// Copyright (c) 2017 Google Inc.

//

// 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.

#ifndef SOURCE_OPT_STRENGTH_REDUCTION_PASS_H_

#define SOURCE_OPT_STRENGTH_REDUCTION_PASS_H_

#include "source/opt/def_use_manager.h"

#include "source/opt/ir_context.h"

#include "source/opt/module.h"

#include "source/opt/pass.h"

namespace spvtools {

namespace opt {

// See optimizer.hpp for documentation.

class StrengthReductionPass : public Pass {

 public:

  const char* name() const override { return "strength-reduction"; }

  Status Process() override;

 private:

  // Replaces multiple by power of 2 with an equivalent bit shift.

  // Returns true if something changed.

  Status ReplaceMultiplyByPowerOf2(BasicBlock::iterator*);

  // Scan the types and constants in the module looking for the integer

  // types that we are

  // interested in.  The shift operation needs a small unsigned integer.  We

  // need to find

  // them or create them.  We do not want duplicates.

  void FindIntTypesAndConstants();

  // Get the id for the given constant.  If it does not exist, it will be

  // created.  The parameter must be between 0 and 32 inclusive.

  uint32_t GetConstantId(uint32_t);

  // Replaces certain instructions in function bodies with presumably cheaper

  // ones. Returns true if something changed.

  Status ScanFunctions();

  // Type ids for the types of interest, or 0 if they do not exist.

  uint32_t int32_type_id_;

  uint32_t uint32_type_id_;

  // constant_ids[i] is the id for unsigned integer constant i.

  // We set the limit at 32 because a bit shift of a 32-bit integer does not

  // need a value larger than 32.

  uint32_t constant_ids_[33];

};

}  // namespace opt

}  // namespace spvtools

#endif  // SOURCE_OPT_STRENGTH_REDUCTION_PASS_H_