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  1. //===- Solver.h -------------------------------------------------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. //  This file defines an interface for a SAT solver that can be used by
  10. //  dataflow analyses.
  11. //
  12. //===----------------------------------------------------------------------===//
  13.  
  14. #ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_SOLVER_H
  15. #define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_SOLVER_H
  16.  
  17. #include "clang/Analysis/FlowSensitive/Value.h"
  18. #include "llvm/ADT/DenseMap.h"
  19. #include "llvm/ADT/DenseSet.h"
  20. #include <optional>
  21.  
  22. namespace clang {
  23. namespace dataflow {
  24.  
  25. /// An interface for a SAT solver that can be used by dataflow analyses.
  26. class Solver {
  27. public:
  28.   struct Result {
  29.     enum class Status {
  30.       /// Indicates that there exists a satisfying assignment for a boolean
  31.       /// formula.
  32.       Satisfiable,
  33.  
  34.       /// Indicates that there is no satisfying assignment for a boolean
  35.       /// formula.
  36.       Unsatisfiable,
  37.  
  38.       /// Indicates that the solver gave up trying to find a satisfying
  39.       /// assignment for a boolean formula.
  40.       TimedOut,
  41.     };
  42.  
  43.     /// A boolean value is set to true or false in a truth assignment.
  44.     enum class Assignment : uint8_t { AssignedFalse = 0, AssignedTrue = 1 };
  45.  
  46.     /// Constructs a result indicating that the queried boolean formula is
  47.     /// satisfiable. The result will hold a solution found by the solver.
  48.     static Result
  49.     Satisfiable(llvm::DenseMap<AtomicBoolValue *, Assignment> Solution) {
  50.       return Result(Status::Satisfiable, std::move(Solution));
  51.     }
  52.  
  53.     /// Constructs a result indicating that the queried boolean formula is
  54.     /// unsatisfiable.
  55.     static Result Unsatisfiable() { return Result(Status::Unsatisfiable, {}); }
  56.  
  57.     /// Constructs a result indicating that satisfiability checking on the
  58.     /// queried boolean formula was not completed.
  59.     static Result TimedOut() { return Result(Status::TimedOut, {}); }
  60.  
  61.     /// Returns the status of satisfiability checking on the queried boolean
  62.     /// formula.
  63.     Status getStatus() const { return SATCheckStatus; }
  64.  
  65.     /// Returns a truth assignment to boolean values that satisfies the queried
  66.     /// boolean formula if available. Otherwise, an empty optional is returned.
  67.     std::optional<llvm::DenseMap<AtomicBoolValue *, Assignment>>
  68.     getSolution() const {
  69.       return Solution;
  70.     }
  71.  
  72.   private:
  73.     Result(
  74.         enum Status SATCheckStatus,
  75.         std::optional<llvm::DenseMap<AtomicBoolValue *, Assignment>> Solution)
  76.         : SATCheckStatus(SATCheckStatus), Solution(std::move(Solution)) {}
  77.  
  78.     Status SATCheckStatus;
  79.     std::optional<llvm::DenseMap<AtomicBoolValue *, Assignment>> Solution;
  80.   };
  81.  
  82.   virtual ~Solver() = default;
  83.  
  84.   /// Checks if the conjunction of `Vals` is satisfiable and returns the
  85.   /// corresponding result.
  86.   ///
  87.   /// Requirements:
  88.   ///
  89.   ///  All elements in `Vals` must not be null.
  90.   virtual Result solve(llvm::DenseSet<BoolValue *> Vals) = 0;
  91. };
  92.  
  93. } // namespace dataflow
  94. } // namespace clang
  95.  
  96. #endif // LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_SOLVER_H
  97.