IMEX Build Steps

[AllanZyne]

In README, it says

Install MLIR/LLVM and Intel® Extension for MLIR (IMEX, see https://github.com/intel/mlir-extensions).

but I found we can't just follow its build steps, in cmake arguments, we need to add -DLLVM_ENABLE_RTTI=ON and the build target should be "all" (not "check-imex").

In summary, the build and install steps for IMEX is

export IMEXROOT=<your-IMEX-install-dir>

git clone https://github.com/intel/mlir-extensions.git
git clone https://github.com/llvm/llvm-project.git

cd llvm-project
git checkout `cat ../mlir-extensions/build_tools/llvm_version.txt`
git apply ../mlir-extensions/build_tools/patches/*

cmake -G Ninja -B build -S llvm \
   -DLLVM_ENABLE_PROJECTS=mlir \
   -DLLVM_BUILD_EXAMPLES=ON \
   -DLLVM_TARGETS_TO_BUILD="X86" \
   -DCMAKE_BUILD_TYPE=Release \
   -DLLVM_ENABLE_ASSERTIONS=ON \
   -DLLVM_EXTERNAL_PROJECTS="Imex" \
   -DLLVM_ENABLE_RTTI=ON \
   -DCMAKE_INSTALL_PREFIX=$IMEXROOT \
   -DLLVM_EXTERNAL_IMEX_SOURCE_DIR=../mlir-extensions

# For GPU support pass thes cmake variables to enable the required runtime libraries
#  -DIMEX_ENABLE_L0_RUNTIME=1
#  -DIMEX_ENABLE_SYCL_RUNTIME=1
# Additional if using a non system wide Level Zero Loader built from source
#  -DLEVEL_ZERO_DIR=/PATH_TO/level-zero-install

cmake --build build
cmake --install build

[AllanZyne]

BTW, the branch "jit" is removed in repo, and is this file imex_version.txt still useful?