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+// Copyright (c) 2017 The Khronos Group Inc.
+// Copyright (c) 2017 Valve Corporation
+// Copyright (c) 2017 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 LIBSPIRV_OPT_INSERT_EXTRACT_ELIM_PASS_H_
+#define LIBSPIRV_OPT_INSERT_EXTRACT_ELIM_PASS_H_
+
+
+#include <algorithm>
+#include <map>
+#include <unordered_map>
+#include <unordered_set>
+#include <utility>
+
+#include "basic_block.h"
+#include "def_use_manager.h"
+#include "module.h"
+#include "pass.h"
+
+namespace spvtools {
+namespace opt {
+
+// See optimizer.hpp for documentation.
+class InsertExtractElimPass : public Pass {
+ public:
+  InsertExtractElimPass();
+  const char* name() const override { return "insert_extract_elim"; }
+  Status Process(ir::Module*) override;
+
+ private:
+  // Return true if indices of extract |extInst| and insert |insInst| match
+  bool ExtInsMatch(
+    const ir::Instruction* extInst, const ir::Instruction* insInst) const;
+
+  // Return true if indices of extract |extInst| and insert |insInst| conflict,
+  // specifically, if the insert changes bits specified by the extract, but
+  // changes either more bits or less bits than the extract specifies,
+  // meaning the exact value being inserted cannot be used to replace
+  // the extract.
+  bool ExtInsConflict(
+    const ir::Instruction* extInst, const ir::Instruction* insInst) const;
+
+  // Look for OpExtract on sequence of OpInserts in |func|. If there is an
+  // insert with identical indices, replace the extract with the value
+  // that is inserted if possible. Specifically, replace if there is no
+  // intervening insert which conflicts.
+  bool EliminateInsertExtract(ir::Function* func);
+
+  // Initialize extensions whitelist
+  void InitExtensions();
+
+  // Return true if all extensions in this module are allowed by this pass.
+  bool AllExtensionsSupported() const;
+
+  void Initialize(ir::Module* module);
+  Pass::Status ProcessImpl();
+
+  // Module this pass is processing
+  ir::Module* module_;
+
+  // Def-Uses for the module we are processing
+  std::unique_ptr<analysis::DefUseManager> def_use_mgr_;
+
+  // Map from function's result id to function
+  std::unordered_map<uint32_t, ir::Function*> id2function_;
+
+  // Extensions supported by this pass.
+  std::unordered_set<std::string> extensions_whitelist_;
+};
+
+}  // namespace opt
+}  // namespace spvtools
+
+#endif  // LIBSPIRV_OPT_INSERT_EXTRACT_ELIM_PASS_H_
+