[runtimes] Use a response file for runtimes test suites

We don't know which test suites are going to be included by runtimes
builds so we cannot include those before running the sub-build, but
that's not possible during the LLVM build configuration. We instead use
a response file that's populated by the runtimes build as a level of
indirection.

This addresses the issue described in:
https://discourse.llvm.org/t/cmake-regeneration-is-broken/62788

Differential Revision: https://reviews.llvm.org/D132438

Author: petrhosek

llvm/runtimes/CMakeLists.txt

@@ -209,13 +209,7 @@ function(runtime_default_target)
   endforeach()
 
   if(LLVM_INCLUDE_TESTS)
-    include(${LLVM_BINARY_DIR}/runtimes/Tests.cmake OPTIONAL RESULT_VARIABLE have_tests)
-    set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/Tests.cmake)
-    if(have_tests)
-      set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_TESTSUITES ${SUB_LIT_TESTSUITES})
-      set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_PARAMS ${SUB_LIT_PARAMS})
-      set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_EXTRA_ARGS ${SUB_LIT_EXTRA_ARGS})
-    endif()
+    set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_TESTSUITES "@${LLVM_BINARY_DIR}/runtimes/runtimes-bins/lit.tests")
     list(APPEND test_targets runtimes-test-depends check-runtimes)
   endif()
 
@@ -291,13 +285,7 @@ function(runtime_register_target name target)
   endforeach()
 
   if(LLVM_INCLUDE_TESTS)
-    include(${LLVM_BINARY_DIR}/runtimes/${name}/Tests.cmake OPTIONAL RESULT_VARIABLE have_tests)
-    set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${LLVM_BINARY_DIR}/runtimes/${name}/Tests.cmake)
-    if(have_tests)
-      set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_TESTSUITES ${SUB_LIT_TESTSUITES})
-      set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_PARAMS ${SUB_LIT_PARAMS})
-      set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_EXTRA_ARGS ${SUB_LIT_EXTRA_ARGS})
-    endif()
+    set_property(GLOBAL APPEND PROPERTY LLVM_ALL_LIT_TESTSUITES "@${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})
@@ -490,5 +478,7 @@ if(runtimes)
     foreach(target ${test_targets} ${SUB_CHECK_TARGETS})
       add_dependencies(${target} ${RUNTIMES_TEST_DEPENDS})
     endforeach()
+
+    set_property(GLOBAL APPEND PROPERTY LLVM_ALL_ADDITIONAL_TEST_TARGETS runtimes ${RUNTIMES_TEST_DEPENDS})
   endif()
 endif()

runtimes/CMakeLists.txt

@@ -244,15 +244,12 @@ if(LLVM_INCLUDE_TESTS)
                      ${CMAKE_CURRENT_BINARY_DIR}/llvm-lit)
   endif()
 
-  if(LLVM_RUNTIMES_TARGET)
-    configure_file(
-      ${CMAKE_CURRENT_SOURCE_DIR}/Tests.cmake.in
-      ${LLVM_BINARY_DIR}/runtimes/${LLVM_RUNTIMES_TARGET}/Tests.cmake)
-  else()
-    configure_file(
-      ${CMAKE_CURRENT_SOURCE_DIR}/Tests.cmake.in
-      ${LLVM_BINARY_DIR}/runtimes/Tests.cmake)
-  endif()
+  get_property(LLVM_RUNTIMES_LIT_TESTSUITES GLOBAL PROPERTY LLVM_RUNTIMES_LIT_TESTSUITES)
+  string(REPLACE ";" "\n" LLVM_RUNTIMES_LIT_TESTSUITES "${LLVM_RUNTIMES_LIT_TESTSUITES}")
+  file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/lit.tests ${LLVM_RUNTIMES_LIT_TESTSUITES})
+else()
+  # Create empty files so the parent build can use these unconditionally.
+  file(TOUCH ${CMAKE_CURRENT_BINARY_DIR}/lit.tests)
 endif()
 
 get_property(SUB_COMPONENTS GLOBAL PROPERTY SUB_COMPONENTS)