llvm-project/llvm/cmake/modules/LLVMInstallSymlink.cmake

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# We need to execute this script at installation time because the
# DESTDIR environment variable may be unset at configuration time.
# See PR8397.
function(install_symlink name target outdir)
[cmake] Use symlinks for Windows-hosted toolchains built on Unix When cross-compiling for Windows on Unix, the built toolchain will need to be transferred to Windows to actually run. My opinion is that the Unix build should use symlinks, and the transfer to Windows should take care of making those symlinks usable. E.g., I envision tarballs to be a common form of transfer from Unix to Windows, in which case the tarball can be created using --dereference to follow the symlinks. The motivation here is that, when cross-compiling for Windows on Unix, the installation will *already* create symlinks. The reason is that the installation script will be invoked without knowing the host system, so the `if(UNIX)` check in the installation symlink creation script will reflect the build system rather than the host system. We could either make the build and install trees both contain copies or both contain symlinks, and using symlinks is a significant space saving without (in my opinion) having any detrimental effect on the usage of the cross- compiled toolchain on Windows. A secondary motivation is that Windows 10 version 1703 and later finally lift the administrator rights requirement for creating symbolic links (if the system is in Developer Mode), which makes symlinks a lot more practical even on Windows. Of course Unix and Windows symlinks aren't interoperable, but symlinks for Windows toolchains is a reasonable future direction to be going in anyway. Differential Revision: https://reviews.llvm.org/D41314 llvm-svn: 322061
2018-01-09 15:50:18 +08:00
if(CMAKE_HOST_UNIX)
set(LINK_OR_COPY create_symlink)
set(DESTDIR $ENV{DESTDIR})
else()
set(LINK_OR_COPY copy)
endif()
set(bindir "${DESTDIR}${CMAKE_INSTALL_PREFIX}/${outdir}/")
message("Creating ${name}")
execute_process(
COMMAND "${CMAKE_COMMAND}" -E ${LINK_OR_COPY} "${target}" "${name}"
WORKING_DIRECTORY "${bindir}")
endfunction()