[llvm] [SYCL] Add libsycl, a SYCL RT library implementation project (PR #144372)

[Tom Honermann via llvm-commits]

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@@ -0,0 +1,111 @@
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/../../runtimes/cmake/Modules")
+include(WarningFlags)
+
+function(add_sycl_rt_library LIB_NAME LIB_OBJ_NAME)
+  if (NOT LLVM_ENABLE_PIC)
+    message( FATAL_ERROR "Position-Independent Code generation is required for libsycl shared library" )
+  endif()
+  # Add an optional argument so we can get the library name to
+  # link with for Windows Debug version
+  cmake_parse_arguments(ARG "" "IMPLIB_NAME" "COMPILE_OPTIONS;SOURCES" ${ARGN})
+
+  add_library(${LIB_OBJ_NAME} OBJECT ${ARG_SOURCES})
+
+  # Common compilation step setup
+  target_compile_definitions(${LIB_OBJ_NAME} PRIVATE $<$<BOOL:${MSVC}>:_LIBSYCL_BUILD_SYCL_DLL>)
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tahonermann wrote:

The dependency on `MSVC` doesn't seem right here. I think `_LIBSYCL_BUILD_SYCL_DLL` should be defined for any compiler targeting Windows given that the check for this macro in `libsycl/include/sycl/__detail/config.hpp` is target (not compiler) specific.

https://github.com/llvm/llvm-project/pull/144372