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/TargetLibraryInfo.h"
15 #include "llvm/Analysis/VectorUtils.h"
16 #include "llvm/IR/DerivedTypes.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/IR/IRBuilder.h"
19 #include "llvm/IR/Module.h"
20 #include "llvm/Support/raw_ostream.h"
21 using namespace llvm;
22
23 #define DEBUG_TYPE "moduleutils"
24
appendToGlobalArray(const char * Array,Module & M,Function * F,int Priority,Constant * Data)25 static void appendToGlobalArray(const char *Array, Module &M, Function *F,
26 int Priority, Constant *Data) {
27 IRBuilder<> IRB(M.getContext());
28 FunctionType *FnTy = FunctionType::get(IRB.getVoidTy(), false);
29
30 // Get the current set of static global constructors and add the new ctor
31 // to the list.
32 SmallVector<Constant *, 16> CurrentCtors;
33 StructType *EltTy = StructType::get(
34 IRB.getInt32Ty(), PointerType::getUnqual(FnTy), IRB.getInt8PtrTy());
35 if (GlobalVariable *GVCtor = M.getNamedGlobal(Array)) {
36 if (Constant *Init = GVCtor->getInitializer()) {
37 unsigned n = Init->getNumOperands();
38 CurrentCtors.reserve(n + 1);
39 for (unsigned i = 0; i != n; ++i)
40 CurrentCtors.push_back(cast<Constant>(Init->getOperand(i)));
41 }
42 GVCtor->eraseFromParent();
43 }
44
45 // Build a 3 field global_ctor entry. We don't take a comdat key.
46 Constant *CSVals[3];
47 CSVals[0] = IRB.getInt32(Priority);
48 CSVals[1] = F;
49 CSVals[2] = Data ? ConstantExpr::getPointerCast(Data, IRB.getInt8PtrTy())
50 : Constant::getNullValue(IRB.getInt8PtrTy());
51 Constant *RuntimeCtorInit =
52 ConstantStruct::get(EltTy, makeArrayRef(CSVals, EltTy->getNumElements()));
53
54 CurrentCtors.push_back(RuntimeCtorInit);
55
56 // Create a new initializer.
57 ArrayType *AT = ArrayType::get(EltTy, CurrentCtors.size());
58 Constant *NewInit = ConstantArray::get(AT, CurrentCtors);
59
60 // Create the new global variable and replace all uses of
61 // the old global variable with the new one.
62 (void)new GlobalVariable(M, NewInit->getType(), false,
63 GlobalValue::AppendingLinkage, NewInit, Array);
64 }
65
appendToGlobalCtors(Module & M,Function * F,int Priority,Constant * Data)66 void llvm::appendToGlobalCtors(Module &M, Function *F, int Priority, Constant *Data) {
67 appendToGlobalArray("llvm.global_ctors", M, F, Priority, Data);
68 }
69
appendToGlobalDtors(Module & M,Function * F,int Priority,Constant * Data)70 void llvm::appendToGlobalDtors(Module &M, Function *F, int Priority, Constant *Data) {
71 appendToGlobalArray("llvm.global_dtors", M, F, Priority, Data);
72 }
73
appendToUsedList(Module & M,StringRef Name,ArrayRef<GlobalValue * > Values)74 static void appendToUsedList(Module &M, StringRef Name, ArrayRef<GlobalValue *> Values) {
75 GlobalVariable *GV = M.getGlobalVariable(Name);
76 SmallPtrSet<Constant *, 16> InitAsSet;
77 SmallVector<Constant *, 16> Init;
78 if (GV) {
79 if (GV->hasInitializer()) {
80 auto *CA = cast<ConstantArray>(GV->getInitializer());
81 for (auto &Op : CA->operands()) {
82 Constant *C = cast_or_null<Constant>(Op);
83 if (InitAsSet.insert(C).second)
84 Init.push_back(C);
85 }
86 }
87 GV->eraseFromParent();
88 }
89
90 Type *Int8PtrTy = llvm::Type::getInt8PtrTy(M.getContext());
91 for (auto *V : Values) {
92 Constant *C = ConstantExpr::getPointerBitCastOrAddrSpaceCast(V, Int8PtrTy);
93 if (InitAsSet.insert(C).second)
94 Init.push_back(C);
95 }
96
97 if (Init.empty())
98 return;
99
100 ArrayType *ATy = ArrayType::get(Int8PtrTy, Init.size());
101 GV = new llvm::GlobalVariable(M, ATy, false, GlobalValue::AppendingLinkage,
102 ConstantArray::get(ATy, Init), Name);
103 GV->setSection("llvm.metadata");
104 }
105
appendToUsed(Module & M,ArrayRef<GlobalValue * > Values)106 void llvm::appendToUsed(Module &M, ArrayRef<GlobalValue *> Values) {
107 appendToUsedList(M, "llvm.used", Values);
108 }
109
appendToCompilerUsed(Module & M,ArrayRef<GlobalValue * > Values)110 void llvm::appendToCompilerUsed(Module &M, ArrayRef<GlobalValue *> Values) {
111 appendToUsedList(M, "llvm.compiler.used", Values);
112 }
113
114 FunctionCallee
declareSanitizerInitFunction(Module & M,StringRef InitName,ArrayRef<Type * > InitArgTypes)115 llvm::declareSanitizerInitFunction(Module &M, StringRef InitName,
