[runtimes] Create check- targets for LLVM_RUNTIME_DISTRIBUTION_COMPONENTS

[smeenai]

Summary

The sub-component check targets won't be automatically created until the
runtime configurations have run (and the main LLVM configure has rerun
afterwards). Work around this by creating check- targets for components
in LLVM_RUNTIME_DISTRIBUTION_COMPONENTS as well (and making sure they
get the proper test dependencies).

[phosek]

I've been thinking about how to better handle this case, that is to avoid having to run runtime configurations rerun the LLVM configuration. A possible solution would be to move the handling of compiler-rt runtimes to the runtimes build, that is instead of treating compiler-rt as a monolith, we would treat it as a collection of runtimes akin to libunwind, libc++abi or libc++ which would let you do LLVM_ENABLE_RUNTIMES=libunwind;libc++abi;libc++;asan. There is more cleanup needed, and we would also need to deprecate support for LLVM_ENABLE_PROJECTS=compiler-rt first, but I was wondering if you had any thoughts on the idea?

[smeenai]

I think that'd be pretty nice. Right now there's a bunch of different and inconsistent ways to control which parts of compiler-rt you build (e.g. the sanitizers have COMPILER_RT_SANITIZERS_TO_BUILD, but then things like XRay and libfuzzer have dedicated COMPILER_RT_BUILD_* variables), and it'd be great to have a consistent interface instead. I know @compnerd and some others have been interested in reorganizing compiler-rt, and this could be part of that.

llvm/runtimes/CMakeLists.txt

function(runtime_register_target name target)
   endforeach()
 
   if(LLVM_INCLUDE_TESTS)
     set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_TESTSUITES "@${LLVM_BINARY_DIR}/runtimes/runtimes-${name}-bins/lit.tests")
     set(runtimes-test-depends-${name} runtimes-test-depends)
     set(check-runtimes-${name} check-runtimes)
     list(APPEND ${name}_test_targets runtimes-test-depends-${name} check-runtimes-${name})
     list(APPEND test_targets ${${name}_test_targets})
-    foreach(target_name IN LISTS SUB_CHECK_TARGETS)
+
+    set(component_check_targets)
+    foreach(component IN LISTS LLVM_RUNTIME_DISTRIBUTION_COMPONENTS)
+      if(NOT "check-${component}" IN_LIST SUB_CHECK_TARGETS)
+        list(APPEND component_check_targets "check-${component}")
+      endif()
+    endforeach()
+
+    foreach(target_name IN LISTS SUB_CHECK_TARGETS component_check_targets)
       set(${target_name}-${name} ${target_name})
       list(APPEND ${name}_test_targets ${target_name}-${name})
       list(APPEND test_targets ${target_name}-${name})
     endforeach()
     set(test_targets "${test_targets}" PARENT_SCOPE)
   endif()
 
   set(${name}_extra_args ${ARG_CMAKE_ARGS})