CbC/CbC_llvm: lld/MachO/SyntheticSections.cpp comparison

comparison lld/MachO/SyntheticSections.cpp @ 207:2e18cbf3894f

LLVM12

author	Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date	Tue, 08 Jun 2021 06:07:14 +0900
parents	0572611fdcc8
children	5f17cb93ff66

comparison

equal deleted inserted replaced

-:0572611fdcc8
+:2e18cbf3894f
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 #include "SyntheticSections.h"
+#include "ConcatOutputSection.h"
 #include "Config.h"
 #include "ExportTrie.h"
 #include "InputFiles.h"
+#include "MachOStructs.h"
 #include "OutputSegment.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
 #include "Writer.h"
 #include "lld/Common/ErrorHandler.h"
+#include "lld/Common/Memory.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Config/llvm-config.h"
 #include "llvm/Support/EndianStream.h"
+#include "llvm/Support/FileSystem.h"
 #include "llvm/Support/LEB128.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/SHA256.h"
+#if defined(__APPLE__)
+#include <sys/mman.h>
+#endif
+#ifdef LLVM_HAVE_LIBXAR
+#include <fcntl.h>
+#include <xar/xar.h>
+#endif
 using namespace llvm;
 using namespace llvm::MachO;
 using namespace llvm::support;
 using namespace llvm::support::endian;
+using namespace lld;
-namespace lld {
+using namespace lld::macho;
-namespace macho {
+InStruct macho::in;
+std::vector<SyntheticSection *> macho::syntheticSections;
 SyntheticSection::SyntheticSection(const char *segname, const char *name)
-: OutputSection(SyntheticKind, name) {
+: OutputSection(SyntheticKind, name), segname(segname) {
-// Synthetic sections always know which segment they belong to so hook
+isec = make<InputSection>();
-// them up when they're made
+isec->segname = segname;
-getOrCreateOutputSegment(segname)->addOutputSection(this);
+isec->name = name;
+isec->parent = this;
+isec->outSecOff = 0;
+syntheticSections.push_back(this);
 }
 // dyld3's MachOLoaded::getSlide() assumes that the __TEXT segment starts
 // from the beginning of the file (i.e. the header).
 MachHeaderSection::MachHeaderSection()
-: SyntheticSection(segment_names::text, section_names::header) {}
+: SyntheticSection(segment_names::text, section_names::header) {
+// XXX: This is a hack. (See D97007)
+// Setting the index to 1 to pretend that this section is the text
+// section.
+index = 1;
+isec->isFinal = true;
+}
 void MachHeaderSection::addLoadCommand(LoadCommand *lc) {
 loadCommands.push_back(lc);
 sizeOfCmds += lc->getSize();
 }
-size_t MachHeaderSection::getSize() const {
+uint64_t MachHeaderSection::getSize() const {
-return sizeof(mach_header_64) + sizeOfCmds;
+uint64_t size = target->headerSize + sizeOfCmds + config->headerPad;
+// If we are emitting an encryptable binary, our load commands must have a
+// separate (non-encrypted) page to themselves.
+if (config->emitEncryptionInfo)
+size = alignTo(size, target->getPageSize());
+return size;
+}
+static uint32_t cpuSubtype() {
+uint32_t subtype = target->cpuSubtype;
+if (config->outputType == MH_EXECUTE && !config->staticLink &&
+target->cpuSubtype == CPU_SUBTYPE_X86_64_ALL &&
+config->platform() == PlatformKind::macOS &&
+config->platformInfo.minimum >= VersionTuple(10, 5))
+subtype |= CPU_SUBTYPE_LIB64;
+return subtype;
 }
 void MachHeaderSection::writeTo(uint8_t *buf) const {
-auto *hdr = reinterpret_cast<mach_header_64 *>(buf);
+auto *hdr = reinterpret_cast<mach_header *>(buf);
-hdr->magic = MH_MAGIC_64;
+hdr->magic = target->magic;
-hdr->cputype = CPU_TYPE_X86_64;
+hdr->cputype = target->cpuType;
-hdr->cpusubtype = CPU_SUBTYPE_X86_64_ALL | CPU_SUBTYPE_LIB64;
+hdr->cpusubtype = cpuSubtype();
 hdr->filetype = config->outputType;
 hdr->ncmds = loadCommands.size();
 hdr->sizeofcmds = sizeOfCmds;
-hdr->flags = MH_NOUNDEFS | MH_DYLDLINK | MH_TWOLEVEL;
+hdr->flags = MH_DYLDLINK;
+if (config->namespaceKind == NamespaceKind::twolevel)
+hdr->flags |= MH_NOUNDEFS | MH_TWOLEVEL;
 if (config->outputType == MH_DYLIB && !config->hasReexports)
 hdr->flags |= MH_NO_REEXPORTED_DYLIBS;
-uint8_t *p = reinterpret_cast<uint8_t *>(hdr + 1);
+if (config->markDeadStrippableDylib)
-for (LoadCommand *lc : loadCommands) {
+hdr->flags |= MH_DEAD_STRIPPABLE_DYLIB;
+if (config->outputType == MH_EXECUTE && config->isPic)
+hdr->flags |= MH_PIE;
+if (in.exports->hasWeakSymbol || in.weakBinding->hasNonWeakDefinition())
+hdr->flags |= MH_WEAK_DEFINES;
+if (in.exports->hasWeakSymbol || in.weakBinding->hasEntry())
+hdr->flags |= MH_BINDS_TO_WEAK;
+for (const OutputSegment *seg : outputSegments) {
+for (const OutputSection *osec : seg->getSections()) {
+if (isThreadLocalVariables(osec->flags)) {
+hdr->flags |= MH_HAS_TLV_DESCRIPTORS;
+break;
+}
+}
+}
+uint8_t *p = reinterpret_cast<uint8_t *>(hdr) + target->headerSize;
+for (const LoadCommand *lc : loadCommands) {
 lc->writeTo(p);
 p += lc->getSize();
 }
 }
 PageZeroSection::PageZeroSection()
 : SyntheticSection(segment_names::pageZero, section_names::pageZero) {}
-GotSection::GotSection()
+RebaseSection::RebaseSection()
-: SyntheticSection(segment_names::dataConst, section_names::got) {
+: LinkEditSection(segment_names::linkEdit, section_names::rebase) {}
-align = 8;
+namespace {
+struct Rebase {
+OutputSegment *segment = nullptr;
+uint64_t offset = 0;
+uint64_t consecutiveCount = 0;
+};
+} // namespace
+// Rebase opcodes allow us to describe a contiguous sequence of rebase location
+// using a single DO_REBASE opcode. To take advantage of it, we delay emitting
+// `DO_REBASE` until we have reached the end of a contiguous sequence.
