[llvm-dev] vrp

[Davide Italiano via llvm-dev]

On Tue, Aug 8, 2017 at 2:14 AM, Anastasiya Ruzhanskaya
<anastasiya.ruzhanskaya at frtk.ru> wrote:
> Maybe there is a concrete document or paper about VRP in llvm (what it
> exactly has)? After studying the code, seems that the answer is : llvm can't
> detect borders with help of cmp statements but I still want to be sure.
>

To the best of my knowledge, LVI in llvm tries to emulate a standard
fixpoint algorithm on a meet semilattice ( see, e.g.
http://www.lighterra.com/papers/valuerangeprop/Patterson1995-ValueRangeProp.pdf
for details, on a bit-by-bit basis).
I haven't debugged your testcase but if you have something that should
be caught by VRP (but it's not), you may consider reporting a bug at
bugs.llvm.org

Thanks,

--
Davide