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//===----- MachOLinkGraphBuilder.h - MachO LinkGraph builder ----*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// Generic MachO LinkGraph building code.
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
#include "llvm/Object/MachO.h"
#include "EHFrameSupportImpl.h"
#include "JITLinkGeneric.h"
#include <list>
namespace llvm {
namespace jitlink {
class MachOLinkGraphBuilder {
virtual ~MachOLinkGraphBuilder();
Expected<std::unique_ptr<LinkGraph>> buildGraph();
struct NormalizedSymbol {
friend class MachOLinkGraphBuilder;
NormalizedSymbol(Optional<StringRef> Name, uint64_t Value, uint8_t Type,
uint8_t Sect, uint16_t Desc, Linkage L, Scope S)
: Name(Name), Value(Value), Type(Type), Sect(Sect), Desc(Desc), L(L),
S(S) {
assert((!Name || !Name->empty()) && "Name must be none or non-empty");
NormalizedSymbol(const NormalizedSymbol &) = delete;
NormalizedSymbol &operator=(const NormalizedSymbol &) = delete;
NormalizedSymbol(NormalizedSymbol &&) = delete;
NormalizedSymbol &operator=(NormalizedSymbol &&) = delete;
Optional<StringRef> Name;
uint64_t Value = 0;
uint8_t Type = 0;
uint8_t Sect = 0;
uint16_t Desc = 0;
Linkage L = Linkage::Strong;
Scope S = Scope::Default;
Symbol *GraphSymbol = nullptr;
// Normalized section representation. Section and segment names are guaranteed
// to be null-terminated, hence the extra bytes on SegName and SectName.
class NormalizedSection {
friend class MachOLinkGraphBuilder;
NormalizedSection() = default;
char SectName[17];
char SegName[17];
uint64_t Address = 0;
uint64_t Size = 0;
uint64_t Alignment = 0;
uint32_t Flags = 0;
const char *Data = nullptr;
Section *GraphSection = nullptr;
std::map<JITTargetAddress, Symbol *> CanonicalSymbols;
using SectionParserFunction = std::function<Error(NormalizedSection &S)>;
MachOLinkGraphBuilder(const object::MachOObjectFile &Obj, Triple TT,
LinkGraph::GetEdgeKindNameFunction GetEdgeKindName);
LinkGraph &getGraph() const { return *G; }
const object::MachOObjectFile &getObject() const { return Obj; }
void addCustomSectionParser(StringRef SectionName,
SectionParserFunction Parse);
virtual Error addRelocations() = 0;
/// Create a symbol.
template <typename... ArgTs>
NormalizedSymbol &createNormalizedSymbol(ArgTs &&... Args) {
NormalizedSymbol *Sym = reinterpret_cast<NormalizedSymbol *>(
new (Sym) NormalizedSymbol(std::forward<ArgTs>(Args)...);
return *Sym;
/// Index is zero-based (MachO section indexes are usually one-based) and
/// assumed to be in-range. Client is responsible for checking.
NormalizedSection &getSectionByIndex(unsigned Index) {
auto I = IndexToSection.find(Index);
assert(I != IndexToSection.end() && "No section recorded at index");
return I->second;
/// Try to get the section at the given index. Will return an error if the
/// given index is out of range, or if no section has been added for the given
/// index.
Expected<NormalizedSection &> findSectionByIndex(unsigned Index) {
auto I = IndexToSection.find(Index);
if (I == IndexToSection.end())
return make_error<JITLinkError>("No section recorded for index " +
formatv("{0:d}", Index));
return I->second;
/// Try to get the symbol at the given index. Will return an error if the
/// given index is out of range, or if no symbol has been added for the given
/// index.
Expected<NormalizedSymbol &> findSymbolByIndex(uint64_t Index) {
auto I = IndexToSymbol.find(Index);
if (I == IndexToSymbol.end())
return make_error<JITLinkError>("No symbol at index " +
formatv("{0:d}", Index));
assert(I->second && "Null symbol at index");
return *I->second;
/// Returns the symbol with the highest address not greater than the search
/// address, or null if no such symbol exists.
