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      1 //===- StringTableBuilder.h - String table building utility -----*- 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 #ifndef LLVM_MC_STRINGTABLEBUILDER_H
     10 #define LLVM_MC_STRINGTABLEBUILDER_H
     11 
     12 #include "llvm/ADT/CachedHashString.h"
     13 #include "llvm/ADT/DenseMap.h"
     14 #include "llvm/ADT/StringRef.h"
     15 #include <cstddef>
     16 #include <cstdint>
     17 
     18 namespace llvm {
     19 
     20 class raw_ostream;
     21 
     22 /// Utility for building string tables with deduplicated suffixes.
     23 class StringTableBuilder {
     24 public:
     25   enum Kind {
     26     ELF,
     27     WinCOFF,
     28     MachO,
     29     MachO64,
     30     MachOLinked,
     31     MachO64Linked,
     32     RAW,
     33     DWARF,
     34     XCOFF
     35   };
     36 
     37 private:
     38   DenseMap<CachedHashStringRef, size_t> StringIndexMap;
     39   size_t Size = 0;
     40   Kind K;
     41   unsigned Alignment;
     42   bool Finalized = false;
     43 
     44   void finalizeStringTable(bool Optimize);
     45   void initSize();
     46 
     47 public:
     48   StringTableBuilder(Kind K, unsigned Alignment = 1);
     49   ~StringTableBuilder();
     50 
     51   /// Add a string to the builder. Returns the position of S in the
     52   /// table. The position will be changed if finalize is used.
     53   /// Can only be used before the table is finalized.
     54   size_t add(CachedHashStringRef S);
     55   size_t add(StringRef S) { return add(CachedHashStringRef(S)); }
     56 
     57   /// Analyze the strings and build the final table. No more strings can
     58   /// be added after this point.
     59   void finalize();
     60 
     61   /// Finalize the string table without reording it. In this mode, offsets
     62   /// returned by add will still be valid.
     63   void finalizeInOrder();
     64 
     65   /// Get the offest of a string in the string table. Can only be used
     66   /// after the table is finalized.
     67   size_t getOffset(CachedHashStringRef S) const;
     68   size_t getOffset(StringRef S) const {
     69     return getOffset(CachedHashStringRef(S));
     70   }
     71 
     72   /// Check if a string is contained in the string table. Since this class
     73   /// doesn't store the string values, this function can be used to check if
     74   /// storage needs to be done prior to adding the string.
     75   bool contains(StringRef S) const {
     76     return contains(CachedHashStringRef(S));
     77   }
     78   bool contains(CachedHashStringRef S) const {
     79     return StringIndexMap.count(S);
     80   }
     81 
     82   size_t getSize() const { return Size; }
     83   void clear();
     84 
     85   void write(raw_ostream &OS) const;
     86   void write(uint8_t *Buf) const;
     87 
     88 private:
     89   bool isFinalized() const { return Finalized; }
     90 };
     91 
     92 } // end namespace llvm
     93 
     94 #endif // LLVM_MC_STRINGTABLEBUILDER_H
     95