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

[Kseniya Tikhomirova via llvm-commits]

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@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 SYCL enum class backend that is
+/// implementation-defined and is populated with a unique identifier for each
+/// SYCL backend that the SYCL implementation can support.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBSYCL___IMPL_BACKEND_HPP
+#define _LIBSYCL___IMPL_BACKEND_HPP
+
+#include <sycl/__impl/detail/config.hpp>
+
+#include <string_view>
+#include <type_traits>
+
+_LIBSYCL_BEGIN_NAMESPACE_SYCL
+
+// SYCL 2020 4.1. Backends.
+enum class backend : unsigned char {
+  opencl = 0,
+  level_zero,
+  cuda,
+  hip,
+};
+
+namespace detail {
+template <typename T> struct is_backend_info_desc : std::false_type {};
+} // namespace detail
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KseniyaTikhomirova wrote:

that's strange, I was adding this, maybe I accidentally removed it when was removing commented out code.
returned it back https://github.com/llvm/llvm-project/pull/166927/commits/be625458ff6e96566fa521a8e8c042397b625c84

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