c4b0f9959a
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 --------- Signed-off-by: Tikhomirova, Kseniya <kseniya.tikhomirova@intel.com>
120 lines
3.7 KiB
ReStructuredText
120 lines
3.7 KiB
ReStructuredText
===========================
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SYCL runtime implementation
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===========================
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.. contents::
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:local:
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.. _index:
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Current Status
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==============
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The implementation is in the very early stages of upstreaming. The first
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milestone is to get
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support for a simple SYCL application with device code using Unified Shared
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Memory:
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.. code-block:: c++
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#include <sycl/sycl.hpp>
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class TestKernel;
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int main() {
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sycl::queue q;
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const size_t dataSize = 32;
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int *dataPtr = sycl::malloc_shared<int>(32, q);
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for (int i = 0; i < dataSize; ++i)
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dataPtr[i] = 0;
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q.submit([&](sycl::handler &cgh) {
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cgh.parallel_for<TestKernel>(
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sycl::range<1>(dataSize),
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[=](sycl::id<1> idx) { dataPtr[idx] = idx[0]; });
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});
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q.wait();
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bool error = false;
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for (int i = 0; i < dataSize; ++i)
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if (dataPtr[i] != i) error = true;
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free(dataPtr, q);
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return error;
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}
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This requires at least partial support of the following functionality on the
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libsycl side:
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* ``sycl::platform`` class
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* ``sycl::device`` class
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* ``sycl::context`` class
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* ``sycl::queue`` class
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* ``sycl::handler`` class
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* ``sycl::id`` and ``sycl::range`` classes
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* Unified shared memory allocation/deallocation
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* Program manager, an internal component for retrieving and using device images
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from the multi-architectural binaries
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Build steps
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===========
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To build LLVM with libsycl runtime enabled the following script can be used.
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.. code-block:: console
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#!/bin/sh
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build_llvm=`pwd`/build-llvm
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installprefix=`pwd`/install
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llvm=`pwd`
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mkdir -p $build_llvm
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mkdir -p $installprefix
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cmake -G Ninja -S $llvm/llvm -B $build_llvm \
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-DLLVM_ENABLE_PROJECTS="clang" \
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-DLLVM_INSTALL_UTILS=ON \
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-DCMAKE_INSTALL_PREFIX=$installprefix \
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-DLLVM_ENABLE_RUNTIMES="offload;openmp;libsycl" \
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-DCMAKE_BUILD_TYPE=Release \
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# must be default and configured in liboffload,
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# requires level zero, see offload/cmake/Modules/LibomptargetGetDependencies.cmake
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-DLIBOMPTARGET_PLUGINS_TO_BUILD=level_zero
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ninja -C $build_llvm install
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Limitations
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===========
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Libsycl is not currently supported on Windows because it depends on liboffload
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which doesn't currently support Windows.
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TODO for added SYCL classes
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===========================
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* ``exception``: methods with context are not implemented, to add once context is ready
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* ``platform``: deprecated info descriptor is not implemented (info::platform::extensions), to implement on RT level with ``device::get_info<info::device::aspects>()``
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* ``device``:
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* ``get_info``: to find an efficient way to map descriptors to liboffload types, add other descriptors, add cache of info data
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* ``has(aspect)``: same as get_info
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* ``create_sub_devices``: partitioning is not supported by liboffload now, blocked
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* ``has_extension``: deprecated API, to implement on RT level with ``device::has``
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* device selection: to add compatibility with old SYCL 1.2.1 device selectors, still part of SYCL 2020 specification
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* ``context``: to implement get_info, properties & public constructors once context support is added to liboffload
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* ``queue``: to implement USM methods, to implement synchronization methods, to implement submit & copy with accessors (low priority), get_info & properties, ctors that accepts context (blocked by lack of liboffload support)
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* ``property_list``: to fully implement and integrate with existing SYCL runtime classes supporting it
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* usm allocations:
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* add aligned functions (blocked by liboffload support)
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* forward templated funcs to alignment methods (rewrite current impl)
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* handle sub devices once they are implemented (blocked by liboffload support)
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* general opens:
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* define a way to report errors from object dtors. |