+static void encodeDoRebase(Rebase &rebase, raw_svector_ostream &os) {
+assert(rebase.consecutiveCount != 0);
+if (rebase.consecutiveCount <= REBASE_IMMEDIATE_MASK) {
+os << static_cast<uint8_t>(REBASE_OPCODE_DO_REBASE_IMM_TIMES |
+rebase.consecutiveCount);
+} else {
+os << static_cast<uint8_t>(REBASE_OPCODE_DO_REBASE_ULEB_TIMES);
+encodeULEB128(rebase.consecutiveCount, os);
+}
+rebase.consecutiveCount = 0;
+}
+static void encodeRebase(const OutputSection *osec, uint64_t outSecOff,
+Rebase &lastRebase, raw_svector_ostream &os) {
+OutputSegment *seg = osec->parent;
+uint64_t offset = osec->getSegmentOffset() + outSecOff;
+if (lastRebase.segment != seg || lastRebase.offset != offset) {
+if (lastRebase.consecutiveCount != 0)
+encodeDoRebase(lastRebase, os);
+if (lastRebase.segment != seg) {
+os << static_cast<uint8_t>(REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB |
+seg->index);
+encodeULEB128(offset, os);
+lastRebase.segment = seg;
+lastRebase.offset = offset;
+} else {
+assert(lastRebase.offset != offset);
+os << static_cast<uint8_t>(REBASE_OPCODE_ADD_ADDR_ULEB);
+encodeULEB128(offset - lastRebase.offset, os);
+lastRebase.offset = offset;
+}
+}
+++lastRebase.consecutiveCount;
+// DO_REBASE causes dyld to both perform the binding and increment the offset
+lastRebase.offset += target->wordSize;
+}
+void RebaseSection::finalizeContents() {
+if (locations.empty())
+return;
+raw_svector_ostream os{contents};
+Rebase lastRebase;
+os << static_cast<uint8_t>(REBASE_OPCODE_SET_TYPE_IMM | REBASE_TYPE_POINTER);
+llvm::sort(locations, [](const Location &a, const Location &b) {
+return a.isec->getVA() < b.isec->getVA();
+});
+for (const Location &loc : locations)
+encodeRebase(loc.isec->parent, loc.isec->outSecOff + loc.offset, lastRebase,
+os);
+if (lastRebase.consecutiveCount != 0)
+encodeDoRebase(lastRebase, os);
+os << static_cast<uint8_t>(REBASE_OPCODE_DONE);
+}
+void RebaseSection::writeTo(uint8_t *buf) const {
+memcpy(buf, contents.data(), contents.size());
+}
+NonLazyPointerSectionBase::NonLazyPointerSectionBase(const char *segname,
+const char *name)
+: SyntheticSection(segname, name) {
+align = target->wordSize;
 flags = S_NON_LAZY_SYMBOL_POINTERS;
+}
-// TODO: section_64::reserved1 should be an index into the indirect symbol
-// table, which we do not currently emit
+void macho::addNonLazyBindingEntries(const Symbol *sym,
-}
+const InputSection *isec, uint64_t offset,
+int64_t addend) {
-void GotSection::addEntry(DylibSymbol &sym) {
+if (const auto *dysym = dyn_cast<DylibSymbol>(sym)) {
-if (entries.insert(&sym)) {
+in.binding->addEntry(dysym, isec, offset, addend);
-sym.gotIndex = entries.size() - 1;
+if (dysym->isWeakDef())
-}
+in.weakBinding->addEntry(sym, isec, offset, addend);
+} else if (const auto *defined = dyn_cast<Defined>(sym)) {
+in.rebase->addEntry(isec, offset);
+if (defined->isExternalWeakDef())
+in.weakBinding->addEntry(sym, isec, offset, addend);
+} else {
+// Undefined symbols are filtered out in scanRelocations(); we should never
+// get here
+llvm_unreachable("cannot bind to an undefined symbol");
+}
+}
+void NonLazyPointerSectionBase::addEntry(Symbol *sym) {
+if (entries.insert(sym)) {
+assert(!sym->isInGot());
+sym->gotIndex = entries.size() - 1;
+addNonLazyBindingEntries(sym, isec, sym->gotIndex * target->wordSize);
+}
+}
+void NonLazyPointerSectionBase::writeTo(uint8_t *buf) const {
+for (size_t i = 0, n = entries.size(); i < n; ++i)
+if (auto *defined = dyn_cast<Defined>(entries[i]))
+write64le(&buf[i * target->wordSize], defined->getVA());
 }
 BindingSection::BindingSection()
-: SyntheticSection(segment_names::linkEdit, section_names::binding) {}
+: LinkEditSection(segment_names::linkEdit, section_names::binding) {}
-bool BindingSection::isNeeded() const { return in.got->isNeeded(); }
+namespace {
+struct Binding {
+OutputSegment *segment = nullptr;
+uint64_t offset = 0;
+int64_t addend = 0;
+int16_t ordinal = 0;
+};
+} // namespace
+// Encode a sequence of opcodes that tell dyld to write the address of symbol +
+// addend at osec->addr + outSecOff.
+//
+// The bind opcode "interpreter" remembers the values of each binding field, so
+// we only need to encode the differences between bindings. Hence the use of
+// lastBinding.
