[llvm-dev] Status of new pass manager work

[Sean Silva via llvm-dev]

On Thu, May 5, 2016 at 1:24 PM, Chandler Carruth <chandlerc at gmail.com>
wrote:

> On Thu, May 5, 2016 at 12:12 PM Sean Silva <chisophugis at gmail.com> wrote:
>
>> On Thu, May 5, 2016 at 1:29 AM, Chandler Carruth via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Greetings folks,
>>>
>>> I just wanted to post a brief update on the status of the new pass
>>> manager. Philip asked me to do this at last month's social and Life
>>> intervened, but he's still got a great point, so I wanted to get it out
>>> there with one day to spare before he nagged me again. =D
>>>
>>> I'll keep it very brief and high level. If folks have questions about
>>> anything, happy to dig into it.
>>>
>>> - The core framework is there. It works, and we even have CGSCC passes
>>> using both Module and Function analyses with caching and everything. Yay!
>>> We also have initial loop pass infrastructure thanks to Justin! Yay!
>>>
>>> - The biggest missing piece of infrastructure IMO is communicating
>>> invalidation information between two parts of the pass manager itself when
>>> they are operating over the results of an analysis. Both the loop passes
>>> and the CGSCC passes really need this. I'm currently working on this and
>>> hope to finish the first cut at CGSCC stuff for this in a few days.
>>>
>>> - The second biggest missing piece is a good system for managing sets of
>>> related analyses for the purpose of invalidation. Justin and I have
>>> discussed using designated enums that form sets, but there hasn't been a
>>> lot of concrete progress here.
>>>
>>
>> Can we maybe just have a function for each "set"? e.g. you just call
>> `preserveAllCFGPasses(PA)`.
>> We can maybe stamp out `preserveAllCFGPasses` and any others from the
>> .def file to make sure there is a single point of truth.
>>
>
> My preference would be to keep the participation in a set local to the
> analysis implementation.
>

Do you envision a generic set mechanism or just a couple hardcoded sets?

-- Sean Silva


>
>
>>
>> -- Sean Silva
>>
>>
>>>
>>> - Most of the rest is porting passes. Lots of folks have started to help
>>> here which is great, but there is still likely room for help on this front.
>>> Much of this is independent of the missing infrastructure fortunately. Some
>>> good examples are GVN, SROA, and the LoopInfo passes. Fair warning, CGSCC
>>> passes are *much* harder to port than others and interact with some of the
>>> missing infrastructure. Other passes are much easier IMO.
>>>
>>> There may be more that I'm missing, but hopefully this helps people have
>>> an idea of where things are.
>>>
>>> -Chandler
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>>
>>
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