initial SYCL build system and examples

.github/workflows/ubuntu-sycl.yml

@@ -0,0 +1,57 @@
+name: Ubuntu SYCL
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    types: [opened, reopened, synchronize]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+env:
+  NPROC: 2
+  GCE_CLI_GHA_VERSION: "302.0.0"
+
+jobs:
+  ubuntu-sycl:
+    runs-on: ubuntu-20.04
+    strategy:
+      fail-fast: false
+      matrix:
+        SHARED: [ON, OFF]
+    steps:
+      - name: Checkout source code
+        uses: actions/checkout@v2
+      - name: Maximize build space
+        run: |
+          source util/ci_utils.sh
+          maximize_ubuntu_github_actions_build_space
+      - name: Docker build
+        run: |
+          if [ "${{ matrix.SHARED }}" = "ON" ]; then
+            docker/docker_build.sh sycl-shared
+          else
+            docker/docker_build.sh sycl-static
+          fi
+      - name: Docker test
+        run: |
+          if [ "${{ matrix.SHARED }}" = "ON" ]; then
+            docker/docker_test.sh sycl-shared
+          else
+            docker/docker_test.sh sycl-static
+          fi
+      - name: GCloud CLI setup
+        if: ${{ github.ref == 'refs/heads/master' }}
+        uses: google-github-actions/[email protected]
+        with:
+          version: ${{ env.GCE_CLI_GHA_VERSION }}
+          service_account_key: ${{ secrets.GCE_SA_KEY_DOCS_CI }}
+          project_id: ${{ secrets.GCE_DOCS_PROJECT }}
+          export_default_credentials: true
+      - name: Upload ccache to GCS
+        if: ${{ github.ref == 'refs/heads/master' }}
+        run: |
+          gsutil cp ${GITHUB_WORKSPACE}/open3d-ci-sycl.tar.gz gs://open3d-ci-cache/ || true

3rdparty/README_SYCL.md

@@ -0,0 +1,88 @@
+# Open3D SYCL
+
+Note: this file will be moved to the `docs` folder once SYCL support is mature.
+
+## Concepts
+
+- **OpenCL**: Low-level programming interface for heterogeneous platforms.
+- **SYCL**: High-level programming interface for heterogeneous platforms. SYCL
+  was originally based on OpenCL but now SYCL is an independent standard.
+- **DPC++**: Intel's implementation of the SYCL standard.
+- **oneAPI**: A collection of open standards, including DPC++, oneMKL, oneTBB, etc.
+
+Open3D's SYCL support runs on DPC++ and requires oneAPI dependencies. For
+convenience, in the source code, we use the term "SYCL" although we may be
+referring to "DPC++".
+
+## Setup
+
+1. Install oneAPI for Linux: [install via apt-get](https://www.intel.com/content/www/us/en/develop/documentation/installation-guide-for-intel-oneapi-toolkits-linux/top/installation/install-using-package-managers/apt.html)
+2. Prepare environment
+   ```bash
+   # Source environments
+   source /opt/intel/oneapi/setvars.sh
+
+   # We'll be using oneAPI's distribution of conda and Python
+   # Python 3.6+ will work
+   conda create -n sycl python=3.8
+   conda activate sycl
+   ```
+3. Check your environment
+   ```bash
+   which icx        # /opt/intel/oneapi/compiler/<version>/linux/bin/icx
+   which icpx       # /opt/intel/oneapi/compiler/<version>/linux/bin/icpx
+   which python     # ${HOME}/.conda/envs/sycl/bin/python
+   python --version # Python 3.8.12 :: Intel Corporation
+   ```
+4. Config and build
+   ```bash
+   cmake -DBUILD_SYCL_MODULE=ON -DCMAKE_C_COMPILER=icx -DCMAKE_CXX_COMPILER=icpx ..
+   make -j$(nproc)
+   ```
+5. Run demos
+   We provide several ways to run SYCL demos. This ensures the linking are
+   correct and all run-time dependencies are satisfied.
+   ```bash
+   # C++ test
+   make tests -j$(nproc)
+   ./bin/tests --gtest_filter="*SYCLDemo*"
+
+   # C++ example
+   make SYCLDemo -j$(nproc)
+   ./bin/examples/SYCLDemo
+
+   # Python
+   make install-pip-package -j$(nproc)
+   pytest ../python/test/core/test_sycl_utils.py -s
+   ```
+
+## Known limitations/requirement
+
+- Limitations (not implemented yet)
+  - Only supports Linux
+  - Only supports `BUILD_CUDA_MODULE=OFF`
+  - ML ops not supported (C++17 cannot be enabled for TF)
+- Requirements (required by DPC++)
+  - Only supports `GLIBCXX_USE_CXX11_ABI=ON`
+  - Only supports `set(CMAKE_CXX_STANDARD 17)`
+
+
+## List of oneAPI Python packages
+
+To make `pip install open3d` works out-of-the box on SYCL-enabled platforms,
+we can utilize runtime libraries released via PyPI. This feature needs to be
+implemented.
+
+User:
+- https://pypi.org/user/IntelAutomationEngineering/
+
+Libraries:
+- dpcpp-cpp-rt     https://pypi.org/project/dpcpp-cpp-rt/#history
+- mkl              https://pypi.org/project/mkl/#history
+- mkl-static       https://pypi.org/project/mkl-static/#history
+- mkl-include      https://pypi.org/project/mkl-include/#history
+- mkl-dpcpp        https://pypi.org/project/mkl-dpcpp/#history
+- mkl-devel-dpcpp  https://pypi.org/project/mkl-devel-dpcpp/#history
+- ipp              https://pypi.org/project/ipp/#history
+- ipp-static       https://pypi.org/project/ipp-static/#history
+- tbb              https://pypi.org/project/tbb/#history

