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Remove unneeded overflow check in integer division

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* src/data.c (arith_driver): Remove unnecessary runtime test,
since integer overflow is impossible on division of fixnums,
given that the worst case is MOST_NEGATIVE_FIXNUM / -1 which is
representable as an EMACS_INT (albeit not as a fixnum).
This commit is contained in:
Paul Eggert 2019-11-05 22:55:23 -08:00
parent 0661a39d1b
commit 6039acb861
1 changed files with 3 additions and 4 deletions
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src/data.c
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@ -2944,7 +2944,7 @@ arith_driver (enum arithop code, ptrdiff_t nargs, Lisp_Object *args,
/* Set ACCUM to the next operation's result if it fits,
else exit the loop. */
bool overflow = false;
intmax_t a UNINIT;
intmax_t a;
switch (code)
{
case Aadd : overflow = INT_ADD_WRAPV (accum, next, &a); break;
@ -2953,9 +2953,8 @@ arith_driver (enum arithop code, ptrdiff_t nargs, Lisp_Object *args,
case Adiv:
if (next == 0)
xsignal0 (Qarith_error);
overflow = INT_DIVIDE_OVERFLOW (accum, next);
if (!overflow)
a = accum / next;
eassert (! INT_DIVIDE_OVERFLOW (accum, next));
a = accum / next;
break;
case Alogand: accum &= next; continue;
case Alogior: accum |= next; continue;