[Mlir-commits] [mlir] [mlir] Add fast walk-based pattern rewrite driver (PR #113825)

[Jakub Kuderski]

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+//===- WALKPATTERNREWRITEDRIVER.h - Walk Pattern Rewrite Driver -*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Declares a helper function to walk the given op and apply rewrite patterns.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef MLIR_TRANSFORMS_WALKPATTERNREWRITEDRIVER_H_
+#define MLIR_TRANSFORMS_WALKPATTERNREWRITEDRIVER_H_
+
+#include "mlir/IR/Visitors.h"
+#include "mlir/Rewrite/FrozenRewritePatternSet.h"
+
+namespace mlir {
+
+/// A fast walk-based pattern rewrite driver. Rewrites ops nested under the
+/// given operation by walking it and applying the highest benefit patterns.
+/// This rewriter *does not* wait until a fixpoint is reached and *does not*
+/// visit modified or newly replaced ops. Also *does not* perform folding or
+/// dead-code elimination.
+///
+/// This is intended as the simplest and most lightweight pattern rewriter in
+/// cases when a simple walk gets the job done.
+///
+/// Note: Does not apply patterns to the given operation itself.
+void walkAndApplyPatterns(Operation *op,
----------------
kuhar wrote:

The walk driver is somewhat opinionated: it does not revisit ops modified in place or newly created ones, not all erasures are valid, etc. We may be able to relax these restrictions without sacrificing too much performance.  With this in mind, I think that adding it to `Operation::` is premature and it doesn't give us much value over a free function.

https://github.com/llvm/llvm-project/pull/113825