[lld] [cmake] Support running tests in stand-alone builds

[mgorny]

Summary

Add the CMake bits necessary to run lld tests (and unittests) when
building stand-alone. The code is based on the equivalent code in clang,
and includes:

1. checking for Python, searching for lit and necessary LLVM test tools

(FileCount and not),

2. building LLVM test tools (FileCount and not) from LLVM sources if

they are not installed,

3. building gtest libraries from LLVM sources,

4. adjusting dependencies so that test targets depend only on those LLVM

targets that are available for a particular variant of stand-alone
build.

With this patch, I am able to successfully run 1002 (+10 unsupported)
lit tests on Gentoo using installed LLVM.

[mgorny]

Le ping.

[compnerd]

LG beyond the few nits.

CMakeLists.txt

67

No spaces around the condition.

110

No space around the condition

test/CMakeLists.txt

29

I think that I would rather see this as:

set(LLD_TEST_DEPS lld)
if(NOT LLD_BUILT_STANDALONE)
  list(APPEND LLD_TEST_DEPS FileCheck not llvm-ar ...)
endif()

CMakeLists.txt

 # Check if lld is built as a standalone project.
 if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   project(lld)
   cmake_minimum_required(VERSION 3.4.3)
 
   set(CMAKE_INCLUDE_CURRENT_DIR ON)
   set(LLD_BUILT_STANDALONE TRUE)
 
   find_program(LLVM_CONFIG_PATH "llvm-config" DOC "Path to llvm-config binary")
   if(NOT LLVM_CONFIG_PATH)
     message(FATAL_ERROR "llvm-config not found: specify LLVM_CONFIG_PATH")
   endif()
 
-  execute_process(COMMAND "${LLVM_CONFIG_PATH}" "--obj-root" "--includedir"
+  execute_process(COMMAND "${LLVM_CONFIG_PATH}"
+                          "--obj-root"
+                          "--includedir"
                           "--cmakedir"
+                          "--src-root"
                   RESULT_VARIABLE HAD_ERROR
                   OUTPUT_VARIABLE LLVM_CONFIG_OUTPUT
                   OUTPUT_STRIP_TRAILING_WHITESPACE)
   if(HAD_ERROR)
     message(FATAL_ERROR "llvm-config failed with status ${HAD_ERROR}")
   endif()
 
   string(REGEX REPLACE "[ \t]*[\r\n]+[ \t]*" ";" LLVM_CONFIG_OUTPUT "${LLVM_CONFIG_OUTPUT}")
 
   list(GET LLVM_CONFIG_OUTPUT 0 OBJ_ROOT)
   list(GET LLVM_CONFIG_OUTPUT 1 MAIN_INCLUDE_DIR)
   list(GET LLVM_CONFIG_OUTPUT 2 LLVM_CMAKE_PATH)
+  list(GET LLVM_CONFIG_OUTPUT 3 MAIN_SRC_DIR)
 
   set(LLVM_OBJ_ROOT ${OBJ_ROOT} CACHE PATH "path to LLVM build tree")
   set(LLVM_MAIN_INCLUDE_DIR ${MAIN_INCLUDE_DIR} CACHE PATH "path to llvm/include")
+  set(LLVM_MAIN_SRC_DIR ${MAIN_SRC_DIR} CACHE PATH "Path to LLVM source tree")
 
   file(TO_CMAKE_PATH ${LLVM_OBJ_ROOT} LLVM_BINARY_DIR)
 
   if(NOT EXISTS "${LLVM_CMAKE_PATH}/LLVMConfig.cmake")
     message(FATAL_ERROR "LLVMConfig.cmake not found")
   endif()
   include("${LLVM_CMAKE_PATH}/LLVMConfig.cmake")
 
   list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_PATH}")
 
   set(PACKAGE_VERSION "${LLVM_PACKAGE_VERSION}")
   include_directories("${LLVM_BINARY_DIR}/include" ${LLVM_INCLUDE_DIRS})
   link_directories(${LLVM_LIBRARY_DIRS})
 
