[cfe-dev] Clang CFG - To build a variant of CFG

[Artem Dergachev via cfe-dev]

Yep, you've found the right piece of code, and you should be able to 
tweak it to change the CFG in that manner. CFGBuilder is solely 
responsible for the CFG.

I also want to point out that the current CFG is correct: it reflects 
the short-circuit nature of logical operators. So i'm surprised you need 
this change.

There is a selection of existing CFG-based analyses in lib/Analysis, you 
may be able to learn from them or even re-use some of them. And we've 
got the whole Static Analyzer that performs symbolic execution over the CFG.

On 6/14/18 9:45 PM, Shamiek Mangipudi via cfe-dev wrote:
> Hi,
>
> I recently started working on control flow analysis of C programs 
> using CFG generated by clang. I noticed that clang generates basic 
> blocks for each condition of a compound condition it encounters in if 
> statment (or in loop conditions). I wanted to have only one basic 
> basic with the entire compound condition instead of having basic 
> blocks for each condition.
>
> I am outlining my attempts and the direction in which I tried. Please 
> let me know if there is a better way to what I am trying to achieve or 
> I should take an entirely new direction.
>
> Thanks.
> Shamiek
>
> My attempts:
> I first looked at CFG::BuildOptions() 
> (https://clang.llvm.org/doxygen/classclang_1_1CFG_1_1BuildOptions.html 
> <https://clang.llvm.org/doxygen/classclang_1_1CFG_1_1BuildOptions.html>) and 
> did not find anything there.
>
> Then I went to to CFGBuilder::VisitIfStmt and found the line that 
> causes creation of basic blocks for individual conditions of the 
> compound condition 
> (https://clang.llvm.org/doxygen/CFG_8cpp_source.html#l02180). Should I 
> try and change the code here or there might be deeper implications for 
> changing code here. Please suggest.
>
>
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