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 Value;
37
38 namespace orc {
39
40 class ObjectLayer;
41
42 /// This iterator provides a convenient way to iterate over the elements
43 /// of an llvm.global_ctors/llvm.global_dtors instance.
44 ///
45 /// The easiest way to get hold of instances of this class is to use the
46 /// getConstructors/getDestructors functions.
47 class CtorDtorIterator {
48 public:
49 /// Accessor for an element of the global_ctors/global_dtors array.
50 ///
51 /// This class provides a read-only view of the element with any casts on
52 /// the function stripped away.
53 struct Element {
ElementElement54 Element(unsigned Priority, Function *Func, Value *Data)
55 : Priority(Priority), Func(Func), Data(Data) {}
56
57 unsigned Priority;
58 Function *Func;
59 Value *Data;
60 };
61
62 /// Construct an iterator instance. If End is true then this iterator
63 /// acts as the end of the range, otherwise it is the beginning.
64 CtorDtorIterator(const GlobalVariable *GV, bool End);
65
66 /// Test iterators for equality.
67 bool operator==(const CtorDtorIterator &Other) const;
68
69 /// Test iterators for inequality.
70 bool operator!=(const CtorDtorIterator &Other) const;
71
72 /// Pre-increment iterator.
73 CtorDtorIterator& operator++();
74
75 /// Post-increment iterator.
76 CtorDtorIterator operator++(int);
77
78 /// Dereference iterator. The resulting value provides a read-only view
79 /// of this element of the global_ctors/global_dtors list.
80 Element operator*() const;
81
82 private:
83 const ConstantArray *InitList;
84 unsigned I;
85 };
86
87 /// Create an iterator range over the entries of the llvm.global_ctors
88 /// array.
89 iterator_range<CtorDtorIterator> getConstructors(const Module &M);
90
91 /// Create an iterator range over the entries of the llvm.global_ctors
92 /// array.
93 iterator_range<CtorDtorIterator> getDestructors(const Module &M);
94
95 /// This iterator provides a convenient way to iterate over GlobalValues that
96 /// have initialization effects.
97 class StaticInitGVIterator {
98 public:
99 StaticInitGVIterator() = default;
100
StaticInitGVIterator(Module & M)101 StaticInitGVIterator(Module &M)
102 : I(M.global_values().begin()), E(M.global_values().end()),
103 ObjFmt(Triple(M.getTargetTriple()).getObjectFormat()) {
104 if (I != E) {
105 if (!isStaticInitGlobal(*I))
106 moveToNextStaticInitGlobal();
107 } else
108 I = E = Module::global_value_iterator();
109 }
110
111 bool operator==(const StaticInitGVIterator &O) const { return I == O.I; }
112 bool operator!=(const StaticInitGVIterator &O) const { return I != O.I; }
113
114 StaticInitGVIterator &operator++() {
115 assert(I != E && "Increment past end of range");
116 moveToNextStaticInitGlobal();
117 return *this;
118 }
119
120 GlobalValue &operator*() { return *I; }
121
122 private:
123 bool isStaticInitGlobal(GlobalValue &GV);
moveToNextStaticInitGlobal()124 void moveToNextStaticInitGlobal() {
125 ++I;
126 while (I != E && !isStaticInitGlobal(*I))
127 ++I;
128 if (I == E)
129 I = E = Module::global_value_iterator();
130 }
131
132 Module::global_value_iterator I, E;
133 Triple::ObjectFormatType ObjFmt;
134 };
135
136 /// Create an iterator range over the GlobalValues that contribute to static
137 /// initialization.
getStaticInitGVs(Module & M)138 inline iterator_range<StaticInitGVIterator> getStaticInitGVs(Module &M) {
139 return make_range(StaticInitGVIterator(M), StaticInitGVIterator());
140 }
141
142 class CtorDtorRunner {
143 public:
CtorDtorRunner(JITDylib & JD)144 CtorDtorRunner(JITDylib &JD) : JD(JD) {}
145 void add(iterator_range<CtorDtorIterator> CtorDtors);
146 Error run();
147
148 private:
149 using CtorDtorList = std::vector<SymbolStringPtr>;
150 using CtorDtorPriorityMap = std::map<unsigned, CtorDtorList>;
151
152 JITDylib &JD;
153 CtorDtorPriorityMap CtorDtorsByPriority;
154 };
155
156 /// Support class for static dtor execution. For hosted (in-process) JITs
157 /// only!
158 ///
159 /// If a __cxa_atexit function isn't found C++ programs that use static
160 /// destructors will fail to link. However, we don't want to use the host
161 /// process's __cxa_atexit, because it will schedule JIT'd destructors to run
162 /// after the JIT has been torn down, which is no good. This class makes it easy
163 /// to override __cxa_atexit (and the related __dso_handle).
164 ///
165 /// To use, clients should manually call searchOverrides from their symbol
166 /// resolver. This should generally be done after attempting symbol resolution
167 /// inside the JIT, but before searching the host process's symbol table. When
168 /// the client determines that destructors should be run (generally at JIT
169 /// teardown or after a return from main), the runDestructors method should be
170 /// called.
171 class LocalCXXRuntimeOverridesBase {
172 public:
173 /// Run any destructors recorded by the overriden __cxa_atexit function
174 /// (CXAAtExitOverride).