116 ArrayRef<Type *> InitArgTypes) {
117 assert(!InitName.empty() && "Expected init function name");
118 return M.getOrInsertFunction(
119 InitName,
120 FunctionType::get(Type::getVoidTy(M.getContext()), InitArgTypes, false),
121 AttributeList());
122 }
123
createSanitizerCtor(Module & M,StringRef CtorName)124 Function *llvm::createSanitizerCtor(Module &M, StringRef CtorName) {
125 Function *Ctor = Function::createWithDefaultAttr(
126 FunctionType::get(Type::getVoidTy(M.getContext()), false),
127 GlobalValue::InternalLinkage, 0, CtorName, &M);
128 Ctor->addAttribute(AttributeList::FunctionIndex, Attribute::NoUnwind);
129 BasicBlock *CtorBB = BasicBlock::Create(M.getContext(), "", Ctor);
130 ReturnInst::Create(M.getContext(), CtorBB);
131 return Ctor;
132 }
133
createSanitizerCtorAndInitFunctions(Module & M,StringRef CtorName,StringRef InitName,ArrayRef<Type * > InitArgTypes,ArrayRef<Value * > InitArgs,StringRef VersionCheckName)134 std::pair<Function *, FunctionCallee> llvm::createSanitizerCtorAndInitFunctions(
135 Module &M, StringRef CtorName, StringRef InitName,
136 ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
137 StringRef VersionCheckName) {
138 assert(!InitName.empty() && "Expected init function name");
139 assert(InitArgs.size() == InitArgTypes.size() &&
140 "Sanitizer's init function expects different number of arguments");
141 FunctionCallee InitFunction =
142 declareSanitizerInitFunction(M, InitName, InitArgTypes);
143 Function *Ctor = createSanitizerCtor(M, CtorName);
144 IRBuilder<> IRB(Ctor->getEntryBlock().getTerminator());
145 IRB.CreateCall(InitFunction, InitArgs);
146 if (!VersionCheckName.empty()) {
147 FunctionCallee VersionCheckFunction = M.getOrInsertFunction(
148 VersionCheckName, FunctionType::get(IRB.getVoidTy(), {}, false),
149 AttributeList());
150 IRB.CreateCall(VersionCheckFunction, {});
151 }
152 return std::make_pair(Ctor, InitFunction);
153 }
154
155 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)156 llvm::getOrCreateSanitizerCtorAndInitFunctions(
157 Module &M, StringRef CtorName, StringRef InitName,
158 ArrayRef<Type *> InitArgTypes, ArrayRef<Value *> InitArgs,
159 function_ref<void(Function *, FunctionCallee)> FunctionsCreatedCallback,
160 StringRef VersionCheckName) {
161 assert(!CtorName.empty() && "Expected ctor function name");
162
163 if (Function *Ctor = M.getFunction(CtorName))
164 // FIXME: Sink this logic into the module, similar to the handling of
165 // globals. This will make moving to a concurrent model much easier.
166 if (Ctor->arg_size() == 0 ||
167 Ctor->getReturnType() == Type::getVoidTy(M.getContext()))
168 return {Ctor, declareSanitizerInitFunction(M, InitName, InitArgTypes)};
169
170 Function *Ctor;
171 FunctionCallee InitFunction;
172 std::tie(Ctor, InitFunction) = llvm::createSanitizerCtorAndInitFunctions(
173 M, CtorName, InitName, InitArgTypes, InitArgs, VersionCheckName);
174 FunctionsCreatedCallback(Ctor, InitFunction);
175 return std::make_pair(Ctor, InitFunction);
176 }
177
getOrCreateInitFunction(Module & M,StringRef Name)178 Function *llvm::getOrCreateInitFunction(Module &M, StringRef Name) {
179 assert(!Name.empty() && "Expected init function name");
180 if (Function *F = M.getFunction(Name)) {
181 if (F->arg_size() != 0 ||
182 F->getReturnType() != Type::getVoidTy(M.getContext())) {
183 std::string Err;
184 raw_string_ostream Stream(Err);
185 Stream << "Sanitizer interface function defined with wrong type: " << *F;
186 report_fatal_error(Err);
187 }
188 return F;
189 }
190 Function *F =
191 cast<Function>(M.getOrInsertFunction(Name, AttributeList(),
192 Type::getVoidTy(M.getContext()))
193 .getCallee());
194
195 appendToGlobalCtors(M, F, 0);
196
197 return F;
198 }
199
filterDeadComdatFunctions(Module & M,SmallVectorImpl<Function * > & DeadComdatFunctions)200 void llvm::filterDeadComdatFunctions(
201 Module &M, SmallVectorImpl<Function *> &DeadComdatFunctions) {
202 // Build a map from the comdat to the number of entries in that comdat we
203 // think are dead. If this fully covers the comdat group, then the entire
204 // group is dead. If we find another entry in the comdat group though, we'll
205 // have to preserve the whole group.
