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 <string>
28#include <utility>
29#include <vector>
30
31namespace llvm {
32
33class ConstantArray;
34class GlobalVariable;
35class Function;
36class Module;
37class TargetMachine;
38class Value;
39
40namespace orc {
41
42class ObjectLayer;
43
44/// This iterator provides a convenient way to iterate over the elements
45/// of an llvm.global_ctors/llvm.global_dtors instance.
46///
47/// The easiest way to get hold of instances of this class is to use the
48/// getConstructors/getDestructors functions.
49class CtorDtorIterator {
50public:
51 /// Accessor for an element of the global_ctors/global_dtors array.
52 ///
53 /// This class provides a read-only view of the element with any casts on
54 /// the function stripped away.
55 struct Element {
56 Element(unsigned Priority, Function *Func, Value *Data)
57 : Priority(Priority), Func(Func), Data(Data) {}
58
59 unsigned Priority;
60 Function *Func;
61 Value *Data;
62 };
63
64 /// Construct an iterator instance. If End is true then this iterator
65 /// acts as the end of the range, otherwise it is the beginning.
66 CtorDtorIterator(const GlobalVariable *GV, bool End);
67
68 /// Test iterators for equality.
69 bool operator==(const CtorDtorIterator &Other) const;
70
71 /// Test iterators for inequality.
72 bool operator!=(const CtorDtorIterator &Other) const;
73
74 /// Pre-increment iterator.
75 CtorDtorIterator& operator++();
76
77 /// Post-increment iterator.
78 CtorDtorIterator operator++(int);
79
80 /// Dereference iterator. The resulting value provides a read-only view
81 /// of this element of the global_ctors/global_dtors list.
82 Element operator*() const;
83
84private:
85 const ConstantArray *InitList;
86 unsigned I;
87};
88
89/// Create an iterator range over the entries of the llvm.global_ctors
90/// array.
91iterator_range<CtorDtorIterator> getConstructors(const Module &M);
92
93/// Create an iterator range over the entries of the llvm.global_ctors
94/// array.
95iterator_range<CtorDtorIterator> getDestructors(const Module &M);
96
97/// This iterator provides a convenient way to iterate over GlobalValues that
98/// have initialization effects.
99class StaticInitGVIterator {
100public:
101 StaticInitGVIterator() = default;
102
103 StaticInitGVIterator(Module &M)
104 : I(M.global_values().begin()), E(M.global_values().end()),
105 ObjFmt(Triple(M.getTargetTriple()).getObjectFormat()) {
106 if (I != E) {
107 if (!isStaticInitGlobal(*I))
108 moveToNextStaticInitGlobal();
109 } else
110 I = E = Module::global_value_iterator();
111 }
112
113 bool operator==(const StaticInitGVIterator &O) const { return I == O.I; }
114 bool operator!=(const StaticInitGVIterator &O) const { return I != O.I; }
115
116 StaticInitGVIterator &operator++() {
117 assert(I != E && "Increment past end of range");
118 moveToNextStaticInitGlobal();
119 return *this;
120 }
121
122 GlobalValue &operator*() { return *I; }
123
124private:
125 bool isStaticInitGlobal(GlobalValue &GV);
126 void moveToNextStaticInitGlobal() {
127 ++I;
128 while (I != E && !isStaticInitGlobal(*I))
129 ++I;
130 if (I == E)
131 I = E = Module::global_value_iterator();
132 }
133
134 Module::global_value_iterator I, E;
135 Triple::ObjectFormatType ObjFmt;
136};
137
138/// Create an iterator range over the GlobalValues that contribute to static
139/// initialization.
140inline iterator_range<StaticInitGVIterator> getStaticInitGVs(Module &M) {
141 return make_range(StaticInitGVIterator(M), StaticInitGVIterator());
142}
143
144class CtorDtorRunner {
145public:
146 CtorDtorRunner(JITDylib &JD) : JD(JD) {}
147 void add(iterator_range<CtorDtorIterator> CtorDtors);
148 Error run();
149
150private:
151 using CtorDtorList = std::vector<SymbolStringPtr>;
152 using CtorDtorPriorityMap = std::map<unsigned, CtorDtorList>;
153
154 JITDylib &JD;
155 CtorDtorPriorityMap CtorDtorsByPriority;
156};
157
158/// Support class for static dtor execution. For hosted (in-process) JITs
159/// only!
160///
161/// If a __cxa_atexit function isn't found C++ programs that use static
162/// destructors will fail to link. However, we don't want to use the host
163/// process's __cxa_atexit, because it will schedule JIT'd destructors to run
164/// after the JIT has been torn down, which is no good. This class makes it easy
165/// to override __cxa_atexit (and the related __dso_handle).
166///
167/// To use, clients should manually call searchOverrides from their symbol
168/// resolver. This should generally be done after attempting symbol resolution
169/// inside the JIT, but before searching the host process's symbol table. When
170/// the client determines that destructors should be run (generally at JIT
171/// teardown or after a return from main), the runDestructors method should be
172/// called.
