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