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 { ELF, WinCOFF, MachO, RAW, DWARF, XCOFF };
26 
27 private:
28   DenseMap<CachedHashStringRef, size_t> StringIndexMap;
29   size_t Size = 0;
30   Kind K;
31   unsigned Alignment;
32   bool Finalized = false;
33 
34   void finalizeStringTable(bool Optimize);
35   void initSize();
36 
37 public:
38   StringTableBuilder(Kind K, unsigned Alignment = 1);
39   ~StringTableBuilder();
40 
41   /// Add a string to the builder. Returns the position of S in the
42   /// table. The position will be changed if finalize is used.
43   /// Can only be used before the table is finalized.
44   size_t add(CachedHashStringRef S);
add(StringRef S)45   size_t add(StringRef S) { return add(CachedHashStringRef(S)); }
46 
47   /// Analyze the strings and build the final table. No more strings can
48   /// be added after this point.
49   void finalize();
50 
51   /// Finalize the string table without reording it. In this mode, offsets
52   /// returned by add will still be valid.
53   void finalizeInOrder();
54 
55   /// Get the offest of a string in the string table. Can only be used
56   /// after the table is finalized.
57   size_t getOffset(CachedHashStringRef S) const;
getOffset(StringRef S)58   size_t getOffset(StringRef S) const {
59     return getOffset(CachedHashStringRef(S));
60   }
61 
62   /// Check if a string is contained in the string table. Since this class
63   /// doesn't store the string values, this function can be used to check if
64   /// storage needs to be done prior to adding the string.
contains(StringRef S)65   bool contains(StringRef S) const {
66     return contains(CachedHashStringRef(S));
67   }
contains(CachedHashStringRef S)68   bool contains(CachedHashStringRef S) const {
69     return StringIndexMap.count(S);
70   }
71 
getSize()72   size_t getSize() const { return Size; }
73   void clear();
74 
75   void write(raw_ostream &OS) const;
76   void write(uint8_t *Buf) const;
77 
78 private:
isFinalized()79   bool isFinalized() const { return Finalized; }
80 };
81 
82 } // end namespace llvm
83 
84 #endif // LLVM_MC_STRINGTABLEBUILDER_H
85