1 //===---- ExecutionUtils.cpp - Utilities for executing functions in Orc ---===//
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 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
10 
11 #include "llvm/ExecutionEngine/Orc/Layer.h"
12 #include "llvm/IR/Constants.h"
13 #include "llvm/IR/Function.h"
14 #include "llvm/IR/GlobalVariable.h"
15 #include "llvm/IR/Module.h"
16 #include "llvm/Support/TargetRegistry.h"
17 #include "llvm/Target/TargetMachine.h"
18 
19 namespace llvm {
20 namespace orc {
21 
22 int runAsMain(int (*Main)(int, char *[]), ArrayRef<std::string> Args,
23               Optional<StringRef> ProgramName) {
24   std::vector<std::unique_ptr<char[]>> ArgVStorage;
25   std::vector<char *> ArgV;
26 
27   ArgVStorage.reserve(Args.size() + (ProgramName ? 1 : 0));
28   ArgV.reserve(Args.size() + 1 + (ProgramName ? 1 : 0));
29 
30   if (ProgramName) {
31     ArgVStorage.push_back(std::make_unique<char[]>(ProgramName->size() + 1));
32     llvm::copy(*ProgramName, &ArgVStorage.back()[0]);
33     ArgVStorage.back()[ProgramName->size()] = '\0';
34     ArgV.push_back(ArgVStorage.back().get());
35   }
36 
37   for (auto &Arg : Args) {
38     ArgVStorage.push_back(std::make_unique<char[]>(Arg.size() + 1));
39     llvm::copy(Arg, &ArgVStorage.back()[0]);
40     ArgVStorage.back()[Arg.size()] = '\0';
41     ArgV.push_back(ArgVStorage.back().get());
42   }
43   ArgV.push_back(nullptr);
44 
45   return Main(Args.size() + !!ProgramName, ArgV.data());
46 }
47 
48 CtorDtorIterator::CtorDtorIterator(const GlobalVariable *GV, bool End)
49   : InitList(
50       GV ? dyn_cast_or_null<ConstantArray>(GV->getInitializer()) : nullptr),
51     I((InitList && End) ? InitList->getNumOperands() : 0) {
52 }
53 
54 bool CtorDtorIterator::operator==(const CtorDtorIterator &Other) const {
55   assert(InitList == Other.InitList && "Incomparable iterators.");
56   return I == Other.I;
57 }
58 
59 bool CtorDtorIterator::operator!=(const CtorDtorIterator &Other) const {
60   return !(*this == Other);
61 }
62 
63 CtorDtorIterator& CtorDtorIterator::operator++() {
64   ++I;
65   return *this;
66 }
67 
68 CtorDtorIterator CtorDtorIterator::operator++(int) {
69   CtorDtorIterator Temp = *this;
70   ++I;
71   return Temp;
72 }
73 
74 CtorDtorIterator::Element CtorDtorIterator::operator*() const {
75   ConstantStruct *CS = dyn_cast<ConstantStruct>(InitList->getOperand(I));
76   assert(CS && "Unrecognized type in llvm.global_ctors/llvm.global_dtors");
77 
78   Constant *FuncC = CS->getOperand(1);
79   Function *Func = nullptr;
80 
81   // Extract function pointer, pulling off any casts.
82   while (FuncC) {
83     if (Function *F = dyn_cast_or_null<Function>(FuncC)) {
84       Func = F;
85       break;
86     } else if (ConstantExpr *CE = dyn_cast_or_null<ConstantExpr>(FuncC)) {
87       if (CE->isCast())
88         FuncC = dyn_cast_or_null<ConstantExpr>(CE->getOperand(0));
89       else
90         break;
91     } else {
92       // This isn't anything we recognize. Bail out with Func left set to null.
