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Slight bignum-fixnum multiplication optimization

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* libguile/integers.c (scm_integer_mul_zi): Use mpn_mul_1.
This commit is contained in:
Andy Wingo 2022-01-30 21:15:58 +01:00
parent 54bbe0b284
commit 62fc44e6ee
1 changed files with 8 additions and 4 deletions
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12
libguile/integers.c
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@ -3094,13 +3094,17 @@ scm_integer_mul_zi (struct scm_bignum *x, scm_t_inum y)
return SCM_INUM0; return SCM_INUM0;
struct scm_bignum *result = allocate_bignum (xn + 1); struct scm_bignum *result = allocate_bignum (xn + 1);
mp_limb_t *rd = bignum_limbs (result);
const mp_limb_t *xd = bignum_limbs (x); const mp_limb_t *xd = bignum_limbs (x);
mp_limb_t yd[1] = { long_magnitude (y) }; mp_limb_t yd = long_magnitude (y);
int negate = bignum_is_negative (x) != (y < 0); int negate = bignum_is_negative (x) != (y < 0);
mpn_mul (bignum_limbs (result), xd, xn, yd, 1); mp_limb_t hi = mpn_mul_1 (rd, xd, xn, yd);
if (hi)
rd[xn] = hi;
else
result->u.z.size--;
scm_remember_upto_here_1 (x); scm_remember_upto_here_1 (x);
return normalize_bignum return normalize_bignum (bignum_negate_if (negate, (result)));
(bignum_negate_if (negate, (bignum_trim1 (result))));
} }
} }
} }