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

Kseniya Tikhomirova via llvm-commits llvm-commits at lists.llvm.org
Mon Jun 16 08:38:17 PDT 2025


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

This patch introduces libsycl, a SYCL runtime library implementation, as a top-level LLVM runtime project.
SYCL spec: https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html

Commit contains the basic folder layout and CMake infrastructure to build a dummy SYCL library.

This is part of the SYCL support upstreaming effort. The relevant RFCs can be found here:

https://discourse.llvm.org/t/rfc-add-full-support-for-the-sycl-programming-model/74080
https://discourse.llvm.org/t/rfc-sycl-runtime-upstreaming/74479

Upcoming PRs:
- UR offloading library fetch & build 
- partial implementation of sycl::platform: requires offloading layer, requires classes for backend loading & enumeration.

>From 5bbfeca3e2d9df8b3c962dbc588616c76eaeefeb Mon Sep 17 00:00:00 2001
From: Kseniya Tikhomirova <kseniya.tikhomirova at intel.com>
Date: Mon, 16 Jun 2025 17:24:45 +0200
Subject: [PATCH] [SYCL] Add libsycl, a SYCL RT library implementation project
 (#3)

This patch introduces libsycl, a SYCL runtime library implementation, as a top-level LLVM runtime project. It contains the basic folder layout and CMake infrastructure to build a dummy SYCL library.
---
 libsycl/.clang-format                  |   1 +
 libsycl/.clang-tidy                    |  17 ++
 libsycl/CMakeLists.txt                 | 128 ++++++++++++
 libsycl/LICENSE.txt                    | 278 +++++++++++++++++++++++++
 libsycl/README.md                      |  20 ++
 libsycl/docs/index.rst                 |  69 ++++++
 libsycl/include/sycl/detail/config.hpp |  64 ++++++
 libsycl/include/sycl/platform.hpp      |  31 +++
 libsycl/include/sycl/sycl.hpp          |  14 ++
 libsycl/src/CMakeLists.txt             | 109 ++++++++++
 libsycl/src/ld-version-script.txt      |  19 ++
 libsycl/src/platform.cpp               |  17 ++
 libsycl/src/version.hpp.in             |  16 ++
 llvm/CMakeLists.txt                    |   2 +-
 runtimes/CMakeLists.txt                |   2 +-
 15 files changed, 785 insertions(+), 2 deletions(-)
 create mode 100644 libsycl/.clang-format
 create mode 100644 libsycl/.clang-tidy
 create mode 100644 libsycl/CMakeLists.txt
 create mode 100644 libsycl/LICENSE.txt
 create mode 100644 libsycl/README.md
 create mode 100644 libsycl/docs/index.rst
 create mode 100644 libsycl/include/sycl/detail/config.hpp
 create mode 100644 libsycl/include/sycl/platform.hpp
 create mode 100644 libsycl/include/sycl/sycl.hpp
 create mode 100644 libsycl/src/CMakeLists.txt
 create mode 100644 libsycl/src/ld-version-script.txt
 create mode 100644 libsycl/src/platform.cpp
 create mode 100644 libsycl/src/version.hpp.in

diff --git a/libsycl/.clang-format b/libsycl/.clang-format
new file mode 100644
index 0000000000000..9b3aa8b7213b2
--- /dev/null
+++ b/libsycl/.clang-format
@@ -0,0 +1 @@
+BasedOnStyle: LLVM
diff --git a/libsycl/.clang-tidy b/libsycl/.clang-tidy
new file mode 100644
index 0000000000000..cdc7a2981a41d
--- /dev/null
+++ b/libsycl/.clang-tidy
@@ -0,0 +1,17 @@
+Checks: >
+  -*,
+  clang-analyzer-*,
+  clang-diagnostic-*,
+  cppcoreguidelines-*,
+  -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
+  -cppcoreguidelines-pro-bounds-constant-array-index,
