Set the path to the shared cmake modules based on the llvm directory

[mstorsjo]

Summary

It’s still possible to build parts of the main llvm build (lld, clang etc) by symlinking them into llvm/tools.

[Ericson2314]

@mstorsjo I hope this fixes the issue you had in https://reviews.llvm.org/D115568#3215445. I just whipped this up coding blind. If you could test it to ensure it solves your issue, that would be much appreciated!

[mstorsjo]

In D116472#3215562, @Ericson2314 wrote:

@mstorsjo I hope this fixes the issue you had in https://reviews.llvm.org/D115568#3215445. I just whipped this up coding blind. If you could test it to ensure it solves your issue, that would be much appreciated!

Thanks!

We shouldn’t need this for the runtimes; they have their own story for how they’re built (which is complicated enough in other ways), and I don’t think anyone is symlinking then around.

Secondly, we’d need to set this in llvm/CMakeLists.txt too, to make it work automatically.

I can try to fix the patch and commandeer it.

[mstorsjo]

Removed the changes to runtimes; the ways they are built is a separate story - afaik we mandate the monorepo layout there (and the symlinking setup isn't used there afaik).

Added a default setting in llvm/CMakeLists.txt, renamed to match LLVM_THIRD_PARTY_DIR. Made it a plain internal variable - it's not supposed to user settable in general (I think we're moving to mandate the monorepo layout overall).

[mstorsjo]

Removing reviewers/subscribers that shouldn’t be affected by this patch any longer.

flang/CMakeLists.txt

 endif()
 # Always build tco tool
 set(LLVM_BUILD_TOOLS ON)
 
 include_directories(BEFORE
   ${FLANG_BINARY_DIR}/include
   ${FLANG_SOURCE_DIR}/include)
 
+if(NOT DEFINED LLVM_COMMON_CMAKE_UTILS)
+  set(LLVM_COMMON_CMAKE_UTILS ${FLANG_SOURCE_DIR}/../cmake)
+endif()
+
 # Add Flang-centric modules to cmake path.
 list(INSERT CMAKE_MODULE_PATH 0
   "${FLANG_SOURCE_DIR}/cmake/modules"
-  "${FLANG_SOURCE_DIR}/../cmake/Modules"
+  "${LLVM_COMMON_CMAKE_UTILS}/Modules"
   )
 include(AddFlang)
 
 if (NOT DEFAULT_SYSROOT)
   set(DEFAULT_SYSROOT "" CACHE PATH
     "The <path> to use for the system root for all compiler invocations (--sysroot=<path>).")
 endif()
 

lld/CMakeLists.txt

 if (CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
   message(FATAL_ERROR "In-source builds are not allowed. CMake would overwrite "
 "the makefiles distributed with LLVM. Please create a directory and run cmake "
 "from there, passing the path to this source directory as the last argument. "
 "This process created the file `CMakeCache.txt' and the directory "
 "`CMakeFiles'. Please delete them.")
 endif()
 
+if(NOT DEFINED LLVM_COMMON_CMAKE_UTILS)
+  set(LLVM_COMMON_CMAKE_UTILS ${LLD_SOURCE_DIR}/../cmake)
+endif()
+
 # Add path for custom modules.
 list(INSERT CMAKE_MODULE_PATH 0
   "${LLD_SOURCE_DIR}/cmake/modules"
-  "${LLD_SOURCE_DIR}/../cmake/Modules"
+  "${LLVM_COMMON_CMAKE_UTILS}/Modules"
   )
 
 include(AddLLD)
 
 option(LLD_USE_VTUNE
        "Enable VTune user task tracking."
        OFF)
 if (LLD_USE_VTUNE)

llvm/CMakeLists.txt

 # Each of them corresponds to llvm-config's.
 set(LLVM_TOOLS_BINARY_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR}) # --bindir
 set(LLVM_LIBRARY_DIR      ${LLVM_LIBRARY_OUTPUT_INTDIR}) # --libdir
 set(LLVM_MAIN_SRC_DIR     ${CMAKE_CURRENT_SOURCE_DIR}  ) # --src-root
 set(LLVM_MAIN_INCLUDE_DIR ${LLVM_MAIN_SRC_DIR}/include ) # --includedir
 set(LLVM_BINARY_DIR       ${CMAKE_CURRENT_BINARY_DIR}  ) # --prefix
 
 set(LLVM_THIRD_PARTY_DIR  ${CMAKE_CURRENT_SOURCE_DIR}/../third-party)
+set(LLVM_COMMON_CMAKE_UTILS ${CMAKE_CURRENT_SOURCE_DIR}/../cmake)
 
 # Note: LLVM_CMAKE_DIR does not include generated files
 set(LLVM_CMAKE_DIR ${LLVM_MAIN_SRC_DIR}/cmake/modules)
 set(LLVM_EXAMPLES_BINARY_DIR ${LLVM_BINARY_DIR}/examples)
 set(LLVM_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
 
 # List of all targets to be built by default:
 set(LLVM_ALL_TARGETS