1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
//===- StringTableBuilder.cpp - String table building utility -------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/StringTableBuilder.h"
#include "llvm/ADT/CachedHashString.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <utility>
#include <vector>
using namespace llvm;
StringTableBuilder::~StringTableBuilder() = default;
void StringTableBuilder::initSize() {
// Account for leading bytes in table so that offsets returned from add are
// correct.
switch (K) {
case RAW:
case DWARF:
Size = 0;
break;
case MachOLinked:
case MachO64Linked:
Size = 2;
break;
case MachO:
case MachO64:
case ELF:
// Start the table with a NUL byte.
Size = 1;
break;
case XCOFF:
case WinCOFF:
// Make room to write the table size later.
Size = 4;
break;
}
}
StringTableBuilder::StringTableBuilder(Kind K, unsigned Alignment)
: K(K), Alignment(Alignment) {
initSize();
}
void StringTableBuilder::write(raw_ostream &OS) const {
assert(isFinalized());
SmallString<0> Data;
Data.resize(getSize());
write((uint8_t *)Data.data());
OS << Data;
}
using StringPair = std::pair<CachedHashStringRef, size_t>;
void StringTableBuilder::write(uint8_t *Buf) const {
assert(isFinalized());
for (const StringPair &P : StringIndexMap) {
StringRef Data = P.first.val();
if (!Data.empty())
memcpy(Buf + P.second, Data.data(), Data.size());
}
// The COFF formats store the size of the string table in the first 4 bytes.
// For Windows, the format is little-endian; for AIX, it is big-endian.
if (K == WinCOFF)
support::endian::write32le(Buf, Size);
else if (K == XCOFF)
support::endian::write32be(Buf, Size);
}
// Returns the character at Pos from end of a string.
static int charTailAt(StringPair *P, size_t Pos) {
StringRef S = P->first.val();
if (Pos >= S.size())
return -1;
return (unsigned char)S[S.size() - Pos - 1];
}
// Three-way radix quicksort. This is much faster than std::sort with strcmp
// because it does not compare characters that we already know the same.
static void multikeySort(MutableArrayRef<StringPair *> Vec, int Pos) {
tailcall:
if (Vec.size() <= 1)
return;
// Partition items so that items in [0, I) are greater than the pivot,
// [I, J) are the same as the pivot, and [J, Vec.size()) are less than
// the pivot.
int Pivot = charTailAt(Vec[0], Pos);
size_t I = 0;
size_t J = Vec.size();
for (size_t K = 1; K < J;) {
int C = charTailAt(Vec[K], Pos);
if (C > Pivot)
std::swap(Vec[I++], Vec[K++]);
else if (C < Pivot)
std::swap(Vec[--J], Vec[K]);
else
K++;
}
multikeySort(Vec.slice(0, I), Pos);
multikeySort(Vec.slice(J), Pos);
// multikeySort(Vec.slice(I, J - I), Pos + 1), but with
// tail call optimization.
if (Pivot != -1) {
Vec = Vec.slice(I, J - I);
++Pos;
goto tailcall;
}
}
void StringTableBuilder::finalize() {
assert(K != DWARF);
finalizeStringTable(/*Optimize=*/true);
}
void StringTableBuilder::finalizeInOrder() {
finalizeStringTable(/*Optimize=*/false);
}
void StringTableBuilder::finalizeStringTable(bool Optimize) {
Finalized = true;
if (Optimize) {
std::vector<StringPair *> Strings;
Strings.reserve(StringIndexMap.size());
for (StringPair &P : StringIndexMap)
Strings.push_back(&P);
multikeySort(Strings, 0);
initSize();
StringRef Previous;
for (StringPair *P : Strings) {
StringRef S = P->first.val();
if (Previous.endswith(S)) {
size_t Pos = Size - S.size() - (K != RAW);
if (!(Pos & (Alignment - 1))) {
P->second = Pos;
continue;
}
}
Size = alignTo(Size, Alignment);
P->second = Size;
Size += S.size();
if (K != RAW)
++Size;
Previous = S;
}
}
if (K == MachO || K == MachOLinked)
Size = alignTo(Size, 4); // Pad to multiple of 4.
if (K == MachO64 || K == MachO64Linked)
Size = alignTo(Size, 8); // Pad to multiple of 8.
// According to ld64 the string table of a final linked Mach-O binary starts
// with " ", i.e. the first byte is ' ' and the second byte is zero. In
// 'initSize()' we reserved the first two bytes for holding this string.
if (K == MachOLinked || K == MachO64Linked)
StringIndexMap[CachedHashStringRef(" ")] = 0;
// The first byte in an ELF string table must be null, according to the ELF
// specification. In 'initSize()' we reserved the first byte to hold null for
// this purpose and here we actually add the string to allow 'getOffset()' to
// be called on an empty string.
if (K == ELF)
StringIndexMap[CachedHashStringRef("")] = 0;
}
void StringTableBuilder::clear() {
Finalized = false;
StringIndexMap.clear();
}
size_t StringTableBuilder::getOffset(CachedHashStringRef S) const {
assert(isFinalized());
auto I = StringIndexMap.find(S);
assert(I != StringIndexMap.end() && "String is not in table!");
return I->second;
}
size_t StringTableBuilder::add(CachedHashStringRef S) {
if (K == WinCOFF)
assert(S.size() > COFF::NameSize && "Short string in COFF string table!");
assert(!isFinalized());
auto P = StringIndexMap.insert(std::make_pair(S, 0));
if (P.second) {
size_t Start = alignTo(Size, Alignment);
P.first->second = Start;
Size = Start + S.size() + (K != RAW);
}
return P.first->second;
}
|
