[LLVMdev] getting pointer to CFG object for any given C program

Duncan Sands baldrick at free.fr
Sun Oct 7 06:34:05 PDT 2012

Hi Rajendra, since this seems to be a question about clang and its AST, not
about LLVM (which is lower level), you should send it to the clang mailing
list instead.

Ciao, Duncan.
> Let say we have a C program, and we want to get pointer to CFG object for this code
> in order to traverse basic blocks and do some analysis using CFG object.
>  From my main program main.cpp, how can I get pointer to CFG object if argv[1] =
> hello.c ?
> I have seen following places among many in clang/lib or clang/include:
> llvm-3.1.src/tools/clang/lib/StaticAnalyzer/Checkers/DebugCheckers.cpp:96
>    - calls checkASTCodeBody(const Decl *D, AnalysisManager& mgr, BugReporter &BR)
>      if (CFG *cfg = mgr.getCFG(D)) call cfg->dump()
> llvm-3.1.src/tools/clang/lib/StaticAnalyzer/Frontend/AnalysisConsumer.cpp:472
>    - AnalysisConsumer::HandleCode(Decl *D, AnalysisMode Mode, SetOfConstDecls
> *VisitedCallees)
> /usr/home3/rks/llvm/llvm-3.1.src/tools/clang/lib/Analysis/CFG.cpp:3166
>    - CFG* CFG::buildCFG(const Decl *D, Stmt *Statement, ASTContext *C, const
> BuildOptions &BO) {
>      CFGBuilder Builder(C, BO);
>      return Builder.buildCFG(D, Statement);
>      }
> I have tried to debug clang using gdb (by running r -cc1 -analyze
> -analyser-checker=Debug.DumpCFG hello.c from within gdb)
> and now I know something about flow but exactly not able to figure out how to
> get pointer to CFG object in my program?
> Since CFG is being built by recursive visit to AST, I cannot direct do anything
> with objects of classes such as CFG, CFGBuilder or CFGBlock.
> My query may be trivial for many of you but I have spent a lot of time to figure
> this out without success.
> Any help is much appreciated.
> Rajendra
> http://www.cse.iitb.ac.in/~rks
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

More information about the llvm-dev mailing list