[llvm-dev] IR Pass Ordering Sensitivity

[Kavon Farvardin via llvm-dev]

> something simpler will do, IMHO. Happy to discuss this further if
> folks are in California next week :)

Yes, I'll be in California next week, let's chat!

We could make use of the autotuner I'm currently building:

https://github.com/kavon/autotune

It tries to find an optimal sequence of IR passes, and I've run into a bunch of different bugs with it so far (e.g., it seems structurizecfg interacts poorly with 'invoke'). I'll start submitting bug reports for them soon.

~kavon

> On Oct 14, 2017, at 5:52 PM, Davide Italiano via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> On Sat, Oct 14, 2017 at 11:05 AM, John Regehr via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
>> These are definitely LLVM bugs. It would be best to report reduced test
>> cases against top of tree.
>> 
>> We should have some automated infrastructure for finding these too...
>> 
>> John
>> 
> 
> Zhendong & friends generally do that (and reported many bugs :) I
> tried that myself, but never got to automate the whole procedure.
> While the problem is combinatorial in nature, evidence shows that you
> don't need to enumerate all the possible combination of passes to
> break LLVM. I think an `opt` option would be a good start. You can
> then take the testsuite and run with that, or generate random IR with
> llvm-stress and pipe that to opt. The swift folks have a slightly more
> sophisticated infrastructure for doing this (you can dump the SIL
> pipeline in a YAML file, and then IIRC, feed that back to `sil-opt`),
> but something simpler will do, IMHO. Happy to discuss this further if
> folks are in California next week :)
> 
> Thanks,
> 
> --
> Davide
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