APEX is a tool that can extract active code path from the C program source code and recompile this path into new, standalone executable.

In order to run APEX, you need to have llvm installed:

• https://llvm.org/docs/GettingStarted.html
• https://releases.llvm.org/3.8.0/docs/CMake.html

If you want to build LLVM from source, run:

cd src
./build_llvm.sh

After getting LLVM, APEX needs to be built. Run the following command to build APEX:

make build

First, you need to compile your C program into LLVM bitcode since APEX cannot work directly with the C source code.

clang -c -g -emit-llvm main.c -o main.bc

After obtaining bitcode, we can now run APEX via apex.py launcher:

python apex.py main.bc main.c 16

apex.py requires three arguments. See usage for full description:

usage: apex.py [-h] [--export EXPORT] code file line

positional arguments:
  code             C source code compiled into LLVM bytecode.
  file             Target file name (NOT FULL PATH).
  line             Target line number.

optional arguments:
  -h, --help       show this help message and exit
  --export EXPORT  true/false for exporting call graphs.

APEX produces extracted executable called extracted along with the build directory (containing various files, logs, etc.).

Since APEX is under development, there are currently some serious limitations:

• It is possible to extract values only from integer variables.
• APEX can handle small programs (see examples direcotry), but may have problems with bigger ones.
• (Probably tons more that I don't know about.)