Move llvm util dependencies from clang-tools-extra to add_lit_target.

[hokein]

Summary

Address fixme in r301762. And would simplify the cmake file in
clang-tools-extra.

[sammccall]

(again I'd just inline this into three add_dependencies calls, but up to you)

[steveire]

inlining this into three add_dependencies calls would remove the if (TARGET) conditions. Are those dependencies conditionally built?

[hokein]

In D52713#1250947, @steveire wrote:

inlining this into three add_dependencies calls would remove the if (TARGET) conditions. Are those dependencies conditionally built?

Yeah, I believe these targets are built conditionally, see https://reviews.llvm.org/D29851.

[mgorny]

I would like to request reverting this. It's established standard within LLVM to explicitly specify the dependencies the particular test suite relies on.

This change causes the -DLLVM_OCAML_OUT_OF_TREE=1 to start wrongly depending on additional test utility targets, causing building an unnecessary second copy of LLVMSupport.

[hokein]

Hi @mgorny, sorry for the trouble it might cause.

In D52713#1305164, @mgorny wrote:

I would like to request reverting this. It's established standard within LLVM to explicitly specify the dependencies the particular test suite relies on.
This change causes the -DLLVM_OCAML_OUT_OF_TREE=1 to start wrongly depending on additional test utility targets, causing building an unnecessary second copy of LLVMSupport.

I'm not an expert on this. It seems to me that FileCheck, count, not are reasonable dependencies to lit tests, and from what I se, lit tests of llvm, clang and clang-tools-extra are using these dep tools.
+ @chapuni, maybe you have ideas here? since you are the original author of the code r301762.

[mgorny]

This particular build method uses system-wide installation of these tools.

[hokein]

In D52713#1305291, @mgorny wrote:

This particular build method uses system-wide installation of these tools.

Sounds fair enough. I sent you two patches to move this back to clang-tools-extra.

llvm/trunk/cmake/modules/AddLLVM.cmake

add_custom_target(${target}
       COMMENT "${comment}"
       USES_TERMINAL
       )
   else()
     add_custom_target(${target}
       COMMAND ${CMAKE_COMMAND} -E echo "${target} does nothing, no tools built.")
     message(STATUS "${target} does nothing.")
   endif()
+
+  # Add lit test dependencies.
+  set(llvm_utils_deps
+    FileCheck count not
+  )
+  foreach(dep ${llvm_utils_deps})
+    if (TARGET ${dep})
+      add_dependencies(${target} ${dep})
+    endif()
+  endforeach()
+
   if (ARG_DEPENDS)
     add_dependencies(${target} ${ARG_DEPENDS})
   endif()
 
   # Tests should be excluded from "Build Solution".
   set_target_properties(${target} PROPERTIES EXCLUDE_FROM_DEFAULT_BUILD ON)
 endfunction()