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  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.