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
|
//===-- ModuleUtils.cpp - Functions to manipulate Modules -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This family of functions perform manipulations on Modules.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
static void appendToGlobalArray(const char *Array, Module &M, Function *F,
int Priority, Constant *Data) {
IRBuilder<> IRB(M.getContext());
FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
// Get the current set of static global constructors and add the new ctor
// to the list.
SmallVector<Constant *, 16> CurrentCtors;
StructType *EltTy;
if (GlobalVariable *GVCtor = M.getNamedGlobal(Array)) {
ArrayType *ATy = cast<ArrayType>(GVCtor->getValueType());
StructType *OldEltTy = cast<StructType>(ATy->getElementType());
// Upgrade a 2-field global array type to the new 3-field format if needed.
if (Data && OldEltTy->getNumElements() < 3)
EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
IRB.getInt8PtrTy(), nullptr);
else
EltTy = OldEltTy;
if (Constant *Init = GVCtor->getInitializer()) {
unsigned n = Init->getNumOperands();
CurrentCtors.reserve(n + 1);
for (unsigned i = 0; i != n; ++i) {
auto Ctor = cast<Constant>(Init->getOperand(i));
if (EltTy != OldEltTy)
Ctor = ConstantStruct::get(
EltTy, Ctor->getAggregateElement((unsigned)0),
Ctor->getAggregateElement(1),
Constant::getNullValue(IRB.getInt8PtrTy()), nullptr);
CurrentCtors.push_back(Ctor);
}
}
GVCtor->eraseFromParent();
} else {
// Use the new three-field struct if there isn't one already.
EltTy = StructType::get(IRB.getInt32Ty(), PointerType::getUnqual(FnTy),
IRB.getInt8PtrTy(), nullptr);
}
// Build a 2 or 3 field global_ctor entry. We don't take a comdat key.
Constant *CSVals[3];
CSVals[0] = IRB.getInt32(Priority);
CSVals[1] = F;
// FIXME: Drop support for the two element form in LLVM 4.0.
if (EltTy->getNumElements() >= 3)
CSVals[2] = Data ? ConstantExpr::getPointerCast(Data, IRB.getInt8PtrTy())
: Constant::getNullValue(IRB.getInt8PtrTy());
Constant *RuntimeCtorInit =
ConstantStruct::get(EltTy, makeArrayRef(CSVals, EltTy->getNumElements()));
CurrentCtors.push_back(RuntimeCtorInit);
// Create a new initializer.
ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
// Create the new global variable and replace all uses of
// the old global variable with the new one.
(void)new GlobalVariable(M, NewInit->getType(), false,
GlobalValue::AppendingLinkage, NewInit, Array);
}
void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority, Constant *Data) {
appendToGlobalArray("llvm.global_ctors", M, F, Priority, Data);
}
void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *Data) {
appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
}
static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *> Values) {
GlobalVariable *GV = M.getGlobalVariable(Name);
SmallPtrSet<Constant *, 16> InitAsSet;
SmallVector<Constant *, 16> Init;
if (GV) {
ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
for (auto &Op : CA->operands()) {
Constant *C = cast_or_null<Constant>(Op);
if (InitAsSet.insert(C).second)
Init.push_back(C);
}
GV->eraseFromParent();
}
Type *Int8PtrTy = llvm::Type::getInt8PtrTy(M.getContext());
for (auto *V : Values) {
Constant *C = ConstantExpr::getBitCast(V, Int8PtrTy);
if (InitAsSet.insert(C).second)
Init.push_back(C);
}
if (Init.empty())
return;
ArrayType *ATy = ArrayType::get(Int8PtrTy, Init.size());
GV = new llvm::GlobalVariable(M, ATy, false, GlobalValue::AppendingLinkage,
ConstantArray::get(ATy, Init), Name);
