[CMake] Add BINARY_DIR argument for add_lit_testsuites

We're doing some slightly odd things with LIT in the offload-test-suite.
Specifically we generate multiple binary directories to configure and
run tests with different configurations from the same source root.

In this configuration the subdirectory targets need to instead point to
the correct generated binary directory and use test filtering to get a
subset of tests.

Author: llvm-beanz

llvm/cmake/modules/AddLLVM.cmake

@@ -2192,7 +2192,7 @@ endfunction()
 
 function(add_lit_testsuites project directory)
   if (NOT LLVM_ENABLE_IDE)
-    cmake_parse_arguments(ARG "EXCLUDE_FROM_CHECK_ALL" "FOLDER" "PARAMS;DEPENDS;ARGS" ${ARGN})
+    cmake_parse_arguments(ARG "EXCLUDE_FROM_CHECK_ALL" "FOLDER;BINARY_DIR" "PARAMS;DEPENDS;ARGS" ${ARGN})
 
     if (NOT ARG_FOLDER)
       get_subproject_title(subproject_title)
@@ -2213,13 +2213,18 @@ function(add_lit_testsuites project directory)
       endif()
 
       # Create a check- target for the directory.
-      string(REPLACE ${directory} "" name_slash ${lit_suite})
+      string(REPLACE "${directory}/" "" name_slash ${lit_suite})
       if (name_slash)
+        set(filter ${name_slash})
         string(REPLACE "/" "-" name_slash ${name_slash})
         string(REPLACE "\\" "-" name_dashes ${name_slash})
-        string(TOLOWER "${project}${name_dashes}" name_var)
+        string(TOLOWER "${project}-${name_dashes}" name_var)
+        set(lit_args ${lit_suite})
+        if (ARG_BINARY_DIR)
+          set(lit_args ${ARG_BINARY_DIR} --filter=${filter})
+        endif()
         add_lit_target("check-${name_var}" "Running lit suite ${lit_suite}"
-          ${lit_suite}
+          ${lit_args}
           ${EXCLUDE_FROM_CHECK_ALL}
           PARAMS ${ARG_PARAMS}
           DEPENDS ${ARG_DEPENDS}