Symbol *getSymbolByAddress(NormalizedSection &NSec,
JITTargetAddress Address) {
auto I = NSec.CanonicalSymbols.upper_bound(Address);
if (I == NSec.CanonicalSymbols.begin())
return nullptr;
return std::prev(I)->second;
/// Returns the symbol with the highest address not greater than the search
/// address, or an error if no such symbol exists.
Expected<Symbol &> findSymbolByAddress(NormalizedSection &NSec,
JITTargetAddress Address) {
auto *Sym = getSymbolByAddress(NSec, Address);
if (Sym)
if (Address <= Sym->getAddress() + Sym->getSize())
return *Sym;
return make_error<JITLinkError>("No symbol covering address " +
formatv("{0:x16}", Address));
static Linkage getLinkage(uint16_t Desc);
static Scope getScope(StringRef Name, uint8_t Type);
static bool isAltEntry(const NormalizedSymbol &NSym);
static bool isDebugSection(const NormalizedSection &NSec);
static bool isZeroFillSection(const NormalizedSection &NSec);
getRelocationInfo(const object::relocation_iterator RelItr) {
MachO::any_relocation_info ARI =
MachO::relocation_info RI;
RI.r_address = ARI.r_word0;
RI.r_symbolnum = ARI.r_word1 & 0xffffff;
RI.r_pcrel = (ARI.r_word1 >> 24) & 1;
RI.r_length = (ARI.r_word1 >> 25) & 3;
RI.r_extern = (ARI.r_word1 >> 27) & 1;
RI.r_type = (ARI.r_word1 >> 28);
return RI;
static unsigned getPointerSize(const object::MachOObjectFile &Obj);
static support::endianness getEndianness(const object::MachOObjectFile &Obj);
void setCanonicalSymbol(NormalizedSection &NSec, Symbol &Sym) {
auto *&CanonicalSymEntry = NSec.CanonicalSymbols[Sym.getAddress()];
// There should be no symbol at this address, or, if there is,
// it should be a zero-sized symbol from an empty section (which
// we can safely override).
assert((!CanonicalSymEntry || CanonicalSymEntry->getSize() == 0) &&
"Duplicate canonical symbol at address");
CanonicalSymEntry = &Sym;
Section &getCommonSection();
void addSectionStartSymAndBlock(unsigned SecIndex, Section &GraphSec,
uint64_t Address, const char *Data,
uint64_t Size, uint32_t Alignment,
bool IsLive);
Error createNormalizedSections();
Error createNormalizedSymbols();
/// Create graph blocks and symbols for externals, absolutes, commons and
/// all defined symbols in sections without custom parsers.
Error graphifyRegularSymbols();
/// Create and return a graph symbol for the given normalized symbol.
/// NSym's GraphSymbol member will be updated to point at the newly created
/// symbol.
Symbol &createStandardGraphSymbol(NormalizedSymbol &Sym, Block &B,
size_t Size, bool IsText,
bool IsNoDeadStrip, bool IsCanonical);
/// Create graph blocks and symbols for all sections.
Error graphifySectionsWithCustomParsers();
/// Graphify cstring section.
Error graphifyCStringSection(NormalizedSection &NSec,
std::vector<NormalizedSymbol *> NSyms);
// Put the BumpPtrAllocator first so that we don't free any of the underlying
// memory until the Symbol/Addressable destructors have been run.
BumpPtrAllocator Allocator;
const object::MachOObjectFile &Obj;
std::unique_ptr<LinkGraph> G;
DenseMap<unsigned, NormalizedSection> IndexToSection;
Section *CommonSection = nullptr;
DenseMap<uint32_t, NormalizedSymbol *> IndexToSymbol;
StringMap<SectionParserFunction> CustomSectionParserFunctions;
/// A pass to split up __LD,__compact_unwind sections.
class CompactUnwindSplitter {
CompactUnwindSplitter(StringRef CompactUnwindSectionName)
: CompactUnwindSectionName(CompactUnwindSectionName) {}
Error operator()(LinkGraph &G);
StringRef CompactUnwindSectionName;
} // end namespace jitlink
} // end namespace llvm