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//===- ExecutionUtils.h - Utilities for executing code in Orc ---*- 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
//
//===----------------------------------------------------------------------===//
//
// Contains utilities for executing code in Orc.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
#define LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
#include "llvm/ADT/iterator_range.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/ExecutionEngine/Orc/Core.h"
#include "llvm/ExecutionEngine/Orc/Mangling.h"
#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
#include "llvm/ExecutionEngine/Orc/Shared/OrcError.h"
#include "llvm/ExecutionEngine/RuntimeDyld.h"
#include "llvm/Object/Archive.h"
#include "llvm/Support/DynamicLibrary.h"
#include <algorithm>
#include <cstdint>
#include <utility>
#include <vector>
namespace llvm {
class ConstantArray;
class GlobalVariable;
class Function;
class Module;
class Value;
namespace object {
class MachOUniversalBinary;
}
namespace orc {
class ObjectLayer;
/// This iterator provides a convenient way to iterate over the elements
/// of an llvm.global_ctors/llvm.global_dtors instance.
///
/// The easiest way to get hold of instances of this class is to use the
/// getConstructors/getDestructors functions.
class CtorDtorIterator {
public:
/// Accessor for an element of the global_ctors/global_dtors array.
///
/// This class provides a read-only view of the element with any casts on
/// the function stripped away.
struct Element {
Element(unsigned Priority, Function *Func, Value *Data)
: Priority(Priority), Func(Func), Data(Data) {}
unsigned Priority;
Function *Func;
Value *Data;
};
/// Construct an iterator instance. If End is true then this iterator
/// acts as the end of the range, otherwise it is the beginning.
CtorDtorIterator(const GlobalVariable *GV, bool End);
/// Test iterators for equality.
bool operator==(const CtorDtorIterator &Other) const;
/// Test iterators for inequality.
bool operator!=(const CtorDtorIterator &Other) const;
/// Pre-increment iterator.
CtorDtorIterator& operator++();
/// Post-increment iterator.
CtorDtorIterator operator++(int);
/// Dereference iterator. The resulting value provides a read-only view
/// of this element of the global_ctors/global_dtors list.
Element operator*() const;
private:
const ConstantArray *InitList;
unsigned I;
};
/// Create an iterator range over the entries of the llvm.global_ctors
/// array.
iterator_range<CtorDtorIterator> getConstructors(const Module &M);
/// Create an iterator range over the entries of the llvm.global_ctors
/// array.
iterator_range<CtorDtorIterator> getDestructors(const Module &M);
/// This iterator provides a convenient way to iterate over GlobalValues that
/// have initialization effects.
class StaticInitGVIterator {
public:
StaticInitGVIterator() = default;
StaticInitGVIterator(Module &M)
: I(M.global_values().begin()), E(M.global_values().end()),
ObjFmt(Triple(M.getTargetTriple()).getObjectFormat()) {
if (I != E) {
if (!isStaticInitGlobal(*I))
moveToNextStaticInitGlobal();
} else
I = E = Module::global_value_iterator();
}
bool operator==(const StaticInitGVIterator &O) const { return I == O.I; }
bool operator!=(const StaticInitGVIterator &O) const { return I != O.I; }
StaticInitGVIterator &operator++() {
assert(I != E && "Increment past end of range");
moveToNextStaticInitGlobal();
return *this;
}
GlobalValue &operator*() { return *I; }
private:
bool isStaticInitGlobal(GlobalValue &GV);
void moveToNextStaticInitGlobal() {
++I;
while (I != E && !isStaticInitGlobal(*I))
++I;
if (I == E)
I = E = Module::global_value_iterator();
}
Module::global_value_iterator I, E;
Triple::ObjectFormatType ObjFmt;
};
/// Create an iterator range over the GlobalValues that contribute to static
/// initialization.
inline iterator_range<StaticInitGVIterator> getStaticInitGVs(Module &M) {
return make_range(StaticInitGVIterator(M), StaticInitGVIterator());
}
class CtorDtorRunner {
public:
CtorDtorRunner(JITDylib &JD) : JD(JD) {}
void add(iterator_range<CtorDtorIterator> CtorDtors);
Error run();
private:
using CtorDtorList = std::vector<SymbolStringPtr>;
using CtorDtorPriorityMap = std::map<unsigned, CtorDtorList>;
JITDylib &JD;
CtorDtorPriorityMap CtorDtorsByPriority;
};
/// Support class for static dtor execution. For hosted (in-process) JITs
/// only!
