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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
|
//===-- RecordStreamer.cpp - Record asm defined and used symbols ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "RecordStreamer.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Module.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSymbol.h"
using namespace llvm;
void RecordStreamer::markDefined(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Global:
S = DefinedGlobal;
break;
case NeverSeen:
case Defined:
case Used:
S = Defined;
break;
case DefinedWeak:
break;
case UndefinedWeak:
S = DefinedWeak;
}
}
void RecordStreamer::markGlobal(const MCSymbol &Symbol,
MCSymbolAttr Attribute) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Defined:
S = (Attribute == MCSA_Weak) ? DefinedWeak : DefinedGlobal;
break;
case NeverSeen:
case Global:
case Used:
S = (Attribute == MCSA_Weak) ? UndefinedWeak : Global;
break;
case UndefinedWeak:
case DefinedWeak:
break;
}
}
void RecordStreamer::markUsed(const MCSymbol &Symbol) {
State &S = Symbols[Symbol.getName()];
switch (S) {
case DefinedGlobal:
case Defined:
case Global:
case DefinedWeak:
case UndefinedWeak:
break;
case NeverSeen:
case Used:
S = Used;
break;
}
}
void RecordStreamer::visitUsedSymbol(const MCSymbol &Sym) { markUsed(Sym); }
RecordStreamer::RecordStreamer(MCContext &Context, const Module &M)
: MCStreamer(Context), M(M) {}
RecordStreamer::const_iterator RecordStreamer::begin() {
return Symbols.begin();
}
RecordStreamer::const_iterator RecordStreamer::end() { return Symbols.end(); }
void RecordStreamer::EmitInstruction(const MCInst &Inst,
const MCSubtargetInfo &STI, bool) {
MCStreamer::EmitInstruction(Inst, STI);
}
void RecordStreamer::EmitLabel(MCSymbol *Symbol, SMLoc Loc) {
MCStreamer::EmitLabel(Symbol);
markDefined(*Symbol);
}
void RecordStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
markDefined(*Symbol);
MCStreamer::EmitAssignment(Symbol, Value);
}
bool RecordStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
MCSymbolAttr Attribute) {
if (Attribute == MCSA_Global || Attribute == MCSA_Weak)
markGlobal(*Symbol, Attribute);
if (Attribute == MCSA_LazyReference)
markUsed(*Symbol);
return true;
}
void RecordStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
uint64_t Size, unsigned ByteAlignment,
SMLoc Loc) {
markDefined(*Symbol);
}
void RecordStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
unsigned ByteAlignment) {
markDefined(*Symbol);
}
RecordStreamer::State RecordStreamer::getSymbolState(const MCSymbol *Sym) {
auto SI = Symbols.find(Sym->getName());
if (SI == Symbols.end())
return NeverSeen;
return SI->second;
}
void RecordStreamer::emitELFSymverDirective(StringRef AliasName,
const MCSymbol *Aliasee) {
SymverAliasMap[Aliasee].push_back(AliasName);
}
iterator_range<RecordStreamer::const_symver_iterator>
RecordStreamer::symverAliases() {
return {SymverAliasMap.begin(), SymverAliasMap.end()};
}
void RecordStreamer::flushSymverDirectives() {
// Mapping from mangled name to GV.
StringMap<const GlobalValue *> MangledNameMap;
// The name in the assembler will be mangled, but the name in the IR
// might not, so we first compute a mapping from mangled name to GV.
Mangler Mang;
SmallString<64> MangledName;
for (const GlobalValue &GV : M.global_values()) {
if (!GV.hasName())
continue;
MangledName.clear();
MangledName.reserve(GV.getName().size() + 1);
Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
MangledNameMap[MangledName] = &GV;
}
// Walk all the recorded .symver aliases, and set up the binding
// for each alias.
for (auto &Symver : SymverAliasMap) {
const MCSymbol *Aliasee = Symver.first;
MCSymbolAttr Attr = MCSA_Invalid;
bool IsDefined = false;
// First check if the aliasee binding was recorded in the asm.
RecordStreamer::State state = getSymbolState(Aliasee);
switch (state) {
case RecordStreamer::Global:
case RecordStreamer::DefinedGlobal:
Attr = MCSA_Global;
break;
case RecordStreamer::UndefinedWeak:
case RecordStreamer::DefinedWeak:
Attr = MCSA_Weak;
break;
default:
break;
}
switch (state) {
case RecordStreamer::Defined:
case RecordStreamer::DefinedGlobal:
case RecordStreamer::DefinedWeak:
IsDefined = true;
break;
case RecordStreamer::NeverSeen:
case RecordStreamer::Global:
case RecordStreamer::Used:
case RecordStreamer::UndefinedWeak:
break;
}
if (Attr == MCSA_Invalid || !IsDefined) {
const GlobalValue *GV = M.getNamedValue(Aliasee->getName());
if (!GV) {
auto MI = MangledNameMap.find(Aliasee->getName());
if (MI != MangledNameMap.end())
GV = MI->second;
}
if (GV) {
// If we don't have a symbol attribute from assembly, then check if
// the aliasee was defined in the IR.
if (Attr == MCSA_Invalid) {
if (GV->hasExternalLinkage())
Attr = MCSA_Global;
else if (GV->hasLocalLinkage())
Attr = MCSA_Local;
else if (GV->isWeakForLinker())
Attr = MCSA_Weak;
}
IsDefined = IsDefined || !GV->isDeclarationForLinker();
}
}
// Set the detected binding on each alias with this aliasee.
for (auto AliasName : Symver.second) {
std::pair<StringRef, StringRef> Split = AliasName.split("@@@");
SmallString<128> NewName;
if (!Split.second.empty() && !Split.second.startswith("@")) {
// Special processing for "@@@" according
// https://sourceware.org/binutils/docs/as/Symver.html
const char *Separator = IsDefined ? "@@" : "@";
AliasName =
(Split.first + Separator + Split.second).toStringRef(NewName);
}
MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
// TODO: Handle "@@@". Depending on SymbolAttribute value it needs to be
// converted into @ or @@.
const MCExpr *Value = MCSymbolRefExpr::create(Aliasee, getContext());
if (IsDefined)
markDefined(*Alias);
// Don't use EmitAssignment override as it always marks alias as defined.
MCStreamer::EmitAssignment(Alias, Value);
if (Attr != MCSA_Invalid)
EmitSymbolAttribute(Alias, Attr);
}
}
}
|
