1//===- SymExpr.h - Management of Symbolic Values ----------------*- 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 SymExpr and SymbolData.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SYMEXPR_H
14#define LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SYMEXPR_H
15
16#include "clang/AST/Type.h"
17#include "clang/Basic/LLVM.h"
18#include "llvm/ADT/FoldingSet.h"
19#include "llvm/ADT/SmallVector.h"
20#include "llvm/ADT/iterator_range.h"
21#include <cassert>
22
23namespace clang {
24namespace ento {
25
26class MemRegion;
27
28/// Symbolic value. These values used to capture symbolic execution of
29/// the program.
30class SymExpr : public llvm::FoldingSetNode {
31  virtual void anchor();
32
33public:
34  enum Kind {
35#define SYMBOL(Id, Parent) Id##Kind,
36#define SYMBOL_RANGE(Id, First, Last) BEGIN_##Id = First, END_##Id = Last,
37#include "clang/StaticAnalyzer/Core/PathSensitive/Symbols.def"
38  };
39
40private:
41  Kind K;
42
43protected:
44  SymExpr(Kind k) : K(k) {}
45
46  static bool isValidTypeForSymbol(QualType T) {
47    // FIXME: Depending on whether we choose to deprecate structural symbols,
48    // this may become much stricter.
49    return !T.isNull() && !T->isVoidType();
50  }
51
52  mutable unsigned Complexity = 0;
53
54public:
55  virtual ~SymExpr() = default;
56
57  Kind getKind() const { return K; }
58
59  virtual void dump() const;
60
61  virtual void dumpToStream(raw_ostream &os) const {}
62
63  virtual QualType getType() const = 0;
64  virtual void Profile(llvm::FoldingSetNodeID &profile) = 0;
65
66  /// Iterator over symbols that the current symbol depends on.
67  ///
68  /// For SymbolData, it's the symbol itself; for expressions, it's the
69  /// expression symbol and all the operands in it. Note, SymbolDerived is
70  /// treated as SymbolData - the iterator will NOT visit the parent region.
71  class symbol_iterator {
72    SmallVector<const SymExpr *, 5> itr;
73
74    void expand();
75
76  public:
77    symbol_iterator() = default;
78    symbol_iterator(const SymExpr *SE);
79
80    symbol_iterator &operator++();
81    const SymExpr *operator*();
82
83    bool operator==(const symbol_iterator &X) const;
84    bool operator!=(const symbol_iterator &X) const;
85  };
86
87  llvm::iterator_range<symbol_iterator> symbols() const {
88    return llvm::make_range(symbol_iterator(this), symbol_iterator());
89  }
90
91  virtual unsigned computeComplexity() const = 0;
92
93  /// Find the region from which this symbol originates.
94  ///
95  /// Whenever the symbol was constructed to denote an unknown value of
96  /// a certain memory region, return this region. This method
97  /// allows checkers to make decisions depending on the origin of the symbol.
98  /// Symbol classes for which the origin region is known include
99  /// SymbolRegionValue which denotes the value of the region before
100  /// the beginning of the analysis, and SymbolDerived which denotes the value
101  /// of a certain memory region after its super region (a memory space or
102  /// a larger record region) is default-bound with a certain symbol.
103  /// It might return null.
104  virtual const MemRegion *getOriginRegion() const { return nullptr; }
105};
106
107inline raw_ostream &operator<<(raw_ostream &os,
108                               const clang::ento::SymExpr *SE) {
109  SE->dumpToStream(os);
110  return os;
111}
112
113using SymbolRef = const SymExpr *;
114using SymbolRefSmallVectorTy = SmallVector<SymbolRef, 2>;
115using SymbolID = unsigned;
116
117/// A symbol representing data which can be stored in a memory location
118/// (region).
119class SymbolData : public SymExpr {
120  const SymbolID Sym;
121
122  void anchor() override;
123
124protected:
125  SymbolData(Kind k, SymbolID sym) : SymExpr(k), Sym(sym) {
126    assert(classof(this));
127  }
128
129public:
130  ~SymbolData() override = default;
131
132  /// Get a string representation of the kind of the region.
133  virtual StringRef getKindStr() const = 0;
134
135  SymbolID getSymbolID() const { return Sym; }
136
137  unsigned computeComplexity() const override {
138    return 1;
139  };
140
141  // Implement isa<T> support.
142  static inline bool classof(const SymExpr *SE) {
143    Kind k = SE->getKind();
144    return k >= BEGIN_SYMBOLS && k <= END_SYMBOLS;
145  }
146};
147
148} // namespace ento
149} // namespace clang
150
151#endif // LLVM_CLANG_STATICANALYZER_CORE_PATHSENSITIVE_SYMEXPR_H
152