+  -cppcoreguidelines-pro-bounds-pointer-arithmetic,
+  -cppcoreguidelines-pro-type-member-init,
+  -cppcoreguidelines-pro-type-union-access,
+  google-*,
+  -google-build-using-namespace,
+  -google-explicit-constructor,
+  -google-runtime-references,
+  misc-*,
+  -misc-macro-parentheses,
+  -misc-unused-parameters
diff --git a/libsycl/CMakeLists.txt b/libsycl/CMakeLists.txt
new file mode 100644
index 0000000000000..a20ad3a598616
--- /dev/null
+++ b/libsycl/CMakeLists.txt
@@ -0,0 +1,128 @@
+#===============================================================================
+# Setup Project
+#===============================================================================
+cmake_minimum_required(VERSION 3.20.0)
+
+set(LLVM_SUBPROJECT_TITLE "libsycl")
+
+set(LIBSYCL_SOURCE_DIR  ${CMAKE_CURRENT_SOURCE_DIR})
+set(LIBSYCL_BINARY_DIR  ${CMAKE_CURRENT_BINARY_DIR})
+
+set(CMAKE_CXX_STANDARD 17 CACHE STRING "C++ standard to conform to")
+set(CMAKE_CXX_STANDARD_REQUIRED YES)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+#===============================================================================
+# Setup CMake Options
+#===============================================================================
+
+option(LIBSYCL_ENABLE_WERROR "Treat all warnings as errors in the libsycl project" OFF)
+
+#===============================================================================
+# Configure System
+#===============================================================================
+
+set_property(GLOBAL PROPERTY USE_FOLDERS ON)
+
+set(LIBSYCL_SHARED_OUTPUT_NAME "sycl" CACHE STRING "Output name for the shared libsycl runtime library.")
+
+if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+  set(LIBSYCL_TARGET_SUBDIR ${LLVM_DEFAULT_TARGET_TRIPLE})
+  if(LIBSYCL_LIBDIR_SUBDIR)
+    string(APPEND LIBSYCL_TARGET_SUBDIR /${LIBSYCL_LIBDIR_SUBDIR})
+  endif()
+  cmake_path(NORMAL_PATH LIBSYCL_TARGET_SUBDIR)
+  set(LIBSYCL_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR}/${LIBSYCL_TARGET_SUBDIR})
+  set(LIBSYCL_INSTALL_LIBRARY_DIR lib${LLVM_LIBDIR_SUFFIX}/${LIBSYCL_TARGET_SUBDIR} CACHE STRING
+      "Path where built libsycl libraries should be installed.")
+  unset(LIBSYCL_TARGET_SUBDIR)
+else()
+  if(LLVM_LIBRARY_OUTPUT_INTDIR)
+    set(LIBSYCL_LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})
+  else()
+    set(LIBSYCL_LIBRARY_DIR ${CMAKE_BINARY_DIR}/lib${LIBSYCL_LIBDIR_SUFFIX})
+  endif()
+  set(LIBSYCL_INSTALL_LIBRARY_DIR lib${LIBSYCL_LIBDIR_SUFFIX} CACHE STRING
+      "Path where built libsycl libraries should be installed.")
+endif()
+
+set(LIBSYCL_INCLUDE_DIR include)
+set(LIBSYCL_BUILD_INCLUDE_DIR ${LLVM_BINARY_DIR}/${LIBSYCL_INCLUDE_DIR})
+set(LIBSYCL_SOURCE_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/include)
+
+set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${LIBSYCL_LIBRARY_DIR})
+set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${LIBSYCL_LIBRARY_DIR})
+set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${LIBSYCL_LIBRARY_DIR})
+
+set(LIBSYCL_MAJOR_VERSION 0)
+set(LIBSYCL_MINOR_VERSION 1)
+set(LIBSYCL_PATCH_VERSION 0)
+set(LIBSYCL_VERSION_STRING "${LIBSYCL_MAJOR_VERSION}.${LIBSYCL_MINOR_VERSION}.${LIBSYCL_PATCH_VERSION}")
+set(LIBSYCL_ABI_NAMESPACE "V${LIBSYCL_MAJOR_VERSION}" CACHE STRING
+    "The inline ABI namespace used by libsycl. It defaults to Vn where `n` is the current ABI version.")
