1 //===-- ModuleUtils.cpp - Functions to manipulate Modules -----------------===//
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 // This family of functions perform manipulations on Modules.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/Transforms/Utils/ModuleUtils.h"
14 #include "llvm/Analysis/VectorUtils.h"
15 #include "llvm/IR/DerivedTypes.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/IR/IRBuilder.h"
18 #include "llvm/IR/Module.h"
19 #include "llvm/Support/raw_ostream.h"
20
21 using namespace llvm;
22
appendToGlobalArray(const char * Array,Module & M,Function * F,int Priority,Constant * Data)23 static void appendToGlobalArray(const char *Array, Module &M, Function *F,
24 int Priority, Constant *Data) {
25 IRBuilder<> IRB(M.getContext());
26 FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
27
28 // Get the current set of static global constructors and add the new ctor
29 // to the list.
30 SmallVector<Constant *, 16> CurrentCtors;
31 StructType *EltTy = StructType::get(
32 IRB.getInt32Ty(), PointerType::getUnqual(FnTy), IRB.getInt8PtrTy());
33 if (GlobalVariable *GVCtor = M.getNamedGlobal(Array)) {
34 if (Constant *Init = GVCtor->getInitializer()) {
35 unsigned n = Init->getNumOperands();
36 CurrentCtors.reserve(n + 1);
37 for (unsigned i = 0; i != n; ++i)
38 CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
39 }
40 GVCtor->eraseFromParent();
41 }
42
43 // Build a 3 field global_ctor entry. We don't take a comdat key.
44 Constant *CSVals[3];
45 CSVals[0] = IRB.getInt32(Priority);
46 CSVals[1] = F;
47 CSVals[2] = Data ? ConstantExpr::getPointerCast(Data, IRB.getInt8PtrTy())
48 : Constant::getNullValue(IRB.getInt8PtrTy());
49 Constant *RuntimeCtorInit =
50 ConstantStruct::get(EltTy, makeArrayRef(CSVals, EltTy->getNumElements()));
51
52 CurrentCtors.push_back(RuntimeCtorInit);
53
54 // Create a new initializer.
55 ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
56 Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
57
58 // Create the new global variable and replace all uses of
59 // the old global variable with the new one.
60 (void)new GlobalVariable(M, NewInit->getType(), false,
61 GlobalValue::AppendingLinkage, NewInit, Array);
62 }
63
appendToGlobalCtors(Module & M,Function * F,int Priority,Constant * Data)64 void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority, Constant *Data) {
65 appendToGlobalArray("llvm.global_ctors", M, F, Priority, Data);
66 }
67
appendToGlobalDtors(Module & M,Function * F,int Priority,Constant * Data)68 void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *Data) {
69 appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
70 }
71
appendToUsedList(Module & M,StringRef Name,ArrayRef<GlobalValue * > Values)72 static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *> Values) {
73 GlobalVariable *GV = M.getGlobalVariable(Name);
74 SmallPtrSet<Constant *, 16> InitAsSet;
75 SmallVector<Constant *, 16> Init;
76 if (GV) {
77 auto *CA = cast<ConstantArray>(GV->getInitializer());
78 for (auto &Op : CA->operands()) {
79 Constant *C = cast_or_null<Constant>(Op);
80 if (InitAsSet.insert(C).second)
81 Init.push_back(C);
82 }
83 GV->eraseFromParent();
84 }
85
86 Type *Int8PtrTy = llvm::Type::getInt8PtrTy(M.getContext());
87 for (auto *V : Values) {
88 Constant *C = ConstantExpr::getBitCast(V, Int8PtrTy);
89 if (InitAsSet.insert(C).second)
90 Init.push_back(C);
91 }
92
93 if (Init.empty())
94 return;
95
96 ArrayType *ATy = ArrayType::get(Int8PtrTy, Init.size());
97 GV = new llvm::GlobalVariable(M, ATy, false, GlobalValue::AppendingLinkage,
98 ConstantArray::get(ATy, Init), Name);
99 GV->setSection("llvm.metadata");
100 }
101
appendToUsed(Module & M,ArrayRef<GlobalValue * > Values)102 void llvm::appendToUsed(Module &M, ArrayRef<GlobalValue *> Values) {
103 appendToUsedList(M, "llvm.used", Values);
104 }
105
appendToCompilerUsed(Module & M,ArrayRef<GlobalValue * > Values)106 void llvm::appendToCompilerUsed(Module &M, ArrayRef<GlobalValue *> Values) {
107 appendToUsedList(M, "llvm.compiler.used", Values);
108 }
109
110 FunctionCallee
declareSanitizerInitFunction(Module & M,StringRef InitName,ArrayRef<Type * > InitArgTypes)111 llvm::declareSanitizerInitFunction(Module &M, StringRef InitName,
