[llvm-dev] Commit module to Git after each Pass

[Fedor Sergeev via llvm-dev]

For this to be really usable in this setup we need additionally to:
   - extend -print-module-scope to cover basic block passes
   - introduce a clear way to separate module IRs as those are being 
printed by -print-after-all

But yes, it should work, and a wrapper that pipes to git fast-import 
seems to be the best way to handle it.

regards,
   Fedor.

On 03/15/2018 12:31 AM, Daniel Neilson via llvm-dev wrote:
> The print-module-after-all type of option exists in upstream:
>   -print-module-scope                                     - When 
> printing IR for print-[before|after]{-all} always print a module IR
>
> commit 7d160f714357f6784ead669ce516e94991c12e5a
> Author: Fedor Sergeev <fedor.sergeev at azul.com 
> <mailto:fedor.sergeev at azul.com>>
> Date:   Fri Dec 1 17:42:46 2017 +0000
>
>     IR printing improvement for function passes - introducing 
> -print-module-scope
>
>
>     Summary:
>     When debugging function passes it happens to be rather useful to dump
>     the whole module before the transformation and then use this dump
>     to analyze this single transformation by running it separately
>     on that particular module state.
>
>
>     Introducing
>         -print-module-scope
>     debugging option that forces all the function-level IR dumps
>     to become whole-module dumps.
>
>
>     This option builds on top of normal dumping controls like
>        -print-before/after
>        -filter-print-funcs
>
>
>     The plan is to eventually extend this option to cover other local 
> passes
>     (at least loop passes) but that should go as a separate change.
>
>
> Loop passes here:
> commit 5608259c999fb77c5d6093895696f4daebe6b8cd
> Author: Fedor Sergeev <fedor.sergeev at azul.com 
> <mailto:fedor.sergeev at azul.com>>
> Date:   Fri Dec 1 18:33:58 2017 +0000
>
>     IR printing improvement for loop passes - handle -print-module-scope
>
>
> -Daniel
>
>
>> On Mar 14, 2018, at 3:51 PM, Philip Reames via llvm-dev 
>> <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>>
>> This is interesting, and might be useful.  I don't know that this is 
>> broadly useful enough for upstream inclusion, but if you could post 
>> this to github somewhere, I might play with it.
>>
>> There might also be room to factor out common functionality.  We've 
>> also run into the need to print whole-module instead of containing 
>> construct (i.e. this loop).  If we added upstream support for 
>> something along the lines of -print-module-after-all, building the 
>> git history could easily be done as a post processing step.
>>
>> Philip
>>
>>
>> On 03/06/2018 10:43 AM, Alexandre Isoard via llvm-dev wrote:
>>> Hello,
>>>
>>> I had a stupid idea recently that turned out not so stupid after 
>>> all. I wanted to be able to "see" an entire pass pipeline in action 
>>> to find unnecessary transformations and/or missed opportunities and 
>>> generally improve the debug-ability of LLVM.
>>>
>>> So as the title suggest, I implemented an equivalent of 
>>> "-print-after-all" but instead of printing into stdout I dump into a 
>>> file that get commit into a temporary git. There are some quirks 
>>> with it but it's working and is actually awesome. For example, at 
>>> first sight, I see multiple time lcssa and instcombine cancelling 
>>> each other's work.
>>>
>>> Of course, that has a big impact on compile time when enabled, but 
>>> that's still practical (git being quite good at its job) when debugging.
>>>
>>> There are improvement I can make, but would you guys be interested 
>>> in such feature?
>>>
>>> -- 
>>> *Alexandre Isoard*
>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
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>
>
>
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