[LLVMdev] LoopPass symbol error

Giacomo Tagliabue giacomo.tag at gmail.com
Thu May 9 07:34:42 PDT 2013

Also, every method inherited by LoopBase causes the same error, while Loop
methods go smooth.

On 9 May 2013 01:05, Andrew Trick <atrick at apple.com> wrote:

> On May 8, 2013, at 7:43 PM, Giacomo Tagliabue <giacomo.tag at gmail.com>
> wrote:
>  Hello,
> I am building a loop pass following these instructions:
> http://llvm.org/docs/WritingAnLLVMPass.html
> Everything works fine, I did it many times for Function Passes, but in the
> runOnLoopmethod, whenever I call a method of the loop L passed as argument,
> for example L->begin(), I get the following error:
> opt: symbol lookup error:
>> /home/giacomo/llvmcsfv/Debug+Asserts/lib/Acsl.so: undefined symbol:
>> _ZNK4llvm8LoopBaseINS_10BasicBlockENS_4LoopEE5beginEv
> Where Acsl is the name of the loadable module. If I remove all the
> instructions from runOnPass but a debug print, it works fine (it prints
> it), so the problem is not the module.
> Does anybody have any Idea?
> Thank you very much,
> Giacomo
> I'm not sure why your dynamic linker looks in Acsl.so.
> llvm::LoopBase<llvm::BasicBlock, llvm::Loop>::begin() is explicitly
> instantiated in LoopInfo.cpp. With a debug build on darwin, that symbol is
> undefined in my dynamically loaded module, but exported by the opt binary.
> So a dynamically loaded loop pass as you described works fine for me.
> Someone else should try this on linux with shared libs.
> You can also try removing these lines from LoopInfo.h, which seem
> superfluous to me:
> __extension__ extern template class LoopBase<BasicBlock, Loop>;
> __extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
> -Andy
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