// Copyright (c) 2020 Google LLC
//
// 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_FUZZ_TRANSFORMATION_ACCESS_CHAIN_H_
#define SOURCE_FUZZ_TRANSFORMATION_ACCESS_CHAIN_H_

#include <utility>

#include "source/fuzz/fact_manager.h"
#include "source/fuzz/protobufs/spirvfuzz_protobufs.h"
#include "source/fuzz/transformation.h"
#include "source/opt/ir_context.h"

namespace spvtools {
namespace fuzz {

class TransformationAccessChain : public Transformation {
 public:
  explicit TransformationAccessChain(
      const protobufs::TransformationAccessChain& message);

  TransformationAccessChain(
      uint32_t fresh_id, uint32_t pointer_id,
      const std::vector<uint32_t>& index_id,
      const protobufs::InstructionDescriptor& instruction_to_insert_before);

  // - |message_.fresh_id| must be fresh
  // - |message_.instruction_to_insert_before| must identify an instruction
  //   before which it is legitimate to insert an OpAccessChain instruction
  // - |message_.pointer_id| must be a result id with pointer type that is
  //   available (according to dominance rules) at the insertion point.
  // - The pointer must not be OpConstantNull or OpUndef
  // - |message_.index_id| must be a sequence of ids of 32-bit integer constants
  //   such that it is possible to walk the pointee type of
  //   |message_.pointer_id| using these indices, remaining in-bounds.
  // - If type t is the final type reached by walking these indices, the module
  //   must include an instruction "OpTypePointer SC %t" where SC is the storage
  //   class associated with |message_.pointer_id|
  bool IsApplicable(opt::IRContext* context,
                    const FactManager& fact_manager) const override;

  // Adds an instruction of the form:
  //   |message_.fresh_id| = OpAccessChain %ptr |message_.index_id|
  // where %ptr is the result if of an instruction declaring a pointer to the
  // type reached by walking the pointee type of |message_.pointer_id| using
  // the indices in |message_.index_id|, and with the same storage class as
  // |message_.pointer_id|.
  //
  // If |fact_manager| reports that |message_.pointer_id| has an irrelevant
  // pointee value, then the fact that |message_.fresh_id| (the result of the
  // access chain) also has an irrelevant pointee value is also recorded.
  void Apply(opt::IRContext* context, FactManager* fact_manager) const override;

  protobufs::Transformation ToMessage() const override;

 private:
  // Returns {false, 0} if |index_id| does not correspond to a 32-bit integer
  // constant.  Otherwise, returns {true, value}, where value is the value of
  // the 32-bit integer constant to which |index_id| corresponds.
  std::pair<bool, uint32_t> GetIndexValue(opt::IRContext* context,
                                          uint32_t index_id) const;

  protobufs::TransformationAccessChain message_;
};

}  // namespace fuzz
}  // namespace spvtools

#endif  // SOURCE_FUZZ_TRANSFORMATION_ACCESS_CHAIN_H_