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+// 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_LIVENESS_H_
+#define SOURCE_OPT_LIVENESS_H_
+
+#include <cstdint>
+#include <unordered_set>
+
+namespace spvtools {
+namespace opt {
+
+class IRContext;
+class Instruction;
+
+namespace analysis {
+
+class Type;
+
+// This class represents the liveness of the input variables of a module
+class LivenessManager {
+ public:
+  LivenessManager(IRContext* ctx);
+
+  // Copy liveness info into |live_locs| and |builtin_locs|.
+  void GetLiveness(std::unordered_set<uint32_t>* live_locs,
+                   std::unordered_set<uint32_t>* live_builtins);
+
+  // Return true if builtin |bi| is being analyzed.
+  bool IsAnalyzedBuiltin(uint32_t bi);
+
+  // Determine starting loc |offset| and the type |cur_type| of
+  // access chain |ac|. Set |no_loc| to true if no loc found.
+  // |is_patch| indicates if patch variable. |input| is true
+  // if input variable, otherwise output variable.
+  void AnalyzeAccessChainLoc(const Instruction* ac,
+                             const analysis::Type** curr_type, uint32_t* offset,
+                             bool* no_loc, bool is_patch, bool input = true);
+
+  // Return size of |type_id| in units of locations
+  uint32_t GetLocSize(const analysis::Type* type) const;
+
+ private:
+  IRContext* context() const { return ctx_; }
+
+  // Initialize analysis
+  void InitializeAnalysis();
+
+  // Analyze |id| for builtin var and struct members. Return true if builtins
+  // found.
+  bool AnalyzeBuiltIn(uint32_t id);
+
+  // Mark all live locations resulting from |user| of |var| at |loc|.
+  void MarkRefLive(const Instruction* user, Instruction* var);
+
+  // Mark |count| locations starting at location |start|.
+  void MarkLocsLive(uint32_t start, uint32_t count);
+
+  // Return type of component of aggregate type |agg_type| at |index|
+  const analysis::Type* GetComponentType(uint32_t index,
+                                         const analysis::Type* agg_type) const;
+
+  // Return offset of |index| into aggregate type |agg_type| in units of
+  // input locations
+  uint32_t GetLocOffset(uint32_t index, const analysis::Type* agg_type) const;
+
+  // Populate live_locs_ and live_builtins_
+  void ComputeLiveness();
+
+  // IR context that owns this liveness manager.
+  IRContext* ctx_;
+
+  // True if live_locs_ and live_builtins_ are computed
+  bool computed_;
+
+  // Live locations
+  std::unordered_set<uint32_t> live_locs_;
+
+  // Live builtins
+  std::unordered_set<uint32_t> live_builtins_;
+};
+
+}  // namespace analysis
+}  // namespace opt
+}  // namespace spvtools
+
+#endif  // SOURCE_OPT_LIVENESS_H_