[libclc] Fix cross in-tree builds (llvm#97392)

When performing cross in-tree builds, we need native versions of various
tools, we cannot assume the cross builds that are part of the current
build are executable. LLVM provides the setup_host_tool function to
handle this, either picking up versions of tools from
LLVM_NATIVE_TOOL_DIR, or implicitly building native versions as needed.
Use it for libclc too.

LLVM's setup_host_tool function assumes the project is LLVM, so this
also needs libclc's project() to be conditional on it being built
standalone. Luckily, the only change this needs is using
CMAKE_CURRENT_SOURCE_DIR instead of PROJECT_SOURCE_DIR.

libclc/CMakeLists.txt

@@ -1,11 +1,13 @@
 cmake_minimum_required(VERSION 3.20.0)
 
-project( libclc VERSION 0.2.0 LANGUAGES CXX C)
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+  project(libclc VERSION 0.2.0 LANGUAGES CXX C)
+endif()
 
 set(CMAKE_CXX_STANDARD 17)
 
 # Add path for custom modules
-list( INSERT CMAKE_MODULE_PATH 0 "${PROJECT_SOURCE_DIR}/cmake/modules" )
+list( INSERT CMAKE_MODULE_PATH 0 "${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules" )
 
 set( LIBCLC_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR} )
 set( LIBCLC_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR} )
@@ -49,12 +51,12 @@ if( LIBCLC_STANDALONE_BUILD OR CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DI
     message( FATAL_ERROR "libclc needs at least LLVM ${LIBCLC_MIN_LLVM}" )
   endif()
 
-  # Import required tools as targets
+  # Import required tools
   if( NOT EXISTS ${LIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR} )
     foreach( tool IN ITEMS clang llvm-as llvm-link opt )
       find_program( LLVM_TOOL_${tool} ${tool} PATHS ${LLVM_TOOLS_BINARY_DIR} NO_DEFAULT_PATH )
-      add_executable( libclc::${tool} IMPORTED GLOBAL )
-      set_target_properties( libclc::${tool} PROPERTIES IMPORTED_LOCATION ${LLVM_TOOL_${tool}} )
+      set( ${tool}_exe ${LLVM_TOOL_${tool}} )
+      set( ${tool}_target )
     endforeach()
   endif()
 else()
@@ -71,9 +73,10 @@ else()
   endif()
 
   if( NOT EXISTS ${LIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR} )
-    foreach( tool IN ITEMS clang llvm-as llvm-link opt )
-      add_executable(libclc::${tool} ALIAS ${tool})
-    endforeach()
+    setup_host_tool( clang CLANG clang_exe clang_target )
+    setup_host_tool( llvm-as LLVM_AS llvm-as_exe llvm-as_target )
+    setup_host_tool( llvm-link LLVM_LINK llvm-link_exe llvm-link_target )
+    setup_host_tool( opt OPT opt_exe opt_target )
   endif()
 endif()
 
@@ -88,14 +91,13 @@ if( EXISTS ${LIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR} )
   foreach( tool IN ITEMS clang llvm-as llvm-link opt )
     find_program( LLVM_CUSTOM_TOOL_${tool} ${tool}
       PATHS ${LIBCLC_CUSTOM_LLVM_TOOLS_BINARY_DIR} NO_DEFAULT_PATH )
-    add_executable( libclc::${tool} IMPORTED GLOBAL )
-    set_target_properties( libclc::${tool} PROPERTIES
-      IMPORTED_LOCATION ${LLVM_CUSTOM_TOOL_${tool}} )
+    set( ${tool}_exe ${LLVM_CUSTOM_TOOL_${tool}} )
+    set( ${tool}_target )
   endforeach()
 endif()
 
