StringTableBuilder.cpp revision cd81d94322a39503e4a3e87b6ee03d4fcb3465fb 
1//===-- StringTableBuilder.cpp - String table building utility ------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#include "llvm/MC/StringTableBuilder.h"
11#include "llvm/ADT/SmallVector.h"
12
13using namespace llvm;
14
15static bool compareBySuffix(StringRef a, StringRef b) {
16  size_t sizeA = a.size();
17  size_t sizeB = b.size();
18  size_t len = std::min(sizeA, sizeB);
19  for (size_t i = 0; i < len; ++i) {
20    char ca = a[sizeA - i - 1];
21    char cb = b[sizeB - i - 1];
22    if (ca != cb)
23      return ca > cb;
24  }
25  return sizeA > sizeB;
26}
27
28void StringTableBuilder::finalize() {
29  SmallVector<StringRef, 8> Strings;
30  for (auto i = StringIndexMap.begin(), e = StringIndexMap.end(); i != e; ++i)
31    Strings.push_back(i->getKey());
32
33  std::sort(Strings.begin(), Strings.end(), compareBySuffix);
34
35  // FIXME: Starting with a null byte is ELF specific. Generalize this so we
36  // can use the class with other object formats.
37  StringTable += '\x00';
38
39  StringRef Previous;
40  for (StringRef s : Strings) {
41    if (Previous.endswith(s)) {
42      StringIndexMap[s] = StringTable.size() - 1 - s.size();
43      continue;
44    }
45
46    StringIndexMap[s] = StringTable.size();
47    StringTable += s;
48    StringTable += '\x00';
49    Previous = s;
50  }
51}
52