[llvm-dev] LLVM log file

[Sudakshina Dutta via llvm-dev]

Dear all,

In the optimization phase, the compiler applies some optimization to
generate an optimized program. The optimization applied in the optimization
pass depends on the source program; hence, the number of optimizations
applied differs from source program to source program. By mentioning
"applied" transformation, I wanted to know what all transformations are
applied for a specific input program when subjected to the LLVM optimizer.

Thanks,
Sudakshina


On Sun, 24 Jan 2021, 09:27 Stefanos Baziotis, <stefanos.baziotis at gmail.com>
wrote:

> Hi Sudakshina,
>
> Not really sure what you mean by "applied", so, let me offer some more
> ideas other than Brian's and Adrian's great suggestions. First, there are
> some
> diagnostics / remarks flags in Clang like the -R family [1] or some -f
> flags about printing optimization reports [2] from Clang. They can be
> useful or useless depending
> on your case. They can also be parsed relatively easily.
>
> If you just want to see a list of passes that were attempted in your code,
> you can do it with: `-mllvm -opt-bisect-limit=-1`
> You can also use `-mllvm-debug-pass=Arguments` to see the arguments that
> were passed.
>
> Moving into opt, you can use something like `print-after-all`, which was
> already mentioned. If you don't know what these flags do, is they show you
> the IR in different stages in the pipeline (e.g., `print-after-all` shows
> you each pass attempted and how the IR is after it).
>
> Hope it helps,
> Stefanos
>
> [1]
> https://clang.llvm.org/docs/ClangCommandLineReference.html#diagnostic-flags
> [2]
> https://clang.llvm.org/docs/UsersManual.html#cmdoption-f-no-save-optimization-record
>
> Στις Κυρ, 24 Ιαν 2021 στις 5:47 π.μ., ο/η Adrian Vogelsgesang via llvm-dev
> <llvm-dev at lists.llvm.org> έγραψε:
>
>> I used “-print-changed”, “-print-before-all”, “print-after-all” last time
>> I wanted to see the passes together with their inout/output IR modules.
>>
>> In my case, I used them through “clang++”, i.e. I had to prefix them with
>> “-mllvm”
>> > clang++ test_file.cpp -mllvm -print-after-all
>>
>>
>>
>> *From: *llvm-dev <llvm-dev-bounces at lists.llvm.org> on behalf of Brian
>> Cain via llvm-dev <llvm-dev at lists.llvm.org>
>> *Date: *Sunday, 24. January 2021 at 04:40
>> *To: *Sudakshina Dutta <sudakshina at iitgoa.ac.in>
>> *Cc: *LLVM Development List <llvm-dev at lists.llvm.org>
>> *Subject: *Re: [llvm-dev] LLVM log file
>>
>> I don't know if it's exhaustive but there's the "remarks" feature:
>>
>>
>>
>>
>> https://llvm.org/docs/Remarks.html#introduction-to-the-llvm-remark-diagnostics
>>
>>
>>
>> On Sat, Jan 23, 2021 at 9:20 PM Sudakshina Dutta via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>> Dear all,
>>
>>
>>
>> Good morning. I want to know whether LLVM creates any log file consisting
>> of applied optimizations in the optimization phase. It will be really
>> useful for the researchers who work on compilers, formal methods, etc.
>>
>>
>>
>> Thanks,
>>
>> Sudakshina
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
>>
>>
>> --
>>
>> -Brian
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
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