[llvm] [Offload] Implement the remaining initial Offload API (PR #122106)

[Callum Fare via llvm-commits]

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@@ -0,0 +1,48 @@
+//===-- Memory.td - Memory definitions for Offload ---------*- tablegen -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains Offload API definitions related to memory allocations
+//
+//===----------------------------------------------------------------------===//
+
+def : Enum {
+  let name = "ol_alloc_type_t";
+  let desc = "Represents the type of allocation made with olMemAlloc.";
+  let etors = [
+    Etor<"HOST", "Host allocation">,
+    Etor<"DEVICE", "Device allocation">,
+    Etor<"SHARED", "Shared allocation">
+  ];
+}
+
+def : Function {
+  let name = "olMemAlloc";
+  let desc = "Creates a memory allocation on the specified device.";
+  let params = [
+    Param<"ol_device_handle_t", "Device", "handle of the device to allocate on", PARAM_IN>,
+    Param<"ol_alloc_type_t", "Type", "type of the allocation", PARAM_IN>,
+    Param<"size_t", "Size", "size of the allocation in bytes", PARAM_IN>,
+    Param<"void**", "AllocationOut", "output for the allocated pointer", PARAM_OUT>
+  ];
+  let returns = [
+    Return<"OL_ERRC_INVALID_SIZE", [
+      "`Size == 0`"
+    ]>
+  ];
+}
+
+def : Function {
+  let name = "olMemFree";
+  let desc = "Frees a memory allocation previously made by olMemAlloc.";
+  let params = [
+    Param<"ol_device_handle_t", "Device", "handle of the device to allocate on", PARAM_IN>,
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callumfare wrote:

I could reinstate the device and kind parameters to remove the map but anything else will require a plugin change:
* The MemoryManager currently belongs to the device, not the platform
* `dataDelete` would need to be changed or an overload added to remove the `TargetAllocTy` argument and let the plugins deduce it if necessary

I'd rather avoid plugin changes in this PR and just expose the existing functionality, to avoid dragging out the review process any longer. I think we're all on the same page that the API is a work in progress so we can make breaking changes to this function after this PR. 

>From the Codeplay/Intel side of things, probably our highest priority TODO after this is investigating any gaps between memory capabilities in UR and offload, including whether the equivalent of UR's contexts is needed, which ties into all of this.

https://github.com/llvm/llvm-project/pull/122106