LLVM 3.8

Building KLEE with LLVM 3.8

NOTE: This is the documentation for KLEE 2.2, which might differ from the latest version of KLEE from the master branch. For documentation relevant to KLEE’s master branch see the homepage.

The current procedure for building KLEE with LLVM 3.8 is outlined below.

Install dependencies: KLEE requires all the dependencies of LLVM, which are discussed here. In particular, you should install the following programs and libraries, listed below as Ubuntu packages:

$ sudo apt-get install build-essential curl libcap-dev git cmake libncurses5-dev python-minimal python-pip unzip libtcmalloc-minimal4 libgoogle-perftools-dev libsqlite3-dev doxygen
$ pip3 install tabulate

Install LLVM 3.8: KLEE is built on top of LLVM; the first steps are to get a working LLVM installation. See Getting Started with the LLVM System for more information.

NOTE: KLEE is currently tested on Linux x86-64, and might break on x86-32.

If you are using a recent Ubuntu (e.g. 16.04 LTS) or Debian, we recommend you to use the LLVM packages provided by LLVM itself.
```
$ sudo apt-get install clang-3.8 llvm-3.8 llvm-3.8-dev llvm-3.8-tools  
```
That’s it for LLVM. If you want to install it manually, please refer to the official LLVM Getting Started documentation.
Install constraint solver(s)

KLEE supports multiple different constraint solvers. You must install at least one to build KLEE.
- STP Historically KLEE was built around STP so support for this solver is the most stable. For build instructions, see here.
- Z3 is a more recent addition to KLEE but is reasonably stable. You should use Z3 version ≥ 4.4. For build instructions, see here.
- metaSMT supports various solvers, including Boolector, STP and Z3. We recommend branch v4.rc1 (git clone -b v4.rc1 ...). For build instructions, see here.
(Optional) Build uclibc and the POSIX environment model: By default, KLEE works on closed programs (programs that don’t use any external code such as C library functions). However, if you want to use KLEE to run real programs you will want to enable the KLEE POSIX runtime, which is built on top of the uClibc C library.

To build klee-uclibc run:
```
$ git clone https://github.com/klee/klee-uclibc.git  
$ cd klee-uclibc  
$ ./configure --make-llvm-lib  
$ make -j2  
$ cd .. 
```
When clang or llvm-config are not in your PATH or have a custom prefix/suffix, configure may fail to detect their location. You can use the --with-cc and --with-llvm-config flags to set the paths manually.

NOTE: If you are on a different target (i.e., not i386 or x64), you will need to run make config and select the correct target. The defaults for the other uClibc configuration variables should be fine.

To tell KLEE to use klee-uclibc and use the POSIX runtime pass -DENABLE_POSIX_RUNTIME=ON and -DKLEE_UCLIBC_PATH=<KLEE_UCLIBC_SOURCE_DIR> to CMake when configuring KLEE in step 8 where <KLEE_UCLIBC_SOURCE_DIR> is the absolute path to the cloned klee-uclibc git repository.
(Optional) Get Google test sources:

For unit tests we use the Google test libraries. If you don’t want to run the unit tests you can skip this step but you will need to pass -DENABLE_UNIT_TESTS=OFF to CMake when configuring KLEE in step 8.

We depend on a version 1.7.0 right now so grab the sources for it.
```
$ curl -OL https://github.com/google/googletest/archive/release-1.7.0.zip
$ unzip release-1.7.0.zip
```
This will create a directory called googletest-release-1.7.0.
(Optional) Install lit:

For testing the lit tool is used. If you LLVM from a build tree you can skip this step as the build system will try to use llvm-lit in the directory containing the LLVM binaries.

If you don’t want to run the tests you can skip this step but you will need to pass -DENABLE_UNIT_TESTS=OFF and -DENABLE_SYSTEM_TESTS=OFF to CMake when configuring KLEE in step 8.
```
$ pip install lit
```

Get KLEE source:

$ git clone https://github.com/klee/klee.git

Configure KLEE:

KLEE must be built “out of source” so first make a binary build directory. You can create this where ever you like.
```
$ mkdir klee_build_dir
```
Now cd into the build directory and run CMake to configure KLEE where <KLEE_SRC_DIRECTORY> is the path to the KLEE git repository you cloned in step 7.
```
$ cd klee_build_dir
$ cmake <CMAKE_OPTIONS> <KLEE_SRC_DIRECTORY>
```
<CMAKE_OPTIONS> are the configuration options. These are documented in README-CMake.md.