 foreach( tool IN ITEMS clang opt llvm-as llvm-link )
-  if( NOT TARGET libclc::${tool} )
+  if( NOT EXISTS "${${tool}_exe}" AND NOT TARGET "${${tool}_target}" )
     message( FATAL_ERROR "libclc toolchain incomplete - missing tool ${tool}!" )
   endif()
 endforeach()
@@ -165,8 +167,11 @@ set(LLVM_LINK_COMPONENTS
 )
 if( LIBCLC_STANDALONE_BUILD )
   add_llvm_executable( prepare_builtins utils/prepare-builtins.cpp )
+  set( prepare_builtins_exe prepare_builtins )
+  set( prepare_builtins_target prepare_builtins )
 else()
   add_llvm_utility( prepare_builtins utils/prepare-builtins.cpp )
+  setup_host_tool( prepare_builtins PREPARE_BUILTINS prepare_builtins_exe prepare_builtins_target )
 endif()
 target_compile_definitions( prepare_builtins PRIVATE ${LLVM_VERSION_DEFINE} )
 # These were not properly reported in early LLVM and we don't need them
@@ -211,15 +216,15 @@ if( ENABLE_RUNTIME_SUBNORMAL )
   foreach( file IN ITEMS subnormal_use_default subnormal_disable )
     link_bc(
        TARGET ${file}
-       INPUTS ${PROJECT_SOURCE_DIR}/generic/lib/${file}.ll
+       INPUTS ${CMAKE_CURRENT_SOURCE_DIR}/generic/lib/${file}.ll
     )
     install( FILES $<TARGET_PROPERTY:${file},TARGET_FILE> ARCHIVE
       DESTINATION "${CMAKE_INSTALL_DATADIR}/clc" )
   endforeach()
 endif()
 
 find_package( Python3 REQUIRED COMPONENTS Interpreter )
-file( TO_CMAKE_PATH ${PROJECT_SOURCE_DIR}/generic/lib/gen_convert.py script_loc )
+file( TO_CMAKE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/generic/lib/gen_convert.py script_loc )
 add_custom_command(
   OUTPUT convert.cl
   COMMAND ${Python3_EXECUTABLE} ${script_loc} > convert.cl
@@ -264,7 +269,7 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
   foreach( l ${dirs} ${DARCH} ${DARCH}-${OS} ${DARCH}-${VENDOR}-${OS} )
     foreach( s "SOURCES" "SOURCES_${LLVM_MAJOR}.${LLVM_MINOR}" )
       file( TO_CMAKE_PATH ${l}/lib/${s} file_loc )
-      file( TO_CMAKE_PATH ${PROJECT_SOURCE_DIR}/${file_loc} loc )
+      file( TO_CMAKE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/${file_loc} loc )
       # Prepend the location to give higher priority to
       # specialized implementation
       if( EXISTS ${loc} )
@@ -339,7 +344,7 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
     list( APPEND build_flags
       -D__CLC_INTERNAL
       -D${CLC_TARGET_DEFINE}
-      -I${PROJECT_SOURCE_DIR}/generic/include
+      -I${CMAKE_CURRENT_SOURCE_DIR}/generic/include
       # FIXME: Fix libclc to not require disabling this noisy warning
       -Wno-bitwise-conditional-parentheses
     )
@@ -360,9 +365,9 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
         # the path (e.g., ironing out any ".."), then make it relative to the
         # root directory again, and use that relative path component for the
         # binary path.
-        get_filename_component( abs_path ${file} ABSOLUTE BASE_DIR ${PROJECT_SOURCE_DIR} )
-        file( RELATIVE_PATH root_rel_path ${PROJECT_SOURCE_DIR} ${abs_path} )
-        set( input_file ${PROJECT_SOURCE_DIR}/${file} )
+        get_filename_component( abs_path ${file} ABSOLUTE BASE_DIR ${CMAKE_CURRENT_SOURCE_DIR} )
+        file( RELATIVE_PATH root_rel_path ${CMAKE_CURRENT_SOURCE_DIR} ${abs_path} )
+        set( input_file ${CMAKE_CURRENT_SOURCE_DIR}/${file} )
         set( output_file "${LIBCLC_ARCH_OBJFILE_DIR}/${root_rel_path}.bc" )
       endif()
 
@@ -373,7 +378,7 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
         INPUT ${input_file}
         OUTPUT ${output_file}
         EXTRA_OPTS "${mcpu}" -fno-builtin -nostdlib
-                   "${build_flags}" -I${PROJECT_SOURCE_DIR}/${file_dir}
+                   "${build_flags}" -I${CMAKE_CURRENT_SOURCE_DIR}/${file_dir}
         DEPENDENCIES generate_convert.cl clspv-generate_convert.cl
       )
       list( APPEND bytecode_files ${output_file} )
@@ -407,9 +412,9 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
 
