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Building with QIR-EE/XACC Support

QIR-EE is a useful tool for targeting NISQ hardware with QIR via XACC. Qwerty can pass QIR to QIR-EE, but it takes some work to make them work together. Note the integration between QIR-EE and Qwerty is currently experimental.

Step 1: Build XACC

  1. Clone the ORNL fork of the XACC git repository
  2. Do the classic inside the cloned XACC repo: 
    $ mkdir build && cd build
$ cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug ..
$ ninja install

Step 2: Build QIR-EE

  1. Check out the qwerty branch of our lab's fork of the QIR-EE git repository

  2. Set up your LLVM environment variables properly as described in the Qwerty build instructions

  3. Run the following insided the cloned repo:

    $ mkdir build && cd build
$ cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DQIREE_BUILD_TESTS=FALSE -DXACC_DIR=$HOME/.xacc -DBUILD_SHARED_LIBS=FALSE -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ..
$ ninja install

    The -DBUILD_SHARED_LIBS=FALSE -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE portion is pretty crucial to avoid many linker errors related to both QIR-EE and Qwerty using LLVM. Turning off the tests stops CMake from going on a fishing expedition to find googletest. The path passed as XACC_DIR, ~/.xacc, is the default XACC install dir. Heads up, if you encounter weird build problems, I would recommend deleting and re-creating the build directory and doing rm -rvf ~/.xacc/include/qiree* (somehow old installed QIREE headers take precedence over ones in your working tree).

    If you want to build the tests, try this command line instead:

    $ cmake -G Ninja -DCMAKE_BUILD_TYPE=Debug -DGTest_ROOT=$HOME/bin/gtest -DXACC_DIR=$HOME/.xacc -DBUILD_SHARED_LIBS=FALSE -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ..

    which assumes you previously built googletest like this:

    $ git clone https://github.com/google/googletest.git
$ mkdir googletest/build && cd googletest/build
$ cmake -G Ninja -DCMAKE_INSTALL_PREFIX=$HOME/bin/gtest -DCMAKE_POSITION_INDEPENDENT_CODE=TRUE ..
$ ninja install

    The -fPIC flag is really important to avoid linker errors.

Step 3: Build Qwerty

  1. With the virtual environment activated and your LLVM environment variables set up as in step (3) above, try: 
    $ QWERTY_USE_QIREE=true QIREE_DIR=$HOME/.xacc/ XACC_DIR=$HOME/.xacc/ pip install -v .
    I set $QIREE_DIR to ~/.xacc is because that's where QIR-EE seems to install itself by default.
  2. Run a simple example and check that QIR-EE actually ran: 
    $ QWERTY_DEBUG=1 python examples/ghz_flip.py 3 qpp
$ cat qiree.log
tuple ret length 3 distinct results 2
tuple ret result 000 count 1061
tuple ret result 111 count 987
tuple discarded length 0 distinct results 0

Note that right now the Python wheel built for QIR-EE+Qwerty is not portable. This is because of the following:

  1. It is dependent on many XACC shared libraries in ~/.xacc
  2. As such, the rpath is hardcoded to look up libraries in that path. Otherwise, you would need to obnoxiously set $LD_LIBRARY_PATH to ~/.xacc/lib every time you ran a Qwerty example

We need to address this by either allowing XACC to be built as a static library (extremely difficult) or packaging up these shared objects in the wheel.