206 SmallDenseMap<Comdat *, int, 16> ComdatEntriesCovered;
207 for (Function *F : DeadComdatFunctions) {
208 Comdat *C = F->getComdat();
209 assert(C && "Expected all input GVs to be in a comdat!");
210 ComdatEntriesCovered[C] += 1;
211 }
212
213 auto CheckComdat = [&](Comdat &C) {
214 auto CI = ComdatEntriesCovered.find(&C);
215 if (CI == ComdatEntriesCovered.end())
216 return;
217
218 // If this could have been covered by a dead entry, just subtract one to
219 // account for it.
220 if (CI->second > 0) {
221 CI->second -= 1;
222 return;
223 }
224
225 // If we've already accounted for all the entries that were dead, the
226 // entire comdat is alive so remove it from the map.
227 ComdatEntriesCovered.erase(CI);
228 };
229
230 auto CheckAllComdats = [&] {
231 for (Function &F : M.functions())
232 if (Comdat *C = F.getComdat()) {
233 CheckComdat(*C);
234 if (ComdatEntriesCovered.empty())
235 return;
236 }
237 for (GlobalVariable &GV : M.globals())
238 if (Comdat *C = GV.getComdat()) {
239 CheckComdat(*C);
240 if (ComdatEntriesCovered.empty())
241 return;
242 }
243 for (GlobalAlias &GA : M.aliases())
244 if (Comdat *C = GA.getComdat()) {
245 CheckComdat(*C);
246 if (ComdatEntriesCovered.empty())
247 return;
248 }
249 };
250 CheckAllComdats();
251
252 if (ComdatEntriesCovered.empty()) {
253 DeadComdatFunctions.clear();
254 return;
255 }
256
257 // Remove the entries that were not covering.
258 erase_if(DeadComdatFunctions, [&](GlobalValue *GV) {
259 return ComdatEntriesCovered.find(GV->getComdat()) ==
260 ComdatEntriesCovered.end();
261 });
262 }
263
getUniqueModuleId(Module * M)264 std::string llvm::getUniqueModuleId(Module *M) {
265 MD5 Md5;
266 bool ExportsSymbols = false;
267 auto AddGlobal = [&](GlobalValue &GV) {
268 if (GV.isDeclaration() || GV.getName().startswith("llvm.") ||
269 !GV.hasExternalLinkage() || GV.hasComdat())
270 return;
271 ExportsSymbols = true;
272 Md5.update(GV.getName());
273 Md5.update(ArrayRef<uint8_t>{0});
274 };
275
276 for (auto &F : *M)
277 AddGlobal(F);
278 for (auto &GV : M->globals())
279 AddGlobal(GV);
280 for (auto &GA : M->aliases())
281 AddGlobal(GA);
282 for (auto &IF : M->ifuncs())
283 AddGlobal(IF);
284
285 if (!ExportsSymbols)
286 return "";
287
288 MD5::MD5Result R;
289 Md5.final(R);
290
291 SmallString<32> Str;
292 MD5::stringifyResult(R, Str);
293 return ("." + Str).str();
294 }
295
setVectorVariantNames(CallInst * CI,const SmallVector<std::string,8> & VariantMappings)296 void VFABI::setVectorVariantNames(
297 CallInst *CI, const SmallVector<std::string, 8> &VariantMappings) {
298 if (VariantMappings.empty())
299 return;
300
301 SmallString<256> Buffer;
302 llvm::raw_svector_ostream Out(Buffer);
303 for (const std::string &VariantMapping : VariantMappings)
304 Out << VariantMapping << ",";
305 // Get rid of the trailing ','.
306 assert(!Buffer.str().empty() && "Must have at least one char.");
307 Buffer.pop_back();
308
309 Module *M = CI->getModule();
310 #ifndef NDEBUG
311 for (const std::string &VariantMapping : VariantMappings) {
312 LLVM_DEBUG(dbgs() << "VFABI: adding mapping '" << VariantMapping << "'\n");
313 Optional<VFInfo> VI = VFABI::tryDemangleForVFABI(VariantMapping, *M);
314 assert(VI.hasValue() && "Cannot add an invalid VFABI name.");
315 assert(M->getNamedValue(VI.getValue().VectorName) &&
316 "Cannot add variant to attribute: "
317 "vector function declaration is missing.");
318 }
319 #endif
320 CI->addAttribute(
321 AttributeList::FunctionIndex,
322 Attribute::get(M->getContext(), MappingsAttrName, Buffer.str()));
323 }
324