1 //===- ExecutionUtils.h - Utilities for executing code in Orc ---*- C++ -*-===//
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 // Contains utilities for executing code in Orc.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #ifndef LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
14 #define LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
15
16 #include "llvm/ADT/StringMap.h"
17 #include "llvm/ADT/iterator_range.h"
18 #include "llvm/ExecutionEngine/JITSymbol.h"
19 #include "llvm/ExecutionEngine/Orc/Core.h"
20 #include "llvm/ExecutionEngine/Orc/Mangling.h"
21 #include "llvm/ExecutionEngine/Orc/Shared/OrcError.h"
22 #include "llvm/ExecutionEngine/RuntimeDyld.h"
23 #include "llvm/Object/Archive.h"
24 #include "llvm/Support/DynamicLibrary.h"
25 #include <algorithm>
26 #include <cstdint>
27 #include <utility>
28 #include <vector>
29
30 namespace llvm {
31
32 class ConstantArray;
33 class GlobalVariable;
34 class Function;
35 class Module;
36 class TargetMachine;
37 class Value;
38
39 namespace orc {
40
41 class ObjectLayer;
42
43 /// This iterator provides a convenient way to iterate over the elements
44 /// of an llvm.global_ctors/llvm.global_dtors instance.
45 ///
46 /// The easiest way to get hold of instances of this class is to use the
47 /// getConstructors/getDestructors functions.
48 class CtorDtorIterator {
49 public:
50 /// Accessor for an element of the global_ctors/global_dtors array.
51 ///
52 /// This class provides a read-only view of the element with any casts on
53 /// the function stripped away.
54 struct Element {
ElementElement55 Element(unsigned Priority, Function *Func, Value *Data)
56 : Priority(Priority), Func(Func), Data(Data) {}
57
58 unsigned Priority;
59 Function *Func;
60 Value *Data;
61 };
62
63 /// Construct an iterator instance. If End is true then this iterator
64 /// acts as the end of the range, otherwise it is the beginning.
65 CtorDtorIterator(const GlobalVariable *GV, bool End);
66
67 /// Test iterators for equality.
68 bool operator==(const CtorDtorIterator &Other) const;
69
70 /// Test iterators for inequality.
71 bool operator!=(const CtorDtorIterator &Other) const;
72
73 /// Pre-increment iterator.
74 CtorDtorIterator& operator++();
75
76 /// Post-increment iterator.
77 CtorDtorIterator operator++(int);
78
79 /// Dereference iterator. The resulting value provides a read-only view
80 /// of this element of the global_ctors/global_dtors list.
81 Element operator*() const;
82
83 private:
84 const ConstantArray *InitList;
85 unsigned I;
86 };
87
88 /// Create an iterator range over the entries of the llvm.global_ctors
89 /// array.
90 iterator_range<CtorDtorIterator> getConstructors(const Module &M);
91
92 /// Create an iterator range over the entries of the llvm.global_ctors
93 /// array.
94 iterator_range<CtorDtorIterator> getDestructors(const Module &M);
95
96 /// This iterator provides a convenient way to iterate over GlobalValues that
97 /// have initialization effects.
98 class StaticInitGVIterator {
99 public:
100 StaticInitGVIterator() = default;
101
StaticInitGVIterator(Module & M)102 StaticInitGVIterator(Module &M)
103 : I(M.global_values().begin()), E(M.global_values().end()),
104 ObjFmt(Triple(M.getTargetTriple()).getObjectFormat()) {
105 if (I != E) {
106 if (!isStaticInitGlobal(*I))
107 moveToNextStaticInitGlobal();
108 } else
109 I = E = Module::global_value_iterator();
110 }
111
112 bool operator==(const StaticInitGVIterator &O) const { return I == O.I; }
113 bool operator!=(const StaticInitGVIterator &O) const { return I != O.I; }
114
115 StaticInitGVIterator &operator++() {
116 assert(I != E && "Increment past end of range");
117 moveToNextStaticInitGlobal();
118 return *this;
119 }
120
121 GlobalValue &operator*() { return *I; }
122
123 private:
124 bool isStaticInitGlobal(GlobalValue &GV);
moveToNextStaticInitGlobal()125 void moveToNextStaticInitGlobal() {
126 ++I;
127 while (I != E && !isStaticInitGlobal(*I))
128 ++I;
129 if (I == E)
130 I = E = Module::global_value_iterator();
131 }
132
133 Module::global_value_iterator I, E;
134 Triple::ObjectFormatType ObjFmt;
135 };
136
137 /// Create an iterator range over the GlobalValues that contribute to static
138 /// initialization.
getStaticInitGVs(Module & M)139 inline iterator_range<StaticInitGVIterator> getStaticInitGVs(Module &M) {
140 return make_range(StaticInitGVIterator(M), StaticInitGVIterator());
141 }
142
143 class CtorDtorRunner {
144 public:
CtorDtorRunner(JITDylib & JD)145 CtorDtorRunner(JITDylib &JD) : JD(JD) {}
146 void add(iterator_range<CtorDtorIterator> CtorDtors);
147 Error run();
148
149 private:
150 using CtorDtorList = std::vector<SymbolStringPtr>;
151 using CtorDtorPriorityMap = std::map<unsigned, CtorDtorList>;
152
153 JITDylib &JD;
154 CtorDtorPriorityMap CtorDtorsByPriority;
155 };
156
157 /// Support class for static dtor execution. For hosted (in-process) JITs
158 /// only!
159 ///
160 /// If a __cxa_atexit function isn't found C++ programs that use static
161 /// destructors will fail to link. However, we don't want to use the host
162 /// process's __cxa_atexit, because it will schedule JIT'd destructors to run
163 /// after the JIT has been torn down, which is no good. This class makes it easy
164 /// to override __cxa_atexit (and the related __dso_handle).
