Use GNUInstallDirs to define install locations for documentation

[t-tye]

Summary

Use CMake's GNUInstallDirs include file to define the install
CMAKE_INSTALL_DATADIR and CMAKE_INSTALL_MANDIR. (Was unable to use
CMAKE_INSTALL_DOCDIR as the CMake files define the PROJECT_NAME as LLVM for
all projects.)

[scott.linder]

I think the change itself LGTM, but I did a grep for GNUInstallDirs and it it only used in two other places currently. I suppose that means it is OK to use, but it does seem to imply there can be cases where we install to inconsistent locations. I don't know who to add to get more info on this, though?

[t-tye]

In D106338#2905365, @scott.linder wrote:

I think the change itself LGTM, but I did a grep for GNUInstallDirs and it it only used in two other places currently. I suppose that means it is OK to use, but it does seem to imply there can be cases where we install to inconsistent locations. I don't know who to add to get more info on this, though?

Right. I did check and saw GNUInstallDirs was being used elsewhere in relation to the documentation installing. So making this change seemed consistent. I think all documentation installing is now using GNUInstallDirs, but I did not check how other non-documentation install rules are being done. I would be happy to update this review if someone can advise.

llvm/CMakeLists.txt

 
 option (LLVM_BUILD_DOCS "Build the llvm documentation." OFF)
 option (LLVM_INCLUDE_DOCS "Generate build targets for llvm documentation." ON)
 option (LLVM_ENABLE_DOXYGEN "Use doxygen to generate llvm API documentation." OFF)
 option (LLVM_ENABLE_SPHINX "Use Sphinx to generate llvm documentation." OFF)
 option (LLVM_ENABLE_OCAMLDOC "Build OCaml bindings documentation." ON)
 option (LLVM_ENABLE_BINDINGS "Build bindings." ON)
 
-set(LLVM_INSTALL_DOXYGEN_HTML_DIR "share/doc/llvm/doxygen-html"
+include(GNUInstallDirs)
+set(LLVM_INSTALL_DOXYGEN_HTML_DIR "${CMAKE_INSTALL_DATADIR}/doc/llvm/doxygen-html"
     CACHE STRING "Doxygen-generated HTML documentation install directory")
-set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "share/doc/llvm/ocaml-html"
+set(LLVM_INSTALL_OCAMLDOC_HTML_DIR "${CMAKE_INSTALL_DATADIR}/doc/llvm/ocaml-html"
     CACHE STRING "OCamldoc-generated HTML documentation install directory")
 
 option (LLVM_BUILD_EXTERNAL_COMPILER_RT
   "Build compiler-rt as an external project." OFF)
 
 option (LLVM_VERSION_PRINTER_SHOW_HOST_TARGET_INFO
   "Show target and host info when tools are invoked with --version." ON)
 

 if (NOT TENSORFLOW_AOT_PATH STREQUAL "")
   set(LLVM_HAVE_TF_AOT "ON" CACHE BOOL "Tensorflow AOT available")
   set(TENSORFLOW_AOT_COMPILER
     "${TENSORFLOW_AOT_PATH}/../../../../bin/saved_model_cli"
     CACHE PATH "Path to the Tensorflow AOT compiler")
   include_directories(${TENSORFLOW_AOT_PATH}/include)
   add_subdirectory(${TENSORFLOW_AOT_PATH}/xla_aot_runtime_src
     ${CMAKE_ARCHIVE_OUTPUT_DIRECTORY}/tf_runtime)
-  install(TARGETS tf_xla_runtime EXPORT LLVMExports 
+  install(TARGETS tf_xla_runtime EXPORT LLVMExports
     ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX} COMPONENT tf_xla_runtime)
   set_property(GLOBAL APPEND PROPERTY LLVM_EXPORTS tf_xla_runtime)
 endif()
 
 # Keep the legacy CMake flag ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER for
 # compatibility.
 set(LLVM_ENABLE_NEW_PASS_MANAGER ${ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER})
 

llvm/cmake/modules/AddSphinxTarget.cmake

+include(GNUInstallDirs)
 
 # Create sphinx target
 if (LLVM_ENABLE_SPHINX)
   message(STATUS "Sphinx enabled.")
   find_package(Sphinx REQUIRED)
   if (LLVM_BUILD_DOCS AND NOT TARGET sphinx)
     add_custom_target(sphinx ALL)
   endif()
function (add_sphinx_target builder project)
   endif()
 
   if (LLVM_BUILD_DOCS)
     add_dependencies(sphinx ${SPHINX_TARGET_NAME})
 
     # Handle installation
     if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY)
       if (builder STREQUAL man)
-        if (CMAKE_INSTALL_MANDIR)
-          set(INSTALL_MANDIR ${CMAKE_INSTALL_MANDIR}/)
-        else()
-          set(INSTALL_MANDIR share/man/)
-        endif()
         # FIXME: We might not ship all the tools that these man pages describe
         install(DIRECTORY "${SPHINX_BUILD_DIR}/" # Slash indicates contents of
                 COMPONENT "${project}-sphinx-man"
-                DESTINATION ${INSTALL_MANDIR}man1)
+                DESTINATION "${CMAKE_INSTALL_MANDIR}/man1")
 
         if(NOT LLVM_ENABLE_IDE)
           add_llvm_install_targets("install-${SPHINX_TARGET_NAME}"
                                    DEPENDS ${SPHINX_TARGET_NAME}
                                    COMPONENT "${project}-sphinx-man")
         endif()
       elseif (builder STREQUAL html)
         string(TOUPPER "${project}" project_upper)
-        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "share/doc/${project}/html"
+        set(${project_upper}_INSTALL_SPHINX_HTML_DIR "${CMAKE_INSTALL_DATADIR}/doc/${project}/html"
             CACHE STRING "HTML documentation install directory for ${project}")
 
         # '/.' indicates: copy the contents of the directory directly into
         # the specified destination, without recreating the last component
         # of ${SPHINX_BUILD_DIR} implicitly.
         install(DIRECTORY "${SPHINX_BUILD_DIR}/."
                 COMPONENT "${project}-sphinx-html"
                 DESTINATION "${${project_upper}_INSTALL_SPHINX_HTML_DIR}")