GV->setSection("llvm.metadata");
}
void llvm::appendToUsed(Module &M, ArrayRef<GlobalValue *> Values) {
appendToUsedList(M, "llvm.used", Values);
}
void llvm::appendToCompilerUsed(Module &M, ArrayRef<GlobalValue *> Values) {
appendToUsedList(M, "llvm.compiler.used", Values);
}
Function *llvm::checkSanitizerInterfaceFunction(Constant *FuncOrBitcast) {
if (isa<Function>(FuncOrBitcast))
return cast<Function>(FuncOrBitcast);
FuncOrBitcast->print(errs());
errs() << '\n';
std::string Err;
raw_string_ostream Stream(Err);
Stream << "Sanitizer interface function redefined: " << *FuncOrBitcast;
report_fatal_error(Err);
}
std::pair<Function *, Function *> llvm::createSanitizerCtorAndInitFunctions(
Module &M, StringRef CtorName, StringRef InitName,
ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
StringRef VersionCheckName) {
assert(!InitName.empty() && "Expected init function name");
assert(InitArgs.size() == InitArgTypes.size() &&
"Sanitizer's init function expects different number of arguments");
Function *Ctor = Function::Create(
FunctionType::get(Type::getVoidTy(M.getContext()), false),
GlobalValue::InternalLinkage, CtorName, &M);
BasicBlock *CtorBB = BasicBlock::Create(M.getContext(), "", Ctor);
IRBuilder<> IRB(ReturnInst::Create(M.getContext(), CtorBB));
Function *InitFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
InitName, FunctionType::get(IRB.getVoidTy(), InitArgTypes, false),
AttributeList()));
InitFunction->setLinkage(Function::ExternalLinkage);
IRB.CreateCall(InitFunction, InitArgs);
if (!VersionCheckName.empty()) {
Function *VersionCheckFunction =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
VersionCheckName, FunctionType::get(IRB.getVoidTy(), {}, false),
AttributeList()));
IRB.CreateCall(VersionCheckFunction, {});
}
return std::make_pair(Ctor, InitFunction);
}
void llvm::filterDeadComdatFunctions(
Module &M, SmallVectorImpl<Function *> &DeadComdatFunctions) {
// Build a map from the comdat to the number of entries in that comdat we
// think are dead. If this fully covers the comdat group, then the entire
// group is dead. If we find another entry in the comdat group though, we'll
// have to preserve the whole group.
SmallDenseMap<Comdat *, int, 16> ComdatEntriesCovered;
for (Function *F : DeadComdatFunctions) {
Comdat *C = F->getComdat();
assert(C && "Expected all input GVs to be in a comdat!");
ComdatEntriesCovered[C] += 1;
}
auto CheckComdat = [&](Comdat &C) {
auto CI = ComdatEntriesCovered.find(&C);
if (CI == ComdatEntriesCovered.end())
return;
// If this could have been covered by a dead entry, just subtract one to
// account for it.
if (CI->second > 0) {
CI->second -= 1;
return;
}
// If we've already accounted for all the entries that were dead, the
// entire comdat is alive so remove it from the map.
ComdatEntriesCovered.erase(CI);
};
auto CheckAllComdats = [&] {
for (Function &F : M.functions())
if (Comdat *C = F.getComdat()) {
CheckComdat(*C);
if (ComdatEntriesCovered.empty())
return;
}
for (GlobalVariable &GV : M.globals())
if (Comdat *C = GV.getComdat()) {
CheckComdat(*C);
if (ComdatEntriesCovered.empty())
return;
}
for (GlobalAlias &GA : M.aliases())
if (Comdat *C = GA.getComdat()) {
CheckComdat(*C);
if (ComdatEntriesCovered.empty())
return;
}
};
CheckAllComdats();
if (ComdatEntriesCovered.empty()) {
DeadComdatFunctions.clear();
return;
}
// Remove the entries that were not covering.
erase_if(DeadComdatFunctions, [&](GlobalValue *GV) {
return ComdatEntriesCovered.find(GV->getComdat()) ==
ComdatEntriesCovered.end();
});
}
|