175 void runDestructors();
176
177 protected:
toTargetAddress(PtrTy * P)178 template <typename PtrTy> JITTargetAddress toTargetAddress(PtrTy *P) {
179 return static_cast<JITTargetAddress>(reinterpret_cast<uintptr_t>(P));
180 }
181
182 using DestructorPtr = void (*)(void *);
183 using CXXDestructorDataPair = std::pair<DestructorPtr, void *>;
184 using CXXDestructorDataPairList = std::vector<CXXDestructorDataPair>;
185 CXXDestructorDataPairList DSOHandleOverride;
186 static int CXAAtExitOverride(DestructorPtr Destructor, void *Arg,
187 void *DSOHandle);
188 };
189
190 class LocalCXXRuntimeOverrides : public LocalCXXRuntimeOverridesBase {
191 public:
192 Error enable(JITDylib &JD, MangleAndInterner &Mangler);
193 };
194
195 /// An interface for Itanium __cxa_atexit interposer implementations.
196 class ItaniumCXAAtExitSupport {
197 public:
198 struct AtExitRecord {
199 void (*F)(void *);
200 void *Ctx;
201 };
202
203 void registerAtExit(void (*F)(void *), void *Ctx, void *DSOHandle);
204 void runAtExits(void *DSOHandle);
205
206 private:
207 std::mutex AtExitsMutex;
208 DenseMap<void *, std::vector<AtExitRecord>> AtExitRecords;
209 };
210
211 /// A utility class to expose symbols found via dlsym to the JIT.
212 ///
213 /// If an instance of this class is attached to a JITDylib as a fallback
214 /// definition generator, then any symbol found in the given DynamicLibrary that
215 /// passes the 'Allow' predicate will be added to the JITDylib.
216 class DynamicLibrarySearchGenerator : public DefinitionGenerator {
217 public:
218 using SymbolPredicate = std::function<bool(const SymbolStringPtr &)>;
219
220 /// Create a DynamicLibrarySearchGenerator that searches for symbols in the
221 /// given sys::DynamicLibrary.
222 ///
223 /// If the Allow predicate is given then only symbols matching the predicate
224 /// will be searched for. If the predicate is not given then all symbols will
225 /// be searched for.
226 DynamicLibrarySearchGenerator(sys::DynamicLibrary Dylib, char GlobalPrefix,
227 SymbolPredicate Allow = SymbolPredicate());
228
229 /// Permanently loads the library at the given path and, on success, returns
230 /// a DynamicLibrarySearchGenerator that will search it for symbol definitions
231 /// in the library. On failure returns the reason the library failed to load.
232 static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
233 Load(const char *FileName, char GlobalPrefix,
234 SymbolPredicate Allow = SymbolPredicate());
235
236 /// Creates a DynamicLibrarySearchGenerator that searches for symbols in
237 /// the current process.
238 static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
239 GetForCurrentProcess(char GlobalPrefix,
240 SymbolPredicate Allow = SymbolPredicate()) {
241 return Load(nullptr, GlobalPrefix, std::move(Allow));
242 }
243
244 Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
245 JITDylibLookupFlags JDLookupFlags,
246 const SymbolLookupSet &Symbols) override;
247
248 private:
249 sys::DynamicLibrary Dylib;
250 SymbolPredicate Allow;
251 char GlobalPrefix;
252 };
253
254 /// A utility class to expose symbols from a static library.
255 ///
256 /// If an instance of this class is attached to a JITDylib as a fallback
257 /// definition generator, then any symbol found in the archive will result in
258 /// the containing object being added to the JITDylib.
259 class StaticLibraryDefinitionGenerator : public DefinitionGenerator {
260 public:
261 // Interface builder function for objects loaded from this archive.
262 using GetObjectFileInterface =
263 unique_function<Expected<MaterializationUnit::Interface>(
264 ExecutionSession &ES, MemoryBufferRef ObjBuffer)>;
265
266 /// Try to create a StaticLibraryDefinitionGenerator from the given path.
267 ///
268 /// This call will succeed if the file at the given path is a static library
269 /// is a valid archive, otherwise it will return an error.
270 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
271 Load(ObjectLayer &L, const char *FileName,
272 GetObjectFileInterface GetObjFileInterface = GetObjectFileInterface());
273
274 /// Try to create a StaticLibraryDefinitionGenerator from the given path.
275 ///
276 /// This call will succeed if the file at the given path is a static library
277 /// or a MachO universal binary containing a static library that is compatible
278 /// with the given triple. Otherwise it will return an error.
279 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
280 Load(ObjectLayer &L, const char *FileName, const Triple &TT,
281 GetObjectFileInterface GetObjFileInterface = GetObjectFileInterface());
282
283 /// Try to create a StaticLibrarySearchGenerator from the given memory buffer.
284 /// This call will succeed if the buffer contains a valid archive, otherwise
285 /// it will return an error.
286 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
287 Create(ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer,
288 GetObjectFileInterface GetObjFileInterface = GetObjectFileInterface());
289
290 Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
291 JITDylibLookupFlags JDLookupFlags,
292 const SymbolLookupSet &Symbols) override;
293
294 private:
295 StaticLibraryDefinitionGenerator(ObjectLayer &L,
296 std::unique_ptr<MemoryBuffer> ArchiveBuffer,
297 GetObjectFileInterface GetObjFileInterface,
298 Error &Err);
299
300 ObjectLayer &L;
301 GetObjectFileInterface GetObjFileInterface;
302 std::unique_ptr<MemoryBuffer> ArchiveBuffer;
303 std::unique_ptr<object::Archive> Archive;
304 };
305
306 } // end namespace orc
307 } // end namespace llvm
308
309 #endif // LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
310