1//===------ LazyReexports.h -- Utilities for lazy reexports -----*- 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// Lazy re-exports are similar to normal re-exports, except that for callable
10// symbols the definitions are replaced with trampolines that will look up and
11// call through to the re-exported symbol at runtime. This can be used to
12// enable lazy compilation.
13//
14//===----------------------------------------------------------------------===//
15
16#ifndef LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
17#define LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
18
19#include "llvm/ADT/STLExtras.h"
20#include "llvm/ExecutionEngine/Orc/Core.h"
21#include "llvm/ExecutionEngine/Orc/IndirectionUtils.h"
22#include "llvm/ExecutionEngine/Orc/Speculation.h"
23
24namespace llvm {
25
26class Triple;
27
28namespace orc {
29
30/// Manages a set of 'lazy call-through' trampolines. These are compiler
31/// re-entry trampolines that are pre-bound to look up a given symbol in a given
32/// JITDylib, then jump to that address. Since compilation of symbols is
33/// triggered on first lookup, these call-through trampolines can be used to
34/// implement lazy compilation.
35///
36/// The easiest way to construct these call-throughs is using the lazyReexport
37/// function.
38class LazyCallThroughManager {
39public:
40 using NotifyResolvedFunction =
41 unique_function<Error(ExecutorAddr ResolvedAddr)>;
42
43 LazyCallThroughManager(ExecutionSession &ES, ExecutorAddr ErrorHandlerAddr,
44 TrampolinePool *TP);
45
46 // Return a free call-through trampoline and bind it to look up and call
47 // through to the given symbol.
48 Expected<ExecutorAddr>
49 getCallThroughTrampoline(JITDylib &SourceJD, SymbolStringPtr SymbolName,
50 NotifyResolvedFunction NotifyResolved);
51
52 void resolveTrampolineLandingAddress(
53 ExecutorAddr TrampolineAddr,
54 TrampolinePool::NotifyLandingResolvedFunction NotifyLandingResolved);
55
56 virtual ~LazyCallThroughManager() = default;
57
58protected:
59 using NotifyLandingResolvedFunction =
60 TrampolinePool::NotifyLandingResolvedFunction;
61
62 struct ReexportsEntry {
63 JITDylib *SourceJD;
64 SymbolStringPtr SymbolName;
65 };
66
67 ExecutorAddr reportCallThroughError(Error Err);
68 Expected<ReexportsEntry> findReexport(ExecutorAddr TrampolineAddr);
69 Error notifyResolved(ExecutorAddr TrampolineAddr, ExecutorAddr ResolvedAddr);
70 void setTrampolinePool(TrampolinePool &TP) { this->TP = &TP; }
71
72private:
73 using ReexportsMap = std::map<ExecutorAddr, ReexportsEntry>;
74
75 using NotifiersMap = std::map<ExecutorAddr, NotifyResolvedFunction>;
76
77 std::mutex LCTMMutex;
78 ExecutionSession &ES;
79 ExecutorAddr ErrorHandlerAddr;
80 TrampolinePool *TP = nullptr;
81 ReexportsMap Reexports;
82 NotifiersMap Notifiers;
83};
84
85/// A lazy call-through manager that builds trampolines in the current process.
86class LocalLazyCallThroughManager : public LazyCallThroughManager {
87private:
88 using NotifyTargetResolved = unique_function<void(ExecutorAddr)>;
89
90 LocalLazyCallThroughManager(ExecutionSession &ES,
91 ExecutorAddr ErrorHandlerAddr)
92 : LazyCallThroughManager(ES, ErrorHandlerAddr, nullptr) {}
93
94 template <typename ORCABI> Error init() {
95 auto TP = LocalTrampolinePool<ORCABI>::Create(
96 [this](ExecutorAddr TrampolineAddr,
97 TrampolinePool::NotifyLandingResolvedFunction
98 NotifyLandingResolved) {
99 resolveTrampolineLandingAddress(TrampolineAddr,
100 NotifyLandingResolved: std::move(NotifyLandingResolved));
101 });
102
103 if (!TP)
104 return TP.takeError();
105
106 this->TP = std::move(*TP);
107 setTrampolinePool(*this->TP);
108 return Error::success();
109 }
110
111 std::unique_ptr<TrampolinePool> TP;
112
113public:
114 /// Create a LocalLazyCallThroughManager using the given ABI. See
115 /// createLocalLazyCallThroughManager.
116 template <typename ORCABI>
117 static Expected<std::unique_ptr<LocalLazyCallThroughManager>>
118 Create(ExecutionSession &ES, ExecutorAddr ErrorHandlerAddr) {
119 auto LLCTM = std::unique_ptr<LocalLazyCallThroughManager>(
120 new LocalLazyCallThroughManager(ES, ErrorHandlerAddr));
121
122 if (auto Err = LLCTM->init<ORCABI>())
123 return std::move(Err);
124
125 return std::move(LLCTM);
126 }
127};
128
129/// Create a LocalLazyCallThroughManager from the given triple and execution
130/// session.
131Expected<std::unique_ptr<LazyCallThroughManager>>
132createLocalLazyCallThroughManager(const Triple &T, ExecutionSession &ES,
133 ExecutorAddr ErrorHandlerAddr);
134
135/// A materialization unit that builds lazy re-exports. These are callable
136/// entry points that call through to the given symbols.
137/// Unlike a 'true' re-export, the address of the lazy re-export will not
138/// match the address of the re-exported symbol, but calling it will behave
139/// the same as calling the re-exported symbol.
140class LazyReexportsMaterializationUnit : public MaterializationUnit {
141public:
142 LazyReexportsMaterializationUnit(LazyCallThroughManager &LCTManager,
143 IndirectStubsManager &ISManager,
144 JITDylib &SourceJD,
145 SymbolAliasMap CallableAliases,
146 ImplSymbolMap *SrcJDLoc);
147
148 StringRef getName() const override;
149
150private:
151 void materialize(std::unique_ptr<MaterializationResponsibility> R) override;
152 void discard(const JITDylib &JD, const SymbolStringPtr &Name) override;
153 static MaterializationUnit::Interface
154 extractFlags(const SymbolAliasMap &Aliases);
155
156 LazyCallThroughManager &LCTManager;
157 IndirectStubsManager &ISManager;
158 JITDylib &SourceJD;
159 SymbolAliasMap CallableAliases;
160 ImplSymbolMap *AliaseeTable;
161};
162
163/// Define lazy-reexports based on the given SymbolAliasMap. Each lazy re-export
164/// is a callable symbol that will look up and dispatch to the given aliasee on
165/// first call. All subsequent calls will go directly to the aliasee.
166inline std::unique_ptr<LazyReexportsMaterializationUnit>
167lazyReexports(LazyCallThroughManager &LCTManager,
168 IndirectStubsManager &ISManager, JITDylib &SourceJD,
169 SymbolAliasMap CallableAliases,
170 ImplSymbolMap *SrcJDLoc = nullptr) {
171 return std::make_unique<LazyReexportsMaterializationUnit>(
172 args&: LCTManager, args&: ISManager, args&: SourceJD, args: std::move(CallableAliases), args&: SrcJDLoc);
173}
174
175} // End namespace orc
176} // End namespace llvm
177
178#endif // LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
179

source code of llvm/include/llvm/ExecutionEngine/Orc/LazyReexports.h