[llvm] [SYCL] Add platform enumeration and info query using liboffload (PR #166927)

[Andrei Elovikov via llvm-commits]

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@@ -0,0 +1,102 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_PLATFORM_IMPL
+#define _LIBSYCL_PLATFORM_IMPL
+
+#include <sycl/__impl/backend.hpp>
+#include <sycl/__impl/detail/config.hpp>
+#include <sycl/__impl/platform.hpp>
+
+#include "detail/offload/info_code.hpp"
+#include "detail/offload/offload_utils.hpp"
+
+#include <OffloadAPI.h>
+
+#include <memory>
+#include <string>
+#include <type_traits>
+#include <vector>
+
+_LIBSYCL_BEGIN_NAMESPACE_SYCL
+
+namespace detail {
+
+class platform_impl {
+public:
+  /// Constructs platform_impl from a platform handle.
+  ///
+  /// \param Platform is a raw offload library handle representing platform.
+  /// \param PlatformIndex is a platform index in a backend (needed for a proper
+  /// indexing in device selector).
+  //
+  // Platforms can only be created under `GlobalHandler`'s ownership via
+  // `platform_impl::getOrMakePlatformImpl` method.
+  explicit platform_impl(ol_platform_handle_t Platform, size_t PlatformIndex);
+
+  ~platform_impl() = default;
+
+  /// Returns the backend associated with this platform.
+  backend getBackend() const noexcept { return MBackend; }
+
+  /// Returns all SYCL platforms from all backends that are available in the
+  /// system.
+  static std::vector<platform> getPlatforms();
+
+  /// Returns raw underlying offload platform handle.
+  ///
+  /// It does not retain handle. It is caller responsibility to make sure that
+  /// platform stays alive while raw handle is in use.
+  ///
+  /// \return a raw plug-in platform handle.
+  const ol_platform_handle_t &getHandleRef() const { return MOffloadPlatform; }
+
+  /// Returns platform index in a backend (needed for a proper indexing in
+  /// device selector).
+  size_t getPlatformIndex() const { return MOffloadPlatformIndex; }
+
+  /// Queries the cache to see if the specified offloading RT platform has been
+  /// seen before.  If so, return the cached platform_impl, otherwise create a
+  /// new one and cache it.
+  ///
+  /// \param Platform is the offloading RT Platform handle representing the
+  /// platform
+  /// \param PlatformIndex is a platform index in a backend (needed for a proper
+  /// indexing in device selector).
+  /// \return the platform_impl representing the offloading RT platform
+  static platform_impl *getOrMakePlatformImpl(ol_platform_handle_t Platform,
+                                              size_t PlatformIndex);
+
+  /// Queries this SYCL platform for info.
+  ///
+  /// The return type depends on information being queried.
+  template <typename Param> typename Param::return_type get_info() const {
+    // for now we have only std::string properties
+    static_assert(std::is_same_v<typename Param::return_type, std::string>);
+    size_t ExpectedSize = 0;
+    call_and_throw(olGetPlatformInfoSize, MOffloadPlatform,
+                   detail::OffloadInfoCode<Param>::value, &ExpectedSize);
+    std::string Result;
+    Result.resize(ExpectedSize - 1);
+    call_and_throw(olGetPlatformInfo, MOffloadPlatform,
+                   detail::OffloadInfoCode<Param>::value, ExpectedSize,
+                   Result.data());
+    return Result;
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aelovikov-intel wrote:

https://github.com/llvm/llvm-project/pull/168615 was rejected, resolving this.

https://github.com/llvm/llvm-project/pull/166927