+static void encodeBinding(const Symbol *sym, const OutputSection *osec,
+uint64_t outSecOff, int64_t addend,
+bool isWeakBinding, Binding &lastBinding,
+raw_svector_ostream &os) {
+OutputSegment *seg = osec->parent;
+uint64_t offset = osec->getSegmentOffset() + outSecOff;
+if (lastBinding.segment != seg) {
+os << static_cast<uint8_t>(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB |
+seg->index);
+encodeULEB128(offset, os);
+lastBinding.segment = seg;
+lastBinding.offset = offset;
+} else if (lastBinding.offset != offset) {
+os << static_cast<uint8_t>(BIND_OPCODE_ADD_ADDR_ULEB);
+encodeULEB128(offset - lastBinding.offset, os);
+lastBinding.offset = offset;
+}
+if (lastBinding.addend != addend) {
+os << static_cast<uint8_t>(BIND_OPCODE_SET_ADDEND_SLEB);
+encodeSLEB128(addend, os);
+lastBinding.addend = addend;
+}
+uint8_t flags = BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM;
+if (!isWeakBinding && sym->isWeakRef())
+flags |= BIND_SYMBOL_FLAGS_WEAK_IMPORT;
+os << flags << sym->getName() << '\0'
+<< static_cast<uint8_t>(BIND_OPCODE_SET_TYPE_IMM | BIND_TYPE_POINTER)
+<< static_cast<uint8_t>(BIND_OPCODE_DO_BIND);
+// DO_BIND causes dyld to both perform the binding and increment the offset
+lastBinding.offset += target->wordSize;
+}
+// Non-weak bindings need to have their dylib ordinal encoded as well.
+static int16_t ordinalForDylibSymbol(const DylibSymbol &dysym) {
+if (config->namespaceKind == NamespaceKind::flat || dysym.isDynamicLookup())
+return static_cast<int16_t>(BIND_SPECIAL_DYLIB_FLAT_LOOKUP);
+assert(dysym.getFile()->isReferenced());
+return dysym.getFile()->ordinal;
+}
+static void encodeDylibOrdinal(int16_t ordinal, raw_svector_ostream &os) {
+if (ordinal <= 0) {
+os << static_cast<uint8_t>(BIND_OPCODE_SET_DYLIB_SPECIAL_IMM |
+(ordinal & BIND_IMMEDIATE_MASK));
+} else if (ordinal <= BIND_IMMEDIATE_MASK) {
+os << static_cast<uint8_t>(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | ordinal);
+} else {
+os << static_cast<uint8_t>(BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB);
+encodeULEB128(ordinal, os);
+}
+}
+static void encodeWeakOverride(const Defined *defined,
+raw_svector_ostream &os) {
+os << static_cast<uint8_t>(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM |
+BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION)
+<< defined->getName() << '\0';
+}
 // Emit bind opcodes, which are a stream of byte-sized opcodes that dyld
 // interprets to update a record with the following fields:
 //  * segment index (of the segment to write the symbol addresses to, typically
 //    the __DATA_CONST segment which contains the GOT)
 // When dyld sees BIND_OPCODE_DO_BIND, it uses the current record state to bind
 // a symbol in the GOT, and increments the segment offset to point to the next
 // entry. It does *not* clear the record state after doing the bind, so
 // subsequent opcodes only need to encode the differences between bindings.
 void BindingSection::finalizeContents() {
-if (!isNeeded())
-return;
 raw_svector_ostream os{contents};
-os << static_cast<uint8_t>(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB |
+Binding lastBinding;
-in.got->parent->index);
-encodeULEB128(in.got->getSegmentOffset(), os);
+// Since bindings are delta-encoded, sorting them allows for a more compact
-for (const DylibSymbol *sym : in.got->getEntries()) {
+// result. Note that sorting by address alone ensures that bindings for the
-// TODO: Implement compact encoding -- we only need to encode the
+// same segment / section are located together.
-// differences between consecutive symbol entries.
+llvm::sort(bindings, [](const BindingEntry &a, const BindingEntry &b) {
-if (sym->file->ordinal <= BIND_IMMEDIATE_MASK) {
+return a.target.getVA() < b.target.getVA();
-os << static_cast<uint8_t>(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM |
+});
-sym->file->ordinal);
+for (const BindingEntry &b : bindings) {
-} else {
+int16_t ordinal = ordinalForDylibSymbol(*b.dysym);
-error("TODO: Support larger dylib symbol ordinals");
+if (ordinal != lastBinding.ordinal) {
-continue;
+encodeDylibOrdinal(ordinal, os);
+lastBinding.ordinal = ordinal;
 }
-os << static_cast<uint8_t>(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM)
+encodeBinding(b.dysym, b.target.isec->parent,
-<< sym->getName() << '\0'
+b.target.isec->outSecOff + b.target.offset, b.addend,
-<< static_cast<uint8_t>(BIND_OPCODE_SET_TYPE_IMM | BIND_TYPE_POINTER)
+/*isWeakBinding=*/false, lastBinding, os);
-<< static_cast<uint8_t>(BIND_OPCODE_DO_BIND);
+}
-}
+if (!bindings.empty())
+os << static_cast<uint8_t>(BIND_OPCODE_DONE);
-os << static_cast<uint8_t>(BIND_OPCODE_DONE);
 }
 void BindingSection::writeTo(uint8_t *buf) const {
 memcpy(buf, contents.data(), contents.size());
 }
+WeakBindingSection::WeakBindingSection()
+: LinkEditSection(segment_names::linkEdit, section_names::weakBinding) {}
+void WeakBindingSection::finalizeContents() {
+raw_svector_ostream os{contents};
+Binding lastBinding;
+for (const Defined *defined : definitions)
+encodeWeakOverride(defined, os);
+// Since bindings are delta-encoded, sorting them allows for a more compact
+// result.
+llvm::sort(bindings,
+[](const WeakBindingEntry &a, const WeakBindingEntry &b) {
+return a.target.getVA() < b.target.getVA();
+});
+for (const WeakBindingEntry &b : bindings)
+encodeBinding(b.symbol, b.target.isec->parent,
+b.target.isec->outSecOff + b.target.offset, b.addend,
+/*isWeakBinding=*/true, lastBinding, os);
+if (!bindings.empty() || !definitions.empty())
+os << static_cast<uint8_t>(BIND_OPCODE_DONE);
+}
+void WeakBindingSection::writeTo(uint8_t *buf) const {
+memcpy(buf, contents.data(), contents.size());
+}
 StubsSection::StubsSection()
-: SyntheticSection(segment_names::text, "__stubs") {}
+: SyntheticSection(segment_names::text, section_names::stubs) {
+flags = S_SYMBOL_STUBS | S_ATTR_SOME_INSTRUCTIONS | S_ATTR_PURE_INSTRUCTIONS;
-size_t StubsSection::getSize() const {
+// The stubs section comprises machine instructions, which are aligned to
+// 4 bytes on the archs we care about.