+
+#===============================================================================
+# Setup Compiler Flags
+#===============================================================================
+
+# Enable all warnings by default
+if(MSVC)
+  append("/W4" CMAKE_CXX_FLAGS)
+else()
+  append("-Wall -Wextra" CMAKE_CXX_FLAGS)
+endif()
+
+if(LIBSYCL_ENABLE_WERROR)
+  if(MSVC)
+    append("/WX" CMAKE_CXX_FLAGS)
+  else()
+    append("-Werror" CMAKE_CXX_FLAGS)
+  endif()
+endif()
+
+#===============================================================================
+# Setup build & install rules
+#===============================================================================
+
+# Generate headers
+configure_file("${LIBSYCL_SOURCE_DIR}/src/version.hpp.in" "${LIBSYCL_BUILD_INCLUDE_DIR}/sycl/version.hpp")
+
+# Install generated headers.
+install(FILES
+  "${LIBSYCL_BUILD_INCLUDE_DIR}/sycl/version.hpp"
+  DESTINATION "${LIBSYCL_INCLUDE_DIR}/sycl"
+  COMPONENT sycl-headers)
+
+# This is a workaround to detect changes (add or modify) in subtree which
+# are not detected by copy_directory command.
+file(GLOB_RECURSE HEADERS_IN_SYCL_DIR CONFIGURE_DEPENDS "${LIBSYCL_SOURCE_INCLUDE_DIR}/sycl/*")
+
+string(REPLACE "${LIBSYCL_SOURCE_INCLUDE_DIR}" "${LIBSYCL_BUILD_INCLUDE_DIR}"
+  OUT_HEADERS_IN_SYCL_DIR "${HEADERS_IN_SYCL_DIR}")
+
+# Copy SYCL headers from sources to build directory
+add_custom_target(sycl-headers
+  DEPENDS ${OUT_HEADERS_IN_SYCL_DIR})
+
+add_custom_command(
+  OUTPUT  ${OUT_HEADERS_IN_SYCL_DIR}
+  DEPENDS ${HEADERS_IN_SYCL_DIR}
+  COMMAND ${CMAKE_COMMAND} -E copy_directory ${LIBSYCL_SOURCE_INCLUDE_DIR}/sycl ${LIBSYCL_BUILD_INCLUDE_DIR}/sycl
+  COMMENT "Copying SYCL headers...")
+
+install(DIRECTORY "${LIBSYCL_SOURCE_INCLUDE_DIR}/sycl" DESTINATION ${LIBSYCL_INCLUDE_DIR} COMPONENT sycl-headers)
+
+if (WIN32)
+  set(LIBSYCL_RT_LIBS ${LIBSYCL_SHARED_OUTPUT_NAME}${LIBSYCL_MAJOR_VERSION})
+  if (MSVC)
+    list(APPEND LIBSYCL_RT_LIBS ${LIBSYCL_SHARED_OUTPUT_NAME}${LIBSYCL_MAJOR_VERSION}d)
+  endif()
+else()
+  set(LIBSYCL_RT_LIBS ${LIBSYCL_SHARED_OUTPUT_NAME})
+endif()
+
+add_subdirectory(src)
+
+add_custom_target(libsycl-runtime-libraries
+  DEPENDS ${LIBSYCL_RT_LIBS}
+)
diff --git a/libsycl/LICENSE.txt b/libsycl/LICENSE.txt
new file mode 100644
index 0000000000000..5715176572a46
--- /dev/null
+++ b/libsycl/LICENSE.txt
@@ -0,0 +1,278 @@
+==============================================================================
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diff --git a/libsycl/README.md b/libsycl/README.md
new file mode 100644
index 0000000000000..c551e40dd821b
--- /dev/null
+++ b/libsycl/README.md
@@ -0,0 +1,20 @@
+## SYCL runtime library
+
+The libsycl subproject is an implementation of the SYCL runtime library as defined by the
+[SYCL 2020 specification](https://registry.khronos.org/SYCL/specs/sycl-2020/html/sycl-2020.html).
+
+Subproject documentation is available at: [SYCL RT documentation](./docs).
