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