+align = 4;
+reserved2 = target->stubSize;
+}
+uint64_t StubsSection::getSize() const {
 return entries.size() * target->stubSize;
 }
 void StubsSection::writeTo(uint8_t *buf) const {
 size_t off = 0;
-for (const DylibSymbol *sym : in.stubs->getEntries()) {
+for (const Symbol *sym : entries) {
 target->writeStub(buf + off, *sym);
 off += target->stubSize;
 }
 }
-void StubsSection::addEntry(DylibSymbol &sym) {
+void StubsSection::finalize() { isFinal = true; }
-if (entries.insert(&sym))
-sym.stubsIndex = entries.size() - 1;
+bool StubsSection::addEntry(Symbol *sym) {
+bool inserted = entries.insert(sym);
+if (inserted)
+sym->stubsIndex = entries.size() - 1;
+return inserted;
 }
 StubHelperSection::StubHelperSection()
-: SyntheticSection(segment_names::text, "__stub_helper") {}
+: SyntheticSection(segment_names::text, section_names::stubHelper) {
+flags = S_ATTR_SOME_INSTRUCTIONS | S_ATTR_PURE_INSTRUCTIONS;
-size_t StubHelperSection::getSize() const {
+align = 4; // This section comprises machine instructions
+}
+uint64_t StubHelperSection::getSize() const {
 return target->stubHelperHeaderSize +
-in.stubs->getEntries().size() * target->stubHelperEntrySize;
+in.lazyBinding->getEntries().size() * target->stubHelperEntrySize;
 }
-bool StubHelperSection::isNeeded() const {
+bool StubHelperSection::isNeeded() const { return in.lazyBinding->isNeeded(); }
-return !in.stubs->getEntries().empty();
-}
 void StubHelperSection::writeTo(uint8_t *buf) const {
 target->writeStubHelperHeader(buf);
 size_t off = target->stubHelperHeaderSize;
-for (const DylibSymbol *sym : in.stubs->getEntries()) {
+for (const DylibSymbol *sym : in.lazyBinding->getEntries()) {
 target->writeStubHelperEntry(buf + off, *sym, addr + off);
 off += target->stubHelperEntrySize;
 }
 }
 if (stubBinder == nullptr) {
 error("symbol dyld_stub_binder not found (normally in libSystem.dylib). "
 "Needed to perform lazy binding.");
 return;
 }
-in.got->addEntry(*stubBinder);
+stubBinder->reference(RefState::Strong);
+in.got->addEntry(stubBinder);
 inputSections.push_back(in.imageLoaderCache);
-symtab->addDefined("__dyld_private", in.imageLoaderCache, 0);
+// Since this isn't in the symbol table or in any input file, the noDeadStrip
+// argument doesn't matter. It's kept alive by ImageLoaderCacheSection()
+// setting `live` to true on the backing InputSection.
+dyldPrivate =
+make<Defined>("__dyld_private", nullptr, in.imageLoaderCache, 0, 0,
+/*isWeakDef=*/false,
+/*isExternal=*/false, /*isPrivateExtern=*/false,
+/*isThumb=*/false, /*isReferencedDynamically=*/false,
+/*noDeadStrip=*/false);
 }
 ImageLoaderCacheSection::ImageLoaderCacheSection() {
 segname = segment_names::data;
-name = "__data";
+name = section_names::data;
+uint8_t *arr = bAlloc.Allocate<uint8_t>(target->wordSize);
+memset(arr, 0, target->wordSize);
+data = {arr, target->wordSize};
+align = target->wordSize;
+live = true;
 }
 LazyPointerSection::LazyPointerSection()
-: SyntheticSection(segment_names::data, "__la_symbol_ptr") {
+: SyntheticSection(segment_names::data, section_names::lazySymbolPtr) {
-align = 8;
+align = target->wordSize;
 flags = S_LAZY_SYMBOL_POINTERS;
 }
-size_t LazyPointerSection::getSize() const {
+uint64_t LazyPointerSection::getSize() const {
-return in.stubs->getEntries().size() * WordSize;
+return in.stubs->getEntries().size() * target->wordSize;
 }
 bool LazyPointerSection::isNeeded() const {
 return !in.stubs->getEntries().empty();
 }
 void LazyPointerSection::writeTo(uint8_t *buf) const {
 size_t off = 0;
-for (const DylibSymbol *sym : in.stubs->getEntries()) {
+for (const Symbol *sym : in.stubs->getEntries()) {
-uint64_t stubHelperOffset = target->stubHelperHeaderSize +
+if (const auto *dysym = dyn_cast<DylibSymbol>(sym)) {
-sym->stubsIndex * target->stubHelperEntrySize;
+if (dysym->hasStubsHelper()) {
-write64le(buf + off, in.stubHelper->addr + stubHelperOffset);
+uint64_t stubHelperOffset =
-off += WordSize;
+target->stubHelperHeaderSize +
+dysym->stubsHelperIndex * target->stubHelperEntrySize;
+write64le(buf + off, in.stubHelper->addr + stubHelperOffset);
+}
+} else {
+write64le(buf + off, sym->getVA());
+}
+off += target->wordSize;
 }
 }
 LazyBindingSection::LazyBindingSection()
-: SyntheticSection(segment_names::linkEdit, section_names::lazyBinding) {}
+: LinkEditSection(segment_names::linkEdit, section_names::lazyBinding) {}
-bool LazyBindingSection::isNeeded() const { return in.stubs->isNeeded(); }
 void LazyBindingSection::finalizeContents() {
 // TODO: Just precompute output size here instead of writing to a temporary
 // buffer
-for (DylibSymbol *sym : in.stubs->getEntries())
+for (DylibSymbol *sym : entries)
 sym->lazyBindOffset = encode(*sym);
 }
 void LazyBindingSection::writeTo(uint8_t *buf) const {
 memcpy(buf, contents.data(), contents.size());
+}
+void LazyBindingSection::addEntry(DylibSymbol *dysym) {
+if (entries.insert(dysym)) {
+dysym->stubsHelperIndex = entries.size() - 1;
+in.rebase->addEntry(in.lazyPointers->isec,
+dysym->stubsIndex * target->wordSize);
+}
 }
 // Unlike the non-lazy binding section, the bind opcodes in this section aren't
 // interpreted all at once. Rather, dyld will start interpreting opcodes at a
 // given offset, typically only binding a single symbol before it finds a
 uint32_t opstreamOffset = contents.size();
 OutputSegment *dataSeg = in.lazyPointers->parent;
 os << static_cast<uint8_t>(BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB |
 dataSeg->index);
 uint64_t offset = in.lazyPointers->addr - dataSeg->firstSection()->addr +
-sym.stubsIndex * WordSize;
+sym.stubsIndex * target->wordSize;
 encodeULEB128(offset, os);
-if (sym.file->ordinal <= BIND_IMMEDIATE_MASK)
+encodeDylibOrdinal(ordinalForDylibSymbol(sym), os);
-os << static_cast<uint8_t>(BIND_OPCODE_SET_DYLIB_ORDINAL_IMM |
-sym.file->ordinal);
+uint8_t flags = BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM;
-else
+if (sym.isWeakRef())
-fatal("TODO: Support larger dylib symbol ordinals");
+flags |= BIND_SYMBOL_FLAGS_WEAK_IMPORT;
-os << static_cast<uint8_t>(BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM)
+os << flags << sym.getName() << '\0'
-<< sym.getName() << '\0' << static_cast<uint8_t>(BIND_OPCODE_DO_BIND)
+<< static_cast<uint8_t>(BIND_OPCODE_DO_BIND)
 << static_cast<uint8_t>(BIND_OPCODE_DONE);
 return opstreamOffset;
 }
 ExportSection::ExportSection()
-: SyntheticSection(segment_names::linkEdit, section_names::export_) {}
+: LinkEditSection(segment_names::linkEdit, section_names::export_) {}
 void ExportSection::finalizeContents() {
-// TODO: We should check symbol visibility.
