forked from OSchip/llvm-project
60 lines
1.8 KiB
ReStructuredText
60 lines
1.8 KiB
ReStructuredText
=======================
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LLVM Common CMake Utils
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=======================
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What goes here
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--------------
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These are CMake modules to be shared between LLVM projects strictly at build
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time. In other words, they must not be included from an installed CMake module,
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such as the ``Add*.cmake`` ones. Modules that are reachable from installed
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modules should instead go in ``${project}/cmake/modules`` of the most upstream
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project that uses them.
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The advantage of not putting these modules in an existing location like
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``llvm/cmake/modules`` is two-fold:
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- Since they are not installed, we don't have to worry about any out-of-tree
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downstream usage, and thus there is no need for stability.
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- Since they are available as part of the source at build-time, we don't have
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to do the usual stand-alone vs combined-build dances, avoiding much
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complexity.
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How to use
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----------
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For tools, please do:
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.. code-block:: cmake
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if(NOT DEFINED LLVM_COMMON_CMAKE_UTILS)
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set(LLVM_COMMON_CMAKE_UTILS ${LLVM_COMMON_CMAKE_UTILS}/../cmake)
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endif()
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# Add path for custom modules.
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list(INSERT CMAKE_MODULE_PATH 0
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# project-specific module dirs first
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"${LLVM_COMMON_CMAKE_UTILS}/Modules"
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)
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Notes:
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- The ``if(NOT DEFINED ...)`` guard is there because in combined builds, LLVM
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will set this variable. This is useful for legacy builds where projects are
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found in ``llvm/tools`` instead.
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- ``INSERT ... 0`` ensures these new entries are prepended to the front of the
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module path, so nothing might shadow them by mistake.
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For runtime libs, we skip the ``if(NOT DEFINED`` part:
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.. code-block:: cmake
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set(LLVM_COMMON_CMAKE_UTILS ${LLVM_COMMON_CMAKE_UTILS}/../cmake)
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... # same as before
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If ``llvm/tools`` legacy-style combined builds are deprecated, we should then
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skip it everywhere, bringing the tools and runtimes boilerplate back in line.
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