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Try our own `ipow()` if both base and exp are fixnums; fix #3652

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matz committed May 25, 2017
1 parent 9e40586 commit 06c4933f904efa9669d413a57e158cb079c52fee
Showing with 27 additions and 6 deletions.
  1. +27 −6 src/numeric.c
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@@ -52,14 +52,35 @@ static mrb_value
num_pow(mrb_state *mrb, mrb_value x)
{
mrb_value y;
mrb_float d, yv;
mrb_float d;
mrb_get_args(mrb, "o", &y);
yv = mrb_to_flo(mrb, y);
d = pow(mrb_to_flo(mrb, x), yv);
if (mrb_fixnum_p(x) && mrb_fixnum_p(y) && FIXABLE(d) && yv > 0 &&
(d < 0 || (d > 0 && (mrb_int)d > 0)))
return mrb_fixnum_value((mrb_int)d);
if (mrb_fixnum_p(x) && mrb_fixnum_p(y)) {
/* try ipow() */
mrb_int base = mrb_fixnum(x);
mrb_int exp = mrb_fixnum(y);
mrb_int result = 1;
mrb_bool ok = TRUE;
for (;;) {
if (exp & 1) {
if (mrb_int_mul_overflow(result, base, &result)) {
ok = FALSE;
break;
}
}
exp >>= 1;
if (exp == 0) break;
if (mrb_int_mul_overflow(base, base, &base)) {
ok = FALSE;
break;
}
}
if (ok) {
return mrb_fixnum_value(result);
}
}
d = pow(mrb_to_flo(mrb, x), mrb_to_flo(mrb, y));
return mrb_float_value(mrb, d);
}

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