[LLVMdev] Size limitations in MCJIT / ELF Dynamic Linker/ ELF codegen?

[Yaron Keren]

OS is Windows 7 64 bit OS, compiler is 32 bit Visual C++ 2012 with 32 bit.
The target which is i686-pc-mingw32-elf so I can use the ELF dynamic
loader.
Code model, relocation model and and memory manager are whatever default
for this - did not modify.

The Module comes from clang. The source is 1000 or more lines repeating C++
code in one big function:

  A+1;
  A*B.t();

where A and B are matrices from Armadillo http://arma.sourceforge.net/.
This a stress and performance test due to the large number of EH and
temporary objects created.

I am using the Engine Builder and MCJIT unmodified (except the
multi-modules patches which are not relevant as there is only one module)
like this:

  OwningPtr<llvm::ExecutionEngine> EE(llvm::EngineBuilder(M)
                                          .setErrorStr(&Error)
                                          .setUseMCJIT(true)
                                          .create());

to run the function either

  llvm::Function *F = M->getFunction(Name);
  void *FN = EE->getPointerToFunction(F);
or
  uint64_t FN = EE->getFunctionAddress(Name);

followed by

 ((void (*)())FN)();
or
  EE->runFunction(F, std::vector<llvm::GenericValue>());

all work the same with smaller about 1000 lines of the above code module
and crash the same with more code. The call stack is unhelpful Visual C++
says: Frames below may be incorrect and/or missing which indicates a real
problem with it. I have tried to provide less stack space (default is 10M)
for the compiled program without any change.

Yaron



2013/10/22 Kaylor, Andrew <andrew.kaylor at intel.com>

>  I’m not aware of such a limitation.****
>
> ** **
>
> What architecture, code model and relocation model are you using?  Are you
> using the SectionMemoryManager?****
>
> ** **
>
> -Andy****
>
> ** **
>
> *From:* Yaron Keren [mailto:yaron.keren at gmail.com]
> *Sent:* Tuesday, October 22, 2013 8:12 AM
> *To:* <llvmdev at cs.uiuc.edu>; Kaylor, Andrew
> *Subject:* Size limitations in MCJIT / ELF Dynamic Linker/ ELF codegen?***
> *
>
> ** **
>
> I'm running in MCJIT a module generated from one C++ function. Every line
> of the source function uses C++ classes and may throw an exception. As long
> as there are less than (about) 1000 lines, everything works. With more
> lines the compiled code crashes when running it, with no sensible stack
> trace.****
>
> ** **
>
> Is there any kind of hard-coded size limitation in MCJIT / ELF Dynamic
> Linker / ELF codegen / number of EH states in a function ? ****
>
> ** **
>
> I did browse the code but could not find anything obvious. ****
>
> ** **
>
> Yaron****
>
> ** **
>
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