On Thu, Oct 13, 2016 at 6:49 AM, kugan
<kugan.vivekanandara...@linaro.org> wrote:
> Hi Richard,
>> what does this try to do?  Preserve info VRP computed across PTA?
>> I think we didn't yet sort out the nonlocal/escaped vs. null handling
>> properly
>> (or how PTA should handle get_ptr_nonnull).  The way you are using it
>> asks for pt.null to be orthogonal to nonlocal/escaped and thus having
>> nonlocal or escaped would also require setting ptr.null in PTA.  It then
>> would be also more canonical to set it for pt.anything as well.  Which
>> means conservatively handling it would be equivalent to flipping its
>> semantic and changing its name to pt.nonnull.
>> That said, you seem to be simply "reserving" the bit for VRP, keeping it
>> conservatively true when "not computed".  I guess I'm fine with this for
>> now
>> but it should be documented in the header file that way.
> Thanks for the comments.
> To summarize, currently I am not relying on PTA analysis at all. Just saving
> null from VRP (or rather nonnull) and preserving it across PTA. Primary
> intention is to pass it for PARM_DECL SSA names (from ipa-vrp).
> In this case, using  pt.anything/nonlocal/escaped will only make the result
> more pessimistic.
> Ideally, we should improve pt.null within PTA but for now as you said, I
> will document it.
> When we start using pt.null from PTA analysis, we would also have to take
> into account pt.anything/nonlocal/escaped.
> Does that make sense?



> Thanks,
> Kugan

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