+
+libsycl runtime library and headers require C++17 support or higher.
+
+### How to use libsycl with Clang
+
+TBD
+
+#### How to build
+
+TBD
+
+# License
+
+See [LICENSE](./LICENSE.TXT) for details.
diff --git a/libsycl/docs/index.rst b/libsycl/docs/index.rst
new file mode 100644
index 0000000000000..cd33f0f03428d
--- /dev/null
+++ b/libsycl/docs/index.rst
@@ -0,0 +1,69 @@
+.. _index:
+
+Current Status
+==============
+
+The implementation is in the very early stages of upstreaming. The first milestone is to get
+support for a simple SYCL application with device code using Unified Shared Memory:
+
+.. code-block:: c++
+
+   #include <sycl/sycl.hpp>
+   
+   class TestKernel;
+   
+   int main() {
+     sycl::queue q;
+   
+     const size_t dataSize = 32;
+     int *dataPtr = sycl::malloc_shared<int>(32, q);
+     for (int i = 0; i < dataSize; ++i)
+       dataPtr[i] = 0;
+   
+     q.submit([&](sycl::handler &cgh) {
+       cgh.parallel_for<TestKernel>(
+           sycl::range<1>(dataSize),
+           [=](sycl::id<1> idx) { dataPtr[idx] = idx[0]; });
+     });
+     q.wait();
+   
+     bool error = false;
+     for (int i = 0; i < dataSize; ++i)
+       if (dataPtr[i] != i) error = true;
+   
+     free(dataPtr, q);
+   
+     return error;
+   }
+
+This requires at least partial support of the following functionality on the libsycl side:
+  * ``sycl::platform`` class
+  * ``sycl::device`` class
+  * ``sycl::context`` class
+  * ``sycl::queue`` class
+  * ``sycl::handler`` class
+  * ``sycl::id`` and ``sycl::range`` classes
+  * Unified shared memory allocation/deallocation
+  * Program manager, an internal component for retrieving and using device images from the multi-architectural binaries
+
+To build LLVM with libsycl runtime enabled the following script can be used.
+
+.. code-block:: console
+
+  #!/bin/sh
+
+  build_llvm=`pwd`/build-llvm
+  installprefix=`pwd`/install
+  llvm=`pwd`
+  mkdir -p $build_llvm
+  mkdir -p $installprefix
+
+  cmake -G Ninja -S $llvm/llvm -B $build_llvm \
+        -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra" \
+        -DLLVM_INSTALL_UTILS=ON \
+        -DCMAKE_INSTALL_PREFIX=$installprefix \
+        -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libsycl;libunwind" \
+        -DCMAKE_BUILD_TYPE=Release
+
+  ninja -C $build_llvm install
+  
\ No newline at end of file
diff --git a/libsycl/include/sycl/detail/config.hpp b/libsycl/include/sycl/detail/config.hpp
new file mode 100644
index 0000000000000..f7f7b93ee6f51
--- /dev/null
+++ b/libsycl/include/sycl/detail/config.hpp
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declaration of the macros defining attributes for
+/// exported methods and defining API namespaces.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef __LIBSYCL_DETAIL_CONFIG_HPP
+#define __LIBSYCL_DETAIL_CONFIG_HPP
+
+#include <sycl/version.hpp>
+
+#define __LIBSYCL_BEGIN_UNVERSIONED_NAMESPACE namespace sycl {
+#define __LIBSYCL_END_UNVERSIONED_NAMESPACE }
+
+#define __LIBSYCL_BEGIN_VERSIONED_NAMESPACE                                    \
+  __LIBSYCL_BEGIN_UNVERSIONED_NAMESPACE inline namespace __LIBSYCL_ABI_NAMESPACE {
+#define __LIBSYCL_END_VERSIONED_NAMESPACE                                      \
+  }                                                                            \
+  __LIBSYCL_END_UNVERSIONED_NAMESPACE
+
