Index: vendor/lld/dist-release_90/ELF/Writer.cpp
===================================================================
--- vendor/lld/dist-release_90/ELF/Writer.cpp	(revision 351986)
+++ vendor/lld/dist-release_90/ELF/Writer.cpp	(revision 351987)
@@ -1,2689 +1,2691 @@
 //===- Writer.cpp ---------------------------------------------------------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 
 #include "Writer.h"
 #include "AArch64ErrataFix.h"
 #include "CallGraphSort.h"
 #include "Config.h"
 #include "LinkerScript.h"
 #include "MapFile.h"
 #include "OutputSections.h"
 #include "Relocations.h"
 #include "SymbolTable.h"
 #include "Symbols.h"
 #include "SyntheticSections.h"
 #include "Target.h"
 #include "lld/Common/Filesystem.h"
 #include "lld/Common/Memory.h"
 #include "lld/Common/Strings.h"
 #include "lld/Common/Threads.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Support/RandomNumberGenerator.h"
 #include "llvm/Support/SHA1.h"
 #include "llvm/Support/xxhash.h"
 #include <climits>
 
 using namespace llvm;
 using namespace llvm::ELF;
 using namespace llvm::object;
 using namespace llvm::support;
 using namespace llvm::support::endian;
 
 using namespace lld;
 using namespace lld::elf;
 
 namespace {
 // The writer writes a SymbolTable result to a file.
 template <class ELFT> class Writer {
 public:
   Writer() : buffer(errorHandler().outputBuffer) {}
   using Elf_Shdr = typename ELFT::Shdr;
   using Elf_Ehdr = typename ELFT::Ehdr;
   using Elf_Phdr = typename ELFT::Phdr;
 
   void run();
 
 private:
   void copyLocalSymbols();
   void addSectionSymbols();
   void forEachRelSec(llvm::function_ref<void(InputSectionBase &)> fn);
   void sortSections();
   void resolveShfLinkOrder();
   void finalizeAddressDependentContent();
   void sortInputSections();
   void finalizeSections();
   void checkExecuteOnly();
   void setReservedSymbolSections();
 
   std::vector<PhdrEntry *> createPhdrs(Partition &part);
   void removeEmptyPTLoad(std::vector<PhdrEntry *> &phdrEntry);
   void addPhdrForSection(Partition &part, unsigned shType, unsigned pType,
                          unsigned pFlags);
   void assignFileOffsets();
   void assignFileOffsetsBinary();
   void setPhdrs(Partition &part);
   void checkSections();
   void fixSectionAlignments();
   void openFile();
   void writeTrapInstr();
   void writeHeader();
   void writeSections();
   void writeSectionsBinary();
   void writeBuildId();
 
   std::unique_ptr<FileOutputBuffer> &buffer;
 
   void addRelIpltSymbols();
   void addStartEndSymbols();
   void addStartStopSymbols(OutputSection *sec);
 
   uint64_t fileSize;
   uint64_t sectionHeaderOff;
 };
 } // anonymous namespace
 
 static bool isSectionPrefix(StringRef prefix, StringRef name) {
   return name.startswith(prefix) || name == prefix.drop_back();
 }
 
 StringRef elf::getOutputSectionName(const InputSectionBase *s) {
   if (config->relocatable)
     return s->name;
 
   // This is for --emit-relocs. If .text.foo is emitted as .text.bar, we want
   // to emit .rela.text.foo as .rela.text.bar for consistency (this is not
   // technically required, but not doing it is odd). This code guarantees that.
   if (auto *isec = dyn_cast<InputSection>(s)) {
     if (InputSectionBase *rel = isec->getRelocatedSection()) {
       OutputSection *out = rel->getOutputSection();
       if (s->type == SHT_RELA)
         return saver.save(".rela" + out->name);
       return saver.save(".rel" + out->name);
     }
   }
 
