llvm-6502/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
Eli Bendersky c201e6eaf1 RuntimeDyld cleanup:
- Improved parameter names for clarity
- Added comments
- emitCommonSymbols should return void because its return value is not being
  used anywhere
- Attempt to reduce the usage of the RelocationValueRef type. Restricts it 
  for a single goal and may serve as a step for eventual removal.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155908 91177308-0d34-0410-b5e6-96231b3b80d8
2012-05-01 10:41:12 +00:00

291 lines
10 KiB
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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.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_RUNTIME_DYLD_IMPL_H
#define LLVM_RUNTIME_DYLD_IMPL_H
#include "ObjectImage.h"
#include "llvm/ExecutionEngine/RuntimeDyld.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/system_error.h"
#include <map>
using namespace llvm;
using namespace llvm::object;
namespace llvm {
class MemoryBuffer;
class Twine;
/// SectionEntry - represents a section emitted into memory by the dynamic
/// linker.
class SectionEntry {
public:
/// Address - address in the linker's memory where the section resides.
uint8_t *Address;
/// Size - section size.
size_t Size;
/// LoadAddress - the address of the section in the target process's memory.
/// Used for situations in which JIT-ed code is being executed in the address
/// space of a separate process. If the code executes in the same address
/// space where it was JIT-ed, this just equals Address.
uint64_t LoadAddress;
/// StubOffset - used for architectures with stub functions for far
/// relocations (like ARM).
uintptr_t StubOffset;
/// ObjAddress - address of the section in the in-memory object file. Used
/// for calculating relocations in some object formats (like MachO).
uintptr_t ObjAddress;
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) {}
};
/// RelocationEntry - used to represent relocations internally in the dynamic
/// linker.
class RelocationEntry {
public:
/// SectionID - the section this relocation points to.
unsigned SectionID;
/// Offset - offset into the section.
uintptr_t Offset;
/// RelType - relocation type.
uint32_t RelType;
/// Addend - the relocation addend encoded in the instruction itself. Also
/// used to make a relocation section relative instead of symbol relative.
intptr_t Addend;
RelocationEntry(unsigned id, uint64_t offset, uint32_t type, int64_t addend)
: SectionID(id), Offset(offset), RelType(type), Addend(addend) {}
};
/// ObjRelocationInfo - relocation information as read from the object file.
/// Used to pass around data taken from object::RelocationRef, together with
/// the section to which the relocation points (represented by a SectionID).
class ObjRelocationInfo {
public:
unsigned SectionID;
uint64_t Offset;
SymbolRef Symbol;
uint64_t Type;
int64_t AdditionalInfo;
};
class RelocationValueRef {
public:
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 {
protected:
// The MemoryManager to load objects into.
RTDyldMemoryManager *MemMgr;
// A list of all sections emitted by the dynamic linker. These sections are
// referenced in the code by means of their index in this list - SectionID.
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;
// A global symbol table for symbols from all loaded modules. Maps the
// symbol name to a (SectionID, offset in section) pair.
typedef std::pair<unsigned, uintptr_t> SymbolLoc;
typedef StringMap<SymbolLoc> SymbolTableMap;
SymbolTableMap GlobalSymbolTable;
// 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. Symbols are
// external when they aren't found in the global symbol table of all loaded
// modules. This map is indexed by symbol name.
StringMap<RelocationList> ExternalSymbolRelocations;
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
else
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 Given the common symbols discovered in the object file, emit a
/// new section for them and update the symbol mappings in the object and
/// symbol table.
void emitCommonSymbols(ObjectImage &Obj,
const CommonSymbolMap &CommonSymbols,
uint64_t TotalSize,
SymbolTableMap &SymbolTable);
/// \brief Emits section data from the object file to the MemoryManager.
/// \param IsCode if it's true then allocateCodeSection() will be
/// used for emits, 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 Add a relocation entry that uses the given section.
void addRelocationForSection(const RelocationEntry &RE, unsigned SectionID);
// \brief Add a relocation entry that uses the given symbol. This symbol may
// be found in the global symbol table, or it may be external.
void addRelocationForSymbol(const RelocationEntry &RE, StringRef SymbolName);
/// \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 stores it to Relocations
/// or SymbolRelocations (this depends on the object file type).
virtual void processRelocationRef(const ObjRelocationInfo &Rel,
ObjectImage &Obj,
ObjSectionToIDMap &ObjSectionToID,
const SymbolTableMap &Symbols,
StubMap &Stubs) = 0;
/// \brief Resolve relocations to external symbols.
void resolveExternalSymbols();
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;
}
public:
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 (GlobalSymbolTable.find(Name) == GlobalSymbolTable.end())
return 0;
SymbolLoc Loc = GlobalSymbolTable.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
#endif