//===- Canonicalizer.cpp - Canonicalize MLIR operations -------------------===//
//
// Copyright 2019 The MLIR Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// =============================================================================
//
// This transformation pass converts operations into their canonical forms by
// folding constants, applying operation identity transformations etc.
//
//===----------------------------------------------------------------------===//

#include "mlir/IR/MLIRContext.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/Pass/Pass.h"
#include "mlir/Transforms/Passes.h"
using namespace mlir;

namespace {
/// Canonicalize operations in nested regions.
struct Canonicalizer : public OperationPass<Canonicalizer> {
  void runOnOperation() override {
    OwningRewritePatternList patterns;

    // TODO: Instead of adding all known patterns from the whole system lazily
    // add and cache the canonicalization patterns for ops we see in practice
    // when building the worklist.  For now, we just grab everything.
    auto *context = &getContext();
    for (auto *op : context->getRegisteredOperations())
      op->getCanonicalizationPatterns(patterns, context);

    Operation *op = getOperation();
    applyPatternsGreedily(op->getRegions(), patterns);
  }
};
} // end anonymous namespace

/// Create a Canonicalizer pass.
std::unique_ptr<Pass> mlir::createCanonicalizerPass() {
  return std::make_unique<Canonicalizer>();
}

static PassRegistration<Canonicalizer> pass("canonicalize",
                                            "Canonicalize operations");