   // This check is for -z keep-text-section-prefix.  This option separates text
   // sections with prefix ".text.hot", ".text.unlikely", ".text.startup" or
   // ".text.exit".
   // When enabled, this allows identifying the hot code region (.text.hot) in
   // the final binary which can be selectively mapped to huge pages or mlocked,
   // for instance.
   if (config->zKeepTextSectionPrefix)
     for (StringRef v :
          {".text.hot.", ".text.unlikely.", ".text.startup.", ".text.exit."})
       if (isSectionPrefix(v, s->name))
         return v.drop_back();
 
   for (StringRef v :
        {".text.", ".rodata.", ".data.rel.ro.", ".data.", ".bss.rel.ro.",
         ".bss.", ".init_array.", ".fini_array.", ".ctors.", ".dtors.", ".tbss.",
         ".gcc_except_table.", ".tdata.", ".ARM.exidx.", ".ARM.extab."})
     if (isSectionPrefix(v, s->name))
       return v.drop_back();
 
   // CommonSection is identified as "COMMON" in linker scripts.
   // By default, it should go to .bss section.
   if (s->name == "COMMON")
     return ".bss";
 
   return s->name;
 }
 
 static bool needsInterpSection() {
   return !sharedFiles.empty() && !config->dynamicLinker.empty() &&
          script->needsInterpSection();
 }
 
 template <class ELFT> void elf::writeResult() { Writer<ELFT>().run(); }
 
 template <class ELFT>
 void Writer<ELFT>::removeEmptyPTLoad(std::vector<PhdrEntry *> &phdrs) {
   llvm::erase_if(phdrs, [&](const PhdrEntry *p) {
     if (p->p_type != PT_LOAD)
       return false;
     if (!p->firstSec)
       return true;
     uint64_t size = p->lastSec->addr + p->lastSec->size - p->firstSec->addr;
     return size == 0;
   });
 }
 
 template <class ELFT> static void copySectionsIntoPartitions() {
   std::vector<InputSectionBase *> newSections;
   for (unsigned part = 2; part != partitions.size() + 1; ++part) {
     for (InputSectionBase *s : inputSections) {
       if (!(s->flags & SHF_ALLOC) || !s->isLive())
         continue;
       InputSectionBase *copy;
       if (s->type == SHT_NOTE)
         copy = make<InputSection>(cast<InputSection>(*s));
       else if (auto *es = dyn_cast<EhInputSection>(s))
         copy = make<EhInputSection>(*es);
       else
         continue;
       copy->partition = part;
       newSections.push_back(copy);
     }
   }
 
   inputSections.insert(inputSections.end(), newSections.begin(),
                        newSections.end());
 }
 
 template <class ELFT> static void combineEhSections() {
   for (InputSectionBase *&s : inputSections) {
     // Ignore dead sections and the partition end marker (.part.end),
     // whose partition number is out of bounds.
     if (!s->isLive() || s->partition == 255)
       continue;
 
     Partition &part = s->getPartition();
     if (auto *es = dyn_cast<EhInputSection>(s)) {
       part.ehFrame->addSection<ELFT>(es);
       s = nullptr;
     } else if (s->kind() == SectionBase::Regular && part.armExidx &&
                part.armExidx->addSection(cast<InputSection>(s))) {
       s = nullptr;
     }
   }
 
   std::vector<InputSectionBase *> &v = inputSections;
   v.erase(std::remove(v.begin(), v.end(), nullptr), v.end());
 }
 
 static Defined *addOptionalRegular(StringRef name, SectionBase *sec,
                                    uint64_t val, uint8_t stOther = STV_HIDDEN,
                                    uint8_t binding = STB_GLOBAL) {
   Symbol *s = symtab->find(name);
   if (!s || s->isDefined())
     return nullptr;
 
   s->resolve(Defined{/*file=*/nullptr, name, binding, stOther, STT_NOTYPE, val,
                      /*size=*/0, sec});
   return cast<Defined>(s);
 }
 
 static Defined *addAbsolute(StringRef name) {
   Symbol *sym = symtab->addSymbol(Defined{nullptr, name, STB_GLOBAL, STV_HIDDEN,
                                           STT_NOTYPE, 0, 0, nullptr});
   return cast<Defined>(sym);
 }
 
 // The linker is expected to define some symbols depending on
 // the linking result. This function defines such symbols.
 void elf::addReservedSymbols() {
   if (config->emachine == EM_MIPS) {
     // Define _gp for MIPS. st_value of _gp symbol will be updated by Writer
     // so that it points to an absolute address which by default is relative
     // to GOT. Default offset is 0x7ff0.
     // See "Global Data Symbols" in Chapter 6 in the following document:
     // ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
     ElfSym::mipsGp = addAbsolute("_gp");
 
