llvm dev - Feb 2015 - [LLVMdev] Accessing a custom defined llvm pass

Hello all,

I have written one pass to collect information about specific calls in an
llvm IR file and am not trying to reference the results from the first pass
in a second pass.

What is the correct way to reference an additional custom pass in LLVM?  At
the moment the project is set up under the lib/Transforms directory in
source and has the current layout:

Thresholds/
    include/
        Thresholds.h
    Pass1.cpp
    Pass2.cpp
    Makefile

Both of the pass classes are defined in the header file.  In pass two I
have declared that it requires Pass1 using: AU.addRequired<Pass1>() and
get
the result using
getAnalysis<Pass1>().getParamPtrs();

The module compiles correctly, but when trying to load it using opt I get
an error:

Error opening 'Thresholds.dylib': dlopen(Thresholds.dylib, 9): Symbol
not
found: __ZN12_GLOBAL__N_115ParamCallFinder2ID

What is the correct way to reference another custom written pass in LLVM?
Is is possible to do it in this manner or am I completly wrong in my
approach?


Thanks!
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On 2/23/15 10:26 PM, Adam Taylor wrote:
> Hello all,
>
> I have written one pass to collect information about specific calls in 
> an llvm IR file and am not trying to reference the results from the 
> first pass in a second pass.
>
> What is the correct way to reference an additional custom pass in 
> LLVM?  At the moment the project is set up under the lib/Transforms 
> directory in source and has the current layout:
>
> Thresholds/
>     include/
>         Thresholds.h
>     Pass1.cpp
>     Pass2.cpp
>     Makefile
>
> Both of the pass classes are defined in the header file. In pass two I 
> have declared that it requires Pass1 using: AU.addRequired<Pass1>() 
> and get the result using
> getAnalysis<Pass1>().getParamPtrs();
>
> The module compiles correctly, but when trying to load it using opt I 
> get an error:
>
> Error opening 'Thresholds.dylib': dlopen(Thresholds.dylib, 9):
Symbol
> not found: __ZN12_GLOBAL__N_115ParamCallFinder2ID
>
> What is the correct way to reference another custom written pass in 
> LLVM?  Is is possible to do it in this manner or am I completly wrong 
> in my approach?
I don't think there's enough information in this email to determine, 
reliably, what the problem is.  That said, I'm guessing that one of your 
passes is named ParamCallFinder.

If I'm correct, make sure that ParamCallFinder::ID is defined in the 
.cpp file that defines the methods for the pass.  Otherwise, the ID will 
be declared but not defined, and you can get a link error like the one 
you're seeing.

I can't be sure, but I suspect that's the problem.

Regards,

John Criswell
>
>
> Thanks!
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

-- 
John Criswell
Assistant Professor
Department of Computer Science, University of Rochester
http://www.cs.rochester.edu/u/criswell

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Hi John,

Thanks.  That was the problem exactly.  I had declared the pass classes in
an anonymous namespace in a header file and also tried to set the
ParamCallFinder::ID within the header file as well which is not allowed/had
no effect in C++ from what I can gather (I'm not the most familiar with
C++).   I removed the anonymous namespace and set the ParamCallFinderID in
the c++ file with it's implementation and everything worked great.

 I have one further question that has to do with how C++/llvm handles the
anonymous namespaces.  Are they required when declaring function passes or
is my solution okay?  If they anonymous namespaces are needed how can I
access the ParamCallFinder::ID outside of the header file and in the C++
implementation?

Thanks,
Adam Taylor

On Wed, Feb 25, 2015 at 7:45 AM, John Criswell <jtcriswel at gmail.com>
wrote:
>  On 2/23/15 10:26 PM, Adam Taylor wrote:
>
> Hello all,
>
>  I have written one pass to collect information about specific calls in
> an llvm IR file and am not trying to reference the results from the first
> pass in a second pass.
>
>  What is the correct way to reference an additional custom pass in LLVM?
> At the moment the project is set up under the lib/Transforms directory in
> source and has the current layout:
>
>  Thresholds/
>     include/
>         Thresholds.h
>     Pass1.cpp
>     Pass2.cpp
>     Makefile
>
>  Both of the pass classes are defined in the header file.  In pass two I
> have declared that it requires Pass1 using: AU.addRequired<Pass1>()
and get
> the result using
> getAnalysis<Pass1>().getParamPtrs();
>
>  The module compiles correctly, but when trying to load it using opt I
> get an error:
>
>  Error opening 'Thresholds.dylib': dlopen(Thresholds.dylib, 9):
Symbol
> not found: __ZN12_GLOBAL__N_115ParamCallFinder2ID
>
>  What is the correct way to reference another custom written pass in
> LLVM?  Is is possible to do it in this manner or am I completly wrong in my
> approach?
>
>
> I don't think there's enough information in this email to
determine,
> reliably, what the problem is.  That said, I'm guessing that one of
your
> passes is named ParamCallFinder.
>
> If I'm correct, make sure that ParamCallFinder::ID is defined in the
.cpp
> file that defines the methods for the pass.  Otherwise, the ID will be
> declared but not defined, and you can get a link error like the one
you're
> seeing.
>
> I can't be sure, but I suspect that's the problem.
>
> Regards,
>
> John Criswell
>
>
>
>  Thanks!
>
>
> _______________________________________________
> LLVM Developers mailing listLLVMdev at cs.uiuc.edu        
http://llvm.cs.uiuc.eduhttp://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>
>
> --
> John Criswell
> Assistant Professor
> Department of Computer Science, University of
Rochesterhttp://www.cs.rochester.edu/u/criswell
>
>
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