[llvm] [OFFLOAD] Add plugin with support for Intel oneAPI Level Zero (PR #158900)

[Alexey Sachkov via llvm-commits]

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@@ -0,0 +1,73 @@
+//===--- Level Zero Target RTL Implementation -----------------------------===//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// External and other auxilary definitions
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+#include "PluginInterface.h"
+#include "Shared/Requirements.h"
+#include "omptarget.h"
+
+#define LIBOMP_DECL(RetType, FnDecl) RetType __cdecl FnDecl
+
+enum class AllocOptionTy : int32_t {
+  ALLOC_OPT_NONE = 0,
+  ALLOC_OPT_REDUCTION_SCRATCH = 1,
+  ALLOC_OPT_REDUCTION_COUNTER = 2,
+  ALLOC_OPT_HOST_MEM = 3,
+  ALLOC_OPT_SLM = 4,
+};
+
+/// Host runtime routines being used
+extern "C" {
+LIBOMP_DECL(int, omp_get_max_teams(void));
+LIBOMP_DECL(int, omp_get_thread_limit(void));
+LIBOMP_DECL(int, omp_get_teams_thread_limit(void));
+LIBOMP_DECL(double, omp_get_wtime(void));
+} // extern "C"
+
+#ifndef EXTRACT_BITS
+// MSB=63, LSB=0
+#define EXTRACT_BITS(I64, HIGH, LOW)                                           \
+  (((uint64_t)I64) >> (LOW)) & (((uint64_t)1 << ((HIGH) - (LOW) + 1)) - 1)
+#endif
+
+namespace llvm::omp::target::plugin {
+
+/// Default alignmnet for allocation
+constexpr size_t L0Alignment = 0;
----------------
AlexeySachkov wrote:

```suggestion
constexpr size_t L0DefaultAlignment = 0;
```

To better describe the intent

https://github.com/llvm/llvm-project/pull/158900