llvm dev - Dec 2007 - [LLVMdev] Conditional Predicate Extraction

Hi all,
  I am working on the extraction of the conditional predicates from the
basic blocks using LLVM.

I have written a pass using which i am able to extract the conditional as
well as unconditional branch instructions corresponding to different basic
blocks. I have written a separate tool to extract the control flow graph
(granularity of the level of basic blocks). Now i have to extract the
conditions from the IR which causes the branching.

Now, these predicate are in terms of conditions involving temporary
variables (llvm specific), in order to maintain consistent behaviour when
using this information with anyother simulator, it would be better if these
predicates have syntax very similar (or exactly) as that of the high level
language.

The questions are:
1. Is it possible to somehow intersperse IR and highlevel code of the
program (in C or C++).
2. Is it possible to incorporate some optimizations using llvm-gcc to make
the generated IR very close to the high level language, without affecting
the branch information.

Suggestions and answers are welcome.

Regards
Prabhat
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> The questions are:
> 1. Is it possible to somehow intersperse IR and highlevel code of the
program (in C or C++).
> Suggestions and answers are welcome.
You can probably use debug information (generated by llvm gcc on intrinsic
form, see MachineModuleInfo.h) to identify the source ligne for a condition
and the relation between the temporary llvm variable and the high level
language variable.

Perharps it isn't very reliable but I don't see other solution with
llvm.
(But I am just a novice).

If you are just doing flow graph analysis, you can consider doing it at the
C/C++ level. Clang (which only support most of C at the moment) as a little
framework for this kind of analysis and it will probably be expended.

Just my 2cents

Regards,

-- 
Cédric