// Copyright (c) 2024 Epic Games, 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_STRUCT_PACKING_PASS_

#define SOURCE_OPT_STRUCT_PACKING_PASS_

#include <unordered_map>

#include "source/opt/ir_context.h"

#include "source/opt/module.h"

#include "source/opt/pass.h"

namespace spvtools {

namespace opt {

// This pass re-assigns all field offsets under the specified packing rules.

class StructPackingPass final : public Pass {

 public:

  enum class PackingRules {

    Undefined,

    Std140,

    Std140EnhancedLayout,

    Std430,

    Std430EnhancedLayout,

    HlslCbuffer,

    HlslCbufferPackOffset,

    Scalar,

    ScalarEnhancedLayout,

  };

  static PackingRules ParsePackingRuleFromString(const std::string& s);

  StructPackingPass(const char* structToPack, PackingRules rules);

  const char* name() const override { return "struct-packing"; }

  Status Process() override;

  IRContext::Analysis GetPreservedAnalyses() override {

    return IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |

           IRContext::kAnalysisDominatorAnalysis |

           IRContext::kAnalysisLoopAnalysis | IRContext::kAnalysisNameMap |

           IRContext::kAnalysisScalarEvolution |

           IRContext::kAnalysisStructuredCFG | IRContext::kAnalysisConstants |

           IRContext::kAnalysisDebugInfo | IRContext::kAnalysisLiveness;

  }

 private:

  void buildConstantsMap();

  uint32_t findStructIdByName(const char* structName) const;

  std::vector<const analysis::Type*> findStructMemberTypes(

      const Instruction& structDef) const;

  Status assignStructMemberOffsets(

      uint32_t structIdToPack,

      const std::vector<const analysis::Type*>& structMemberTypes);

  uint32_t getPackedAlignment(const analysis::Type& type) const;

  uint32_t getPackedSize(const analysis::Type& type) const;

  uint32_t getPackedArrayStride(const analysis::Array& arrayType) const;

  uint32_t getArrayLength(const analysis::Array& arrayType) const;

  uint32_t getConstantInt(spv::Id id) const;

 private:

  std::string structToPack_;

  PackingRules packingRules_ = PackingRules::Undefined;

  std::unordered_map<spv::Id, Instruction*> constantsMap_;

};

}  // namespace opt

}  // namespace spvtools

#endif  // SOURCE_OPT_STRUCT_PACKING_PASS_