llvm dev - Jun 2008 - [LLVMdev] want to use CallGraph Pass in llc

Hi all,

the CallGraph pass is only available in opt. Is there any substantial reason 
for that? Or is it only because it seems not to be useful for llc?

I want to use it in an backend that is derived from the CBackend. I need the 
information what functions are called in every other function to build 
communication struktures between the functions. The backend is generating 
VHDL from C code. (VHDL is a hardware description language, which means it is 
used to generate hardware, for those who are not familiar with this.)

I've managed to compile my backend with the CallGraph pass, but when it try
to
use it, I get an error, which I could't fix until now.



llc --load=/home/paul/LLVM/install/llvm-2.2/lib/MParSchedule.so
--load=/home/paul/LLVM/install/llvm-2.2/lib/libLLVMVHDLBackend.so -f -march=vhdl
test.o -o llvm.vhd
llc: /home/paul/LLVM/src/llvm-2.2/lib/VMCore/PassManager.cpp:922: virtual void 
llvm::PMDataManager::addLowerLevelRequiredPass(llvm::Pass*, llvm::Pass*): 
Assertion `0 && "Unable to handle Pass that requires lower level
Analysis
pass"' failed.
llc[0x85e922c]
/lib/i686/cmov/libc.so.6(abort+0x101)[0x401e6981]
/lib/i686/cmov/libc.so.6(__assert_fail+0xee)[0x401de10e]
llc(llvm::PMDataManager::addLowerLevelRequiredPass(llvm::Pass*, 
llvm::Pass*)+0x7d)[0x857da0d 



I'm suspecting the reason for the error is connected with the reason that 
caused to make CallGraph a opt only pass.

Thanks for your time !

- Paul

Paul,

On Jun 2, 2008, at 12:38 AM, Paul Arndt wrote:
> Hi all,
>
> the CallGraph pass is only available in opt. Is there any  
> substantial reason
> for that? Or is it only because it seems not to be useful for llc?
No, that's not true.
> I want to use it in an backend that is derived from the CBackend. I  
> need the
> information what functions are called in every other function to build
> communication struktures between the functions. The backend is  
> generating
> VHDL from C code. (VHDL is a hardware description language, which  
> means it is
> used to generate hardware, for those who are not familiar with this.)
>
> I've managed to compile my backend with the CallGraph pass, but when  
> it try to
> use it, I get an error, which I could't fix until now.
>
>
>
> llc --load=/home/paul/LLVM/install/llvm-2.2/lib/MParSchedule.so -- 
> load=/home/paul/LLVM/install/llvm-2.2/lib/libLLVMVHDLBackend.so -f - 
> march=vhdl
> test.o -o llvm.vhd
> llc: /home/paul/LLVM/src/llvm-2.2/lib/VMCore/PassManager.cpp:922:  
> virtual void
> llvm::PMDataManager::addLowerLevelRequiredPass(llvm::Pass*,  
> llvm::Pass*):
> Assertion `0 && "Unable to handle Pass that requires lower
level
> Analysis
> pass"' failed.
> llc[0x85e922c]
> /lib/i686/cmov/libc.so.6(abort+0x101)[0x401e6981]
> /lib/i686/cmov/libc.so.6(__assert_fail+0xee)[0x401de10e]
> llc(llvm::PMDataManager::addLowerLevelRequiredPass(llvm::Pass*,
> llvm::Pass*)+0x7d)[0x857da0d


This error indicates that pass manager is not able to schedule your  
pass.

  918   // Module Level pass may required Function Level analysis info
  919   // (e.g. dominator info). Pass manager uses on the fly  
function pass manager
  920   // to provide this on demand. In that case, in Pass manager  
terminology,
  921   // module level pass is requiring lower level analysis info  
managed by
  922   // lower level pass manager.
  923
  924   // When Pass manager is not able to order required analysis  
info, Pass manager
  925   // checks whether any lower level manager will be able to  
provide this
  926   // analysis info on demand or not.
  927   assert (0 && "Unable to handle Pass that requires lower
level
Analysis pass");


What is the skeleton of your pass structure ?

Use -debug-pass=? argument on the llc command line to understand what  
pass manager is trying to do. Try 'llc --help-hidden' for more info.

-
Devang

Hi Paul,
> > Assertion `0 && "Unable to handle Pass that requires
lower level
> > Analysis
> > pass"' failed.
I have been struggling with the same problem as well, when I wanted to make a
loop pass depend on a module pass (IIRC). You should probably pull your
program through gdb and get a backtrace so you can see what pass is causing
the problem.

Also, a paste of the passes you are trying to schedule would help as well (you
were building your own program, not using the builtin opt / llc / etc, right?

Gr.

Matthijs
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