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,
25                 ArrayRef<std::string> disabledPatterns,
26                 ArrayRef<std::string> enabledPatterns)
27       : config(config) {
28     this->disabledPatterns = disabledPatterns;
29     this->enabledPatterns = enabledPatterns;
30   }
31 
32   Canonicalizer() {
33     // Default constructed Canonicalizer takes its settings from command line
34     // options.
35     config.useTopDownTraversal = topDownProcessingEnabled;
36     config.enableRegionSimplification = enableRegionSimplification;
37     config.maxIterations = maxIterations;
38   }
39 
40   /// Initialize the canonicalizer by building the set of patterns used during
41   /// execution.
42   LogicalResult initialize(MLIRContext *context) override {
43     RewritePatternSet owningPatterns(context);
44     for (auto *dialect : context->getLoadedDialects())
45       dialect->getCanonicalizationPatterns(owningPatterns);
46     for (RegisteredOperationName op : context->getRegisteredOperations())
47       op.getCanonicalizationPatterns(owningPatterns, context);
48 
49     patterns = FrozenRewritePatternSet(std::move(owningPatterns),
50                                        disabledPatterns, enabledPatterns);
51     return success();
52   }
53   void runOnOperation() override {
54     (void)applyPatternsAndFoldGreedily(getOperation()->getRegions(), patterns,
55                                        config);
56   }
57 
58   GreedyRewriteConfig config;
59   FrozenRewritePatternSet patterns;
60 };
61 } // namespace
62 
63 /// Create a Canonicalizer pass.
64 std::unique_ptr<Pass> mlir::createCanonicalizerPass() {
65   return std::make_unique<Canonicalizer>();
66 }
67 
68 /// Creates an instance of the Canonicalizer pass with the specified config.
69 std::unique_ptr<Pass>
70 mlir::createCanonicalizerPass(const GreedyRewriteConfig &config,
71                               ArrayRef<std::string> disabledPatterns,
72                               ArrayRef<std::string> enabledPatterns) {
73   return std::make_unique<Canonicalizer>(config, disabledPatterns,
74                                          enabledPatterns);
75 }
76