+trieBuilder.setImageBase(in.header->addr);
-for (const Symbol *sym : symtab->getSymbols())
+for (const Symbol *sym : symtab->getSymbols()) {
-if (auto *defined = dyn_cast<Defined>(sym))
+if (const auto *defined = dyn_cast<Defined>(sym)) {
+if (defined->privateExtern || !defined->isLive())
+continue;
 trieBuilder.addSymbol(*defined);
+hasWeakSymbol = hasWeakSymbol || sym->isWeakDef();
+}
+}
 size = trieBuilder.build();
 }
 void ExportSection::writeTo(uint8_t *buf) const { trieBuilder.writeTo(buf); }
+FunctionStartsSection::FunctionStartsSection()
+: LinkEditSection(segment_names::linkEdit, section_names::functionStarts) {}
+void FunctionStartsSection::finalizeContents() {
+raw_svector_ostream os{contents};
+uint64_t addr = in.header->addr;
+for (const Symbol *sym : symtab->getSymbols()) {
+if (const auto *defined = dyn_cast<Defined>(sym)) {
+if (!defined->isec || !isCodeSection(defined->isec) || !defined->isLive())
+continue;
+// TODO: Add support for thumbs, in that case
+// the lowest bit of nextAddr needs to be set to 1.
+uint64_t nextAddr = defined->getVA();
+uint64_t delta = nextAddr - addr;
+if (delta == 0)
+continue;
+encodeULEB128(delta, os);
+addr = nextAddr;
+}
+}
+os << '\0';
+}
+void FunctionStartsSection::writeTo(uint8_t *buf) const {
+memcpy(buf, contents.data(), contents.size());
+}
 SymtabSection::SymtabSection(StringTableSection &stringTableSection)
-: SyntheticSection(segment_names::linkEdit, section_names::symbolTable),
+: LinkEditSection(segment_names::linkEdit, section_names::symbolTable),
-stringTableSection(stringTableSection) {
+stringTableSection(stringTableSection) {}
-// TODO: When we introduce the SyntheticSections superclass, we should make
-// all synthetic sections aligned to WordSize by default.
+void SymtabSection::emitBeginSourceStab(DWARFUnit *compileUnit) {
-align = WordSize;
+StabsEntry stab(N_SO);
-}
+SmallString<261> dir(compileUnit->getCompilationDir());
+StringRef sep = sys::path::get_separator();
-size_t SymtabSection::getSize() const {
+// We don't use `path::append` here because we want an empty `dir` to result
-return symbols.size() * sizeof(nlist_64);
+// in an absolute path. `append` would give us a relative path for that case.
+if (!dir.endswith(sep))
+dir += sep;
+stab.strx = stringTableSection.addString(
+saver.save(dir + compileUnit->getUnitDIE().getShortName()));
+stabs.emplace_back(std::move(stab));
+}
+void SymtabSection::emitEndSourceStab() {
+StabsEntry stab(N_SO);
+stab.sect = 1;
+stabs.emplace_back(std::move(stab));
+}
+void SymtabSection::emitObjectFileStab(ObjFile *file) {
+StabsEntry stab(N_OSO);
+stab.sect = target->cpuSubtype;
+SmallString<261> path(!file->archiveName.empty() ? file->archiveName
+: file->getName());
+std::error_code ec = sys::fs::make_absolute(path);
+if (ec)
+fatal("failed to get absolute path for " + path);
+if (!file->archiveName.empty())
+path.append({"(", file->getName(), ")"});
+stab.strx = stringTableSection.addString(saver.save(path.str()));
+stab.desc = 1;
+stab.value = file->modTime;
+stabs.emplace_back(std::move(stab));
+}
+void SymtabSection::emitEndFunStab(Defined *defined) {
+StabsEntry stab(N_FUN);
+stab.value = defined->size;
+stabs.emplace_back(std::move(stab));
+}
+void SymtabSection::emitStabs() {
+for (const std::string &s : config->astPaths) {
+StabsEntry astStab(N_AST);
+astStab.strx = stringTableSection.addString(s);
+stabs.emplace_back(std::move(astStab));
+}
+std::vector<Defined *> symbolsNeedingStabs;
+for (const SymtabEntry &entry :
+concat<SymtabEntry>(localSymbols, externalSymbols)) {
+Symbol *sym = entry.sym;
+assert(sym->isLive() &&
+"dead symbols should not be in localSymbols, externalSymbols");
+if (auto *defined = dyn_cast<Defined>(sym)) {
+if (defined->isAbsolute())
+continue;
+InputSection *isec = defined->isec;
+ObjFile *file = dyn_cast_or_null<ObjFile>(isec->file);
+if (!file || !file->compileUnit)
+continue;
+symbolsNeedingStabs.push_back(defined);
+}
+}
+llvm::stable_sort(symbolsNeedingStabs, [&](Defined *a, Defined *b) {
+return a->isec->file->id < b->isec->file->id;
+});
+// Emit STABS symbols so that dsymutil and/or the debugger can map address
+// regions in the final binary to the source and object files from which they
+// originated.