+#ifndef __SYCL_DEVICE_ONLY__
+#ifndef __LIBSYCL_EXPORT
+#ifdef _WIN32
+
+#define __LIBSYCL_DLL_LOCAL
+
+#if __LIBSYCL_BUILD_SYCL_DLL
+#define __LIBSYCL_EXPORT __declspec(dllexport)
+#define __LIBSYCL_EXPORT_DEPRECATED(x) __declspec(dllexport, deprecated(x))
+#else
+#define __LIBSYCL_EXPORT __declspec(dllimport)
+#define __LIBSYCL_EXPORT_DEPRECATED(x) __declspec(dllimport, deprecated(x))
+#endif //__LIBSYCL_BUILD_SYCL_DLL
+
+#else // _WIN32
+
+#define __LIBSYCL_DLL_LOCAL __attribute__((visibility("hidden")))
+
+#define __LIBSYCL_EXPORT __attribute__((visibility("default")))
+#define __LIBSYCL_EXPORT_DEPRECATED(x)                                         \
+  __attribute__((visibility("default"), deprecated(x)))
+
+#endif // _WIN32
+#endif // __LIBSYCL_EXPORT
+
+#else // __SYCL_DEVICE_ONLY__
+
+#ifndef __LIBSYCL_EXPORT
+#define __LIBSYCL_EXPORT
+#define __LIBSYCL_EXPORT_DEPRECATED(x)
+#define __LIBSYCL_DLL_LOCAL
+#endif
+
+#endif // __SYCL_DEVICE_ONLY__
+
+#endif // __LIBSYCL_DETAIL_CONFIG_HPP
diff --git a/libsycl/include/sycl/platform.hpp b/libsycl/include/sycl/platform.hpp
new file mode 100644
index 0000000000000..bbfbaf7d343f5
--- /dev/null
+++ b/libsycl/include/sycl/platform.hpp
@@ -0,0 +1,31 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declaration of the Platform class, which encapsulates
+/// a single SYCL platform on which kernel functions may be executed.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef __LIBSYCL_PLATFORM_HPP
+#define __LIBSYCL_PLATFORM_HPP
+
+#include <sycl/detail/config.hpp>
+
+__LIBSYCL_BEGIN_VERSIONED_NAMESPACE
+
+class __LIBSYCL_EXPORT platform {
+public:
+  /// Constructs a SYCL platform using the default device.
+  platform();
+
+}; // class platform
+
+__LIBSYCL_END_VERSIONED_NAMESPACE
+
+#endif // __LIBSYCL_PLATFORM_HPP
diff --git a/libsycl/include/sycl/sycl.hpp b/libsycl/include/sycl/sycl.hpp
new file mode 100644
index 0000000000000..136d97805b0cf
--- /dev/null
+++ b/libsycl/include/sycl/sycl.hpp
@@ -0,0 +1,14 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __LIBSYCL_SYCL_HPP
+#define __LIBSYCL_SYCL_HPP
+
+#include <sycl/platform.hpp>
+
+#endif // __LIBSYCL_SYCL_HPP
diff --git a/libsycl/src/CMakeLists.txt b/libsycl/src/CMakeLists.txt
new file mode 100644
index 0000000000000..baec5a685e67d
--- /dev/null
+++ b/libsycl/src/CMakeLists.txt
@@ -0,0 +1,109 @@
+function(add_sycl_rt_library LIB_NAME LIB_OBJ_NAME)
+  # 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>)
+  target_include_directories(
+    ${LIB_OBJ_NAME}
+    PRIVATE
+      ${CMAKE_CURRENT_SOURCE_DIR}
+      ${LIBSYCL_BUILD_INCLUDE_DIR}
+  )
+
+  add_library(${LIB_NAME} SHARED
+              $<TARGET_OBJECTS:${LIB_OBJ_NAME}>)
+
+  if (ARG_COMPILE_OPTIONS)
+    target_compile_options(${LIB_OBJ_NAME} PRIVATE ${ARG_COMPILE_OPTIONS})
+  endif()
+
+  add_dependencies(${LIB_OBJ_NAME}
+    sycl-headers
+  )
+
+  set_target_properties(${LIB_NAME} PROPERTIES LINKER_LANGUAGE CXX)
+
+  if (WIN32)
+    target_link_libraries(${LIB_NAME} PRIVATE shlwapi)
+    if (ARG_IMPLIB_NAME)
+      add_custom_command(
+        TARGET ${LIB_NAME} POST_BUILD
+        COMMAND ${CMAKE_COMMAND} -E copy
+        ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${LIB_NAME}.lib ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${ARG_IMPLIB_NAME}.lib
+        COMMENT "Creating version-agnostic copy of the import library.")
