llvm dev - Jan 2011 - [LLVMdev] CFG Extraction from Assembly Code

Hi,

In LLVM, llc can be used to generate native assembly code for a selected target
processor (-march=target). I  would like to extract/build CFG from the generated
assembly code.
Is this possible in LLVM? Anyone knows how to extract CFG from the assembly
code?
Thanks.

With regards
Yan Lin

> In LLVM, llc can be used to generate native assembly code for a selected
target processor (-march=target). I  would like to extract/build CFG from the
generated assembly code.
> Is this possible in LLVM? Anyone knows how to extract CFG from the assembly
code?
In general, it's not possible to build CFG precisely from assembly
code. Think about indirect calls / branches, for example.

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

On Jan 28, 2011, at 5:54 AM, Yan Lin Aung wrote:
> In LLVM, llc can be used to generate native assembly code for a selected
target processor (-march=target). I  would like to extract/build CFG from the
generated assembly code.
> Is this possible in LLVM? Anyone knows how to extract CFG from the assembly
code?
Do you want to take as input an arbitrary .s file and try to analyze that to
construct a CFG? Or are you asking if LLVM has a CFG available for the machine
code that it's about to emit as an assembly file?

If the latter, which I suspect is the case, then yes, the back end keeps things
organized by basic blocks until very near the end. Have a look at any of the
MachineFunction passes for examples of walking the data structures involved.

For the former, LLVM may not be much help to you. As Anton points out, this is a
tricky problem.


Regards,
  Jim
> Thanks.
> 
> With regards
> Yan Lin
> 
> 
> 
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