1 //===- llvm/ValueSymbolTable.h - Implement a Value Symtab -------*- 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 implements the name/Value symbol table for LLVM.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #ifndef LLVM_IR_VALUESYMBOLTABLE_H
14 #define LLVM_IR_VALUESYMBOLTABLE_H
15 
16 #include "llvm/ADT/StringMap.h"
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/IR/Value.h"
19 #include <cstdint>
20 
21 namespace llvm {
22 
23 class Argument;
24 class BasicBlock;
25 class Function;
26 class GlobalAlias;
27 class GlobalIFunc;
28 class GlobalVariable;
29 class Instruction;
30 template <bool ExtraIteratorBits> struct ilist_iterator_bits;
31 template <unsigned InternalLen> class SmallString;
32 template <typename ValueSubClass, typename ... Args> class SymbolTableListTraits;
33 
34 /// This class provides a symbol table of name/value pairs. It is essentially
35 /// a std::map<std::string,Value*> but has a controlled interface provided by
36 /// LLVM as well as ensuring uniqueness of names.
37 ///
38 class ValueSymbolTable {
39   friend class SymbolTableListTraits<Argument>;
40   friend class SymbolTableListTraits<BasicBlock>;
41   friend class SymbolTableListTraits<Function>;
42   friend class SymbolTableListTraits<GlobalAlias>;
43   friend class SymbolTableListTraits<GlobalIFunc>;
44   friend class SymbolTableListTraits<GlobalVariable>;
45   friend class SymbolTableListTraits<Instruction, ilist_iterator_bits<true>>;
46   friend class Value;
47 
48 /// @name Types
49 /// @{
50 public:
51   /// A mapping of names to values.
52   using ValueMap = StringMap<Value*>;
53 
54   /// An iterator over a ValueMap.
55   using iterator = ValueMap::iterator;
56 
57   /// A const_iterator over a ValueMap.
58   using const_iterator = ValueMap::const_iterator;
59 
60 /// @}
61 /// @name Constructors
62 /// @{
63 
64   ValueSymbolTable(int MaxNameSize = -1) : vmap(0), MaxNameSize(MaxNameSize) {}
65   ~ValueSymbolTable();
66 
67   /// @}
68   /// @name Accessors
69   /// @{
70 
71   /// This method finds the value with the given \p Name in the
72   /// the symbol table.
73   /// @returns the value associated with the \p Name
74   /// Lookup a named Value.
75   Value *lookup(StringRef Name) const {
76     if (MaxNameSize > -1 && Name.size() > (unsigned)MaxNameSize)
77       Name = Name.substr(0, std::max(1u, (unsigned)MaxNameSize));
78 
79     return vmap.lookup(Name);
80   }
81 
82   /// @returns true iff the symbol table is empty
83   /// Determine if the symbol table is empty
84   inline bool empty() const { return vmap.empty(); }
85 
86   /// The number of name/type pairs is returned.
87   inline unsigned size() const { return unsigned(vmap.size()); }
88 
89   /// This function can be used from the debugger to display the
90   /// content of the symbol table while debugging.
91   /// Print out symbol table on stderr
92   void dump() const;
93 
94 /// @}
95 /// @name Iteration
96 /// @{
97 
98   /// Get an iterator that from the beginning of the symbol table.
99   inline iterator begin() { return vmap.begin(); }
100 
101   /// Get a const_iterator that from the beginning of the symbol table.
102   inline const_iterator begin() const { return vmap.begin(); }
103 
104   /// Get an iterator to the end of the symbol table.
105   inline iterator end() { return vmap.end(); }
106 
107   /// Get a const_iterator to the end of the symbol table.
108   inline const_iterator end() const { return vmap.end(); }
109 
110   /// @}
111   /// @name Mutators
112   /// @{
113 private:
114   ValueName *makeUniqueName(Value *V, SmallString<256> &UniqueName);
115 
116   /// This method adds the provided value \p N to the symbol table.  The Value
117   /// must have a name which is used to place the value in the symbol table.
118   /// If the inserted name conflicts, this renames the value.
119   /// Add a named value to the symbol table
120   void reinsertValue(Value *V);
121 
122   /// createValueName - This method attempts to create a value name and insert
123   /// it into the symbol table with the specified name.  If it conflicts, it
124   /// auto-renames the name and returns that instead.
125   ValueName *createValueName(StringRef Name, Value *V);
126 
127   /// This method removes a value from the symbol table.  It leaves the
128   /// ValueName attached to the value, but it is no longer inserted in the
129   /// symtab.
130   void removeValueName(ValueName *V);
131 
132   /// @}
133   /// @name Internal Data
134   /// @{
135 
136   ValueMap vmap;                    ///< The map that holds the symbol table.
137   int MaxNameSize; ///< The maximum size for each name. If the limit is
138                    ///< exceeded, the name is capped.
139   mutable uint32_t LastUnique = 0;  ///< Counter for tracking unique names
140 
141 /// @}
142 };
143 
144 } // end namespace llvm
145 
146 #endif // LLVM_IR_VALUESYMBOLTABLE_H
147