+      install(
+        FILES ${CMAKE_LIBRARY_OUTPUT_DIRECTORY}/${ARG_IMPLIB_NAME}.lib
+        DESTINATION "lib${LLVM_LIBDIR_SUFFIX}" COMPONENT libsycl)
+    endif()
+  endif()
+
+  if (MSVC)
+    # Install stripped PDB
+    check_linker_flag(CXX "LINKER:/PDBSTRIPPED:${LIB_NAME}.stripped.pdb"
+                          LINKER_SUPPORTS_PDBSTRIPPED)
+    if(LINKER_SUPPORTS_PDBSTRIPPED)
+      target_link_options(${LIB_NAME}
+                          PRIVATE "LINKER:/PDBSTRIPPED:${LIB_NAME}.stripped.pdb")
+      install(FILES "${CMAKE_CURRENT_BINARY_DIR}/${LIB_NAME}.stripped.pdb"
+              DESTINATION ${CMAKE_INSTALL_PREFIX}/bin
+              RENAME "${LIB_NAME}.pdb"
+              COMPONENT ${LIB_NAME}
+              OPTIONAL)
+    endif()
+  else()
+    target_compile_options(${LIB_OBJ_NAME} PUBLIC
+                           -fvisibility=hidden -fvisibility-inlines-hidden)
+
+    if (UNIX AND NOT APPLE)
+      set(linker_script "${CMAKE_CURRENT_SOURCE_DIR}/ld-version-script.txt")
+      target_link_libraries(
+          ${LIB_NAME} PRIVATE "-Wl,--version-script=${linker_script}")
+      set_target_properties(${LIB_NAME} PROPERTIES LINK_DEPENDS ${linker_script})
+    endif()
+  endif()
+
+  find_package(Threads REQUIRED)
+
+  target_link_libraries(${LIB_NAME}
+    PRIVATE
+      ${CMAKE_DL_LIBS}
+      ${CMAKE_THREAD_LIBS_INIT}
+  )
+
+  set_target_properties(${LIB_NAME} PROPERTIES
+                        VERSION ${LIBSYCL_VERSION_STRING}
+                        SOVERSION ${LIBSYCL_VERSION_STRING})
+endfunction(add_sycl_rt_library)
+
+set(LIBSYCL_SOURCES
+    "platform.cpp"
+)
+
+if (WIN32)
+set(LIB_NAME "sycl${LIBSYCL_MAJOR_VERSION}")
+else()
+set(LIB_NAME "sycl")
+endif()
+
+# Version-agnostic name of the import library, has effect on Windows only.
