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

[Alex Duran via llvm-commits]

================
@@ -0,0 +1,157 @@
+//===--- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Level Zero RTL Options support
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef OPENMP_LIBOMPTARGET_PLUGINS_NEXTGEN_LEVEL_ZERO_L0OPTIONS_H
+#define OPENMP_LIBOMPTARGET_PLUGINS_NEXTGEN_LEVEL_ZERO_L0OPTIONS_H
+
+#include <level_zero/ze_api.h>
+
+#include "Shared/EnvironmentVar.h"
+
+#include "L0Defs.h"
+
+namespace llvm::omp::target::plugin {
+/// Command submission mode
+enum class CommandModeTy { Sync = 0, Async, AsyncOrdered };
+
+/// Specialization constants used for a module compilation.
+class SpecConstantsTy {
+  std::vector<uint32_t> ConstantIds;
+  std::vector<const void *> ConstantValues;
----------------
adurang wrote:

> What about `unique_ptr` prevents us from having a packed array?
> 
> ```c++
> std::unique_ptr<int[]> arr(new int[N]());
> ```

It's not the pointee that needs to be continguous but the pointers themselves (i.e., std::vector<void *>::data() result). In any case, I used a BumpPtrAllocator as you suggested which seems the better solution.

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