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1=======================2LLVM Common CMake Utils3=======================4 5What goes here6--------------7 8These are CMake modules to be shared between LLVM projects strictly at build9time. In other words, they must not be included from an installed CMake module,10such as the ``Add*.cmake`` ones. Modules that are reachable from installed11modules should instead go in ``${project}/cmake/modules`` of the most upstream12project that uses them.13 14The advantage of not putting these modules in an existing location like15``llvm/cmake/modules`` is two-fold:16 17- Since they are not installed, we don't have to worry about any out-of-tree18 downstream usage, and thus there is no need for stability.19 20- Since they are available as part of the source at build-time, we don't have21 to do the usual stand-alone vs combined-build dances, avoiding much22 complexity.23 24How to use25----------26 27For tools, please do:28 29.. code-block:: cmake30 31 if(NOT DEFINED LLVM_COMMON_CMAKE_UTILS)32 set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)33 endif()34 35 # Add path for custom modules.36 list(INSERT CMAKE_MODULE_PATH 037 # project-specific module dirs first38 "${LLVM_COMMON_CMAKE_UTILS}/Modules"39 )40 41Notes:42 43- The ``if(NOT DEFINED ...)`` guard is there because in combined builds, LLVM44 will set this variable. This is useful for legacy builds where projects are45 found in ``llvm/tools`` instead.46 47- ``INSERT ... 0`` ensures these new entries are prepended to the front of the48 module path, so nothing might shadow them by mistake.49 50For runtime libs, we skip the ``if(NOT DEFINED`` part:51 52.. code-block:: cmake53 54 set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)55 56 ... # same as before57 58If ``llvm/tools`` legacy-style combined builds are deprecated, we should then59skip it everywhere, bringing the tools and runtimes boilerplate back in line.60