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Re: Implement {get,set}_range_info() variants that work with value_range's




On 11/8/18 9:41 AM, Richard Biener wrote:
On Thu, Nov 8, 2018 at 3:05 PM Aldy Hernandez <aldyh@redhat.com> wrote:



On 11/8/18 8:59 AM, Richard Biener wrote:
On Thu, Nov 8, 2018 at 12:52 PM Aldy Hernandez <aldyh@redhat.com> wrote:

get/set_range_info() currently returns the extremes of a range.  I have
implemented overloaded variants that return a proper range.  In the
future we should use actual ranges throughout, and not depend on range
extremes, as depending on this behavior could causes us to lose precision.

I am also including changes to size_must_be_zero_p() to show how we
should be using the range API, as opposed to performing error prone
ad-hoc calculations on ranges and anti-ranges.

Yeah, I've been talking this all along but not being heard...

My girlfriend says I don't listen.  It could be related.

Martin, I'm not saying your code is wrong.  There are numerous other
places in the compiler where we manipulate ranges/anti-ranges directly,
all of which should be adapted in the future.  Everywhere there is a
mention of VR_RANGE/VR_ANTI_RANGE in the compiler is suspect.  We should
ideally be using intersect/union/may_contain_p/null_p, etc.

null_p is a bad name btw, I just confused it with empty_p ... (which we have
as undefined_p).  contains_only_zero_p would be less confusing.

Yes, a horrible name.  I noticed so as I debugged precisely this bit.
How about zero_p?

Probably the same ambiguous connotation?  But yes, way better than null_p.

Well...for starters I started with the nomenclature already in VRP which was range_is_null.

Also, how is zero_p() ambiguous? We want to know if the range is [0, 0]. That reads pretty obvious to me.

Aldy


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