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(JITTargetAddress ResolvedAddr)>;
42
43 LazyCallThroughManager(ExecutionSession &ES,
44 JITTargetAddress ErrorHandlerAddr, 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<JITTargetAddress>
49 getCallThroughTrampoline(JITDylib &SourceJD, SymbolStringPtr SymbolName,
50 NotifyResolvedFunction NotifyResolved);
51
52 void resolveTrampolineLandingAddress(
53 JITTargetAddress 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 JITTargetAddress reportCallThroughError(Error Err);
68 Expected<ReexportsEntry> findReexport(JITTargetAddress TrampolineAddr);
69 Error notifyResolved(JITTargetAddress TrampolineAddr,
70 JITTargetAddress ResolvedAddr);
71 void setTrampolinePool(TrampolinePool &TP) { this->TP = &TP; }
72
73private:
74 using ReexportsMap = std::map<JITTargetAddress, ReexportsEntry>;
75
76 using NotifiersMap = std::map<JITTargetAddress, NotifyResolvedFunction>;
77
78 std::mutex LCTMMutex;
79 ExecutionSession &ES;
80 JITTargetAddress ErrorHandlerAddr;
81 TrampolinePool *TP = nullptr;
82 ReexportsMap Reexports;
83 NotifiersMap Notifiers;
84};
85
86/// A lazy call-through manager that builds trampolines in the current process.
87class LocalLazyCallThroughManager : public LazyCallThroughManager {
88private:
89 using NotifyTargetResolved = unique_function<void(JITTargetAddress)>;
90
91 LocalLazyCallThroughManager(ExecutionSession &ES,
92 JITTargetAddress ErrorHandlerAddr)
93 : LazyCallThroughManager(ES, ErrorHandlerAddr, nullptr) {}
94
95 template <typename ORCABI> Error init() {
96 auto TP = LocalTrampolinePool<ORCABI>::Create(
97 [this](JITTargetAddress TrampolineAddr,
98 TrampolinePool::NotifyLandingResolvedFunction
99 NotifyLandingResolved) {
100 resolveTrampolineLandingAddress(TrampolineAddr,
101 std::move(NotifyLandingResolved));
102 });
103
104 if (!TP)
105 return TP.takeError();
106
107 this->TP = std::move(*TP);
108 setTrampolinePool(*this->TP);
109 return Error::success();
110 }
111
112 std::unique_ptr<TrampolinePool> TP;
113
114public:
115 /// Create a LocalLazyCallThroughManager using the given ABI. See
116 /// createLocalLazyCallThroughManager.
117 template <typename ORCABI>
118 static Expected<std::unique_ptr<LocalLazyCallThroughManager>>
119 Create(ExecutionSession &ES, JITTargetAddress ErrorHandlerAddr) {
120 auto LLCTM = std::unique_ptr<LocalLazyCallThroughManager>(
121 new LocalLazyCallThroughManager(ES, ErrorHandlerAddr));
122
123 if (auto Err = LLCTM->init<ORCABI>())
124 return std::move(Err);
125
126 return std::move(LLCTM);
127 }
128};
129
130/// Create a LocalLazyCallThroughManager from the given triple and execution
131/// session.
132Expected<std::unique_ptr<LazyCallThroughManager>>
133createLocalLazyCallThroughManager(const Triple &T, ExecutionSession &ES,
134 JITTargetAddress ErrorHandlerAddr);
135
136/// A materialization unit that builds lazy re-exports. These are callable
137/// entry points that call through to the given symbols.
138/// Unlike a 'true' re-export, the address of the lazy re-export will not
139/// match the address of the re-exported symbol, but calling it will behave
140/// the same as calling the re-exported symbol.
141class LazyReexportsMaterializationUnit : public MaterializationUnit {
142public:
143 LazyReexportsMaterializationUnit(LazyCallThroughManager &LCTManager,
144 IndirectStubsManager &ISManager,
145 JITDylib &SourceJD,
146 SymbolAliasMap CallableAliases,
147 ImplSymbolMap *SrcJDLoc);
148
149 StringRef getName() const override;
150
151private:
152 void materialize(std::unique_ptr<MaterializationResponsibility> R) override;
153 void discard(const JITDylib &JD, const SymbolStringPtr &Name) override;
154 static SymbolFlagsMap 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 LCTManager, ISManager, SourceJD, std::move(CallableAliases), SrcJDLoc);
173}
174
175} // End namespace orc
176} // End namespace llvm
177
178#endif // LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
179