[CMAKE] Move version control macros to AddLLVM.cmake so they can be reused by clang, etc.

Summary:
Move version control macros, find_first_existing_file and
find_first_existing_vc_file to AddLLVM.cmake so they can be reused by sub projects
like clang.

Differential Revision: https://reviews.llvm.org/D36971

llvm-svn: 312419

1 files changed, 33 insertions, 0 deletions

diff --git a/llvm/cmake/modules/AddLLVM.cmake b/llvm/cmake/modules/AddLLVM.cmake
index 61417865c77..93a55257e38 100644
--- a/llvm/cmake/modules/AddLLVM.cmake
+++ b/llvm/cmake/modules/AddLLVM.cmake
@@ -1499,3 +1499,36 @@ function(setup_dependency_debugging name)
   set(sandbox_command "sandbox-exec -p '(version 1) (allow default) ${deny_attributes_gen} ${deny_intrinsics_gen}'")
   set_target_properties(${name} PROPERTIES RULE_LAUNCH_COMPILE ${sandbox_command})
 endfunction()
+
+# Figure out if we can track VC revisions.
+function(find_first_existing_file out_var)
+  foreach(file ${ARGN})
+    if(EXISTS "${file}")
+      set(${out_var} "${file}" PARENT_SCOPE)
+      return()
+    endif()
+  endforeach()
+endfunction()
+
+macro(find_first_existing_vc_file out_var path)
+    find_program(git_executable NAMES git git.exe git.cmd)
+    # Run from a subdirectory to force git to print an absolute path.
+    execute_process(COMMAND ${git_executable} rev-parse --git-dir
+      WORKING_DIRECTORY ${path}/cmake
+      RESULT_VARIABLE git_result
+      OUTPUT_VARIABLE git_dir
+      ERROR_QUIET)
+    if(git_result EQUAL 0)
+      string(STRIP "${git_dir}" git_dir)
+      set(${out_var} "${git_dir}/logs/HEAD")
+      # 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()
+    else()
+      find_first_existing_file(${out_var}
+        "${path}/.svn/wc.db"   # SVN 1.7
+        "${path}/.svn/entries" # SVN 1.6
+      )
+    endif()
+endmacro()