LLVM CFG to JSON

Exports an LLVM control flow graph (CFG) to JSON. This pass is different from LLVM's standard CFG printer in that it captures both intra and inter procedural edges (i.e., function calls).

Building

git clone https://github.com/adrianherrera/llvm-cfg-to-json.git
cd llvm-cfg-to-json

mkdir build
cd build

# If you have multiple LLVM versions installed, specify the one you want by
# setting LLVM_DIR; e.g., -DLLVM_DIR=`llvm-config-12 --cmakedir`
#
# This probably also requires setting CC/CXX
CC=clang CXX=clang++ cmake ..

Running

clang -fplugin=/path/to/build/libLLVMCFGToJSON.so /path/to/src.c

If using autotools/make/etc., do

CFLAGS="-fplugin=/path/to/build/libLLVMCFGToJSON.so" CXXFLAGS="-fplugin=/path/to/build/libLLVMCFGToJSON.so" ./configure
make

Or CMake:

cmake -DCMAKE_C_FLAGS="-fplugin=/path/to/build/libLLVMCFGToJSON.so" -DCMAKE_CXX_FLAGS="-fplugin=/path/to/build/libLLVMCFGToJSON.so" ...
make

cfg_stats.py

Using the results produced by the LLVM pass, calculate some interesting graph statistics (e.g., number of basic blocks, number of edges, and the graph eccentricity from the CFG's entry point). The script can also (optionally) produce a DOT graph of the CFG.

Running

clang -fplugin=/path/to/build/libLLVMCFGToJSON.so /path/to/src.c
python cfg_stats.py `pwd`/cfg.*.json