CMake: Fix stand-alone clang builds since r353268

[tstellar]

Summary

Handle the case where LLVM_MAIN_SRC_DIR is not set and also use
LLVM_CMAKE_DIR for locating installed cmake files rather than
LLVM_CMAKE_PATH.

[phosek]

LGTM

[smeenai]

clang/lib/Basic/CMakeLists.txt

13

Will this work when using llvm-config instead of LLVM's CMake package?

[andrewrk]

I confirm this solves the issue.

llvm/cmake/modules/AddLLVM.cmake

1739

I think ${path} should still be quoted here for best practice, as well as ${GIT_EXECUTABLE} above.

1745

these variables should be quoted too

[tstellar]

clang/lib/Basic/CMakeLists.txt

13

I will test this and a few other configurations to make sure.

[smeenai]

This could also be improved by teaching clang to use LLVM_BUILD_MAIN_SRC_DIR when that's available.

[tstellar]

Updated patch to fix non-standalone builds. There is more refactoring
that could be done, but this at least restores functionality to before
r353268.

I have tested non-standalone builds and standalone builds with and
without llvm-config.

[smeenai]

LGTM. There's more clean up that could be done here, but this addresses the immediate issue. Thanks!

clang/lib/Basic/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   Core
   MC
   Support
   )
 
 find_first_existing_vc_file("${LLVM_MAIN_SRC_DIR}" llvm_vc)
 find_first_existing_vc_file("${CLANG_SOURCE_DIR}" clang_vc)
 
 # The VC revision include that we want to generate.
 set(version_inc "${CMAKE_CURRENT_BINARY_DIR}/VCSVersion.inc")
 
-set(generate_vcs_version_script "${LLVM_CMAKE_PATH}/GenerateVersionFromVCS.cmake")
+set(generate_vcs_version_script "${LLVM_CMAKE_DIR}/GenerateVersionFromVCS.cmake")
 
 if(llvm_vc)
   set(llvm_source_dir ${LLVM_MAIN_SRC_DIR})
 endif()
 if(clang_vc)
   set(clang_source_dir ${CLANG_SOURCE_DIR})
 endif()
 

llvm/cmake/modules/AddLLVM.cmake

function(setup_dependency_debugging name)
   set(deny_attributes_inc "(deny file* (literal \"${LLVM_BINARY_DIR}/include/llvm/IR/Attributes.inc\"))")
   set(deny_intrinsics_inc "(deny file* (literal \"${LLVM_BINARY_DIR}/include/llvm/IR/Intrinsics.inc\"))")
 
   set(sandbox_command "sandbox-exec -p '(version 1) (allow default) ${deny_attributes_inc} ${deny_intrinsics_inc}'")
   set_target_properties(${name} PROPERTIES RULE_LAUNCH_COMPILE ${sandbox_command})
 endfunction()
 
 function(find_first_existing_vc_file path out_var)
+  if(NOT EXISTS "${path}")
+    return()
+  endif()
   if(EXISTS "${path}/.svn")
     set(svn_files
       "${path}/.svn/wc.db"   # SVN 1.7
       "${path}/.svn/entries" # SVN 1.6
     )
     foreach(file IN LISTS svn_files)
       if(EXISTS "${file}")
         set(${out_var} "${file}" PARENT_SCOPE)
         return()
       endif()
     endforeach()
   else()
     find_package(Git)
     if(GIT_FOUND)
       execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --git-dir
         WORKING_DIRECTORY ${path}
         RESULT_VARIABLE git_result
         OUTPUT_VARIABLE git_output
         ERROR_QUIET)
       if(git_result EQUAL 0)
         string(STRIP "${git_output}" git_output)
         get_filename_component(git_dir ${git_output} ABSOLUTE BASE_DIR ${path})
         # Some branchless cases (e.g. 'repo') may not yet have .git/logs/HEAD
         if (NOT EXISTS "${git_dir}/logs/HEAD")
           file(WRITE "${git_dir}/logs/HEAD" "")
         endif()
         set(${out_var} "${git_dir}/logs/HEAD" PARENT_SCOPE)
       endif()
     endif()
   endif()
 endfunction()