3rdparty/assimp/assimp.cmake

@@ -6,6 +6,14 @@ else()
     set(lib_name assimp)
 endif()
 
+# IntelLLVM (SYCL) compiler defaults to fast math, causing NaN comparison code
+# compilation error.
+if(CMAKE_CXX_COMPILER_ID MATCHES "IntelLLVM")
+    set(assimp_cmake_cxx_flags "${CMAKE_CXX_FLAGS} -ffp-contract=on -fno-fast-math")
+else()
+    set(assimp_cmake_cxx_flags "${CMAKE_CXX_FLAGS}")
+endif()
+
 ExternalProject_Add(
     ext_assimp
     PREFIX assimp
@@ -14,6 +22,8 @@ ExternalProject_Add(
     DOWNLOAD_DIR "${OPEN3D_THIRD_PARTY_DOWNLOAD_DIR}/assimp"
     UPDATE_COMMAND ""
     CMAKE_ARGS
+        ${ExternalProject_CMAKE_ARGS_hidden}
+        -DCMAKE_CXX_FLAGS:STRING=${assimp_cmake_cxx_flags}
         -DBUILD_SHARED_LIBS=OFF
         -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
         -DASSIMP_NO_EXPORT=ON
@@ -23,7 +33,6 @@ ExternalProject_Add(
         -DASSIMP_BUILD_ZLIB=ON
         -DHUNTER_ENABLED=OFF # Renamed to "ASSIMP_HUNTER_ENABLED" in newer assimp.
         -DCMAKE_DEBUG_POSTFIX=
-        ${ExternalProject_CMAKE_ARGS_hidden}
     BUILD_BYPRODUCTS
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}${lib_name}${CMAKE_STATIC_LIBRARY_SUFFIX}
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}IrrXML${CMAKE_STATIC_LIBRARY_SUFFIX}

3rdparty/benchmark/MakeAvailable/CMakeLists.txt

@@ -9,6 +9,11 @@ else()
     add_compile_definitions(_GLIBCXX_USE_CXX11_ABI=0)
 endif()
 
+# IntelLLVM (SYCL) compiler defaults to fast math, causing NaN comparison
+# code compilation error.
+add_compile_options($<$<CXX_COMPILER_ID:IntelLLVM>:-ffp-contract=on>)
+add_compile_options($<$<CXX_COMPILER_ID:IntelLLVM>:-fno-fast-math>)
+
 FetchContent_MakeAvailable(ext_benchmark)
 
 # Set the cache vars introduced by the benchmark lib as advanced to not

3rdparty/embree/embree.cmake

@@ -69,11 +69,12 @@ endif()
 ExternalProject_Add(
     ext_embree
     PREFIX embree
-    URL https://github.com/embree/embree/archive/refs/tags/v3.13.0.tar.gz
-    URL_HASH SHA256=4d86a69508a7e2eb8710d571096ad024b5174834b84454a8020d3a910af46f4f
+    URL https://github.com/embree/embree/archive/refs/tags/v3.13.3.tar.gz
+    URL_HASH SHA256=74ec785afb8f14d28ea5e0773544572c8df2e899caccdfc88509f1bfff58716f
     DOWNLOAD_DIR "${OPEN3D_THIRD_PARTY_DOWNLOAD_DIR}/embree"
     UPDATE_COMMAND ""
     CMAKE_ARGS
+        ${ExternalProject_CMAKE_ARGS_hidden}
         -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
         ${ISA_ARGS}
         -DEMBREE_ISPC_SUPPORT=OFF
@@ -85,7 +86,6 @@ ExternalProject_Add(
         -DEMBREE_GEOMETRY_QUAD=OFF
         -DEMBREE_GEOMETRY_SUBDIVISION=OFF
         -DEMBREE_TASKING_SYSTEM=INTERNAL
-        ${ExternalProject_CMAKE_ARGS_hidden}
         ${WIN_CMAKE_ARGS}
     BUILD_BYPRODUCTS
         <INSTALL_DIR>/${Open3D_INSTALL_LIB_DIR}/${CMAKE_STATIC_LIBRARY_PREFIX}embree3${CMAKE_STATIC_LIBRARY_SUFFIX}