///
/// If a __cxa_atexit function isn't found C++ programs that use static
/// destructors will fail to link. However, we don't want to use the host
/// process's __cxa_atexit, because it will schedule JIT'd destructors to run
/// after the JIT has been torn down, which is no good. This class makes it easy
/// to override __cxa_atexit (and the related __dso_handle).
///
/// To use, clients should manually call searchOverrides from their symbol
/// resolver. This should generally be done after attempting symbol resolution
/// inside the JIT, but before searching the host process's symbol table. When
/// the client determines that destructors should be run (generally at JIT
/// teardown or after a return from main), the runDestructors method should be
/// called.
class LocalCXXRuntimeOverridesBase {
public:
/// Run any destructors recorded by the overriden __cxa_atexit function
/// (CXAAtExitOverride).
void runDestructors();
protected:
using DestructorPtr = void (*)(void *);
using CXXDestructorDataPair = std::pair<DestructorPtr, void *>;
using CXXDestructorDataPairList = std::vector<CXXDestructorDataPair>;
CXXDestructorDataPairList DSOHandleOverride;
static int CXAAtExitOverride(DestructorPtr Destructor, void *Arg,
void *DSOHandle);
};
class LocalCXXRuntimeOverrides : public LocalCXXRuntimeOverridesBase {
public:
Error enable(JITDylib &JD, MangleAndInterner &Mangler);
};
/// An interface for Itanium __cxa_atexit interposer implementations.
class ItaniumCXAAtExitSupport {
public:
struct AtExitRecord {
void (*F)(void *);
void *Ctx;
};
void registerAtExit(void (*F)(void *), void *Ctx, void *DSOHandle);
void runAtExits(void *DSOHandle);
private:
std::mutex AtExitsMutex;
DenseMap<void *, std::vector<AtExitRecord>> AtExitRecords;
};
/// A utility class to expose symbols found via dlsym to the JIT.
///
/// If an instance of this class is attached to a JITDylib as a fallback
/// definition generator, then any symbol found in the given DynamicLibrary that
/// passes the 'Allow' predicate will be added to the JITDylib.
class DynamicLibrarySearchGenerator : public DefinitionGenerator {
public:
using SymbolPredicate = std::function<bool(const SymbolStringPtr &)>;
using AddAbsoluteSymbolsFn = unique_function<Error(JITDylib &, SymbolMap)>;
/// Create a DynamicLibrarySearchGenerator that searches for symbols in the
/// given sys::DynamicLibrary.
///
/// If the Allow predicate is given then only symbols matching the predicate
/// will be searched for. If the predicate is not given then all symbols will
/// be searched for.
///
/// If \p AddAbsoluteSymbols is provided, it is used to add the symbols to the
/// \c JITDylib; otherwise it uses JD.define(absoluteSymbols(...)).
DynamicLibrarySearchGenerator(
sys::DynamicLibrary Dylib, char GlobalPrefix,
SymbolPredicate Allow = SymbolPredicate(),
AddAbsoluteSymbolsFn AddAbsoluteSymbols = nullptr);
/// Permanently loads the library at the given path and, on success, returns
/// a DynamicLibrarySearchGenerator that will search it for symbol definitions
/// in the library. On failure returns the reason the library failed to load.
static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
Load(const char *FileName, char GlobalPrefix,
SymbolPredicate Allow = SymbolPredicate(),
AddAbsoluteSymbolsFn AddAbsoluteSymbols = nullptr);
/// Creates a DynamicLibrarySearchGenerator that searches for symbols in
/// the current process.
static Expected<std::unique_ptr<DynamicLibrarySearchGenerator>>
GetForCurrentProcess(char GlobalPrefix,
SymbolPredicate Allow = SymbolPredicate(),
AddAbsoluteSymbolsFn AddAbsoluteSymbols = nullptr) {
return Load(nullptr, GlobalPrefix, std::move(Allow),
std::move(AddAbsoluteSymbols));
}
Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
JITDylibLookupFlags JDLookupFlags,
const SymbolLookupSet &Symbols) override;
private:
sys::DynamicLibrary Dylib;
SymbolPredicate Allow;
AddAbsoluteSymbolsFn AddAbsoluteSymbols;
char GlobalPrefix;
};
/// A utility class to expose symbols from a static library.
