build: remove use of llvm-config

[compnerd]

Summary

Update the CMake build to use the LLVM CMake Config package rather than invoking llvm-config to find the parameters. Users can specify -DLLVM_DIR= to CMake to indicate where the LLVM build is (as opposed to -DLLVM_CONFIG=. For uses where the system provides LLVM or LLVM's build output is in the CMake search path, no parameters are necessary. This removes use of llvm-config which is helpful on the path to removing llvm-config from LLVM.

[mgorny]

Will overriding LLVM_BUILD_MAIN_SRC_DIR work? Gentoo relies on being able to provide sources in another directory since all builds are done in isolated temporary directories.

[compnerd]

@mgorny, no, you should specify -DLLVM_DIR=/path/to/where/the/config/lives instead.

[mgorny]

I don't think that's going to work on top of unconfigured sources.

[mgorny]

Could you please update this to match the LLD version?

CMakeLists.txt

 if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
   project(Clang)
 
-  # Rely on llvm-config.
-  set(CONFIG_OUTPUT)
-  if(LLVM_CONFIG)
-    set (LLVM_CONFIG_FOUND 1)
-    message(STATUS "Found LLVM_CONFIG as ${LLVM_CONFIG}")
-    message(DEPRECATION "Using llvm-config to detect the LLVM installation is \
-          deprecated.  The installed cmake files should be used \
-          instead.  CMake should be able to detect your LLVM install \
-          automatically, but you can also use LLVM_DIR to specify \
-          the path containing LLVMConfig.cmake.")
-    set(CONFIG_COMMAND ${LLVM_CONFIG}
-      "--assertion-mode"
-      "--bindir"
-      "--libdir"
-      "--includedir"
-      "--prefix"
-      "--src-root"
-      "--cmakedir")
-    execute_process(
-      COMMAND ${CONFIG_COMMAND}
-      RESULT_VARIABLE HAD_ERROR
-      OUTPUT_VARIABLE CONFIG_OUTPUT
-    )
-    if(NOT HAD_ERROR)
-      string(REGEX REPLACE
-        "[ \t]*[\r\n]+[ \t]*" ";"
-        CONFIG_OUTPUT ${CONFIG_OUTPUT})
-    else()
-      string(REPLACE ";" " " CONFIG_COMMAND_STR "${CONFIG_COMMAND}")
-      message(STATUS "${CONFIG_COMMAND_STR}")
-      message(FATAL_ERROR "llvm-config failed with status ${HAD_ERROR}")
-    endif()
-
-    list(GET CONFIG_OUTPUT 0 ENABLE_ASSERTIONS)
-    list(GET CONFIG_OUTPUT 1 TOOLS_BINARY_DIR)
-    list(GET CONFIG_OUTPUT 2 LIBRARY_DIR)
-    list(GET CONFIG_OUTPUT 3 INCLUDE_DIR)
-    list(GET CONFIG_OUTPUT 4 LLVM_OBJ_ROOT)
-    list(GET CONFIG_OUTPUT 5 MAIN_SRC_DIR)
-    list(GET CONFIG_OUTPUT 6 LLVM_CONFIG_CMAKE_PATH)
-
-    # Normalize LLVM_CMAKE_PATH. --cmakedir might contain backslashes.
-    # CMake assumes slashes as PATH.
-    file(TO_CMAKE_PATH ${LLVM_CONFIG_CMAKE_PATH} LLVM_CMAKE_PATH)
-  endif()
-
-
-  if(NOT MSVC_IDE)
-    set(LLVM_ENABLE_ASSERTIONS ${ENABLE_ASSERTIONS}
-      CACHE BOOL "Enable assertions")
-    # Assertions should follow llvm-config's.
-    mark_as_advanced(LLVM_ENABLE_ASSERTIONS)
-  endif()
-
-  find_package(LLVM REQUIRED HINTS "${LLVM_CMAKE_PATH}")
+  find_package(LLVM REQUIRED CONFIG NO_CMAKE_FIND_ROOT_PATH)
   list(APPEND CMAKE_MODULE_PATH ${LLVM_DIR})
 
