[flang] Fix out-of-tree build with missing acc_gen target

[clementval]

Summary

This pacth fix out-of-tree build of Flang after the introduction of acc_gen.

[sscalpone]

Tested against a build and install directory; both work great. Thanks.

llvm/cmake/modules/AddLLVM.cmake

 #   Add ${name} as an llvm plugin.
 #   If option LLVM_${name_upper}_LINK_INTO_TOOLS is set to ON, the plugin is registered statically.
 #   Otherwise a pluggable shared library is registered.
 #
 #   If NO_MODULE is specified, when option LLVM_${name_upper}_LINK_INTO_TOOLS is set to OFF,
 #   only an object library is built, and no module is built. This is specific to the Polly use case.
 #
 #   The SUBPROJECT argument contains the LLVM project the plugin belongs
-#   to. If set, the plugin will link statically by default it if the 
+#   to. If set, the plugin will link statically by default it if the
 #   project was enabled.
 function(add_llvm_pass_plugin name)
   cmake_parse_arguments(ARG
     "NO_MODULE" "SUBPROJECT" ""
     ${ARGN})
 
   string(TOUPPER ${name} name_upper)
 
if(LLVM_${name_upper}_LINK_INTO_TOOLS)
     target_compile_definitions(${name} PRIVATE LLVM_${name_upper}_LINK_INTO_TOOLS)
     set_property(TARGET ${name} APPEND PROPERTY COMPILE_DEFINITIONS LLVM_LINK_INTO_TOOLS)
     if (TARGET intrinsics_gen)
       add_dependencies(obj.${name} intrinsics_gen)
     endif()
     if (TARGET omp_gen)
       add_dependencies(obj.${name} omp_gen)
     endif()
+    if (TARGET acc_gen)
+      add_dependencies(obj.${name} acc_gen)
+    endif()
     set_property(GLOBAL APPEND PROPERTY LLVM_STATIC_EXTENSIONS ${name})
   elseif(NOT ARG_NO_MODULE)
     add_llvm_library(${name} MODULE ${ARG_UNPARSED_ARGUMENTS})
   else()
     add_llvm_library(${name} OBJECT ${ARG_UNPARSED_ARGUMENTS})
   endif()
   message(STATUS "Registering ${name} as a pass plugin (static build: ${LLVM_${name_upper}_LINK_INTO_TOOLS})")
 

llvm/cmake/modules/LLVMConfig.cmake.in

 set(LLVM_ENABLE_SHARED_LIBS @BUILD_SHARED_LIBS@)
 
 if(NOT TARGET LLVMSupport)
   set(LLVM_EXPORTED_TARGETS "@LLVM_CONFIG_EXPORTS@")
   include("@LLVM_CONFIG_EXPORTS_FILE@")
   @llvm_config_include_buildtree_only_exports@
 endif()
 
-# By creating intrinsics_gen and omp_gen here, subprojects that depend on LLVM's
-# tablegen-generated headers can always depend on this target whether building
-# in-tree with LLVM or not.
+# By creating intrinsics_gen, omp_gen and acc_gen here, subprojects that depend
+# on LLVM's tablegen-generated headers can always depend on this target whether
+# building in-tree with LLVM or not.
 if(NOT TARGET intrinsics_gen)
   add_custom_target(intrinsics_gen)
 endif()
 if(NOT TARGET omp_gen)
   add_custom_target(omp_gen)
 endif()
+if(NOT TARGET acc_gen)
+  add_custom_target(acc_gen)
+endif()
 
 set_property(GLOBAL PROPERTY LLVM_TARGETS_CONFIGURED On)
 include(${LLVM_CMAKE_DIR}/LLVM-Config.cmake)