     // On MIPS O32 ABI, _gp_disp is a magic symbol designates offset between
     // start of function and 'gp' pointer into GOT.
     if (symtab->find("_gp_disp"))
       ElfSym::mipsGpDisp = addAbsolute("_gp_disp");
 
     // The __gnu_local_gp is a magic symbol equal to the current value of 'gp'
     // pointer. This symbol is used in the code generated by .cpload pseudo-op
     // in case of using -mno-shared option.
     // https://sourceware.org/ml/binutils/2004-12/msg00094.html
     if (symtab->find("__gnu_local_gp"))
       ElfSym::mipsLocalGp = addAbsolute("__gnu_local_gp");
   } else if (config->emachine == EM_PPC) {
     // glibc *crt1.o has a undefined reference to _SDA_BASE_. Since we don't
     // support Small Data Area, define it arbitrarily as 0.
     addOptionalRegular("_SDA_BASE_", nullptr, 0, STV_HIDDEN);
   }
 
   // The Power Architecture 64-bit v2 ABI defines a TableOfContents (TOC) which
   // combines the typical ELF GOT with the small data sections. It commonly
   // includes .got .toc .sdata .sbss. The .TOC. symbol replaces both
   // _GLOBAL_OFFSET_TABLE_ and _SDA_BASE_ from the 32-bit ABI. It is used to
   // represent the TOC base which is offset by 0x8000 bytes from the start of
   // the .got section.
   // We do not allow _GLOBAL_OFFSET_TABLE_ to be defined by input objects as the
   // correctness of some relocations depends on its value.
   StringRef gotSymName =
       (config->emachine == EM_PPC64) ? ".TOC." : "_GLOBAL_OFFSET_TABLE_";
 
   if (Symbol *s = symtab->find(gotSymName)) {
     if (s->isDefined()) {
       error(toString(s->file) + " cannot redefine linker defined symbol '" +
             gotSymName + "'");
       return;
     }
 
     uint64_t gotOff = 0;
     if (config->emachine == EM_PPC64)
       gotOff = 0x8000;
 
     s->resolve(Defined{/*file=*/nullptr, gotSymName, STB_GLOBAL, STV_HIDDEN,
                        STT_NOTYPE, gotOff, /*size=*/0, Out::elfHeader});
     ElfSym::globalOffsetTable = cast<Defined>(s);
   }
 
   // __ehdr_start is the location of ELF file headers. Note that we define
   // this symbol unconditionally even when using a linker script, which
   // differs from the behavior implemented by GNU linker which only define
   // this symbol if ELF headers are in the memory mapped segment.
   addOptionalRegular("__ehdr_start", Out::elfHeader, 0, STV_HIDDEN);
 
   // __executable_start is not documented, but the expectation of at
   // least the Android libc is that it points to the ELF header.
   addOptionalRegular("__executable_start", Out::elfHeader, 0, STV_HIDDEN);
 
   // __dso_handle symbol is passed to cxa_finalize as a marker to identify
   // each DSO. The address of the symbol doesn't matter as long as they are
   // different in different DSOs, so we chose the start address of the DSO.
   addOptionalRegular("__dso_handle", Out::elfHeader, 0, STV_HIDDEN);
 
   // If linker script do layout we do not need to create any standart symbols.
   if (script->hasSectionsCommand)
     return;
 
   auto add = [](StringRef s, int64_t pos) {
     return addOptionalRegular(s, Out::elfHeader, pos, STV_DEFAULT);
   };
 
   ElfSym::bss = add("__bss_start", 0);
   ElfSym::end1 = add("end", -1);
   ElfSym::end2 = add("_end", -1);
   ElfSym::etext1 = add("etext", -1);
   ElfSym::etext2 = add("_etext", -1);
   ElfSym::edata1 = add("edata", -1);
   ElfSym::edata2 = add("_edata", -1);
 }
 
 static OutputSection *findSection(StringRef name, unsigned partition = 1) {
   for (BaseCommand *base : script->sectionCommands)
     if (auto *sec = dyn_cast<OutputSection>(base))
       if (sec->name == name && sec->partition == partition)
         return sec;
   return nullptr;
 }
 
 // Initialize Out members.
 template <class ELFT> static void createSyntheticSections() {
   // Initialize all pointers with NULL. This is needed because
   // you can call lld::elf::main more than once as a library.
   memset(&Out::first, 0, sizeof(Out));
 
   auto add = [](InputSectionBase *sec) { inputSections.push_back(sec); };
 
   in.shStrTab = make<StringTableSection>(".shstrtab", false);
 
