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Arithmetic overflows now return float rather than wrapping around.

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* data.c: Include <intprops.h>.
(arith_driver): Use floating point if the accumulator would otherwise
go out of EMACS_INT range.
(arith_driver, Fadd1, Fsub1): Use floating point if the result is
out of Emacs fixnum range.
* bytecode.c (exec_byte_code): Likewise, for Bsub1, Badd1, Bnegate.
This commit is contained in:
Paul Eggert 2011-05-03 00:51:38 -07:00
parent fed14fd752
commit 7fc4768c45
3 changed files with 91 additions and 49 deletions
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8
src/ChangeLog
View file

@ -1,5 +1,13 @@
2011-05-03 Paul Eggert <eggert@cs.ucla.edu>
Arithmetic overflows now return float rather than wrapping around.
* data.c: Include <intprops.h>.
(arith_driver): Use floating point if the accumulator would otherwise
go out of EMACS_INT range.
(arith_driver, Fadd1, Fsub1): Use floating point if the result is
out of Emacs fixnum range.
* bytecode.c (exec_byte_code): Likewise, for Bsub1, Badd1, Bnegate.
* callproc.c (Fcall_process): Use 'volatile' to avoid vfork clobbering.
* process.c (Fformat_network_address): Fix typo: args2 -> *args2.

6
src/bytecode.c
View file

@ -1186,7 +1186,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
{
Lisp_Object v1;
v1 = TOP;
if (INTEGERP (v1))
if (INTEGERP (v1) && MOST_NEGATIVE_FIXNUM < XINT (v1))
{
XSETINT (v1, XINT (v1) - 1);
TOP = v1;
@ -1204,7 +1204,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
{
Lisp_Object v1;
v1 = TOP;
if (INTEGERP (v1))
if (INTEGERP (v1) && XINT (v1) < MOST_POSITIVE_FIXNUM)
{
XSETINT (v1, XINT (v1) + 1);
TOP = v1;
@ -1290,7 +1290,7 @@ exec_byte_code (Lisp_Object bytestr, Lisp_Object vector, Lisp_Object maxdepth,
{
Lisp_Object v1;
v1 = TOP;
if (INTEGERP (v1))
if (INTEGERP (v1) && - MOST_POSITIVE_FIXNUM <= XINT (v1))
{
XSETINT (v1, - XINT (v1));
TOP = v1;

126
src/data.c
View file

@ -22,6 +22,9 @@ along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>. */
#include <signal.h>
#include <stdio.h>
#include <setjmp.h>
#include <intprops.h>
#include "lisp.h"
#include "puresize.h"
#include "character.h"
@ -2426,10 +2429,8 @@ static Lisp_Object float_arith_driver (double, size_t, enum arithop,
static Lisp_Object
arith_driver (enum arithop code, size_t nargs, register Lisp_Object *args)
{
register Lisp_Object val;
register size_t argnum;
register EMACS_INT accum = 0;
register EMACS_INT next;
switch (SWITCH_ENUM_CAST (code))
{
@ -2451,58 +2452,89 @@ arith_driver (enum arithop code, size_t nargs, register Lisp_Object *args)
for (argnum = 0; argnum < nargs; argnum++)
{
EMACS_INT a = accum;
int use_float = 0;
/* Using args[argnum] as argument to CHECK_NUMBER_... */
val = args[argnum];
Lisp_Object val = args[argnum];
CHECK_NUMBER_OR_FLOAT_COERCE_MARKER (val);
args[argnum] = val;
if (FLOATP (val))
return float_arith_driver ((double) accum, argnum, code,
nargs, args);
args[argnum] = val;
next = XINT (args[argnum]);
switch (SWITCH_ENUM_CAST (code))
use_float = 1;
else
{
case Aadd:
accum += next;
break;
case Asub:
accum = argnum ? accum - next : nargs == 1 ? - next : next;
break;
case Amult:
accum *= next;
break;
case Adiv:
if (!argnum)
accum = next;
else
EMACS_INT next = XINT (val);
switch (SWITCH_ENUM_CAST (code))
{
if (next == 0)
xsignal0 (Qarith_error);
accum /= next;
case Aadd:
if (next < 0
? a < TYPE_MINIMUM (EMACS_INT) - next
: TYPE_MAXIMUM (EMACS_INT) - next < a)
use_float = 1;
else
a += next;
break;
case Asub:
if (argnum == 0 && nargs != 1)
a = next;
else if (next < 0
? TYPE_MAXIMUM (EMACS_INT) + next < a
: a < TYPE_MINIMUM (EMACS_INT) + next)
use_float = 1;
else
a -= next;
break;
case Amult:
if (next < 0
? (a < 0
? a < TYPE_MAXIMUM (EMACS_INT) / next
: next != -1 && TYPE_MINIMUM (EMACS_INT) / next < a)
: (next != 0
&& (a < 0
? a < TYPE_MINIMUM (EMACS_INT) / next
: TYPE_MAXIMUM (EMACS_INT) / next < a)))
use_float = 1;
else
a *= next;
break;
case Adiv:
if (!argnum)
a = next;
else
{
if (next == 0)
xsignal0 (Qarith_error);
a /= next;
}
break;
case Alogand:
a &= next;
break;
case Alogior:
a |= next;
break;
case Alogxor:
a ^= next;
break;
case Amax:
if (!argnum || a < next)
a = next;
break;
case Amin:
if (!argnum || next < a)
a = next;
break;
}
break;
case Alogand:
accum &= next;
break;
case Alogior:
accum |= next;
break;
case Alogxor:
accum ^= next;
break;
case Amax:
if (!argnum || next > accum)
accum = next;
break;
case Amin:
if (!argnum || next < accum)
accum = next;
break;
}
if (use_float)
return float_arith_driver (accum, argnum, code, nargs, args);
accum = a;
}
XSETINT (val, accum);
return val;
return make_fixnum_or_float (accum);
}
#undef isnan
@ -2777,7 +2809,8 @@ Markers are converted to integers. */)
if (FLOATP (number))
return (make_float (1.0 + XFLOAT_DATA (number)));
if (XINT (number) + 1 == MOST_POSITIVE_FIXNUM + 1)
return make_float (XINT (number) + 1);
XSETINT (number, XINT (number) + 1);
return number;
}
@ -2791,7 +2824,8 @@ Markers are converted to integers. */)
if (FLOATP (number))
return (make_float (-1.0 + XFLOAT_DATA (number)));
if (XINT (number) - 1 == MOST_NEGATIVE_FIXNUM - 1)
return make_float (XINT (number) - 1);
XSETINT (number, XINT (number) - 1);
return number;
}