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//===-- RuntimeDyldImpl.h - Run-time dynamic linker for MC-JIT --*- C++ -*-===//
// The LLVM Compiler Infrastructure
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
// Interface for the implementations of runtime dynamic linker facilities.
#include "llvm/ExecutionEngine/RuntimeDyld.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Twine.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Memory.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/system_error.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/ADT/Triple.h"
#include <map>
#include "llvm/Support/Format.h"
#include "ObjectImage.h"
using namespace llvm;
using namespace llvm::object;
namespace llvm {
class SectionEntry {
uint8_t* Address;
size_t Size;
uint64_t LoadAddress; // For each section, the address it will be
// considered to live at for relocations. The same
// as the pointer to the above memory block for
// hosted JITs.
uintptr_t StubOffset; // It's used for architecturies with stub
// functions for far relocations like ARM.
uintptr_t ObjAddress; // Section address in object file. It's use for
// calculate MachO relocation addend
SectionEntry(uint8_t* address, size_t size, uintptr_t stubOffset,
uintptr_t objAddress)
: Address(address), Size(size), LoadAddress((uintptr_t)address),
StubOffset(stubOffset), ObjAddress(objAddress) {}
class RelocationEntry {
unsigned SectionID; // Section the relocation is contained in.
uintptr_t Offset; // Offset into the section for the relocation.
uint32_t Data; // Relocatino data. Including type of relocation
// and another flags and parameners from
intptr_t Addend; // Addend encoded in the instruction itself, if any,
// plus the offset into the source section for
// the symbol once the relocation is resolvable.
RelocationEntry(unsigned id, uint64_t offset, uint32_t data, int64_t addend)
: SectionID(id), Offset(offset), Data(data), Addend(addend) {}
// Raw relocation data from object file
class ObjRelocationInfo {
unsigned SectionID;
uint64_t Offset;
SymbolRef Symbol;
uint64_t Type;
int64_t AdditionalInfo;
class RelocationValueRef {
unsigned SectionID;
intptr_t Addend;
const char *SymbolName;
RelocationValueRef(): SectionID(0), Addend(0), SymbolName(0) {}
inline bool operator==(const RelocationValueRef &Other) const {
return std::memcmp(this, &Other, sizeof(RelocationValueRef)) == 0;
inline bool operator <(const RelocationValueRef &Other) const {
return std::memcmp(this, &Other, sizeof(RelocationValueRef)) < 0;
class RuntimeDyldImpl {
// The MemoryManager to load objects into.
RTDyldMemoryManager *MemMgr;
// A list of emmitted sections.
typedef SmallVector<SectionEntry, 64> SectionList;
SectionList Sections;
// Keep a map of sections from object file to the SectionID which
// references it.
typedef std::map<SectionRef, unsigned> ObjSectionToIDMap;
// Master symbol table. As modules are loaded and external symbols are
// resolved, their addresses are stored here as a SectionID/Offset pair.
typedef std::pair<unsigned, uintptr_t> SymbolLoc;
StringMap<SymbolLoc> SymbolTable;
typedef DenseMap<const char*, SymbolLoc> LocalSymbolMap;
// Keep a map of common symbols to their sizes
typedef std::map<SymbolRef, unsigned> CommonSymbolMap;
// For each symbol, keep a list of relocations based on it. Anytime
// its address is reassigned (the JIT re-compiled the function, e.g.),
// the relocations get re-resolved.
// The symbol (or section) the relocation is sourced from is the Key
// in the relocation list where it's stored.
typedef SmallVector<RelocationEntry, 64> RelocationList;
// Relocations to sections already loaded. Indexed by SectionID which is the
// source of the address. The target where the address will be writen is
// SectionID/Offset in the relocation itself.
DenseMap<unsigned, RelocationList> Relocations;
// Relocations to external symbols that are not yet resolved.
// Indexed by symbol name.