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/${CMAKE_CFG_INTDIR}/bin)
   find_program(LLVM_TABLEGEN_EXE "llvm-tblgen" ${LLVM_TOOLS_BINARY_DIR} NO_DEFAULT_PATH)
 
   include(AddLLVM)
   include(TableGen)
   include(HandleLLVMOptions)
+
+  if(LLVM_INCLUDE_TESTS)
+    set(Python_ADDITIONAL_VERSIONS 2.7)
+    include(FindPythonInterp)
+    if(NOT PYTHONINTERP_FOUND)
+      message(FATAL_ERROR
+"Unable to find Python interpreter, required for testing.
+
+Please install Python or specify the PYTHON_EXECUTABLE CMake variable.")
+    endif()
+
+    if( ${PYTHON_VERSION_STRING} VERSION_LESS 2.7 )
+      message(FATAL_ERROR "Python 2.7 or newer is required")
+    endif()
+
+    # Check prebuilt llvm/utils.
+    if(EXISTS ${LLVM_TOOLS_BINARY_DIR}/FileCheck${CMAKE_EXECUTABLE_SUFFIX}
+        AND EXISTS ${LLVM_TOOLS_BINARY_DIR}/not${CMAKE_EXECUTABLE_SUFFIX})
+      set(LLVM_UTILS_PROVIDED ON)
+    endif()
+
+    if(EXISTS ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
+      # Note: path not really used, except for checking if lit was found
+      set(LLVM_LIT ${LLVM_MAIN_SRC_DIR}/utils/lit/lit.py)
+      if(NOT LLVM_UTILS_PROVIDED)
+        add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/FileCheck utils/FileCheck)
+        add_subdirectory(${LLVM_MAIN_SRC_DIR}/utils/not utils/not)
+        set(LLVM_UTILS_PROVIDED ON)
+        set(LLD_TEST_DEPS FileCheck not)
+      endif()
+      set(UNITTEST_DIR ${LLVM_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 ${UNITTEST_DIR}/CMakeLists.txt)
+        add_subdirectory(${UNITTEST_DIR} utils/unittest)
+      endif()
+    else()
+      # Seek installed Lit.
+      find_program(LLVM_LIT
+                   NAMES llvm-lit lit.py lit
+                   PATHS "${LLVM_MAIN_SRC_DIR}/utils/lit"
+                   DOC "Path to lit.py")
+    endif()
+
+    if(LLVM_LIT)
+      # Define the default arguments to use with 'lit', and an option for the user
+      # to override.
+      set(LIT_ARGS_DEFAULT "-sv")
+      if (MSVC OR XCODE)
+        set(LIT_ARGS_DEFAULT "${LIT_ARGS_DEFAULT} --no-progress-bar")
+      endif()
+      set(LLVM_LIT_ARGS "${LIT_ARGS_DEFAULT}" CACHE STRING "Default options for lit")
+
+      # On Win32 hosts, provide an option to specify the path to the GnuWin32 tools.
+      if( WIN32 AND NOT CYGWIN )
+        set(LLVM_LIT_TOOLS_DIR "" CACHE PATH "Path to GnuWin32 tools")
+      endif()
+    else()
+      set(LLVM_INCLUDE_TESTS OFF)
+    endif()
+  endif()
 endif()
 
 set(LLD_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(LLD_INCLUDE_DIR ${LLD_SOURCE_DIR}/include )
 set(LLD_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 
 # Compute the LLD version from the LLVM version.
 string(REGEX MATCH "[0-9]+\\.[0-9]+(\\.[0-9]+)?" LLD_VERSION

test/CMakeLists.txt

 configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/lit.site.cfg.in
   ${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg)
 configure_lit_site_cfg(
   ${CMAKE_CURRENT_SOURCE_DIR}/Unit/lit.site.cfg.in
   ${CMAKE_CURRENT_BINARY_DIR}/Unit/lit.site.cfg
   )
 
+if (NOT LLD_BUILT_STANDALONE)
   set(LLD_TEST_DEPS
     FileCheck not llvm-ar llvm-as llvm-dis llvm-dwarfdump llvm-nm
-  llc lld llvm-config llvm-objdump llvm-readobj yaml2obj obj2yaml
+    llc llvm-config llvm-objdump llvm-readobj yaml2obj obj2yaml
     llvm-mc llvm-lib llvm-pdbdump opt
     )
+endif()
+set(LLD_TEST_DEPS ${LLD_TEST_DEPS} lld)
+
 if (LLVM_INCLUDE_TESTS)
   set(LLD_TEST_DEPS ${LLD_TEST_DEPS} LLDUnitTests)
 endif()
 
 set(LLD_TEST_PARAMS
   lld_site_config=${CMAKE_CURRENT_BINARY_DIR}/lit.site.cfg
   )