[llvm] [mlir][bufferization] Generalize tensor slice rules to subset ops (PR #65619)

[Martin Erhart via llvm-commits]

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@@ -0,0 +1,118 @@
+//===-- SubsetOpInterface.td - Tensor subsets --------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBSET_OP_INTERFACE
+#define SUBSET_OP_INTERFACE
+
+include "mlir/IR/OpBase.td"
+
+def SubsetOpInterface : OpInterface<"SubsetOpInterface"> {
+  let description = [{
+    This interface can be implemented by ops that insert a source tensor into
+    a destination tensor.
+
+    The elements in the destination tensor that are overwritten by this
+    insertion are called the "subset". How the subset is defined is up to the
+    op. E.g., "tensor.insert_slice" defines the subset via a hyperrectangular
+    slice. A scatter operation could define the subset via a list of indices.
+
+    Ops that deal with tensor subsets come in two flavours:
+    - Insertion flavor: Ops that insert a source tensor into a destination
+      tensor at the specified subset. Such ops usually return a new destination
+      tensor and implement the `DestinationStyleOpInterface`. Insertion ops can
+      implement the `SubsetOpInterface`. Example: "tensor.insert_slice"
+    - Extraction flavor: Ops that define a tensor subset. They extract a
+      specified subset from a tensor. There is currently no op interface for
+      such ops. Example: "tensor.extract_slice"
+
+    This interface provides helper methods for efficient bufferization of
+    subset-based tensor IR. Tensor subsets can bufferize to buffer "views"/
+    "aliases" (in contrast to one or multiple less efficient buffer allocation).
+
+    This interface is queried by One-Shot Bufferize to detect cases where a
+    seeming read-after-write is not actually a conflict because the respective
+    ops are operating on equivalent subsets. More details can be found in the
----------------
maerhart wrote:

Maybe add a link to the concrete subsection in the doc?
This should probably also refer to the interface method below (the example is helpful for understanding this paragraph).

https://github.com/llvm/llvm-project/pull/65619