+set(IMPLIB_NAME "sycl")
+
+add_sycl_rt_library(${LIB_NAME} sycl_object COMPILE_OPTIONS ${LIBSYCL_EXTRA_OPTS}
+                    SOURCES ${LIBSYCL_SOURCES} IMPLIB_NAME ${IMPLIB_NAME})
+
+if (WIN32)
+  add_library(sycl ALIAS ${LIB_NAME})
+endif()
+
+if (CMAKE_SYSTEM_NAME STREQUAL Windows)
+  set_target_properties(${LIB_NAME} PROPERTIES DEBUG_POSTFIX d)
+endif()
+
+install(TARGETS ${LIBSYCL_RT_LIBS}
+  ARCHIVE DESTINATION "lib${LLVM_LIBDIR_SUFFIX}" COMPONENT libsycl
+  LIBRARY DESTINATION "lib${LLVM_LIBDIR_SUFFIX}" COMPONENT libsycl
+  RUNTIME DESTINATION "bin" COMPONENT libsycl)
diff --git a/libsycl/src/ld-version-script.txt b/libsycl/src/ld-version-script.txt
new file mode 100644
index 0000000000000..90bfe2ac7309f
--- /dev/null
+++ b/libsycl/src/ld-version-script.txt
@@ -0,0 +1,19 @@
+{
+  /* Do not use extern "C++" matcher for C++ functions,                     */
+  /* because vtable and typeinfo symbols make extern "C++" patterns more    */
+  /* complicated than patterns against mangled names.                       */
+  /*                                                                        */
+  /* With extern "C++" we have to match for "vtable for sycl::foo", but */
+  /* not match for "vtable for std::__internal<sycl::foo>".             */
+
+  global:
+    /* Export everything from sycl namespace */
+    _ZNK4sycl*;  /* function */
+    _ZN4sycl*;   /* function */
+    _ZTIN4sycl*; /* typeinfo */
+    _ZTSN4sycl*; /* typeinfo name */
+    _ZTVN4sycl*; /* vtable */
+
+  local:
+    *;
+};
diff --git a/libsycl/src/platform.cpp b/libsycl/src/platform.cpp
new file mode 100644
index 0000000000000..d2c0a47ceba82
--- /dev/null
+++ b/libsycl/src/platform.cpp
@@ -0,0 +1,17 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <sycl/platform.hpp>
+
+#include <stdexcept>
+
+__LIBSYCL_BEGIN_VERSIONED_NAMESPACE
+
+platform::platform() { throw std::runtime_error("Unimplemented"); }
+
+__LIBSYCL_END_VERSIONED_NAMESPACE
diff --git a/libsycl/src/version.hpp.in b/libsycl/src/version.hpp.in
new file mode 100644
index 0000000000000..2468a077ce13a
--- /dev/null
+++ b/libsycl/src/version.hpp.in
@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file contains the declaration of SYCL RT version macro.
+///
+//===----------------------------------------------------------------------===//
+#define __LIBSYCL_MAJOR_VERSION ${LIBSYCL_MAJOR_VERSION}
+#define __LIBSYCL_MINOR_VERSION ${LIBSYCL_MINOR_VERSION}
+#define __LIBSYCL_PATCH_VERSION ${LIBSYCL_PATCH_VERSION}
+#define __LIBSYCL_ABI_NAMESPACE ${LIBSYCL_ABI_NAMESPACE}
diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index 0849bec26d56a..f1beea79883d8 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -141,7 +141,7 @@ endforeach()
 # As we migrate runtimes to using the bootstrapping build, the set of default runtimes
 # should grow as we remove those runtimes from LLVM_ENABLE_PROJECTS above.
 set(LLVM_DEFAULT_RUNTIMES "libcxx;libcxxabi;libunwind")
-set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload;flang-rt;libclc")
+set(LLVM_SUPPORTED_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;openmp;llvm-libgcc;offload;flang-rt;libclc;libsycl")
 set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
   "Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
 if(LLVM_ENABLE_RUNTIMES STREQUAL "all")
diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
index 878b2eee38618..2e498a92318d9 100644
--- a/runtimes/CMakeLists.txt
+++ b/runtimes/CMakeLists.txt
@@ -36,7 +36,7 @@ list(INSERT CMAKE_MODULE_PATH 0
 # We order libraries to mirror roughly how they are layered, except that compiler-rt can depend
 # on libc++, so we put it after.
 set(LLVM_DEFAULT_RUNTIMES "libc;libunwind;libcxxabi;pstl;libcxx;compiler-rt;libclc;openmp;offload")
-set(LLVM_SUPPORTED_RUNTIMES "${LLVM_DEFAULT_RUNTIMES};llvm-libgcc;flang-rt")
+set(LLVM_SUPPORTED_RUNTIMES "${LLVM_DEFAULT_RUNTIMES};llvm-libgcc;flang-rt;libsycl")
 set(LLVM_ENABLE_RUNTIMES "" CACHE STRING
   "Semicolon-separated list of runtimes to build, or \"all\" (${LLVM_DEFAULT_RUNTIMES}). Supported runtimes are ${LLVM_SUPPORTED_RUNTIMES}.")
 if(LLVM_ENABLE_RUNTIMES STREQUAL "all" )



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