[llvm-dev] Dependency Info from AST

Siddharth Shankar Swain via llvm-dev llvm-dev at lists.llvm.org
Tue Sep 19 10:41:48 PDT 2017

So we are primarily focusing on improving clang SA capability to do cross
file analysis, but with nm analysis on object file can we have the clang SA
with it for analysis. Our aim is to find bugs or security vulnerabilities
across files with the help of clang SA.

On Tue, Sep 19, 2017 at 11:01 PM, Chris Bieneman <beanz at apple.com> wrote:

> On Sep 19, 2017, at 10:09 AM, Siddharth Shankar Swain <
> h2015096 at pilani.bits-pilani.ac.in> wrote:
> 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 ?
> There is a tutorial on ASTVisitors here:
> http://clang.llvm.org/docs/RAVFrontendAction.html
> What is `nm` on the object files ?
> nm is a standard unix tool:
> https://en.wikipedia.org/wiki/Nm_%28Unix%29
> <https://en.wikipedia.org/wiki/Nm_(Unix)>
> -Chris
> 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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