112 ArrayRef<Type *> InitArgTypes) {
113 assert(!InitName.empty() && "Expected init function name");
114 return M.getOrInsertFunction(
115 InitName,
116 FunctionType::get(Type::getVoidTy(M.getContext()), InitArgTypes, false),
117 AttributeList());
118 }
119
createSanitizerCtorAndInitFunctions(Module & M,StringRef CtorName,StringRef InitName,ArrayRef<Type * > InitArgTypes,ArrayRef<Value * > InitArgs,StringRef VersionCheckName)120 std::pair<Function *, FunctionCallee> llvm::createSanitizerCtorAndInitFunctions(
121 Module &M, StringRef CtorName, StringRef InitName,
122 ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
123 StringRef VersionCheckName) {
124 assert(!InitName.empty() && "Expected init function name");
125 assert(InitArgs.size() == InitArgTypes.size() &&
126 "Sanitizer's init function expects different number of arguments");
127 FunctionCallee InitFunction =
128 declareSanitizerInitFunction(M, InitName, InitArgTypes);
129 Function *Ctor = Function::Create(
130 FunctionType::get(Type::getVoidTy(M.getContext()), false),
131 GlobalValue::InternalLinkage, CtorName, &M);
132 BasicBlock *CtorBB = BasicBlock::Create(M.getContext(), "", Ctor);
133 IRBuilder<> IRB(ReturnInst::Create(M.getContext(), CtorBB));
134 IRB.CreateCall(InitFunction, InitArgs);
135 if (!VersionCheckName.empty()) {
136 FunctionCallee VersionCheckFunction = M.getOrInsertFunction(
137 VersionCheckName, FunctionType::get(IRB.getVoidTy(), {}, false),
138 AttributeList());
139 IRB.CreateCall(VersionCheckFunction, {});
140 }
141 return std::make_pair(Ctor, InitFunction);
142 }
143
144 std::pair<Function *, FunctionCallee>
getOrCreateSanitizerCtorAndInitFunctions(Module & M,StringRef CtorName,StringRef InitName,ArrayRef<Type * > InitArgTypes,ArrayRef<Value * > InitArgs,function_ref<void (Function *,FunctionCallee)> FunctionsCreatedCallback,StringRef VersionCheckName)145 llvm::getOrCreateSanitizerCtorAndInitFunctions(
146 Module &M, StringRef CtorName, StringRef InitName,
147 ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
148 function_ref<void(Function *, FunctionCallee)> FunctionsCreatedCallback,
149 StringRef VersionCheckName) {
150 assert(!CtorName.empty() && "Expected ctor function name");
151
152 if (Function *Ctor = M.getFunction(CtorName))
153 // FIXME: Sink this logic into the module, similar to the handling of
154 // globals. This will make moving to a concurrent model much easier.
155 if (Ctor->arg_size() == 0 ||
156 Ctor->getReturnType() == Type::getVoidTy(M.getContext()))
157 return {Ctor, declareSanitizerInitFunction(M, InitName, InitArgTypes)};
158
159 Function *Ctor;
160 FunctionCallee InitFunction;
161 std::tie(Ctor, InitFunction) = llvm::createSanitizerCtorAndInitFunctions(
162 M, CtorName, InitName, InitArgTypes, InitArgs, VersionCheckName);
163 FunctionsCreatedCallback(Ctor, InitFunction);
164 return std::make_pair(Ctor, InitFunction);
165 }
166
getOrCreateInitFunction(Module & M,StringRef Name)167 Function *llvm::getOrCreateInitFunction(Module &M, StringRef Name) {
168 assert(!Name.empty() && "Expected init function name");
169 if (Function *F = M.getFunction(Name)) {
170 if (F->arg_size() != 0 ||
171 F->getReturnType() != Type::getVoidTy(M.getContext())) {
172 std::string Err;
173 raw_string_ostream Stream(Err);
174 Stream << "Sanitizer interface function defined with wrong type: " << *F;
175 report_fatal_error(Err);
176 }
177 return F;
178 }
179 Function *F =
180 cast<Function>(M.getOrInsertFunction(Name, AttributeList(),
181 Type::getVoidTy(M.getContext()))
182 .getCallee());
183
184 appendToGlobalCtors(M, F, 0);
185
186 return F;
187 }
188
filterDeadComdatFunctions(Module & M,SmallVectorImpl<Function * > & DeadComdatFunctions)189 void llvm::filterDeadComdatFunctions(
190 Module &M, SmallVectorImpl<Function *> &DeadComdatFunctions) {
191 // Build a map from the comdat to the number of entries in that comdat we
192 // think are dead. If this fully covers the comdat group, then the entire
193 // group is dead. If we find another entry in the comdat group though, we'll
194 // have to preserve the whole group.
