1 //===- Canonicalizer.cpp - Canonicalize MLIR operations -------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This transformation pass converts operations into their canonical forms by
10 // folding constants, applying operation identity transformations etc.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "PassDetail.h"
15 #include "mlir/Pass/Pass.h"
16 #include "mlir/Transforms/GreedyPatternRewriteDriver.h"
17 #include "mlir/Transforms/Passes.h"
18 
19 using namespace mlir;
20 
21 namespace {
22 /// Canonicalize operations in nested regions.
23 struct Canonicalizer : public CanonicalizerBase<Canonicalizer> {
24   Canonicalizer(const GreedyRewriteConfig &config) : config(config) {}
25 
26   Canonicalizer() {
27     // Default constructed Canonicalizer takes its settings from command line
28     // options.
29     config.useTopDownTraversal = topDownProcessingEnabled;
30     config.enableRegionSimplification = enableRegionSimplification;
31     config.maxIterations = maxIterations;
32   }
33 
34   /// Initialize the canonicalizer by building the set of patterns used during
35   /// execution.
36   LogicalResult initialize(MLIRContext *context) override {
37     RewritePatternSet owningPatterns(context);
38     for (auto *dialect : context->getLoadedDialects())
39       dialect->getCanonicalizationPatterns(owningPatterns);
40     for (auto *op : context->getRegisteredOperations())
41       op->getCanonicalizationPatterns(owningPatterns, context);
42     patterns = std::move(owningPatterns);
43     return success();
44   }
45   void runOnOperation() override {
46     (void)applyPatternsAndFoldGreedily(getOperation()->getRegions(), patterns,
47                                        config);
48   }
49 
50   GreedyRewriteConfig config;
51   FrozenRewritePatternSet patterns;
52 };
53 } // end anonymous namespace
54 
55 /// Create a Canonicalizer pass.
56 std::unique_ptr<Pass> mlir::createCanonicalizerPass() {
57   return std::make_unique<Canonicalizer>();
58 }
59 
60 /// Creates an instance of the Canonicalizer pass with the specified config.
61 std::unique_ptr<Pass>
62 createCanonicalizerPass(const GreedyRewriteConfig &config) {
63   return std::make_unique<Canonicalizer>(config);
64 }
65