| //===-- Arena.h -------------------------------*- C++ -------------------*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| #ifndef LLVM_CLANG_ANALYSIS_FLOWSENSITIVE__ARENA_H |
| #define LLVM_CLANG_ANALYSIS_FLOWSENSITIVE__ARENA_H |
| |
| #include "clang/Analysis/FlowSensitive/Formula.h" |
| #include "clang/Analysis/FlowSensitive/StorageLocation.h" |
| #include "clang/Analysis/FlowSensitive/Value.h" |
| #include <vector> |
| |
| namespace clang::dataflow { |
| |
| /// The Arena owns the objects that model data within an analysis. |
| /// For example, `Value`, `StorageLocation`, `Atom`, and `Formula`. |
| class Arena { |
| public: |
| Arena() : True(makeAtom()), False(makeAtom()) {} |
| Arena(const Arena &) = delete; |
| Arena &operator=(const Arena &) = delete; |
| |
| /// Creates a `T` (some subclass of `StorageLocation`), forwarding `args` to |
| /// the constructor, and returns a reference to it. |
| /// |
| /// The `DataflowAnalysisContext` takes ownership of the created object. The |
| /// object will be destroyed when the `DataflowAnalysisContext` is destroyed. |
| template <typename T, typename... Args> |
| std::enable_if_t<std::is_base_of<StorageLocation, T>::value, T &> |
| create(Args &&...args) { |
| // Note: If allocation of individual `StorageLocation`s turns out to be |
| // costly, consider creating specializations of `create<T>` for commonly |
| // used `StorageLocation` subclasses and make them use a `BumpPtrAllocator`. |
| return *cast<T>( |
| Locs.emplace_back(std::make_unique<T>(std::forward<Args>(args)...)) |
| .get()); |
| } |
| |
| /// Creates a `T` (some subclass of `Value`), forwarding `args` to the |
| /// constructor, and returns a reference to it. |
| /// |
| /// The `DataflowAnalysisContext` takes ownership of the created object. The |
| /// object will be destroyed when the `DataflowAnalysisContext` is destroyed. |
| template <typename T, typename... Args> |
| std::enable_if_t<std::is_base_of<Value, T>::value, T &> |
| create(Args &&...args) { |
| // Note: If allocation of individual `Value`s turns out to be costly, |
| // consider creating specializations of `create<T>` for commonly used |
| // `Value` subclasses and make them use a `BumpPtrAllocator`. |
| return *cast<T>( |
| Vals.emplace_back(std::make_unique<T>(std::forward<Args>(args)...)) |
| .get()); |
| } |
| |
| /// Creates a BoolValue wrapping a particular formula. |
| /// |
| /// Passing in the same formula will result in the same BoolValue. |
| /// FIXME: Interning BoolValues but not other Values is inconsistent. |
| /// Decide whether we want Value interning or not. |
| BoolValue &makeBoolValue(const Formula &); |
| |
| /// Creates a fresh atom and wraps in in an AtomicBoolValue. |
| /// FIXME: For now, identical-address AtomicBoolValue <=> identical atom. |
| /// Stop relying on pointer identity and remove this guarantee. |
| AtomicBoolValue &makeAtomValue() { |
| return cast<AtomicBoolValue>(makeBoolValue(makeAtomRef(makeAtom()))); |
| } |
| |
| /// Creates a fresh Top boolean value. |
| TopBoolValue &makeTopValue() { |
| // No need for deduplicating: there's no way to create aliasing Tops. |
| return create<TopBoolValue>(makeAtomRef(makeAtom())); |
| } |
| |
| /// Returns a symbolic integer value that models an integer literal equal to |
| /// `Value`. These literals are the same every time. |
| /// Integer literals are not typed; the type is determined by the `Expr` that |
| /// an integer literal is associated with. |
| IntegerValue &makeIntLiteral(llvm::APInt Value); |
| |
| // Factories for boolean formulas. |
| // Formulas are interned: passing the same arguments return the same result. |
| // For commutative operations like And/Or, interning ignores order. |
| // Simplifications are applied: makeOr(X, X) => X, etc. |
| |
| /// Returns a formula for the conjunction of `LHS` and `RHS`. |
| const Formula &makeAnd(const Formula &LHS, const Formula &RHS); |
| |
| /// Returns a formula for the disjunction of `LHS` and `RHS`. |
| const Formula &makeOr(const Formula &LHS, const Formula &RHS); |
| |
| /// Returns a formula for the negation of `Val`. |
| const Formula &makeNot(const Formula &Val); |
| |
| /// Returns a formula for `LHS => RHS`. |
| const Formula &makeImplies(const Formula &LHS, const Formula &RHS); |
| |
| /// Returns a formula for `LHS <=> RHS`. |
| const Formula &makeEquals(const Formula &LHS, const Formula &RHS); |
| |
| /// Returns a formula for the variable A. |
| const Formula &makeAtomRef(Atom A); |
| |
| /// Returns a formula for a literal true/false. |
| const Formula &makeLiteral(bool Value) { |
| return makeAtomRef(Value ? True : False); |
| } |
| |
| /// Returns a new atomic boolean variable, distinct from any other. |
| Atom makeAtom() { return static_cast<Atom>(NextAtom++); }; |
| |
| /// Creates a fresh flow condition and returns a token that identifies it. The |
| /// token can be used to perform various operations on the flow condition such |
| /// as adding constraints to it, forking it, joining it with another flow |
| /// condition, or checking implications. |
| Atom makeFlowConditionToken() { return makeAtom(); } |
| |
| private: |
| llvm::BumpPtrAllocator Alloc; |
| |
| // Storage for the state of a program. |
| std::vector<std::unique_ptr<StorageLocation>> Locs; |
| std::vector<std::unique_ptr<Value>> Vals; |
| |
| // Indices that are used to avoid recreating the same integer literals and |
| // composite boolean values. |
| llvm::DenseMap<llvm::APInt, IntegerValue *> IntegerLiterals; |
| using FormulaPair = std::pair<const Formula *, const Formula *>; |
| llvm::DenseMap<FormulaPair, const Formula *> Ands; |
| llvm::DenseMap<FormulaPair, const Formula *> Ors; |
| llvm::DenseMap<const Formula *, const Formula *> Nots; |
| llvm::DenseMap<FormulaPair, const Formula *> Implies; |
| llvm::DenseMap<FormulaPair, const Formula *> Equals; |
| llvm::DenseMap<Atom, const Formula *> AtomRefs; |
| |
| llvm::DenseMap<const Formula *, BoolValue *> FormulaValues; |
| unsigned NextAtom = 0; |
| |
| Atom True, False; |
| }; |
| |
| } // namespace clang::dataflow |
| |
| #endif // LLVM_CLANG_ANALYSIS_FLOWSENSITIVE__ARENA_H |