This repository builds C++ based frontend for the Intel Quantum Compiler. It is used in conjunction with the Intel Quantum Passes. It adapts the clang and LLVM compiler to use Quantum Intrinsics, and includes several header files with specific quantum libraries and functions.
Building the compiler is very similar to standard LLVM, and requires the same software, found here.
After ensuring the system requirements are met, use the following commands:
mkdir build
cd build
cmake -G Ninja -S ../llvm -B . -DLLVM_INSTALL_UTILS=ON -DCMAKE_INSTALL_PREFIX=<iqc_install_dir> -DLLVM_ENABLE_PROJECTS="clang;lld" -DCMAKE_BUILD_TYPE=Release
ninja -C . install
<iqc_install_dir> is the location where you want IQC to be installed. If it is not specified, it will attempt to be installed to /usr/bin. If you do not want to install the compiler anywhere, simply use the command ninja -C . instead.
Much of the information that's helpful to use and develop with LLVM is helpful for our compiler as well, but this is some frequently useful advice.
In order to to get full debug information and assertions, pass the -DCMAKE_BUILD_TYPE=Debug rather than Release.
In order to get "print debugging" for LLVM classes through the .dump() method, include -DLLVM_ENABLE_DUMP=On to the cmake invocation.
If you find you need to generate your own intrinsics, the TableGen files for these can be found in llvm/include/llvm/IR/IntrinsicsQuantum.td.
If you find you need to add to the library of quantum functions, they can be found in clang/include/Quantum. The same conventions can be used, mainly the use of the noinline and the .qbbs_text attributes. These attributes ensure that the functions are not improperly inlined, which can cause problems later on in the compilation process.