text: // Copyright (c) 2022 The Khronos Group Inc.
  // Copyright (c) 2022 LunarG 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_ELIMINATE_DEAD_INPUT_COMPONENTS_H_
  #define SOURCE_OPT_ELIMINATE_DEAD_INPUT_COMPONENTS_H_
  
  #include <unordered_map>
  
  #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 EliminateDeadInputComponentsPass : public Pass {
   public:
    explicit EliminateDeadInputComponentsPass() {}
  
    const char* name() const override { return "reduce-load-size"; }
    Status Process() override;
  
    // Return the mask of preserved Analyses.
    IRContext::Analysis GetPreservedAnalyses() override {
      return IRContext::kAnalysisDefUse |
             IRContext::kAnalysisInstrToBlockMapping |
             IRContext::kAnalysisCombinators | IRContext::kAnalysisCFG |
             IRContext::kAnalysisDominatorAnalysis |
             IRContext::kAnalysisLoopAnalysis | IRContext::kAnalysisNameMap |
             IRContext::kAnalysisConstants | IRContext::kAnalysisTypes;
    }
  
   private:
    // Find the max constant used to index the variable declared by |var|
    // through OpAccessChain or OpInBoundsAccessChain. If any non-constant
    // indices or non-Op*AccessChain use of |var|, return |original_max|.
    unsigned FindMaxIndex(Instruction& var, unsigned original_max);
  
    // Change the length of the array |inst| to |length|
    void ChangeArrayLength(Instruction& inst, unsigned length);
  };
  
  }  // namespace opt
  }  // namespace spvtools
  
  #endif  // SOURCE_OPT_ELIMINATE_DEAD_INPUT_COMPONENTS_H_
  