z3/README-CMake.md

Z3's CMake build system

CMake is a "meta build system" that reads a description of the project written in the CMakeLists.txt files and emits a build system for that project of your choice using one of CMake's "generators". This allows CMake to support many different platforms and build tools. You can run cmake --help to see the list of supported "generators" on your platform. Example generators include "UNIX Makfiles" and "Visual Studio 12 2013".

Getting started

The general workflow when using CMake is the following

1. Create a new build directory
2. Configure the project
3. Generate the build system
4. Invoke the build system to build the project

To perform steps 2 and 3 you can choose from three different tools

• cmake
• ccmake
• cmake-gui

cmake is a command line tool and is what you should use if you are writing a script to build Z3. This tool performs steps 1 and 2 in one go without user interaction. The ccmake and cmake-gui tools are more interactive and allow you to change various options. In both these tools the basic steps to follow are:

1. Configure.
2. Change any options you wish. Everytime you change a set of options You should configure again. This may cause new options to appear
3. Generate.

For information see https://cmake.org/runningcmake/

Note when invoking CMake you give it the path to the source directory. This is the top-level directory in the Z3 repository containing a CMakeLists.txt. That file should contain the line project(Z3 C CXX). If you give it a path deeper into the Z3 repository (e.g. the src directory) the configure step will fail.

What follows is a brief walk through of how to build Z3 using various generators.

Unix Makefiles

Run the following in the top level directory of the Z3 repository.

mkdir build
cd build
cmake -G "Unix Makefiles" ../
make -j4

Note that on some platforms "Unix Makesfiles" is the default generator so on those platforms you don't need to pass -G "Unix Makefiles" command line option to cmake.

Note there is nothing special about the build directory name here. You can call it whatever you like.

Note the "Unix Makefile" generator is a "single" configuration generator which means you pick the build type (e.g. Debug, Release) when you invoke CMake. You can set the build type by passing it to the cmake invocation like so:

cmake -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release ../

See the section on "Build Types" for the different CMake build types.

If you wish to use a different compiler set the CXX and CC environment variables passed to cmake. This must be done at the very first invocation to cmake in the build directory because once configuration has happened the compiler is fixed. If you want to use a different compiler to the one you have already configured you either need to make a new build directory or delete the contents of the current build directory and start again.

For example to use clang the cmake line would be

CC=clang CXX=clang++ cmake ../

Note that CMake build will detect the target architecture that compiler is set up to build for and the generated build system will build for that architecture. If there is a way to tell your compiler to build for a different architecture via compiler flags then you can set the CFLAGS and CXXFLAGS environment variables to have the build target that architecture.

For example if you are on a x86_64 machine and you want to do a 32-bit build and have a multilib version of GCC you can run cmake like this

CFLAGS="-m32" CXXFLAGS="-m32" CC=gcc CXX=g++ cmake ../

Note like with the CC and CXX flags this must be done on the very first invocation to CMake in the build directory.

Ninja

Ninja is a simple build system that is built for speed. It can be significantly faster than "UNIX Makefile"s because it is not a recursive build system and thus doesn't create a new process everytime it traverses into a directory. Ninja is particularly appropriate if you want fast incremental building.

Basic usage is as follows:

mkdir build
cd build
cmake -G "Ninja" ../
ninja

Note the discussion of the CC, CXX, CFLAGS and CXXFLAGS for "Unix Makefiles" also applies here.

Note also that like the "Unix Makefiles" generator, the "Ninja" generator is a single configuration generator so you pick the build type when you invoke cmake by passing CMAKE_BUILD_TYPE=<build_type> to cmake. See the section on "Build Types".

Note that Ninja runs in parallel by default. Use the -j flag to change this.

Note that Ninja also runs on Windows. You just need to run cmake in an environment where the compiler can be found. If you have Visual Studio installed it typically ships with a "Developer Command Prompt Window" that you can use which has the environment variables setup for you.

NMake

NMake is a build system that ships with Visual Studio. You are advised to use Ninja instead which is significantly faster due to supporting concurrent builds. However CMake does support NMake if you wish to use it. Note that NMake is a single configuration generator so you must set CMAKE_BUILD_TYPE to set the build type.

Basic usage:

1. Launch the "Developer Command Prompt Windows"
2. Change to the root of the Z3 repository

mkdir build
cd build
cmake -G "NMake Makefiles" ../
nmake

Visual Studio

For the Visual Studio generators you need to know which version of Visual Studio you wish to use and also what architecture you want to build for.

We'll use the cmake-gui here as it is easier to pick the right generator but this can be scripted if need be.

