llvm dev - Feb 2021 - LLVM data structures between modules

Greetings everyone,

I currently have a pass (Pass 2) that does some transformations. What I
want to do is to have a pass (Pass 1) that runs before Pass 2, collects
some IR information, stores it in a data structure and passes the data
structure to Pass 2 so that I can use it for specific transformations. I
think this can be done with getAnalysisUsage, but I'm not sure how. I would
like to know how to do that exactly, if it's possible.

Another thing, and this is the tricky part, is that I want Pass 1 to run on
all the source files I have first before Pass 2 runs and pass a collective
data structure to Pass 2. In other words, I want Pass 1 to run across all
the modules and source files first, collect information, pass it to Pass 2
then Pass 2 runs. Is there a way to tell LLVM to do this type of "double
compilation"?

Hope I was able to explain this well enough. Please let me know if I wasn't
clear or if you have any questions. Thank you very much!

Best regards,
Mohannad Ismail
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If you want to do cross-file optimization, you're looking for/want to use
something like LTO or ThinLTO. (see, for instance, the whole program
devirtualization work done with ThinLTO recently)

On Wed, Feb 24, 2021 at 12:28 PM Mohannad Ismail via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Greetings everyone,
>
> I currently have a pass (Pass 2) that does some transformations. What I
> want to do is to have a pass (Pass 1) that runs before Pass 2, collects
> some IR information, stores it in a data structure and passes the data
> structure to Pass 2 so that I can use it for specific transformations. I
> think this can be done with getAnalysisUsage, but I'm not sure how. I
would
> like to know how to do that exactly, if it's possible.
>
> Another thing, and this is the tricky part, is that I want Pass 1 to run
> on all the source files I have first before Pass 2 runs and pass a
> collective data structure to Pass 2. In other words, I want Pass 1 to run
> across all the modules and source files first, collect information, pass it
> to Pass 2 then Pass 2 runs. Is there a way to tell LLVM to do this type of
> "double compilation"?
>
> Hope I was able to explain this well enough. Please let me know if I
> wasn't clear or if you have any questions. Thank you very much!
>
> Best regards,
> Mohannad Ismail
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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