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factor: check overflow with ckd_add etc

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* src/factor.c (umul_ppmm, add_ssaaaa, sub_ddmmss, submod)
(mulredc, strto2wide_uint): Prefer ckd_add etc. to doing
overflow checking by hand.
This commit is contained in:
Paul Eggert
2025-05-12 00:09:16 -07:00
parent 229ddeb36a
commit 8dd5b91d2c
1 changed files with 9 additions and 21 deletions
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src/factor.c
+9 -21
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@@ -291,8 +291,7 @@ static void factor (uintmax_t, uintmax_t, struct factors *);
__x3 = (uintmax_t) __uh * __vh; \
\
__x1 += __ll_highpart (__x0);/* This can't give carry. */ \
__x1 += __x2; /* But this indeed can. */ \
if (__x1 < __x2) /* Did we get it? */ \
if (ckd_add (&__x1, __x1, __x2)) /* Did this give a carry? */ \
__x3 += __ll_B; /* Yes, add it in the proper pos. */ \
\
(w1) = __x3 + __ll_highpart (__x1); \
@@ -332,8 +331,7 @@ static void factor (uintmax_t, uintmax_t, struct factors *);
# define add_ssaaaa(sh, sl, ah, al, bh, bl) \
do { \
uintmax_t _add_x; \
_add_x = (al) + (bl); \
(sh) = (ah) + (bh) + (_add_x < (al)); \
(sh) = (ah) + (bh) + ckd_add (&_add_x, al, bl); \
(sl) = _add_x; \
} while (0)
#endif
@@ -360,19 +358,14 @@ static void factor (uintmax_t, uintmax_t, struct factors *);
#ifndef sub_ddmmss
# define sub_ddmmss(rh, rl, ah, al, bh, bl) \
do { \
uintmax_t _cy; \
_cy = (al) < (bl); \
(rl) = (al) - (bl); \
(rh) = (ah) - (bh) - _cy; \
} while (0)
((rh) = (ah) - (bh) - ckd_sub (&(rl), al, bl))
#endif
/* Requires that a < n and b <= n */
#define submod(r,a,b,n) \
do { \
uintmax_t _t = - (uintmax_t) (a < b); \
(r) = ((n) & _t) + (a) - (b); \
uintmax_t _s, _t = -ckd_sub (&_s, a, b); \
(r) = ((n) & _t) + _s; \
} while (0)
#define addmod(r,a,b,n) \
@@ -964,8 +957,7 @@ mulredc (uintmax_t a, uintmax_t b, uintmax_t m, uintmax_t mi)
umul_ppmm (rh, rl, a, b);
q = rl * mi;
umul_ppmm (th, tl, q, m);
xh = rh - th;
if (rh < th)
if (ckd_sub (&xh, rh, th))
xh += m;
return xh;
@@ -2280,22 +2272,18 @@ strto2uintmax (uintmax_t *hip, uintmax_t *lop, char const *s)
c -= '0';
if (UNLIKELY (hi > ~(uintmax_t)0 / 10))
if (UNLIKELY (ckd_mul (&hi, hi, 10)))
{
err = LONGINT_OVERFLOW;
break;
}
hi = 10 * hi;
lo_carry = (lo >> (W_TYPE_SIZE - 3)) + (lo >> (W_TYPE_SIZE - 1));
lo_carry += 10 * lo < 2 * lo;
lo = 10 * lo;
lo += c;
lo_carry += lo < c;
hi += lo_carry;
if (UNLIKELY (hi < lo_carry))
lo_carry += ckd_add (&lo, lo, c);
if (UNLIKELY (ckd_add (&hi, hi, lo_carry)))
{
err = LONGINT_OVERFLOW;
break;