-  # We can't check LLVM_CONFIG here, because find_package(LLVM ...) also sets
-  # LLVM_CONFIG.
-  if (NOT LLVM_CONFIG_FOUND)
-    # Pull values from LLVMConfig.cmake.  We can drop this once the llvm-config
-    # path is removed.
-    set(TOOLS_BINARY_DIR ${LLVM_TOOLS_BINARY_DIR})
-    set(LIBRARY_DIR ${LLVM_LIBRARY_DIR})
-    set(INCLUDE_DIR ${LLVM_INCLUDE_DIR})
-    set(LLVM_OBJ_DIR ${LLVM_BINARY_DIR})
-  endif()
+  if(CMAKE_CROSSCOMPILING)
+    set(LLVM_NATIVE_BUILD "${LLVM_BINARY_DIR}/NATIVE")
+    if(NOT EXISTS "${LLVM_NATIVE_BUILD}")
+      message(FATAL_ERROR
+        "Attempting to cross-compile Clang standalone but no native LLVM build
+        found.  Please cross-compile LLVM as well.")
+    endif()
 
-  set(LLVM_TOOLS_BINARY_DIR ${TOOLS_BINARY_DIR} CACHE PATH "Path to llvm/bin")
-  set(LLVM_LIBRARY_DIR ${LIBRARY_DIR} CACHE PATH "Path to llvm/lib")
-  set(LLVM_MAIN_INCLUDE_DIR ${INCLUDE_DIR} CACHE PATH "Path to llvm/include")
-  set(LLVM_BINARY_DIR ${LLVM_OBJ_ROOT} CACHE PATH "Path to LLVM build tree")
-  set(LLVM_MAIN_SRC_DIR ${MAIN_SRC_DIR} CACHE PATH "Path to LLVM source tree")
+    if(CMAKE_HOST_SYSTEM_NAME MATCHES Windows)
+      set(HOST_EXECUTABLE_SUFFIX ".exe")
+    endif()
 
-  find_program(LLVM_TABLEGEN_EXE "llvm-tblgen" ${LLVM_TOOLS_BINARY_DIR}
-    NO_DEFAULT_PATH)
+    if(NOT CMAKE_CONFIGURATION_TYPES)
+      find_program(LLVM_TABLEGEN_EXE
+        "${LLVM_NATIVE_BUILD}/bin/llvm-tblgen${HOST_EXECUTABLE_SUFFIX}")
+    else()
+      # NOTE: LLVM NATIVE build is always built Release, as is specified in
+      # CrossCompile.cmake
+      find_program(LLVM_TABLEGEN_EXE
+        "${LLVM_NATIVE_BUILD_DIR}/Release/bin/llvm-tblgen${HOST_EXECUTABLE_SUFFIX}")
+    endif()
+  else()
+    find_program(LLVM_TABLEGEN_EXE "llvm-tblgen" ${LLVM_TOOLS_BINARY_DIR}
+      NO_DEFAULT_PATH)
+  endif()
 
   # They are used as destination of target generators.
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)

     set(LLVM_INCLUDE_TESTS ON)
   endif()
 
-  include_directories("${LLVM_BINARY_DIR}/include" "${LLVM_MAIN_INCLUDE_DIR}")
+  include_directories("${LLVM_INCLUDE_DIRS}")
   link_directories("${LLVM_LIBRARY_DIR}")
 
   set( CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin )

       set(LLVM_UTILS_PROVIDED ON)
     endif()
 
