llvm dev - Sep 2017 - Dependency Info from AST

Hi,
Can anyone help if for example we have multiple c files and we want to
analyze their ASTs to find out any dependency between them ( like a
function defined in one c file is used in other, any external variable etc
). How can we do it at the AST level? I mean is there any automated tool or
flag for it in LLVM. If anyone has any idea please tell.
sincerely,
Siddharth
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(Apologies for the re-send Siddharth, I failed to cc the list)

There is no existing tool that I'm aware of which performs this analysis on
the AST. It is possible to do on an AST. You would just need to write an AST
Visitor that finds declarations, definitions, and uses of functions.

Is there a reason you need to do this at the AST level? With C code this
analysis can be trivially performed with `nm` on the object files, so if you
don't have a strong reason for needing to do this on the AST I'd just
write a script to wrap `nm` rather than writing an AST Visitor.

-Chris
> On Sep 14, 2017, at 6:57 AM, Siddharth Shankar Swain via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> 
> Hi,
> Can anyone help if for example we have multiple c files and we want to
analyze their ASTs to find out any dependency between them ( like a function
defined in one c file is used in other, any external variable etc ). How can we
do it at the AST level? I mean is there any automated tool or flag for it in
LLVM. If anyone has any idea please tell.
> sincerely,
> Siddharth
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi Chris,
Thanks for the suggestion i was trying to use the patch
https://reviews.llvm.org/D30691 and ASTimporter concept for cross file
analysis. Can u explain in details the approach u suggested ? What is `nm`
on the object files ? Can u suggest some approach to start on this cross
file analysis tool.
Thanks,
Siddharth

On Tue, Sep 19, 2017 at 9:42 PM, Chris Bieneman <beanz at apple.com>
wrote:
> (Apologies for the re-send Siddharth, I failed to cc the list)
>
> There is no existing tool that I'm aware of which performs this
analysis
> on the AST. It is possible to do on an AST. You would just need to write an
> AST Visitor that finds declarations, definitions, and uses of functions.
>
> Is there a reason you need to do this at the AST level? With C code this
> analysis can be trivially performed with `nm` on the object files, so if
> you don't have a strong reason for needing to do this on the AST
I'd just
> write a script to wrap `nm` rather than writing an AST Visitor.
>
> -Chris
>
> > On Sep 14, 2017, at 6:57 AM, Siddharth Shankar Swain via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> > Hi,
> > Can anyone help if for example we have multiple c files and we want to
> analyze their ASTs to find out any dependency between them ( like a
> function defined in one c file is used in other, any external variable etc
> ). How can we do it at the AST level? I mean is there any automated tool or
> flag for it in LLVM. If anyone has any idea please tell.
> > sincerely,
> > Siddharth
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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