165 ///
166 /// To use, clients should manually call searchOverrides from their symbol
167 /// resolver. This should generally be done after attempting symbol resolution
168 /// inside the JIT, but before searching the host process's symbol table. When
169 /// the client determines that destructors should be run (generally at JIT
170 /// teardown or after a return from main), the runDestructors method should be
171 /// called.
172 class LocalCXXRuntimeOverridesBase {
173 public:
174 /// Run any destructors recorded by the overriden __cxa_atexit function
175 /// (CXAAtExitOverride).
176 void runDestructors();
177
178 protected:
toTargetAddress(PtrTy * P)179 template <typename PtrTy> JITTargetAddress toTargetAddress(PtrTy *P) {
180 return static_cast<JITTargetAddress>(reinterpret_cast<uintptr_t>(P));
181 }
182
183 using DestructorPtr = void (*)(void *);
184 using CXXDestructorDataPair = std::pair<DestructorPtr, void *>;
185 using CXXDestructorDataPairList = std::vector<CXXDestructorDataPair>;
186 CXXDestructorDataPairList DSOHandleOverride;
187 static int CXAAtExitOverride(DestructorPtr Destructor, void *Arg,
188 void *DSOHandle);
189 };
190
191 class LocalCXXRuntimeOverrides : public LocalCXXRuntimeOverridesBase {
192 public:
193 Error enable(JITDylib &JD, MangleAndInterner &Mangler);
194 };
195
196 /// An interface for Itanium __cxa_atexit interposer implementations.
197 class ItaniumCXAAtExitSupport {
198 public:
199 struct AtExitRecord {
200 void (*F)(void *);
201 void *Ctx;
202 };
203
204 void registerAtExit(void (*F)(void *), void *Ctx, void *DSOHandle);
205 void runAtExits(void *DSOHandle);
206
207 private:
208 std::mutex AtExitsMutex;
209 DenseMap<void *, std::vector<AtExitRecord>> AtExitRecords;
210 };
211
212 /// A utility class to expose symbols found via dlsym to the JIT.
213 ///
214 /// If an instance of this class is attached to a JITDylib as a fallback
215 /// definition generator, then any symbol found in the given DynamicLibrary that
216 /// passes the 'Allow' predicate will be added to the JITDylib.
217 class DynamicLibrarySearchGenerator : public DefinitionGenerator {
218 public:
219 using SymbolPredicate = std::function<bool(const SymbolStringPtr &)>;
220
221 /// Create a DynamicLibrarySearchGenerator that searches for symbols in the
222 /// given sys::DynamicLibrary.
223 ///
224 /// If the Allow predicate is given then only symbols matching the predicate
225 /// will be searched for. If the predicate is not given then all symbols will
226 /// be searched for.
227 DynamicLibrarySearchGenerator(sys::DynamicLibrary Dylib, char GlobalPrefix,
228 SymbolPredicate Allow = SymbolPredicate());
229
230 /// Permanently loads the library at the given path and, on success, returns
231 /// a DynamicLibrarySearchGenerator that will search it for symbol definitions
232 /// in the library. On failure returns the reason the library failed to load.
233 static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
234 Load(const char *FileName, char GlobalPrefix,
235 SymbolPredicate Allow = SymbolPredicate());
236
237 /// Creates a DynamicLibrarySearchGenerator that searches for symbols in
238 /// the current process.
239 static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
240 GetForCurrentProcess(char GlobalPrefix,
241 SymbolPredicate Allow = SymbolPredicate()) {
242 return Load(nullptr, GlobalPrefix, std::move(Allow));
243 }
244
245 Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
246 JITDylibLookupFlags JDLookupFlags,
247 const SymbolLookupSet &Symbols) override;
248
249 private:
250 sys::DynamicLibrary Dylib;
251 SymbolPredicate Allow;
252 char GlobalPrefix;
253 };
254
255 /// A utility class to expose symbols from a static library.
256 ///
257 /// If an instance of this class is attached to a JITDylib as a fallback
258 /// definition generator, then any symbol found in the archive will result in
259 /// the containing object being added to the JITDylib.
260 class StaticLibraryDefinitionGenerator : public DefinitionGenerator {
261 public:
262 /// Try to create a StaticLibraryDefinitionGenerator from the given path.
263 ///
264 /// This call will succeed if the file at the given path is a static library
265 /// is a valid archive, otherwise it will return an error.
266 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
267 Load(ObjectLayer &L, const char *FileName);
268
269 /// Try to create a StaticLibraryDefinitionGenerator from the given path.
270 ///
271 /// This call will succeed if the file at the given path is a static library
272 /// or a MachO universal binary containing a static library that is compatible
273 /// with the given triple. Otherwise it will return an error.
274 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
275 Load(ObjectLayer &L, const char *FileName, const Triple &TT);
276
277 /// Try to create a StaticLibrarySearchGenerator from the given memory buffer.
278 /// This call will succeed if the buffer contains a valid archive, otherwise
279 /// it will return an error.
280 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
281 Create(ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer);
282
283 Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
284 JITDylibLookupFlags JDLookupFlags,
285 const SymbolLookupSet &Symbols) override;
286
287 private:
288 StaticLibraryDefinitionGenerator(ObjectLayer &L,
289 std::unique_ptr<MemoryBuffer> ArchiveBuffer,
290 Error &Err);
291
292 ObjectLayer &L;
293 std::unique_ptr<MemoryBuffer> ArchiveBuffer;
294 std::unique_ptr<object::Archive> Archive;
295 };
296
297 } // end namespace orc
298 } // end namespace llvm
299
300 #endif // LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
301