173class LocalCXXRuntimeOverridesBase {
174public:
175 /// Run any destructors recorded by the overriden __cxa_atexit function
176 /// (CXAAtExitOverride).
177 void runDestructors();
178
179protected:
180 template <typename PtrTy> JITTargetAddress toTargetAddress(PtrTy *P) {
181 return static_cast<JITTargetAddress>(reinterpret_cast<uintptr_t>(P));
182 }
183
184 using DestructorPtr = void (*)(void *);
185 using CXXDestructorDataPair = std::pair<DestructorPtr, void *>;
186 using CXXDestructorDataPairList = std::vector<CXXDestructorDataPair>;
187 CXXDestructorDataPairList DSOHandleOverride;
188 static int CXAAtExitOverride(DestructorPtr Destructor, void *Arg,
189 void *DSOHandle);
190};
191
192class LocalCXXRuntimeOverrides : public LocalCXXRuntimeOverridesBase {
193public:
194 Error enable(JITDylib &JD, MangleAndInterner &Mangler);
195};
196
197/// An interface for Itanium __cxa_atexit interposer implementations.
198class ItaniumCXAAtExitSupport {
199public:
200 struct AtExitRecord {
201 void (*F)(void *);
202 void *Ctx;
203 };
204
205 void registerAtExit(void (*F)(void *), void *Ctx, void *DSOHandle);
206 void runAtExits(void *DSOHandle);
207
208private:
209 std::mutex AtExitsMutex;
210 DenseMap<void *, std::vector<AtExitRecord>> AtExitRecords;
211};
212
213/// A utility class to expose symbols found via dlsym to the JIT.
214///
215/// If an instance of this class is attached to a JITDylib as a fallback
216/// definition generator, then any symbol found in the given DynamicLibrary that
217/// passes the 'Allow' predicate will be added to the JITDylib.
218class DynamicLibrarySearchGenerator : public DefinitionGenerator {
219public:
220 using SymbolPredicate = std::function<bool(const SymbolStringPtr &)>;
221
222 /// Create a DynamicLibrarySearchGenerator that searches for symbols in the
223 /// given sys::DynamicLibrary.
224 ///
225 /// If the Allow predicate is given then only symbols matching the predicate
226 /// will be searched for. If the predicate is not given then all symbols will
227 /// be searched for.
228 DynamicLibrarySearchGenerator(sys::DynamicLibrary Dylib, char GlobalPrefix,
229 SymbolPredicate Allow = SymbolPredicate());
230
231 /// Permanently loads the library at the given path and, on success, returns
232 /// a DynamicLibrarySearchGenerator that will search it for symbol definitions
233 /// in the library. On failure returns the reason the library failed to load.
234 static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
235 Load(const char *FileName, char GlobalPrefix,
236 SymbolPredicate Allow = SymbolPredicate());
237
238 /// Creates a DynamicLibrarySearchGenerator that searches for symbols in
239 /// the current process.
240 static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
241 GetForCurrentProcess(char GlobalPrefix,
242 SymbolPredicate Allow = SymbolPredicate()) {
243 return Load(nullptr, GlobalPrefix, std::move(Allow));
244 }
245
246 Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
247 JITDylibLookupFlags JDLookupFlags,
248 const SymbolLookupSet &Symbols) override;
249
250private:
251 sys::DynamicLibrary Dylib;
252 SymbolPredicate Allow;
253 char GlobalPrefix;
254};
255
256/// A utility class to expose symbols from a static library.
257///
258/// If an instance of this class is attached to a JITDylib as a fallback
259/// definition generator, then any symbol found in the archive will result in
260/// the containing object being added to the JITDylib.
261class StaticLibraryDefinitionGenerator : public DefinitionGenerator {
262public:
263 /// Try to create a StaticLibraryDefinitionGenerator from the given path.
264 ///
265 /// This call will succeed if the file at the given path is a static library
266 /// is a valid archive, otherwise it will return an error.
267 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
268 Load(ObjectLayer &L, const char *FileName);
269
270 /// Try to create a StaticLibraryDefinitionGenerator from the given path.
271 ///
272 /// This call will succeed if the file at the given path is a static library
273 /// or a MachO universal binary containing a static library that is compatible
274 /// with the given triple. Otherwise it will return an error.
275 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
276 Load(ObjectLayer &L, const char *FileName, const Triple &TT);
277
278 /// Try to create a StaticLibrarySearchGenerator from the given memory buffer.
279 /// This call will succeed if the buffer contains a valid archive, otherwise
280 /// it will return an error.
281 static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
282 Create(ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer);
283
284 Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
285 JITDylibLookupFlags JDLookupFlags,
286 const SymbolLookupSet &Symbols) override;
287
288private:
289 StaticLibraryDefinitionGenerator(ObjectLayer &L,
290 std::unique_ptr<MemoryBuffer> ArchiveBuffer,
291 Error &Err);
292
293 ObjectLayer &L;
294 std::unique_ptr<MemoryBuffer> ArchiveBuffer;
295 std::unique_ptr<object::Archive> Archive;
296};
297
298} // end namespace orc
299} // end namespace llvm
300
301#endif // LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
302