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