+InputFile *lastFile = nullptr;
+for (Defined *defined : symbolsNeedingStabs) {
+InputSection *isec = defined->isec;
+ObjFile *file = cast<ObjFile>(isec->file);
+if (lastFile == nullptr || lastFile != file) {
+if (lastFile != nullptr)
+emitEndSourceStab();
+lastFile = file;
+emitBeginSourceStab(file->compileUnit);
+emitObjectFileStab(file);
+}
+StabsEntry symStab;
+symStab.sect = defined->isec->parent->index;
+symStab.strx = stringTableSection.addString(defined->getName());
+symStab.value = defined->getVA();
+if (isCodeSection(isec)) {
+symStab.type = N_FUN;
+stabs.emplace_back(std::move(symStab));
+emitEndFunStab(defined);
+} else {
+symStab.type = defined->isExternal() ? N_GSYM : N_STSYM;
+stabs.emplace_back(std::move(symStab));
+}
+}
+if (!stabs.empty())
+emitEndSourceStab();
 }
 void SymtabSection::finalizeContents() {
-// TODO support other symbol types
+auto addSymbol = [&](std::vector<SymtabEntry> &symbols, Symbol *sym) {
-for (Symbol *sym : symtab->getSymbols())
+uint32_t strx = stringTableSection.addString(sym->getName());
-if (isa<Defined>(sym))
+symbols.push_back({sym, strx});
-symbols.push_back({sym, stringTableSection.addString(sym->getName())});
+};
-}
+// Local symbols aren't in the SymbolTable, so we walk the list of object
-void SymtabSection::writeTo(uint8_t *buf) const {
+// files to gather them.
-auto *nList = reinterpret_cast<nlist_64 *>(buf);
+for (const InputFile *file : inputFiles) {
-for (const SymtabEntry &entry : symbols) {
+if (auto *objFile = dyn_cast<ObjFile>(file)) {
+for (Symbol *sym : objFile->symbols) {
+if (auto *defined = dyn_cast_or_null<Defined>(sym)) {
+if (!defined->isExternal() && defined->isLive()) {
+StringRef name = defined->getName();
+if (!name.startswith("l") && !name.startswith("L"))
+addSymbol(localSymbols, sym);
+}
+}
+}
+}
+}
+// __dyld_private is a local symbol too. It's linker-created and doesn't
+// exist in any object file.
+if (Defined *dyldPrivate = in.stubHelper->dyldPrivate)
+addSymbol(localSymbols, dyldPrivate);
+for (Symbol *sym : symtab->getSymbols()) {
+if (!sym->isLive())
+continue;
+if (auto *defined = dyn_cast<Defined>(sym)) {
+if (!defined->includeInSymtab)
+continue;
+assert(defined->isExternal());
+if (defined->privateExtern)
+addSymbol(localSymbols, defined);
+else
+addSymbol(externalSymbols, defined);
+} else if (auto *dysym = dyn_cast<DylibSymbol>(sym)) {
+if (dysym->isReferenced())
+addSymbol(undefinedSymbols, sym);
+}
+}
+emitStabs();
+uint32_t symtabIndex = stabs.size();
+for (const SymtabEntry &entry :
+concat<SymtabEntry>(localSymbols, externalSymbols, undefinedSymbols)) {
+entry.sym->symtabIndex = symtabIndex++;
+}
+}
+uint32_t SymtabSection::getNumSymbols() const {
+return stabs.size() + localSymbols.size() + externalSymbols.size() +
+undefinedSymbols.size();
+}
+// This serves to hide (type-erase) the template parameter from SymtabSection.
+template <class LP> class SymtabSectionImpl : public SymtabSection {
+public:
+SymtabSectionImpl(StringTableSection &stringTableSection)
+: SymtabSection(stringTableSection) {}
+uint64_t getRawSize() const override;
+void writeTo(uint8_t *buf) const override;
+};
+template <class LP> uint64_t SymtabSectionImpl<LP>::getRawSize() const {
+return getNumSymbols() * sizeof(typename LP::nlist);
+}
+template <class LP> void SymtabSectionImpl<LP>::writeTo(uint8_t *buf) const {
+auto *nList = reinterpret_cast<typename LP::nlist *>(buf);
+// Emit the stabs entries before the "real" symbols. We cannot emit them
+// after as that would render Symbol::symtabIndex inaccurate.
+for (const StabsEntry &entry : stabs) {
 nList->n_strx = entry.strx;
-// TODO support other symbol types
+nList->n_type = entry.type;
-// TODO populate n_desc
+nList->n_sect = entry.sect;
+nList->n_desc = entry.desc;
+nList->n_value = entry.value;
+++nList;
+}
+for (const SymtabEntry &entry : concat<const SymtabEntry>(
+localSymbols, externalSymbols, undefinedSymbols)) {
+nList->n_strx = entry.strx;
+// TODO populate n_desc with more flags
 if (auto *defined = dyn_cast<Defined>(entry.sym)) {
-nList->n_type = N_EXT | N_SECT;
+uint8_t scope = 0;
-nList->n_sect = defined->isec->parent->index;
+if (defined->privateExtern) {
-// For the N_SECT symbol type, n_value is the address of the symbol
+// Private external -- dylib scoped symbol.
-nList->n_value = defined->value + defined->isec->getVA();
+// Promote to non-external at link time.
+scope = N_PEXT;
+} else if (defined->isExternal()) {
+// Normal global symbol.
+scope = N_EXT;
+} else {
+// TU-local symbol from localSymbols.
