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);
add(StringRef 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;
getOffset(StringRef S)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.
contains(StringRef S)75   bool contains(StringRef S) const {
76     return contains(CachedHashStringRef(S));
77   }
contains(CachedHashStringRef S)78   bool contains(CachedHashStringRef S) const {
79     return StringIndexMap.count(S);
80   }
81 
getSize()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:
isFinalized()89   bool isFinalized() const { return Finalized; }
90 };
91 
92 } // end namespace llvm
93 
94 #endif // LLVM_MC_STRINGTABLEBUILDER_H
95