[SYCL] Detect changes in sycl headers (#4723)

This is follow up for #4710

When a sub-directory of the DEPENDS directories is modified the change is not
detected by CMake. The change adds a full list of files in the sub-directory to
DEPENDS to detect the change. file(GLOBE_RECURSE) is used with
CONFIGURE_DEPENDS option to rerun configure step if a new entry is added to
the directory structure.
Restore version.hpp in source directory as it is used to build SYCL
library.

Removing a header file is the only case when change is not propagated to
the build and install directory. This problem existed before the change and
TODO was left to fix it in the future.

Author: vladimirlaz

sycl/.gitignore

@@ -0,0 +1 @@
+include/CL/sycl/version.hpp

sycl/CMakeLists.txt

@@ -98,25 +98,32 @@ set(sycl_inc_dir ${CMAKE_CURRENT_SOURCE_DIR}/include)
 set(sycl_src_dir ${CMAKE_CURRENT_SOURCE_DIR}/source)
 set(sycl_plugin_dir ${CMAKE_CURRENT_SOURCE_DIR}/plugins)
 string(TIMESTAMP __SYCL_COMPILER_VERSION "%Y%m%d")
+set(version_header "${sycl_inc_dir}/CL/sycl/version.hpp")
+configure_file("${version_header}.in" "${version_header}")
+
+# This is workaround to detect changes (add or modify) in subtree which
+# are not detected by copy_directory command.
+# TODO: detect and process remove header/directory case
+file(GLOB_RECURSE HEADERS_IN_SYCL_DIR CONFIGURE_DEPENDS "${sycl_inc_dir}/sycl/*")
+file(GLOB_RECURSE HEADERS_IN_CL_DIR CONFIGURE_DEPENDS "${sycl_inc_dir}/CL/*")
 
 # Copy SYCL headers from sources to build directory
 add_custom_target(sycl-headers
   DEPENDS ${SYCL_INCLUDE_BUILD_DIR}/sycl
+          ${SYCL_INCLUDE_BUILD_DIR}/sycl/sycl.hpp
           ${SYCL_INCLUDE_BUILD_DIR}/sycl/CL)
 
 add_custom_command(
   OUTPUT  ${SYCL_INCLUDE_BUILD_DIR}/sycl
+          ${SYCL_INCLUDE_BUILD_DIR}/sycl/sycl.hpp
           ${SYCL_INCLUDE_BUILD_DIR}/sycl/CL
-  DEPENDS ${sycl_inc_dir}/sycl
-          ${sycl_inc_dir}/CL
+  DEPENDS ${HEADERS_IN_SYCL_DIR}
+          ${HEADERS_IN_CL_DIR}
   COMMAND ${CMAKE_COMMAND} -E copy_directory ${sycl_inc_dir}/sycl ${SYCL_INCLUDE_BUILD_DIR}/sycl
   COMMAND ${CMAKE_COMMAND} -E copy_directory ${sycl_inc_dir}/CL ${SYCL_INCLUDE_BUILD_DIR}/sycl/CL
   COMMENT "Copying SYCL headers ...")
 
-configure_file("${sycl_inc_dir}/CL/sycl/version.hpp.in" "${SYCL_INCLUDE_BUILD_DIR}/CL/sycl/version.hpp")
-
-
-# Copy SYCL headers from sources to install directory
+# Copy SYCL headers from source to install directory
 install(DIRECTORY "${sycl_inc_dir}/sycl" DESTINATION ${SYCL_INCLUDE_DIR} COMPONENT sycl-headers)
 install(DIRECTORY "${sycl_inc_dir}/CL" DESTINATION ${SYCL_INCLUDE_DIR}/sycl COMPONENT sycl-headers)
 

xpti/CMakeLists.txt

@@ -77,12 +77,13 @@ set(LIBRARY_OUTPUT_PATH ${CMAKE_BINARY_DIR})
 add_subdirectory(src)
 
 if (LLVM_BINARY_DIR)
+  file(GLOB_RECURSE XPTI_HEADERS_LIST CONFIGURE_DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/include/xpti/*")
   add_custom_target(xpti-headers
     DEPENDS ${LLVM_BINARY_DIR}/include/xpti)
 
   add_custom_command(
     OUTPUT  ${LLVM_BINARY_DIR}/include/xpti
-    DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/include/xpti
+    DEPENDS ${XPTI_HEADERS_LIST}
     COMMAND ${CMAKE_COMMAND} -E copy_directory
       ${CMAKE_CURRENT_SOURCE_DIR}/include/xpti
       ${LLVM_BINARY_DIR}/include/xpti