-    if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
+    if(EXISTS ${LLVM_BUILD_MAIN_SRC_DIR}/utils/lit/lit.py)
       # Note: path not really used, except for checking if lit was found
-      set(LLVM_LIT ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
-      if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/llvm-lit)
-        add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/llvm-lit utils/llvm-lit)
+      set(LLVM_LIT ${LLVM_BUILD_MAIN_SRC_DIR}/utils/lit/lit.py)
+      if(EXISTS ${LLVM_BUILD_MAIN_SRC_DIR}/utils/llvm-lit)
+        add_subdirectory(${LLVM_BUILD_MAIN_SRC_DIR}/utils/llvm-lit utils/llvm-lit)
       endif()
       if(NOT LLVM_UTILS_PROVIDED)
-        add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/FileCheck utils/FileCheck)
-        add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/count utils/count)
-        add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/not utils/not)
+        add_subdirectory(${LLVM_BUILD_MAIN_SRC_DIR}/utils/FileCheck utils/FileCheck)
+        add_subdirectory(${LLVM_BUILD_MAIN_SRC_DIR}/utils/count utils/count)
+        add_subdirectory(${LLVM_BUILD_MAIN_SRC_DIR}/utils/not utils/not)
         set(LLVM_UTILS_PROVIDED ON)
         set(CLANG_TEST_DEPS FileCheck count not)
       endif()
-      set(UNITTEST_DIR ${LLVM_MAIN_SRC_DIR}/utils/unittest)
+      set(UNITTEST_DIR ${LLVM_BUILD_MAIN_SRC_DIR}/utils/unittest)
       if(EXISTS ${UNITTEST_DIR}/googletest/include/gtest/gtest.h
           AND NOT EXISTS ${LLVM_LIBRARY_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}gtest${CMAKE_STATIC_LIBRARY_SUFFIX}
           AND EXISTS ${UNITTEST_DIR}/CMakeLists.txt)

       # Seek installed Lit.
       find_program(LLVM_LIT
                    NAMES llvm-lit lit.py lit
-                   PATHS "${LLVM_MAIN_SRC_DIR}/utils/lit"
+                   PATHS "${LLVM_BUILD_MAIN_SRC_DIR}/utils/lit"
                    DOC "Path to lit.py")
     endif()
 

 
 
 if( CLANG_INCLUDE_TESTS )
-  if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/unittest/googletest/include/gtest/gtest.h)
+  if(EXISTS ${LLVM_BUILD_MAIN_SRC_DIR}/utils/unittest/googletest/include/gtest/gtest.h)
     add_subdirectory(unittests)
     list(APPEND CLANG_TEST_DEPS ClangUnitTests)
     list(APPEND CLANG_TEST_PARAMS

lib/Basic/CMakeLists.txt

   Support
   )
 
-find_first_existing_vc_file(llvm_vc "${LLVM_MAIN_SRC_DIR}")
+find_first_existing_vc_file(llvm_vc "${LLVM_BUILD_MAIN_SRC_DIR}")
 find_first_existing_vc_file(clang_vc "${CLANG_SOURCE_DIR}")
 
 # The VC revision include that we want to generate.

   add_custom_command(OUTPUT "${version_inc}"
     DEPENDS "${llvm_vc}" "${clang_vc}" "${get_svn_script}"
     COMMAND
-    ${CMAKE_COMMAND} "-DFIRST_SOURCE_DIR=${LLVM_MAIN_SRC_DIR}"
+    ${CMAKE_COMMAND} "-DFIRST_SOURCE_DIR=${LLVM_BUILD_MAIN_SRC_DIR}"
                      "-DFIRST_NAME=LLVM"
                      "-DSECOND_SOURCE_DIR=${CLANG_SOURCE_DIR}"
                      "-DSECOND_NAME=SVN"

runtime/CMakeLists.txt

   endif()
 endfunction()
 
-set(COMPILER_RT_SRC_ROOT ${LLVM_MAIN_SRC_DIR}/projects/compiler-rt)
+set(COMPILER_RT_SRC_ROOT ${LLVM_BUILD_MAIN_SRC_DIR}/projects/compiler-rt)
 # Fallback to the external path, if the other one isn't available.
 # This is the same behavior (try "internal", then check the LLVM_EXTERNAL_...
 # variable) as in add_llvm_external_project