195 SmallDenseMap<Comdat *, int, 16> ComdatEntriesCovered;
196 for (Function *F : DeadComdatFunctions) {
197 Comdat *C = F->getComdat();
198 assert(C && "Expected all input GVs to be in a comdat!");
199 ComdatEntriesCovered[C] += 1;
200 }
201
202 auto CheckComdat = [&](Comdat &C) {
203 auto CI = ComdatEntriesCovered.find(&C);
204 if (CI == ComdatEntriesCovered.end())
205 return;
206
207 // If this could have been covered by a dead entry, just subtract one to
208 // account for it.
209 if (CI->second > 0) {
210 CI->second -= 1;
211 return;
212 }
213
214 // If we've already accounted for all the entries that were dead, the
215 // entire comdat is alive so remove it from the map.
216 ComdatEntriesCovered.erase(CI);
217 };
218
219 auto CheckAllComdats = [&] {
220 for (Function &F : M.functions())
221 if (Comdat *C = F.getComdat()) {
222 CheckComdat(*C);
223 if (ComdatEntriesCovered.empty())
224 return;
225 }
226 for (GlobalVariable &GV : M.globals())
227 if (Comdat *C = GV.getComdat()) {
228 CheckComdat(*C);
229 if (ComdatEntriesCovered.empty())
230 return;
231 }
232 for (GlobalAlias &GA : M.aliases())
233 if (Comdat *C = GA.getComdat()) {
234 CheckComdat(*C);
235 if (ComdatEntriesCovered.empty())
236 return;
237 }
238 };
239 CheckAllComdats();
240
241 if (ComdatEntriesCovered.empty()) {
242 DeadComdatFunctions.clear();
243 return;
244 }
245
246 // Remove the entries that were not covering.
247 erase_if(DeadComdatFunctions, [&](GlobalValue *GV) {
248 return ComdatEntriesCovered.find(GV->getComdat()) ==
249 ComdatEntriesCovered.end();
250 });
251 }
252
getUniqueModuleId(Module * M)253 std::string llvm::getUniqueModuleId(Module *M) {
254 MD5 Md5;
255 bool ExportsSymbols = false;
256 auto AddGlobal = [&](GlobalValue &GV) {
257 if (GV.isDeclaration() || GV.getName().startswith("llvm.") ||
258 !GV.hasExternalLinkage() || GV.hasComdat())
259 return;
260 ExportsSymbols = true;
261 Md5.update(GV.getName());
262 Md5.update(ArrayRef<uint8_t>{0});
263 };
264
265 for (auto &F : *M)
266 AddGlobal(F);
267 for (auto &GV : M->globals())
268 AddGlobal(GV);
269 for (auto &GA : M->aliases())
270 AddGlobal(GA);
271 for (auto &IF : M->ifuncs())
272 AddGlobal(IF);
273
274 if (!ExportsSymbols)
275 return "";
276
277 MD5::MD5Result R;
278 Md5.final(R);
279
280 SmallString<32> Str;
281 MD5::stringifyResult(R, Str);
282 return ("$" + Str).str();
283 }
284
setVectorVariantNames(CallInst * CI,const SmallVector<std::string,8> & VariantMappings)285 void VFABI::setVectorVariantNames(
286 CallInst *CI, const SmallVector<std::string, 8> &VariantMappings) {
287 if (VariantMappings.empty())
288 return;
289
290 SmallString<256> Buffer;
291 llvm::raw_svector_ostream Out(Buffer);
292 for (const std::string &VariantMapping : VariantMappings)
293 Out << VariantMapping << ",";
294 // Get rid of the trailing ','.
295 assert(!Buffer.str().empty() && "Must have at least one char.");
296 Buffer.pop_back();
297
298 Module *M = CI->getModule();
299 #ifndef NDEBUG
300 for (const std::string &VariantMapping : VariantMappings) {
301 Optional<VFInfo> VI = VFABI::tryDemangleForVFABI(VariantMapping);
302 assert(VI.hasValue() && "Canno add an invalid VFABI name.");
303 assert(M->getNamedValue(VI.getValue().VectorName) &&
304 "Cannot add variant to attribute: "
305 "vector function declaration is missing.");
306 }
307 #endif
308 CI->addAttribute(
309 AttributeList::FunctionIndex,
310 Attribute::get(M->getContext(), MappingsAttrName, Buffer.str()));
311 }
312