93       break;
94     }
95   }
96 
97   auto *Priority = cast<ConstantInt>(CS->getOperand(0));
98   Value *Data = CS->getNumOperands() == 3 ? CS->getOperand(2) : nullptr;
99   if (Data && !isa<GlobalValue>(Data))
100     Data = nullptr;
101   return Element(Priority->getZExtValue(), Func, Data);
102 }
103 
104 iterator_range<CtorDtorIterator> getConstructors(const Module &M) {
105   const GlobalVariable *CtorsList = M.getNamedGlobal("llvm.global_ctors");
106   return make_range(CtorDtorIterator(CtorsList, false),
107                     CtorDtorIterator(CtorsList, true));
108 }
109 
110 iterator_range<CtorDtorIterator> getDestructors(const Module &M) {
111   const GlobalVariable *DtorsList = M.getNamedGlobal("llvm.global_dtors");
112   return make_range(CtorDtorIterator(DtorsList, false),
113                     CtorDtorIterator(DtorsList, true));
114 }
115 
116 void CtorDtorRunner::add(iterator_range<CtorDtorIterator> CtorDtors) {
117   if (CtorDtors.empty())
118     return;
119 
120   MangleAndInterner Mangle(
121       JD.getExecutionSession(),
122       (*CtorDtors.begin()).Func->getParent()->getDataLayout());
123 
124   for (auto CtorDtor : CtorDtors) {
125     assert(CtorDtor.Func && CtorDtor.Func->hasName() &&
126            "Ctor/Dtor function must be named to be runnable under the JIT");
127 
128     // FIXME: Maybe use a symbol promoter here instead.
129     if (CtorDtor.Func->hasLocalLinkage()) {
130       CtorDtor.Func->setLinkage(GlobalValue::ExternalLinkage);
131       CtorDtor.Func->setVisibility(GlobalValue::HiddenVisibility);
132     }
133 
134     if (CtorDtor.Data && cast<GlobalValue>(CtorDtor.Data)->isDeclaration()) {
135       dbgs() << "  Skipping because why now?\n";
136       continue;
137     }
138 
139     CtorDtorsByPriority[CtorDtor.Priority].push_back(
140         Mangle(CtorDtor.Func->getName()));
141   }
142 }
143 
144 Error CtorDtorRunner::run() {
145   using CtorDtorTy = void (*)();
146 
147   SymbolLookupSet LookupSet;
148   for (auto &KV : CtorDtorsByPriority)
149     for (auto &Name : KV.second)
150       LookupSet.add(Name);
151   assert(!LookupSet.containsDuplicates() &&
152          "Ctor/Dtor list contains duplicates");
153 
154   auto &ES = JD.getExecutionSession();
155   if (auto CtorDtorMap = ES.lookup(
156           makeJITDylibSearchOrder(&JD, JITDylibLookupFlags::MatchAllSymbols),
157           std::move(LookupSet))) {
158     for (auto &KV : CtorDtorsByPriority) {
159       for (auto &Name : KV.second) {
160         assert(CtorDtorMap->count(Name) && "No entry for Name");
161         auto CtorDtor = reinterpret_cast<CtorDtorTy>(
162             static_cast<uintptr_t>((*CtorDtorMap)[Name].getAddress()));
163         CtorDtor();
164       }
165     }
166     CtorDtorsByPriority.clear();
167     return Error::success();
168   } else
169     return CtorDtorMap.takeError();
170 }
171 
172 void LocalCXXRuntimeOverridesBase::runDestructors() {
173   auto& CXXDestructorDataPairs = DSOHandleOverride;
174   for (auto &P : CXXDestructorDataPairs)
175     P.first(P.second);
176   CXXDestructorDataPairs.clear();
177 }
178 
179 int LocalCXXRuntimeOverridesBase::CXAAtExitOverride(DestructorPtr Destructor,
180                                                     void *Arg,
181                                                     void *DSOHandle) {
182   auto& CXXDestructorDataPairs =
183     *reinterpret_cast<CXXDestructorDataPairList*>(DSOHandle);
184   CXXDestructorDataPairs.push_back(std::make_pair(Destructor, Arg));
185   return 0;
186 }
187 
188 Error LocalCXXRuntimeOverrides::enable(JITDylib &JD,
189                                         MangleAndInterner &Mangle) {
190   SymbolMap RuntimeInterposes;
191   RuntimeInterposes[Mangle("__dso_handle")] =
192     JITEvaluatedSymbol(toTargetAddress(&DSOHandleOverride),
193                        JITSymbolFlags::Exported);
194   RuntimeInterposes[Mangle("__cxa_atexit")] =
195     JITEvaluatedSymbol(toTargetAddress(&CXAAtExitOverride),
196                        JITSymbolFlags::Exported);
197 
198   return JD.define(absoluteSymbols(std::move(RuntimeInterposes)));
199 }
200 
201 DynamicLibrarySearchGenerator::DynamicLibrarySearchGenerator(
202     sys::DynamicLibrary Dylib, char GlobalPrefix, SymbolPredicate Allow)