+scope = 0;
+}
+if (defined->isAbsolute()) {
+nList->n_type = scope | N_ABS;
+nList->n_sect = NO_SECT;
+nList->n_value = defined->value;
+} else {
+nList->n_type = scope | N_SECT;
+nList->n_sect = defined->isec->parent->index;
+// For the N_SECT symbol type, n_value is the address of the symbol
+nList->n_value = defined->getVA();
+}
+nList->n_desc |= defined->thumb ? N_ARM_THUMB_DEF : 0;
+nList->n_desc |= defined->isExternalWeakDef() ? N_WEAK_DEF : 0;
+nList->n_desc |=
+defined->referencedDynamically ? REFERENCED_DYNAMICALLY : 0;
+} else if (auto *dysym = dyn_cast<DylibSymbol>(entry.sym)) {
+uint16_t n_desc = nList->n_desc;
+int16_t ordinal = ordinalForDylibSymbol(*dysym);
+if (ordinal == BIND_SPECIAL_DYLIB_FLAT_LOOKUP)
+SET_LIBRARY_ORDINAL(n_desc, DYNAMIC_LOOKUP_ORDINAL);
+else if (ordinal == BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE)
+SET_LIBRARY_ORDINAL(n_desc, EXECUTABLE_ORDINAL);
+else {
+assert(ordinal > 0);
+SET_LIBRARY_ORDINAL(n_desc, static_cast<uint8_t>(ordinal));
+}
+nList->n_type = N_EXT;
+n_desc |= dysym->isWeakDef() ? N_WEAK_DEF : 0;
+n_desc |= dysym->isWeakRef() ? N_WEAK_REF : 0;
+nList->n_desc = n_desc;
 }
 ++nList;
 }
 }
+template <class LP>
+SymtabSection *
+macho::makeSymtabSection(StringTableSection &stringTableSection) {
+return make<SymtabSectionImpl<LP>>(stringTableSection);
+}
+IndirectSymtabSection::IndirectSymtabSection()
+: LinkEditSection(segment_names::linkEdit,
+section_names::indirectSymbolTable) {}
+uint32_t IndirectSymtabSection::getNumSymbols() const {
+return in.got->getEntries().size() + in.tlvPointers->getEntries().size() +
+in.stubs->getEntries().size();
+}
+bool IndirectSymtabSection::isNeeded() const {
+return in.got->isNeeded() || in.tlvPointers->isNeeded() ||
+in.stubs->isNeeded();
+}
+void IndirectSymtabSection::finalizeContents() {
+uint32_t off = 0;
+in.got->reserved1 = off;
+off += in.got->getEntries().size();
+in.tlvPointers->reserved1 = off;
+off += in.tlvPointers->getEntries().size();
+// There is a 1:1 correspondence between stubs and LazyPointerSection
+// entries, so they can share the same sub-array in the table.
+in.stubs->reserved1 = in.lazyPointers->reserved1 = off;
+}
+static uint32_t indirectValue(const Symbol *sym) {
+return sym->symtabIndex != UINT32_MAX ? sym->symtabIndex
+: INDIRECT_SYMBOL_LOCAL;
+}
+void IndirectSymtabSection::writeTo(uint8_t *buf) const {
+uint32_t off = 0;
+for (const Symbol *sym : in.got->getEntries()) {
+write32le(buf + off * sizeof(uint32_t), indirectValue(sym));
+++off;
+}
+for (const Symbol *sym : in.tlvPointers->getEntries()) {
+write32le(buf + off * sizeof(uint32_t), indirectValue(sym));
+++off;
+}
+for (const Symbol *sym : in.stubs->getEntries()) {
+write32le(buf + off * sizeof(uint32_t), indirectValue(sym));
+++off;
+}
+}
 StringTableSection::StringTableSection()
-: SyntheticSection(segment_names::linkEdit, section_names::stringTable) {}
+: LinkEditSection(segment_names::linkEdit, section_names::stringTable) {}
 uint32_t StringTableSection::addString(StringRef str) {
 uint32_t strx = size;
-strings.push_back(str);
+strings.push_back(str); // TODO: consider deduplicating strings
 size += str.size() + 1; // account for null terminator
 return strx;
 }
 void StringTableSection::writeTo(uint8_t *buf) const {
 memcpy(buf + off, str.data(), str.size());
 off += str.size() + 1; // account for null terminator
 }
 }
-InStruct in;
+static_assert((CodeSignatureSection::blobHeadersSize % 8) == 0, "");
+static_assert((CodeSignatureSection::fixedHeadersSize % 8) == 0, "");
-} // namespace macho
-} // namespace lld
+CodeSignatureSection::CodeSignatureSection()
+: LinkEditSection(segment_names::linkEdit, section_names::codeSignature) {
+align = 16; // required by libstuff
+fileName = config->outputFile;
+size_t slashIndex = fileName.rfind("/");
+if (slashIndex != std::string::npos)
+fileName = fileName.drop_front(slashIndex + 1);
+allHeadersSize = alignTo<16>(fixedHeadersSize + fileName.size() + 1);
+fileNamePad = allHeadersSize - fixedHeadersSize - fileName.size();
+}
+uint32_t CodeSignatureSection::getBlockCount() const {
+return (fileOff + blockSize - 1) / blockSize;
+}
+uint64_t CodeSignatureSection::getRawSize() const {
+return allHeadersSize + getBlockCount() * hashSize;
+}
+void CodeSignatureSection::writeHashes(uint8_t *buf) const {
+uint8_t *code = buf;
+uint8_t *codeEnd = buf + fileOff;
+uint8_t *hashes = codeEnd + allHeadersSize;
+while (code < codeEnd) {
+StringRef block(reinterpret_cast<char *>(code),
+std::min(codeEnd - code, static_cast<ssize_t>(blockSize)));
+SHA256 hasher;
+hasher.update(block);
+StringRef hash = hasher.final();
+assert(hash.size() == hashSize);
+memcpy(hashes, hash.data(), hashSize);
+code += blockSize;
+hashes += hashSize;
+}
+#if defined(__APPLE__)
+// This is macOS-specific work-around and makes no sense for any
+// other host OS. See https://openradar.appspot.com/FB8914231
+//
+// The macOS kernel maintains a signature-verification cache to
+// quickly validate applications at time of execve(2).  The trouble
+// is that for the kernel creates the cache entry at the time of the
+// mmap(2) call, before we have a chance to write either the code to
+// sign or the signature header+hashes.  The fix is to invalidate
+// all cached data associated with the output file, thus discarding
+// the bogus prematurely-cached signature.
