[cfe-dev] Inconsistent types used to represent bitwidth

Chris Lattner clattner at apple.com
Wed Oct 3 21:08:59 PDT 2007

On Oct 3, 2007, at 5:17 PM, Hartmut Kaiser wrote:

> Chris,
>>> I'm currently trying to remove some of the warnings spit
>> out on me by
>>> the
>>> VC++ compiler (mostly warnings about possible loss of precision) and
>>> recognized, that the bitwith (size of a type in bits) is
>> represented
>>> using different types all over the place: sometimes unsigned,
>>> sometimes uint32_t and sometimes it's even uint64_t. I really would
>>> like to change that to a more consistent scheme, but need
>> some advice
>>> which type to choose.
>>> Since I
>>> think we can't expect to get anything terribly large as the
>> bitwidth
>>> of a type I'ld say let's go for uint32_t.
>> Hi Hartmut,
>> We should go with uint64_t in general.  There can be large
>> arrays (for example) on 64-bit targets that need this.  For
>> "known little things" like integer types, uint32_t would be
>> sufficient, but it is probably better to be consistent and
>> use uint64_t for everything.
> IIUC, the bitwidth is most of the time the number of bits needed to
> represent the size, i.e. 32 for uint32_t. In this case 64 is the  
> largest
> number these kind of variables will ever hold, no?

Yes, except that what is the size of "uint32_t[100000000000LL]" ?


More information about the cfe-dev mailing list