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Fix bignum bugs with nth, elt, =

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* src/bytecode.c (exec_byte_code): Support bignums
when implementing nth, elt, and =.
* src/lisp.h (SMALL_LIST_LEN_MAX): New constant.
* src/fns.c (Fnthcdr): Use it.
(Felt): Do not reject bignum indexes.
This commit is contained in:
Paul Eggert 2018-08-21 11:40:23 -07:00
parent ad31afc35b
commit 81e7eef822
3 changed files with 20 additions and 29 deletions
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39
src/bytecode.c
View file

@ -832,13 +832,14 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
CASE (Bnth):
{
Lisp_Object v2 = POP, v1 = TOP;
CHECK_FIXNUM (v1);
for (EMACS_INT n = XFIXNUM (v1); 0 < n && CONSP (v2); n--)
if (RANGED_FIXNUMP (0, v1, SMALL_LIST_LEN_MAX))
{
v2 = XCDR (v2);
rarely_quit (n);
for (EMACS_INT n = XFIXNUM (v1); 0 < n && CONSP (v2); n--)
v2 = XCDR (v2);
TOP = CAR (v2);
}
TOP = CAR (v2);
else
TOP = Fnth (v1, v2);
NEXT;
}
@ -985,15 +986,8 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
CASE (Beqlsign):
{
Lisp_Object v2 = POP, v1 = TOP;
if (FLOATP (v1) || FLOATP (v2))
TOP = arithcompare (v1, v2, ARITH_EQUAL);
else
{
CHECK_FIXNUM_OR_FLOAT_COERCE_MARKER (v1);
CHECK_FIXNUM_OR_FLOAT_COERCE_MARKER (v2);
TOP = EQ (v1, v2) ? Qt : Qnil;
}
Lisp_Object v1 = POP;
TOP = arithcompare (TOP, v1, ARITH_EQUAL);
NEXT;
}
@ -1264,23 +1258,16 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
CASE (Belt):
{
if (CONSP (TOP))
Lisp_Object v2 = POP, v1 = TOP;
if (CONSP (v1) && RANGED_FIXNUMP (0, v2, SMALL_LIST_LEN_MAX))
{
/* Exchange args and then do nth. */
Lisp_Object v2 = POP, v1 = TOP;
CHECK_FIXNUM (v2);
/* Like the fast case for Bnth, but with args reversed. */
for (EMACS_INT n = XFIXNUM (v2); 0 < n && CONSP (v1); n--)
{
v1 = XCDR (v1);
rarely_quit (n);
}
v1 = XCDR (v1);
TOP = CAR (v1);
}
else
{
Lisp_Object v1 = POP;
TOP = Felt (TOP, v1);
}
TOP = Felt (v1, v2);
NEXT;
}

5
src/fns.c
View file

@ -1418,7 +1418,7 @@ DEFUN ("nthcdr", Fnthcdr, Snthcdr, 2, 2, 0,
num = XFIXNUM (n);
/* Speed up small lists by omitting circularity and quit checking. */
if (num < 128)
if (num <= SMALL_LIST_LEN_MAX)
{
for (; 0 < num; num--, tail = XCDR (tail))
if (! CONSP (tail))
@ -1503,9 +1503,8 @@ N counts from zero. If LIST is not that long, nil is returned. */)
DEFUN ("elt", Felt, Selt, 2, 2, 0,
doc: /* Return element of SEQUENCE at index N. */)
(register Lisp_Object sequence, Lisp_Object n)
(Lisp_Object sequence, Lisp_Object n)
{
CHECK_FIXNUM (n);
if (CONSP (sequence) || NILP (sequence))
return Fcar (Fnthcdr (n, sequence));

5
src/lisp.h
View file

@ -4694,6 +4694,11 @@ enum
Lisp_String)) \
: make_unibyte_string (str, len))
/* The maximum length of "small" lists, as a heuristic. These lists
are so short that code need not check for cycles or quits while
traversing. */
enum { SMALL_LIST_LEN_MAX = 127 };
/* Loop over conses of the list TAIL, signaling if a cycle is found,
and possibly quitting after each loop iteration. In the loop body,
set TAIL to the current cons. If the loop exits normally,