StringMap<RelocationList> SymbolRelocations;
typedef std::map<RelocationValueRef, uintptr_t> StubMap;
Triple::ArchType Arch;
inline unsigned getMaxStubSize() {
if (Arch == Triple::arm || Arch == Triple::thumb)
return 8; // 32-bit instruction and 32-bit address
return 0;
bool HasError;
std::string ErrorStr;
// Set the error state and record an error string.
bool Error(const Twine &Msg) {
ErrorStr = Msg.str();
HasError = true;
return true;
uint8_t *getSectionAddress(unsigned SectionID) {
return (uint8_t*)Sections[SectionID].Address;
/// \brief Emits a section containing common symbols.
/// \return SectionID.
unsigned emitCommonSymbols(ObjectImage &Obj,
const CommonSymbolMap &Map,
uint64_t TotalSize,
LocalSymbolMap &Symbols);
/// \brief Emits section data from the object file to the MemoryManager.
/// \param IsCode if it's true then allocateCodeSection() will be
/// used for emmits, else allocateDataSection() will be used.
/// \return SectionID.
unsigned emitSection(ObjectImage &Obj,
const SectionRef &Section,
bool IsCode);
/// \brief Find Section in LocalSections. If the secton is not found - emit
/// it and store in LocalSections.
/// \param IsCode if it's true then allocateCodeSection() will be
/// used for emmits, else allocateDataSection() will be used.
/// \return SectionID.
unsigned findOrEmitSection(ObjectImage &Obj,
const SectionRef &Section,
bool IsCode,
ObjSectionToIDMap &LocalSections);
/// \brief If Value.SymbolName is NULL then store relocation to the
/// Relocations, else store it in the SymbolRelocations.
void AddRelocation(const RelocationValueRef &Value, unsigned SectionID,
uintptr_t Offset, uint32_t RelType);
/// \brief Emits long jump instruction to Addr.
/// \return Pointer to the memory area for emitting target address.
uint8_t* createStubFunction(uint8_t *Addr);
/// \brief Resolves relocations from Relocs list with address from Value.
void resolveRelocationList(const RelocationList &Relocs, uint64_t Value);
void resolveRelocationEntry(const RelocationEntry &RE, uint64_t Value);
/// \brief A object file specific relocation resolver
/// \param Address Address to apply the relocation action
/// \param Value Target symbol address to apply the relocation action
/// \param Type object file specific relocation type
/// \param Addend A constant addend used to compute the value to be stored
/// into the relocatable field
virtual void resolveRelocation(uint8_t *LocalAddress,
uint64_t FinalAddress,
uint64_t Value,
uint32_t Type,
int64_t Addend) = 0;
/// \brief Parses the object file relocation and store it to Relocations
/// or SymbolRelocations. Its depend from object file type.
virtual void processRelocationRef(const ObjRelocationInfo &Rel,
ObjectImage &Obj,
ObjSectionToIDMap &ObjSectionToID,
LocalSymbolMap &Symbols, StubMap &Stubs) = 0;
void resolveSymbols();
virtual ObjectImage *createObjectImage(const MemoryBuffer *InputBuffer);
virtual void handleObjectLoaded(ObjectImage *Obj)
// Subclasses may choose to retain this image if they have a use for it
delete Obj;
RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
virtual ~RuntimeDyldImpl();
bool loadObject(const MemoryBuffer *InputBuffer);
void *getSymbolAddress(StringRef Name) {
// FIXME: Just look up as a function for now. Overly simple of course.
// Work in progress.
if (SymbolTable.find(Name) == SymbolTable.end())
return 0;
SymbolLoc Loc = SymbolTable.lookup(Name);
return getSectionAddress(Loc.first) + Loc.second;
void resolveRelocations();
void reassignSectionAddress(unsigned SectionID, uint64_t Addr);
void mapSectionAddress(void *LocalAddress, uint64_t TargetAddress);
// Is the linker in an error state?
bool hasError() { return HasError; }
// Mark the error condition as handled and continue.
void clearError() { HasError = false; }
// Get the error message.
StringRef getErrorString() { return ErrorStr; }
virtual bool isCompatibleFormat(const MemoryBuffer *InputBuffer) const = 0;
} // end namespace llvm