// Copyright (c) 2026 The Khronos Group 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 LIBSPIRV_OPT_NONWRITABLE_PROPAGATION_PASS_H_

#define LIBSPIRV_OPT_NONWRITABLE_PROPAGATION_PASS_H_

#include "source/opt/pass.h"

namespace spvtools {

namespace opt {

// Propagates NonWritable from a buffer's members to the buffer variable.

//

// Some producers decorate every member of a buffer's struct NonWritable

// instead of decorating the variable itself.  That is legal, but consumers

// that read the decoration off the variable -- for example the mapping APIs

// in VK_EXT_descriptor_heap -- do not see it, so the buffer looks writable.

//

// For each buffer variable (OpVariable or OpUntypedVariableKHR) whose

// struct has every member decorated NonWritable, this pass decorates the

// variable NonWritable and then removes the now-redundant member

// decorations.  Every direct member must carry the decoration, whatever its

// type: a struct-typed member without it is writable as far as SPIR-V is

// concerned, so the variable is left alone.

class NonWritablePropagationPass : public Pass {

 public:

  const char* name() const override { return "nonwritable-propagation"; }

  Status Process() override;

  IRContext::Analysis GetPreservedAnalyses() override {

    // Decorations are the only thing added or removed, and the removal goes

    // through the context, so every analysis except the decoration cache

    // survives untouched.

    return IRContext::kAnalysisDefUse |

           IRContext::kAnalysisInstrToBlockMapping |

           IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |

           IRContext::kAnalysisDominatorAnalysis | IRContext::kAnalysisNameMap |

           IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;

  }

 private:

  // Returns the OpTypeStruct backing |var|'s buffer, or nullptr if |var| is

  // not a variable that may carry NonWritable itself.

  Instruction* GetBufferStructType(const Instruction& var) const;

  // Returns true if every member of |struct_type| is decorated NonWritable.

  bool AllMembersNonWritable(const Instruction& struct_type) const;

};

}  // namespace opt

}  // namespace spvtools

#endif  // LIBSPIRV_OPT_NONWRITABLE_PROPAGATION_PASS_H_