+msync(buf, fileOff + getSize(), MS_INVALIDATE);
+#endif
+}
+void CodeSignatureSection::writeTo(uint8_t *buf) const {
+uint32_t signatureSize = static_cast<uint32_t>(getSize());
+auto *superBlob = reinterpret_cast<CS_SuperBlob *>(buf);
+write32be(&superBlob->magic, CSMAGIC_EMBEDDED_SIGNATURE);
+write32be(&superBlob->length, signatureSize);
+write32be(&superBlob->count, 1);
+auto *blobIndex = reinterpret_cast<CS_BlobIndex *>(&superBlob[1]);
+write32be(&blobIndex->type, CSSLOT_CODEDIRECTORY);
+write32be(&blobIndex->offset, blobHeadersSize);
+auto *codeDirectory =
+reinterpret_cast<CS_CodeDirectory *>(buf + blobHeadersSize);
+write32be(&codeDirectory->magic, CSMAGIC_CODEDIRECTORY);
+write32be(&codeDirectory->length, signatureSize - blobHeadersSize);
+write32be(&codeDirectory->version, CS_SUPPORTSEXECSEG);
+write32be(&codeDirectory->flags, CS_ADHOC | CS_LINKER_SIGNED);
+write32be(&codeDirectory->hashOffset,
+sizeof(CS_CodeDirectory) + fileName.size() + fileNamePad);
+write32be(&codeDirectory->identOffset, sizeof(CS_CodeDirectory));
+codeDirectory->nSpecialSlots = 0;
+write32be(&codeDirectory->nCodeSlots, getBlockCount());
+write32be(&codeDirectory->codeLimit, fileOff);
+codeDirectory->hashSize = static_cast<uint8_t>(hashSize);
+codeDirectory->hashType = kSecCodeSignatureHashSHA256;
+codeDirectory->platform = 0;
+codeDirectory->pageSize = blockSizeShift;
+codeDirectory->spare2 = 0;
+codeDirectory->scatterOffset = 0;
+codeDirectory->teamOffset = 0;
+codeDirectory->spare3 = 0;
+codeDirectory->codeLimit64 = 0;
+OutputSegment *textSeg = getOrCreateOutputSegment(segment_names::text);
+write64be(&codeDirectory->execSegBase, textSeg->fileOff);
+write64be(&codeDirectory->execSegLimit, textSeg->fileSize);
+write64be(&codeDirectory->execSegFlags,
+config->outputType == MH_EXECUTE ? CS_EXECSEG_MAIN_BINARY : 0);
+auto *id = reinterpret_cast<char *>(&codeDirectory[1]);
+memcpy(id, fileName.begin(), fileName.size());
+memset(id + fileName.size(), 0, fileNamePad);
+}
+BitcodeBundleSection::BitcodeBundleSection()
+: SyntheticSection(segment_names::llvm, section_names::bitcodeBundle) {}
+class ErrorCodeWrapper {
+public:
+explicit ErrorCodeWrapper(std::error_code ec) : errorCode(ec.value()) {}
+explicit ErrorCodeWrapper(int ec) : errorCode(ec) {}
+operator int() const { return errorCode; }
+private:
+int errorCode;
+};
+#define CHECK_EC(exp)                                                          \
+do {                                                                         \
+ErrorCodeWrapper ec(exp);                                                  \
+if (ec)                                                                    \
+fatal(Twine("operation failed with error code ") + Twine(ec) + ": " +    \
+#exp);                                                             \
+} while (0);
+void BitcodeBundleSection::finalize() {
+#ifdef LLVM_HAVE_LIBXAR
+using namespace llvm::sys::fs;
+CHECK_EC(createTemporaryFile("bitcode-bundle", "xar", xarPath));
+xar_t xar(xar_open(xarPath.data(), O_RDWR));
+if (!xar)
+fatal("failed to open XAR temporary file at " + xarPath);
+CHECK_EC(xar_opt_set(xar, XAR_OPT_COMPRESSION, XAR_OPT_VAL_NONE));
+// FIXME: add more data to XAR
+CHECK_EC(xar_close(xar));
+file_size(xarPath, xarSize);
+#endif // defined(LLVM_HAVE_LIBXAR)
+}
+void BitcodeBundleSection::writeTo(uint8_t *buf) const {
+using namespace llvm::sys::fs;
+file_t handle =
+CHECK(openNativeFile(xarPath, CD_OpenExisting, FA_Read, OF_None),
+"failed to open XAR file");
+std::error_code ec;
+mapped_file_region xarMap(handle, mapped_file_region::mapmode::readonly,
+xarSize, 0, ec);
+if (ec)
+fatal("failed to map XAR file");
+memcpy(buf, xarMap.const_data(), xarSize);
+closeFile(handle);
+remove(xarPath);
+}
+void macho::createSyntheticSymbols() {
+auto addHeaderSymbol = [](const char *name) {
+symtab->addSynthetic(name, in.header->isec, /*value=*/0,
+/*privateExtern=*/true, /*includeInSymtab=*/false,
+/*referencedDynamically=*/false);
+};
+switch (config->outputType) {
+// FIXME: Assign the right address value for these symbols
+// (rather than 0). But we need to do that after assignAddresses().
+case MH_EXECUTE:
+// If linking PIE, __mh_execute_header is a defined symbol in
+//  __TEXT, __text)
+// Otherwise, it's an absolute symbol.
+if (config->isPic)
+symtab->addSynthetic("__mh_execute_header", in.header->isec, /*value=*/0,
+/*privateExtern=*/false, /*includeInSymtab=*/true,
+/*referencedDynamically=*/true);
+else
+symtab->addSynthetic("__mh_execute_header", /*isec=*/nullptr, /*value=*/0,
+/*privateExtern=*/false, /*includeInSymtab=*/true,
+/*referencedDynamically=*/true);
+break;
+// The following symbols are N_SECT symbols, even though the header is not
+// part of any section and that they are private to the bundle/dylib/object
+// they are part of.
+case MH_BUNDLE:
+addHeaderSymbol("__mh_bundle_header");
+break;
+case MH_DYLIB:
+addHeaderSymbol("__mh_dylib_header");
+break;
+case MH_DYLINKER:
+addHeaderSymbol("__mh_dylinker_header");
+break;
+case MH_OBJECT:
+addHeaderSymbol("__mh_object_header");
+break;
+default:
+llvm_unreachable("unexpected outputType");
+break;
+}
+// The Itanium C++ ABI requires dylibs to pass a pointer to __cxa_atexit
+// which does e.g. cleanup of static global variables. The ABI document
+// says that the pointer can point to any address in one of the dylib's
+// segments, but in practice ld64 seems to set it to point to the header,
+// so that's what's implemented here.
+addHeaderSymbol("___dso_handle");
+}
+template SymtabSection *macho::makeSymtabSection<LP64>(StringTableSection &);
+template SymtabSection *macho::makeSymtabSection<ILP32>(StringTableSection &);

Mercurial > hg > CbC > CbC_llvm

comparison lld/MachO/SyntheticSections.cpp @ 207:2e18cbf3894f