203     : Dylib(std::move(Dylib)), Allow(std::move(Allow)),
204       GlobalPrefix(GlobalPrefix) {}
205 
206 Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
207 DynamicLibrarySearchGenerator::Load(const char *FileName, char GlobalPrefix,
208                                     SymbolPredicate Allow) {
209   std::string ErrMsg;
210   auto Lib = sys::DynamicLibrary::getPermanentLibrary(FileName, &ErrMsg);
211   if (!Lib.isValid())
212     return make_error<StringError>(std::move(ErrMsg), inconvertibleErrorCode());
213   return std::make_unique<DynamicLibrarySearchGenerator>(
214       std::move(Lib), GlobalPrefix, std::move(Allow));
215 }
216 
217 Error DynamicLibrarySearchGenerator::tryToGenerate(
218     LookupKind K, JITDylib &JD, JITDylibLookupFlags JDLookupFlags,
219     const SymbolLookupSet &Symbols) {
220   orc::SymbolMap NewSymbols;
221 
222   bool HasGlobalPrefix = (GlobalPrefix != '\0');
223 
224   for (auto &KV : Symbols) {
225     auto &Name = KV.first;
226 
227     if ((*Name).empty())
228       continue;
229 
230     if (Allow && !Allow(Name))
231       continue;
232 
233     if (HasGlobalPrefix && (*Name).front() != GlobalPrefix)
234       continue;
235 
236     std::string Tmp((*Name).data() + HasGlobalPrefix,
237                     (*Name).size() - HasGlobalPrefix);
238     if (void *Addr = Dylib.getAddressOfSymbol(Tmp.c_str())) {
239       NewSymbols[Name] = JITEvaluatedSymbol(
240           static_cast<JITTargetAddress>(reinterpret_cast<uintptr_t>(Addr)),
241           JITSymbolFlags::Exported);
242     }
243   }
244 
245   if (NewSymbols.empty())
246     return Error::success();
247 
248   return JD.define(absoluteSymbols(std::move(NewSymbols)));
249 }
250 
251 Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
252 StaticLibraryDefinitionGenerator::Load(ObjectLayer &L, const char *FileName) {
253   auto ArchiveBuffer = errorOrToExpected(MemoryBuffer::getFile(FileName));
254 
255   if (!ArchiveBuffer)
256     return ArchiveBuffer.takeError();
257 
258   return Create(L, std::move(*ArchiveBuffer));
259 }
260 
261 Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
262 StaticLibraryDefinitionGenerator::Create(
263     ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer) {
264   Error Err = Error::success();
265 
266   std::unique_ptr<StaticLibraryDefinitionGenerator> ADG(
267       new StaticLibraryDefinitionGenerator(L, std::move(ArchiveBuffer), Err));
268 
269   if (Err)
270     return std::move(Err);
271 
272   return std::move(ADG);
273 }
274 
275 Error StaticLibraryDefinitionGenerator::tryToGenerate(
276     LookupKind K, JITDylib &JD, JITDylibLookupFlags JDLookupFlags,
277     const SymbolLookupSet &Symbols) {
278 
279   // Don't materialize symbols from static archives unless this is a static
280   // lookup.
281   if (K != LookupKind::Static)
282     return Error::success();
283 
284   // Bail out early if we've already freed the archive.
285   if (!Archive)
286     return Error::success();
287 
288   DenseSet<std::pair<StringRef, StringRef>> ChildBufferInfos;
289 
290   for (const auto &KV : Symbols) {
291     const auto &Name = KV.first;
292     auto Child = Archive->findSym(*Name);
293     if (!Child)
294       return Child.takeError();
295     if (*Child == None)
296       continue;
297     auto ChildBuffer = (*Child)->getMemoryBufferRef();
298     if (!ChildBuffer)
299       return ChildBuffer.takeError();
300     ChildBufferInfos.insert(
301         {ChildBuffer->getBuffer(), ChildBuffer->getBufferIdentifier()});
302   }
303 
304   for (auto ChildBufferInfo : ChildBufferInfos) {
305     MemoryBufferRef ChildBufferRef(ChildBufferInfo.first,
306                                    ChildBufferInfo.second);
307 
308     if (auto Err =
309             L.add(JD, MemoryBuffer::getMemBuffer(ChildBufferRef), VModuleKey()))
310       return Err;
311   }
312 
313   return Error::success();
314 }
315 
316 StaticLibraryDefinitionGenerator::StaticLibraryDefinitionGenerator(
317     ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer, Error &Err)
318     : L(L), ArchiveBuffer(std::move(ArchiveBuffer)),
319       Archive(std::make_unique<object::Archive>(*this->ArchiveBuffer, Err)) {}
320 
321 } // End namespace orc.
322 } // End namespace llvm.
323