For example if KLEE was being built with STP, the POSIX runtime, klee-uclibc and testing then the command line would look something like this
```
cmake \
  -DENABLE_SOLVER_STP=ON \
  -DENABLE_POSIX_RUNTIME=ON \
  -DENABLE_KLEE_UCLIBC=ON \
  -DKLEE_UCLIBC_PATH=<KLEE_UCLIBC_SOURCE_DIR> \
  -DGTEST_SRC_DIR=<GTEST_SOURCE_DIR> \
  -DENABLE_SYSTEM_TESTS=ON \
  -DENABLE_UNIT_TESTS=ON \
  -DLLVM_CONFIG_BINARY=<PATH_TO_LLVM38_llvm-config> \
  -DLLVMCC=<PATH_TO_clang-3.8> \
  -DLLVMCXX=<PATH_TO_clang++-3.8>
  <KLEE_SRC_DIRECTORY>
```
Where <KLEE_UCLIBC_SOURCE_DIR> is the absolute path the klee-uclibc source tree, <GTEST_SOURCE_DIR> is the absolute path to the Google Test source tree.

NOTE: If LLVM is not found or you need a particular version to be used you can pass -DLLVM_CONFIG_BINARY=<LLVM_CONFIG_BINARY> to CMake where <LLVM_CONFIG_BINARY> is the absolute path to the relevant llvm-config binary. Similarly KLEE needs a C and C++ compiler that can create LLVM bitcode that is compatible with the version of LLVM KLEE is using. If these are not detected automatically -DLLVMCC=<PATH_TO_CLANG> and -DLLVMCXX=<PATH_TO_CLANG++> can be passed to explicitly set these compilers where <PATH_TO_CLANG> is the absolute path to clang and <PATH_TO_CLANG++> is the absolute path to clang++.

NOTE II: By default, KLEE uses tcmalloc as the allocator to support reporting of memory usage above 2GB. If you don’t want to install tcmalloc (libtcmalloc-minimal4 libgoogle-perftools-dev Ubuntu packages) on your system or prefer to use glibc allocator, pass -DENABLE_TCMALLOC=OFF to CMake when configuring KLEE.

Build KLEE:

From the klee_build_dir directory created in the previous step run.

$ make

NOTE: If you see linker errors involving cxx11 you may be running into the dual ABI issue. Here’s an example:

/usr/lib/llvm-3.4/include/llvm/Support/CommandLine.h:905: undefined reference to `vtable for llvm::cl::parser<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >'
CMakeFiles/kleaver.dir/main.cpp.o: In function `main':
/home/user/programs/klee/klee/tools/kleaver/main.cpp:413: undefined reference to `llvm::error_code::message[abi:cxx11]() const'
CMakeFiles/kleaver.dir/main.cpp.o: In function `llvm::cl::opt<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, false, llvm::cl::parser<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > >::~opt()':

This is caused by a mismatch between the ABI used to build LLVM and the ABI used to build KLEE. To fix this delete your KLEE build directory and rerun cmake like so

$ CXXFLAGS="-D_GLIBCXX_USE_CXX11_ABI=0" cmake <CMAKE_OPTIONS> <KLEE_SRC_DIRECTORY>

NOTE: If you see linker errors involving undefined references to typeinfo this is likely an RTTI issue. Here’s an example:

[ 81%] Linking CXX executable ../../bin/kleaver
CMakeFiles/kleaver.dir/main.cpp.o:(.rodata+0x1238): undefined reference to `typeinfo for llvm::cl::Option'
CMakeFiles/kleaver.dir/main.cpp.o:(.rodata+0x1270): undefined reference to `typeinfo for llvm::cl::generic_parser_base'
CMakeFiles/kleaver.dir/main.cpp.o:(.rodata+0x12d0): undefined reference to `typeinfo for llvm::cl::GenericOptionValue'
CMakeFiles/kleaver.dir/main.cpp.o:(.rodata+0x12f8): undefined reference to `typeinfo for llvm::cl::Option'
CMakeFiles/kleaver.dir/main.cpp.o:(.rodata+0x1330): undefined reference to `typeinfo for llvm::cl::generic_parser_base'
CMakeFiles/kleaver.dir/main.cpp.o:(.rodata+0x1390): undefined reference to `typeinfo for llvm::cl::GenericOptionValue'

The issue here is that LLVM was built without RTTI but KLEE is trying to build with RTTI. This is caused by the llvm-config binary not correctly reporting that -fno-rtti needs to be passed to the compiler. To fix this delete your KLEE build directory and rerun cmake like so

$ CXXFLAGS="-fno-rtti" cmake <CMAKE_OPTIONS> <KLEE_SRC_DIRECTORY>

(Optional) Run the main regression test suite

If KLEE was configured with system tests enabled then you can run them like this.
```
$ make systemtests
```
If you want to invoke lit manually use:
```
$ lit test/
```
This way you can run individual tests or subsets of the suite:
```
$ lit test/regression
```
(Optional) Build and run the unit tests:

If KLEE was configured with unit tests enabled then you can build and run the unit tests like this.
```
$ make unittests
```
You’re ready to go! Check the Tutorials page to try KLEE.

NOTE: For testing real applications (e.g. Coreutils), you may need to increase your system’s open file limit (ulimit -n). Something between 10000 and 999999 should work. In most cases, the hard limit will have to be increased first, so it is best to directly edit the /etc/security/limits.conf file.