[cmake] Add LLVM_FORCE_VC_REVISION option (#67125)

This patch adds a LLVM_FORCE_VC_REVISION option to force a custom
VC revision to be included instead of trying to fetch one from a
git command. This is helpful in environments where git is not
available or is non-functional but the vc revision is available
through some other means.

clang/lib/Basic/CMakeLists.txt

@@ -39,6 +39,8 @@ add_custom_command(OUTPUT "${version_inc}"
                            "-DHEADER_FILE=${version_inc}"
                            "-DLLVM_VC_REPOSITORY=${llvm_vc_repository}"
                            "-DLLVM_VC_REVISION=${llvm_vc_revision}"
+                           "-DLLVM_FORCE_VC_REVISION=${LLVM_FORCE_VC_REVISION}"
+                           "-DLLVM_FORCE_VC_REPOSITORY=${LLVM_FORCE_VC_REPOSITORY}"
                            -P "${generate_vcs_version_script}")
 
 # Mark the generated header as being generated.

flang/lib/Common/CMakeLists.txt

@@ -12,14 +12,16 @@ endif()
 if(flang_vc AND LLVM_APPEND_VC_REV)
   set(flang_source_dir ${FLANG_SOURCE_DIR})
 endif()
-
+ 
 # Create custom target to generate the VC revision include.
 add_custom_command(OUTPUT "${version_inc}"
   DEPENDS "${llvm_vc}" "${flang_vc}" "${generate_vcs_version_script}"
   COMMAND ${CMAKE_COMMAND} "-DNAMES=\"LLVM;FLANG\""
                            "-DLLVM_SOURCE_DIR=${llvm_source_dir}"
                            "-DFLANG_SOURCE_DIR=${flang_source_dir}"
                            "-DHEADER_FILE=${version_inc}"
+                           "-DLLVM_FORCE_VC_REVISION=${LLVM_FORCE_VC_REVISION}"
+                           "-DLLVM_FORCE_VC_REPOSITORY=${LLVM_FORCE_VC_REPOSITORY}"
                            -P "${generate_vcs_version_script}")
 
 # Mark the generated header as being generated.

lld/Common/CMakeLists.txt

@@ -13,6 +13,8 @@ add_custom_command(OUTPUT "${version_inc}"
   COMMAND ${CMAKE_COMMAND} "-DNAMES=LLD"
   "-DLLD_SOURCE_DIR=${lld_source_dir}"
   "-DHEADER_FILE=${version_inc}"
+  "-DLLVM_FORCE_VC_REVISION=${LLVM_FORCE_VC_REVISION}"
+  "-DLLVM_FORCE_VC_REPOSITORY=${LLVM_FORCE_VC_REPOSITORY}"
   -P "${generate_vcs_version_script}")
 
 # Mark the generated header as being generated.

lldb/source/Version/CMakeLists.txt

@@ -17,6 +17,8 @@ add_custom_command(OUTPUT "${vcs_version_inc}"
   COMMAND ${CMAKE_COMMAND} "-DNAMES=LLDB"
                            "-DLLDB_SOURCE_DIR=${lldb_source_dir}"
                            "-DHEADER_FILE=${vcs_version_inc}"
+                           "-DLLVM_FORCE_VC_REVISION=${LLVM_FORCE_VC_REVISION}"
+                           "-DLLVM_FORCE_VC_REPOSITORY=${LLVM_FORCE_VC_REPOSITORY}"
                            -P "${generate_vcs_version_script}")
 
 set_source_files_properties("${vcs_version_inc}"

llvm/CMakeLists.txt

@@ -325,6 +325,12 @@ include(VersionFromVCS)
 option(LLVM_APPEND_VC_REV
   "Embed the version control system revision in LLVM" ON)
 
+set(LLVM_FORCE_VC_REVISION
+  "" CACHE STRING "Force custom VC revision for LLVM_APPEND_VC_REV")
+
+set(LLVM_FORCE_VC_REPOSITORY
+  "" CACHE STRING "Force custom VC repository for LLVM_APPEND_VC_REV")
+
 option(LLVM_TOOL_LLVM_DRIVER_BUILD "Enables building the llvm multicall tool" OFF)
 
 set(PACKAGE_NAME LLVM)

llvm/cmake/modules/GenerateVersionFromVCS.cmake

@@ -36,7 +36,14 @@ function(append_info name revision repository)
 endfunction()
 
 foreach(name IN LISTS NAMES)
-  if(${name}_VC_REPOSITORY AND ${name}_VC_REVISION)
+  if(LLVM_FORCE_VC_REVISION AND LLVM_FORCE_VC_REPOSITORY)
+    set(revision ${LLVM_FORCE_VC_REVISION})
+    set(repository ${LLVM_FORCE_VC_REPOSITORY})
+  elseif(LLVM_FORCE_VC_REVISION)
+    set(revision ${LLVM_FORCE_VC_REVISION})
+  elseif(LLVM_FORCE_VC_REPOSITORY)
+    set(repository ${LLVM_FORCE_VC_REPOSITORY})
+  elseif(${name}_VC_REPOSITORY AND ${name}_VC_REVISION)
     set(revision ${${name}_VC_REVISION})
     set(repository ${${name}_VC_REPOSITORY})
   elseif(DEFINED ${name}_SOURCE_DIR)

llvm/docs/CMake.rst

@@ -334,6 +334,15 @@ enabled sub-projects. Nearly all of these variable names begin with
   need revision info can disable this option to avoid re-linking most binaries
   after a branch switch. Defaults to ON.
 
+**LLVM_FORCE_VC_REVISION**:STRING
+  Force a specific Git revision id rather than calling to git to determine it.
+  This is useful in environments where git is not available or non-functional
+  but the VC revision is available through other means.
+
+**LLVM_FORCE_VC_REPOSITORY**:STRING
+  Set the git repository to include in version info rather than calling git to
+  determine it.
+
 **LLVM_BUILD_32_BITS**:BOOL
   Build 32-bit executables and libraries on 64-bit systems. This option is
   available only on some 64-bit Unix systems. Defaults to OFF.

llvm/include/llvm/Support/CMakeLists.txt

@@ -28,13 +28,17 @@ if (fake_version_inc)
     COMMAND ${CMAKE_COMMAND} "-DNAMES=LLVM"
                              "-DLLVM_SOURCE_DIR=${llvm_source_dir}"
                              "-DHEADER_FILE=${version_inc}"
+                             "-DLLVM_FORCE_VC_REVISION=${LLVM_FORCE_VC_REVISION}"
+                             "-DLLVM_FORCE_VC_REPOSITORY=${LLVM_FORCE_VC_REPOSITORY}"
                              -P "${generate_vcs_version_script}")
 else()
   add_custom_command(OUTPUT "${version_inc}"
     DEPENDS "${llvm_vc}" "${generate_vcs_version_script}"
     COMMAND ${CMAKE_COMMAND} "-DNAMES=LLVM"
                              "-DLLVM_SOURCE_DIR=${llvm_source_dir}"
                              "-DHEADER_FILE=${version_inc}"
+                             "-DLLVM_FORCE_VC_REVISION=${LLVM_FORCE_VC_REVISION}"
+                             "-DLLVM_FORCE_VC_REPOSITORY=${LLVM_FORCE_VC_REPOSITORY}"
                              -P "${generate_vcs_version_script}")
 endif()