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//===- Solver.h -------------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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//  This file defines an interface for a SAT solver that can be used by
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//  dataflow analyses.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_SOLVER_H
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#define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_SOLVER_H
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#include "clang/Analysis/FlowSensitive/Value.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/DenseSet.h"
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#include <optional>
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namespace clang {
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namespace dataflow {
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/// An interface for a SAT solver that can be used by dataflow analyses.
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class Solver {
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public:
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  struct Result {
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    enum class Status {
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      /// Indicates that there exists a satisfying assignment for a boolean
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      /// formula.
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      Satisfiable,
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      /// Indicates that there is no satisfying assignment for a boolean
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      /// formula.
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      Unsatisfiable,
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      /// Indicates that the solver gave up trying to find a satisfying
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      /// assignment for a boolean formula.
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      TimedOut,
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    };
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    /// A boolean value is set to true or false in a truth assignment.
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    enum class Assignment : uint8_t { AssignedFalse = 0, AssignedTrue = 1 };
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    /// Constructs a result indicating that the queried boolean formula is
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    /// satisfiable. The result will hold a solution found by the solver.
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    static Result
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    Satisfiable(llvm::DenseMap<AtomicBoolValue *, Assignment> Solution) {
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      return Result(Status::Satisfiable, std::move(Solution));
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    }
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    /// Constructs a result indicating that the queried boolean formula is
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    /// unsatisfiable.
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    static Result Unsatisfiable() { return Result(Status::Unsatisfiable, {}); }
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    /// Constructs a result indicating that satisfiability checking on the
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    /// queried boolean formula was not completed.
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    static Result TimedOut() { return Result(Status::TimedOut, {}); }
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    /// Returns the status of satisfiability checking on the queried boolean
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    /// formula.
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    Status getStatus() const { return SATCheckStatus; }
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    /// Returns a truth assignment to boolean values that satisfies the queried
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    /// boolean formula if available. Otherwise, an empty optional is returned.
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    std::optional<llvm::DenseMap<AtomicBoolValue *, Assignment>>
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    getSolution() const {
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      return Solution;
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    }
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  private:
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    Result(
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        enum Status SATCheckStatus,
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        std::optional<llvm::DenseMap<AtomicBoolValue *, Assignment>> Solution)
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        : SATCheckStatus(SATCheckStatus), Solution(std::move(Solution)) {}
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    Status SATCheckStatus;
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    std::optional<llvm::DenseMap<AtomicBoolValue *, Assignment>> Solution;
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  };
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  virtual ~Solver() = default;
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  /// Checks if the conjunction of `Vals` is satisfiable and returns the
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  /// corresponding result.
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  ///
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  /// Requirements:
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  ///
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  ///  All elements in `Vals` must not be null.
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  virtual Result solve(llvm::DenseSet<BoolValue *> Vals) = 0;
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};
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} // namespace dataflow
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} // namespace clang
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#endif // LLVM_CLANG_ANALYSIS_FLOWSENSITIVE_SOLVER_H