SSA range class and removal of VR_ANTI_RANGEs

[Richard Biener]

On Thu, May 25, 2017 at 5:05 PM, Mike Stump <mikestump@comcast.net> wrote:
> On May 24, 2017, at 1:25 AM, Richard Biener <richard.guenther@gmail.com> wrote:
>>
>> There's trailing_wide_ints.  But having 6 of them is still expensive.
>>
>> Something nice would be to make wide_ints not tied to use HOST_WIDE_INT
>> as basic element type but for example uint32.
>
> wide_int was made so that they would be calculation time efficient at the expense of a little space efficiency.  The underlying type is fairly arbitrary, and indeed, one could add it as a template parameter, and have all the existing code just use HWI for that parameter.  The new space saving version, could pass char, or short, or int, if they wanted to.  The only down side should be an extreme slowdown on operations.  It would be a lot of work to do this... but thought I would mention it.  Earlier on, we used int for testing to ensure that the code was solid, as when using a 64-bit chunk, most code never needs more than 1.  With a 32-bit type, the odds of more than 1 being used spike up considerably.
>

Yes.  I think my original argument was that with 64bits the code path
for >1 element get not very much coverage.

The most difficulties will be generalizing all those HWI using
interfaces in the API...

Richard.