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

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

Reviewed By: sscalpone

Differential Revision: https://reviews.llvm.org/D83835

Author: clementval

llvm/cmake/modules/AddLLVM.cmake

@@ -891,7 +891,7 @@ endmacro(add_llvm_executable name)
 #   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
@@ -928,6 +928,9 @@ function(add_llvm_pass_plugin name)
     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})

llvm/cmake/modules/LLVMConfig.cmake.in

@@ -104,15 +104,18 @@ if(NOT TARGET LLVMSupport)
   @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)