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//===------ LazyReexports.h -- Utilities for lazy reexports -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Lazy re-exports are similar to normal re-exports, except that for callable
// symbols the definitions are replaced with trampolines that will look up and
// call through to the re-exported symbol at runtime. This can be used to
// enable lazy compilation.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
#define LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
#include "llvm/ADT/STLExtras.h"
#include "llvm/ExecutionEngine/Orc/Core.h"
#include "llvm/ExecutionEngine/Orc/IndirectionUtils.h"
#include "llvm/ExecutionEngine/Orc/Speculation.h"
namespace llvm {
class Triple;
namespace orc {
/// Manages a set of 'lazy call-through' trampolines. These are compiler
/// re-entry trampolines that are pre-bound to look up a given symbol in a given
/// JITDylib, then jump to that address. Since compilation of symbols is
/// triggered on first lookup, these call-through trampolines can be used to
/// implement lazy compilation.
///
/// The easiest way to construct these call-throughs is using the lazyReexport
/// function.
class LazyCallThroughManager {
public:
using NotifyResolvedFunction =
unique_function<Error(ExecutorAddr ResolvedAddr)>;
LazyCallThroughManager(ExecutionSession &ES, ExecutorAddr ErrorHandlerAddr,
TrampolinePool *TP);
// Return a free call-through trampoline and bind it to look up and call
// through to the given symbol.
Expected<ExecutorAddr>
getCallThroughTrampoline(JITDylib &SourceJD, SymbolStringPtr SymbolName,
NotifyResolvedFunction NotifyResolved);
void resolveTrampolineLandingAddress(
ExecutorAddr TrampolineAddr,
TrampolinePool::NotifyLandingResolvedFunction NotifyLandingResolved);
virtual ~LazyCallThroughManager() = default;
protected:
using NotifyLandingResolvedFunction =
TrampolinePool::NotifyLandingResolvedFunction;
struct ReexportsEntry {
JITDylib *SourceJD;
SymbolStringPtr SymbolName;
};
ExecutorAddr reportCallThroughError(Error Err);
Expected<ReexportsEntry> findReexport(ExecutorAddr TrampolineAddr);
Error notifyResolved(ExecutorAddr TrampolineAddr, ExecutorAddr ResolvedAddr);
void setTrampolinePool(TrampolinePool &TP) { this->TP = &TP; }
private:
using ReexportsMap = std::map<ExecutorAddr, ReexportsEntry>;
using NotifiersMap = std::map<ExecutorAddr, NotifyResolvedFunction>;
std::mutex LCTMMutex;
ExecutionSession &ES;
ExecutorAddr ErrorHandlerAddr;
TrampolinePool *TP = nullptr;
ReexportsMap Reexports;
NotifiersMap Notifiers;
};
/// A lazy call-through manager that builds trampolines in the current process.
class LocalLazyCallThroughManager : public LazyCallThroughManager {
private:
using NotifyTargetResolved = unique_function<void(ExecutorAddr)>;
LocalLazyCallThroughManager(ExecutionSession &ES,
ExecutorAddr ErrorHandlerAddr)
: LazyCallThroughManager(ES, ErrorHandlerAddr, nullptr) {}
template <typename ORCABI> Error init() {
auto TP = LocalTrampolinePool<ORCABI>::Create(
[this](ExecutorAddr TrampolineAddr,
TrampolinePool::NotifyLandingResolvedFunction
NotifyLandingResolved) {
resolveTrampolineLandingAddress(TrampolineAddr,
std::move(NotifyLandingResolved));
});
if (!TP)
return TP.takeError();
this->TP = std::move(*TP);
setTrampolinePool(*this->TP);
return Error::success();
}
std::unique_ptr<TrampolinePool> TP;
public:
/// Create a LocalLazyCallThroughManager using the given ABI. See
/// createLocalLazyCallThroughManager.
template <typename ORCABI>
static Expected<std::unique_ptr<LocalLazyCallThroughManager>>
Create(ExecutionSession &ES, ExecutorAddr ErrorHandlerAddr) {
auto LLCTM = std::unique_ptr<LocalLazyCallThroughManager>(
new LocalLazyCallThroughManager(ES, ErrorHandlerAddr));
if (auto Err = LLCTM->init<ORCABI>())
return std::move(Err);
return std::move(LLCTM);
}
};
/// Create a LocalLazyCallThroughManager from the given triple and execution
/// session.
Expected<std::unique_ptr<LazyCallThroughManager>>
createLocalLazyCallThroughManager(const Triple &T, ExecutionSession &ES,
ExecutorAddr ErrorHandlerAddr);
/// A materialization unit that builds lazy re-exports. These are callable
/// entry points that call through to the given symbols.
/// Unlike a 'true' re-export, the address of the lazy re-export will not
/// match the address of the re-exported symbol, but calling it will behave
/// the same as calling the re-exported symbol.
class LazyReexportsMaterializationUnit : public MaterializationUnit {
public:
LazyReexportsMaterializationUnit(LazyCallThroughManager &LCTManager,
IndirectStubsManager &ISManager,
JITDylib &SourceJD,
SymbolAliasMap CallableAliases,
ImplSymbolMap *SrcJDLoc);
StringRef getName() const override;
private:
void materialize(std::unique_ptr<MaterializationResponsibility> R) override;
void discard(const JITDylib &JD, const SymbolStringPtr &Name) override;
static MaterializationUnit::Interface
extractFlags(const SymbolAliasMap &Aliases);
LazyCallThroughManager &LCTManager;
IndirectStubsManager &ISManager;
JITDylib &SourceJD;
SymbolAliasMap CallableAliases;
ImplSymbolMap *AliaseeTable;
};
/// Define lazy-reexports based on the given SymbolAliasMap. Each lazy re-export
/// is a callable symbol that will look up and dispatch to the given aliasee on
/// first call. All subsequent calls will go directly to the aliasee.
inline std::unique_ptr<LazyReexportsMaterializationUnit>
lazyReexports(LazyCallThroughManager &LCTManager,
IndirectStubsManager &ISManager, JITDylib &SourceJD,
SymbolAliasMap CallableAliases,
ImplSymbolMap *SrcJDLoc = nullptr) {
return std::make_unique<LazyReexportsMaterializationUnit>(
LCTManager, ISManager, SourceJD, std::move(CallableAliases), SrcJDLoc);
}
} // End namespace orc
} // End namespace llvm
#endif // LLVM_EXECUTIONENGINE_ORC_LAZYREEXPORTS_H
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