[PATCH] D74691: [Attributor] Detect possibly unbounded cycles in functions

[Stefanos Baziotis via Phabricator via llvm-commits]

baziotis added a comment.

In D74691#1892447 <https://reviews.llvm.org/D74691#1892447>, @omarahmed wrote:

> I am sorry but I can't get what the test that the approach of moving on the SCCs fails in as I have tried to test it a bit with tests like that and printed the SCCs that it gets
>
> https://i.imgur.com/fpZhpST.png
>  1 - entry
>  2- condition - body
>  3- return
>  4 - l4
>
> https://i.imgur.com/UJJ3aH0.png
>  1- entry
>  2- l1 - l2 - l3 - l4 - l5
>  3- return
>  4- l6 - l7 - l8
>
> https://i.imgur.com/92NS6rp.png
>  1- entry
>  2- l1 - l2 - l3 - l4 - l5 - l6 - l7
>  3- return
>
> and in all of them it reached the cycle and outputs that the loop does not have a max trip count


Sorry, but I didn't understand your comment very much. The code //I// wrote certainly can't detect max trip count.
It only correctly (hopefully) finds if there's a cycle or not. The second modification also found the size of the cycle.
Did //you// write any code that used `LI` ? In that case, as I said earlier, I have some algorithm in mind that uses `LI`
but I can't seem to be able to get `LI` (i.e. it's always `nullptr`). So, probably the same will be true for you
even if your code is correct. Hopefully we can get an answer about why that happens.


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