///
/// If an instance of this class is attached to a JITDylib as a fallback
/// definition generator, then any symbol found in the archive will result in
/// the containing object being added to the JITDylib.
class StaticLibraryDefinitionGenerator : public DefinitionGenerator {
public:
// Interface builder function for objects loaded from this archive.
using GetObjectFileInterface =
unique_function<Expected<MaterializationUnit::Interface>(
ExecutionSession &ES, MemoryBufferRef ObjBuffer)>;
/// Try to create a StaticLibraryDefinitionGenerator from the given path.
///
/// This call will succeed if the file at the given path is a static library
/// or a MachO universal binary containing a static library that is compatible
/// with the ExecutionSession's triple. Otherwise it will return an error.
static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
Load(ObjectLayer &L, const char *FileName,
GetObjectFileInterface GetObjFileInterface = GetObjectFileInterface());
/// Try to create a StaticLibrarySearchGenerator from the given memory buffer
/// and Archive object.
static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
Create(ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer,
std::unique_ptr<object::Archive> Archive,
GetObjectFileInterface GetObjFileInterface = GetObjectFileInterface());
/// Try to create a StaticLibrarySearchGenerator from the given memory buffer.
/// This call will succeed if the buffer contains a valid archive, otherwise
/// it will return an error.
///
/// This call will succeed if the buffer contains a valid static library or a
/// MachO universal binary containing a static library that is compatible
/// with the ExecutionSession's triple. Otherwise it will return an error.
static Expected<std::unique_ptr<StaticLibraryDefinitionGenerator>>
Create(ObjectLayer &L, std::unique_ptr<MemoryBuffer> ArchiveBuffer,
GetObjectFileInterface GetObjFileInterface = GetObjectFileInterface());
/// Returns a list of filenames of dynamic libraries that this archive has
/// imported. This class does not load these libraries by itself. User is
/// responsible for making sure these libraries are avaliable to the JITDylib.
const std::set<std::string> &getImportedDynamicLibraries() const {
return ImportedDynamicLibraries;
}
Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
JITDylibLookupFlags JDLookupFlags,
const SymbolLookupSet &Symbols) override;
private:
StaticLibraryDefinitionGenerator(ObjectLayer &L,
std::unique_ptr<MemoryBuffer> ArchiveBuffer,
std::unique_ptr<object::Archive> Archive,
GetObjectFileInterface GetObjFileInterface,
Error &Err);
Error buildObjectFilesMap();
static Expected<std::pair<size_t, size_t>>
getSliceRangeForArch(object::MachOUniversalBinary &UB, const Triple &TT);
ObjectLayer &L;
GetObjectFileInterface GetObjFileInterface;
std::set<std::string> ImportedDynamicLibraries;
std::unique_ptr<MemoryBuffer> ArchiveBuffer;
std::unique_ptr<object::Archive> Archive;
DenseMap<SymbolStringPtr, MemoryBufferRef> ObjectFilesMap;
BumpPtrAllocator ObjFileNameStorage;
};
/// A utility class to create COFF dllimport GOT symbols (__imp_*) and PLT
/// stubs.
///
/// If an instance of this class is attached to a JITDylib as a fallback
/// definition generator, PLT stubs and dllimport __imp_ symbols will be
/// generated for external symbols found outside the given jitdylib. Currently
/// only supports x86_64 architecture.
class DLLImportDefinitionGenerator : public DefinitionGenerator {
public:
/// Creates a DLLImportDefinitionGenerator instance.
static std::unique_ptr<DLLImportDefinitionGenerator>
Create(ExecutionSession &ES, ObjectLinkingLayer &L);
Error tryToGenerate(LookupState &LS, LookupKind K, JITDylib &JD,
JITDylibLookupFlags JDLookupFlags,
const SymbolLookupSet &Symbols) override;
private:
DLLImportDefinitionGenerator(ExecutionSession &ES, ObjectLinkingLayer &L)
: ES(ES), L(L) {}
static Expected<unsigned> getTargetPointerSize(const Triple &TT);
static Expected<llvm::endianness> getEndianness(const Triple &TT);
Expected<std::unique_ptr<jitlink::LinkGraph>>
createStubsGraph(const SymbolMap &Resolved);
static StringRef getImpPrefix() { return "__imp_"; }
static StringRef getSectionName() { return "$__DLLIMPORT_STUBS"; }
ExecutionSession &ES;
ObjectLinkingLayer &L;
};
} // end namespace orc
} // end namespace llvm
#endif // LLVM_EXECUTIONENGINE_ORC_EXECUTIONUTILS_H
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