       # Add opt target
       add_custom_command( OUTPUT ${builtins_opt_lib_tgt}.bc
-        COMMAND libclc::opt ${opt_flags} -o ${builtins_opt_lib_tgt}.bc
+        COMMAND ${opt_exe} ${opt_flags} -o ${builtins_opt_lib_tgt}.bc
           ${builtins_link_lib}
-        DEPENDS libclc::opt ${builtins_link_lib} ${builtins_link_lib_tgt}
+        DEPENDS ${opt_target} ${builtins_link_lib} ${builtins_link_lib_tgt}
       )
       add_custom_target( ${builtins_opt_lib_tgt}
         ALL DEPENDS ${builtins_opt_lib_tgt}.bc
@@ -423,15 +428,15 @@ foreach( t ${LIBCLC_TARGETS_TO_BUILD} )
       # Add prepare target
       set( obj_suffix ${arch_suffix}.bc )
       add_custom_command( OUTPUT ${obj_suffix}
-        COMMAND prepare_builtins -o ${obj_suffix} ${builtins_opt_lib}
-        DEPENDS ${builtins_opt_lib} ${builtins_opt_lib_tgt} prepare_builtins )
+        COMMAND ${prepare_builtins_exe} -o ${obj_suffix} ${builtins_opt_lib}
+        DEPENDS ${builtins_opt_lib} ${builtins_opt_lib_tgt} ${prepare_builtins_target} )
       add_custom_target( prepare-${obj_suffix} ALL DEPENDS ${obj_suffix} )
 
       # nvptx-- targets don't include workitem builtins
       if( NOT clang_triple MATCHES ".*ptx.*--$" )
         add_test( NAME external-calls-${obj_suffix}
           COMMAND ./check_external_calls.sh ${CMAKE_CURRENT_BINARY_DIR}/${obj_suffix} ${LLVM_TOOLS_BINARY_DIR}
-          WORKING_DIRECTORY ${PROJECT_SOURCE_DIR} )
+          WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} )
       endif()
 
       install( FILES ${CMAKE_CURRENT_BINARY_DIR}/${obj_suffix} DESTINATION "${CMAKE_INSTALL_DATADIR}/clc" )

libclc/cmake/modules/AddLibclc.cmake

@@ -12,8 +12,8 @@
 # * DEPENDENCIES <string> ...
 #     List of extra dependencies to inject
 #
-# Depends on the libclc::clang and libclc::llvm-as targets for compiling and
-# assembling, respectively.
+# Depends on the clang, llvm-as, and llvm-link targets for compiling,
+# assembling, and linking, respectively.
 function(compile_to_bc)
   cmake_parse_arguments(ARG
     ""
@@ -45,7 +45,7 @@ function(compile_to_bc)
 
   add_custom_command(
     OUTPUT ${ARG_OUTPUT}${TMP_SUFFIX}
-    COMMAND libclc::clang
+    COMMAND ${clang_exe}
       ${TARGET_ARG}
       ${PP_OPTS}
       ${ARG_EXTRA_OPTS}
@@ -58,7 +58,7 @@ function(compile_to_bc)
       -x cl
       ${ARG_INPUT}
     DEPENDS
-      libclc::clang
+      ${clang_target}
       ${ARG_INPUT}
       ${ARG_DEPENDENCIES}
     DEPFILE ${ARG_OUTPUT}.d
@@ -67,8 +67,8 @@ function(compile_to_bc)
   if( ${FILE_EXT} STREQUAL ".ll" )
     add_custom_command(
       OUTPUT ${ARG_OUTPUT}
-      COMMAND libclc::llvm-as -o ${ARG_OUTPUT} ${ARG_OUTPUT}${TMP_SUFFIX}
-      DEPENDS libclc::llvm-as ${ARG_OUTPUT}${TMP_SUFFIX}
+      COMMAND ${llvm-as_exe} -o ${ARG_OUTPUT} ${ARG_OUTPUT}${TMP_SUFFIX}
+      DEPENDS ${llvm-as_target} ${ARG_OUTPUT}${TMP_SUFFIX}
     )
   endif()
 endfunction()
@@ -107,8 +107,8 @@ function(link_bc)
 
   add_custom_command(
     OUTPUT ${ARG_TARGET}.bc
-    COMMAND libclc::llvm-link -o ${ARG_TARGET}.bc ${LINK_INPUT_ARG}
-    DEPENDS libclc::llvm-link ${ARG_DEPENDENCIES} ${ARG_INPUTS} ${RSP_FILE}
+    COMMAND ${llvm-link_exe} -o ${ARG_TARGET}.bc ${LINK_INPUT_ARG}
+    DEPENDS ${llvm-link_target} ${ARG_DEPENDENCIES} ${ARG_INPUTS} ${RSP_FILE}
   )
 
   add_custom_target( ${ARG_TARGET} ALL DEPENDS ${ARG_TARGET}.bc )