_length)
{
emacs_abort ();
}
PUSH (vectorp[op]);
#else
if (BYTE_CODE_SAFE
&& ! (Bconstant <= op && op < Bconstant + const_length))
emacs_abort ();
PUSH (vectorp[op - Bconstant]);
#endif
NEXT;
}
}