Build LLVM

Get our version of LLVM and Clang (closely tied to upstream, with just a couple of changes) from GitHub:

$ git clone https://github.com/cadets/llvm
$ cd llvm/tools
$ git clone https://github.com/cadets/clang
$ cd ../..
$ mkdir -p build/Release    # or build/Debug, etc.
$ cd build/Release
$ cmake -G Ninja -D CMAKE_BUILD_TYPE=Release ../..    # or Debug
$ ninja

Then put the just-build LLVM at the front of your PATH:

$ export PATH=/path/to/your/LLVM/build/bin:$PATH

Build Loom

Build the Loom instrumentation framework:

$ git clone https://github.com/cadets/loom
$ cd loom
$ mkdir -p build/Release    # or build/Debug, etc.
$ cd build/Release
$ cmake -G Ninja -D CMAKE_BUILD_TYPE=Release ../..    # or Debug

Build llvm-prov

Assuming that you have set all of the environment variables above, you should now be able to build the llvm-prov library:

$ git clone https://github.com/cadets/llvm-prov
$ cd llvm-prov
$ mkdir -p build/Release     # or Debug
$ cd build/Release
$ cmake -G Ninja -D CMAKE_BUILD_TYPE=Release \     # or Debug
    -D LOOM_PREFIX=/path/to/loom/build/Release \
    ../..
# or Debug
$ ninja

Then set an environment variable pointing at the llvm-prov library and extend your PATH to include the llvm-prov scripts directory:

$ export LLVM_PROV_PREFIX=/path/to/llvm-prov/build
$ export PATH=/path/to/llvm-prov/source/scripts:$PATH

Build FreeBSD

Check out our version of FreeBSD with I/O metadata support and build world:

$ git clone https://github.com/cadets/freebsd -b llprov freebsd-llprov
$ cd freebsd-llprov
$ llvm-prov-make buildworld     # I often like to append: -j8 2>&1 | tee build.log

Build individual instrumented binaries

To play with instrumentation of a specific tool, use the llvm-prov-make script to enter a build environment within the FreeBSD source tree:

$ llvm-prov-make buildenv

After that, you should be able to enter any of the bin or usr.bin tool directories and run make foo.full.instrumented to get an instrumented binary, or make foo.full.instrumented.ll to build an instrumented textual IR file (more readable than binaries or .bc files). The resulting files will end up in the out-of-tree build directory ("obj directory"), whose location can be found using make(1) itself:

$ make -V .OBJDIR
/var/build/jon/obj/usr/home/jon/freebsd/llprov/bin/cp

You may like to compare the uninstrumented and instrumented versions of files:

$ ln -s `make -V .OBJDIR` obj      # for convenience
$ diff obj/foo.full.ll obj/foo.full.instrumented.ll

Note that /usr/local/bin is not present in the default PATH within a make buildenv environment. You can, however, explicitly reference tools like colordiff(1) by referring to their full paths or by temporarily modifying PATH:

$ diff -u obj/foo.full.ll obj/foo.full.instrumented.ll | /usr/local/bin/wdiff -dn | /usr/local/bin/colordiff