Here are the basic steps:

1. Create an empty build directory
2. Start the cmake-gui program
3. Set "where is the source code" to the root of the Z3 project repository. You can do this by pressing the "Browse Source..." button and picking the directory.
4. Set "where to build the binaries" to the empty build directory you just created. You can do this by pressing the "Browse build..." button and picking the directory.
5. Press the "Configure" button
6. A window will appear asking you to pick the generator to use. Pick the generator that matches the version of Visual Studio you are using. Note also that some of the generator names contain Win64 (e.g. Visual Studio 12 2013 Win64) this indicates a x86 64-bit build. Generator names without this (e.g. Visual Studio 12 2013) are x86 32-bit build.
7. Press the "Finish" button and wait for CMake to finish it's first configure.
8. A set of configuration options will appear which will affect various aspects of the build. Change them as you desire. If you change a set of options press the "Configure" again. Additional options may appear when you do this.
9. When you have finished changing configuration options press the "Generate" button.
10. When generation is done close cmake-gui.
11. In the build directory open the generated Z3.sln solution file created by CMake with Visual Studio.
12. In Visual Studio pick the build type (e.g. Debug, Release) you want.
13. Click "BUILD > Build Solution".

Note that unlike the "Unix Makefile" and "Ninja" generators the Visual Studio generators are multi-configuration generators which means you don't set the build type when invoking CMake. Instead you set the build type inside Visual Studio. See the "Build Type" section for more information.

Build Types

Several build types are supported.

• Release
• Debug
• RelWithDebInfo
• MinSizeRel

For the single configuration generators (e.g. "Unix Makefile" and "Ninja") you set the build type when invoking cmake by passing -DCMAKE_BUILD_TYPE=<build_type> where <build_type> is one of the build types specified above.

For multi-configuration generators (e.g. Visual Studio) you don't set the build type when invoking CMake and instead set the build type within Visual Studio itself.

Useful options

The following useful options can be passed to CMake whilst configuring.

• CMAKE_BUILD_TYPE - STRING. The build type to use. Only relevant for single configuration generators (e.g. "Unix Makefile" and "Ninja").
• CMAKE_INSTALL_PREFIX - STRING. The install prefix to use (e.g. /usr/local/)
• ENABLE_TRACING - BOOL. If set to TRUE enable tracing, if set to FALSE disable tracing.
• BUILD_LIBZ3_SHARED - BOOL. If set to TRUE build libz3 as a shared library otherwise build as a static library.
• ENABLE_EXAMPLE_TARGETS - BOOL. If set to TRUE add the build targets for building the API examples.
• USE_OPENMP - BOOL. If set to TRUE and OpenMP support is detected build with OpenMP support.
• USE_LIB_GMP - BOOL. If set to TRUE use the GNU multiple precision library. If set to FALSE use an internal implementation.

On the command line these can be passed to cmake using the -D option. In ccmake and cmake-gui these can be set in the user interface.

Example

cmake -DCMAKE_BUILD_TYPE=Release -DENABLE_TRACING=FALSE ../

Developer/packager notes

These notes are help developers and packagers of Z3.

Install/Uninstall

Install and uninstall targets are supported. Use CMAKE_INSTALL_PREFIX to set the install prefix.

To install

make install

To uninstall

make uninstall

Note that DESTDIR is supported for staged installs.

To install

mkdir staged
make install DESTDIR=/full/path/to/staged/

to uninstall

make uninstall DESTDIR=/full/path/to/staged

The above also works for Ninja but DESTDIR must be an environment variable instead.

Examining invoked commands

If you are using the "UNIX Makefiles" generator and want to see exactly the commands that are being run you can pass VERBOSE=1 to make.

make VERBOSE=1

If you are using Ninja you can use the -v flag.

Additional targets

To see the list of targets run

make help

There are a few special targets:

• clean all the built targets in the current directory and below
• edit_cache will invoke one of the CMake tools (depending on which is available) to let you change configuration options.
• rebuild_cache will reinvoke cmake for the project.

Setting build type specific flags

The build system supports single configuration and multi-configuration generators. This means it is not possible to know the build type at configure time and therefore ${CMAKE_BUILD_TYPE} should not be conditionally used to set compiler flags or definitions. Instead you should use Generator expressions which are evaluated by the generator.

For example

$<$<CONFIG:Debug>:Z3DEBUG>

If the build type at build time is Debug this evaluates to Z3DEBUG but evaluates to nothing for all other configurations. You can see examples of this in the CMakeLists.txt files.

File-globbing

It is tempting use file-globbing in CMakeLists.txt to find a set for files matching a pattern and use them as the sources to build a target. This however is a bad idea because it prevents CMake from knowing when it needs to rerun itself. This is why source file names are explicitly listed in the CMakeLists.txt so that when changes are made the source files used to build a target automatically triggers a rerun of CMake.

Long story short. Don't use file globbing.