On Sun, Oct 11, 2015 at 4:56 AM, Kugan
<kugan.vivekanandara...@linaro.org> wrote:
>
>
> On 09/10/15 21:29, Richard Biener wrote:
>> + unsigned int prec = tree_to_uhwi (vr1.min);
>>
>> this should use unsigned HOST_WIDE_INT
>>
>> + wide_int sign_bit = wi::shwi (1ULL << (prec - 1),
>> + TYPE_PRECISION (TREE_TYPE (vr0.min)));
>>
>> use wi::one (TYPE_PRECISION (TREE_TYPE (vr0.min))) << (prec - 1);
>>
>> That is, you really need to handle precisions bigger than HOST_WIDE_INT.
>>
>> But I suppose wide_int really misses a test_bit function (it has a set_bit
>> one already).
>>
>> + if (wi::bit_and (must_be_nonzero, sign_bit) == sign_bit)
>> + {
>> + /* If to-be-extended sign bit is one. */
>> + tmin = type_min;
>> + tmax = may_be_nonzero;
>>
>> I think tmax should be zero-extended may_be_nonzero from prec.
>>
>> + else if (wi::bit_and (may_be_nonzero, sign_bit)
>> + != sign_bit)
>> + {
>> + /* If to-be-extended sign bit is zero. */
>> + tmin = must_be_nonzero;
>> + tmax = may_be_nonzero;
>>
>> likewise here tmin/tmax should be zero-extended may/must_be_nonzero from
>> prec.
>>
>> + case SEXT_EXPR:
>> + {
>> + unsigned int prec = tree_to_uhwi (op1);
>> + wide_int sign_bit = wi::shwi (1ULL << (prec - 1),
>> + TYPE_PRECISION (TREE_TYPE
>> (vr0.min)));
>> + wide_int mask = wi::shwi (((1ULL << (prec - 1)) - 1),
>> + TYPE_PRECISION (TREE_TYPE (vr0.max)));
>>
>> this has the same host precision issues of 1ULL (HOST_WIDE_INT).
>> There is wi::mask, eventually you can use wi::set_bit_in_zero to
>> produce the sign-bit wide_int (also above).
>
>
> Thanks Ricahrd. Does the attached patch looks better ?
Yes. That variant is ok once prerequesites have been approved.
Thanks,
Richard.
> Thanks,
> Kugan