   Out::programHeaders = make<OutputSection>("", 0, SHF_ALLOC);
   Out::programHeaders->alignment = config->wordsize;
 
   if (config->strip != StripPolicy::All) {
     in.strTab = make<StringTableSection>(".strtab", false);
     in.symTab = make<SymbolTableSection<ELFT>>(*in.strTab);
     in.symTabShndx = make<SymtabShndxSection>();
   }
 
   in.bss = make<BssSection>(".bss", 0, 1);
   add(in.bss);
 
   // If there is a SECTIONS command and a .data.rel.ro section name use name
   // .data.rel.ro.bss so that we match in the .data.rel.ro output section.
   // This makes sure our relro is contiguous.
   bool hasDataRelRo =
       script->hasSectionsCommand && findSection(".data.rel.ro", 0);
   in.bssRelRo =
       make<BssSection>(hasDataRelRo ? ".data.rel.ro.bss" : ".bss.rel.ro", 0, 1);
   add(in.bssRelRo);
 
   // Add MIPS-specific sections.
   if (config->emachine == EM_MIPS) {
     if (!config->shared && config->hasDynSymTab) {
       in.mipsRldMap = make<MipsRldMapSection>();
       add(in.mipsRldMap);
     }
     if (auto *sec = MipsAbiFlagsSection<ELFT>::create())
       add(sec);
     if (auto *sec = MipsOptionsSection<ELFT>::create())
       add(sec);
     if (auto *sec = MipsReginfoSection<ELFT>::create())
       add(sec);
   }
 
   for (Partition &part : partitions) {
     auto add = [&](InputSectionBase *sec) {
       sec->partition = part.getNumber();
       inputSections.push_back(sec);
     };
 
     if (!part.name.empty()) {
       part.elfHeader = make<PartitionElfHeaderSection<ELFT>>();
       part.elfHeader->name = part.name;
       add(part.elfHeader);
 
       part.programHeaders = make<PartitionProgramHeadersSection<ELFT>>();
       add(part.programHeaders);
     }
 
     if (config->buildId != BuildIdKind::None) {
       part.buildId = make<BuildIdSection>();
       add(part.buildId);
     }
 
     part.dynStrTab = make<StringTableSection>(".dynstr", true);
     part.dynSymTab = make<SymbolTableSection<ELFT>>(*part.dynStrTab);
     part.dynamic = make<DynamicSection<ELFT>>();
     if (config->androidPackDynRelocs) {
       part.relaDyn = make<AndroidPackedRelocationSection<ELFT>>(
           config->isRela ? ".rela.dyn" : ".rel.dyn");
     } else {
       part.relaDyn = make<RelocationSection<ELFT>>(
           config->isRela ? ".rela.dyn" : ".rel.dyn", config->zCombreloc);
     }
 
     if (needsInterpSection())
       add(createInterpSection());
 
     if (config->hasDynSymTab) {
       part.dynSymTab = make<SymbolTableSection<ELFT>>(*part.dynStrTab);
       add(part.dynSymTab);
 
       part.verSym = make<VersionTableSection>();
       add(part.verSym);
 
       if (!config->versionDefinitions.empty()) {
         part.verDef = make<VersionDefinitionSection>();
         add(part.verDef);
       }
 
       part.verNeed = make<VersionNeedSection<ELFT>>();
       add(part.verNeed);
 
       if (config->gnuHash) {
         part.gnuHashTab = make<GnuHashTableSection>();
         add(part.gnuHashTab);
       }
 
       if (config->sysvHash) {
         part.hashTab = make<HashTableSection>();
         add(part.hashTab);
       }
 
       add(part.dynamic);
       add(part.dynStrTab);
       add(part.relaDyn);
     }
 
     if (config->relrPackDynRelocs) {
       part.relrDyn = make<RelrSection<ELFT>>();
       add(part.relrDyn);
     }
 
     if (!config->relocatable) {
       if (config->ehFrameHdr) {
         part.ehFrameHdr = make<EhFrameHeader>();
         add(part.ehFrameHdr);
       }
       part.ehFrame = make<EhFrameSection>();
       add(part.ehFrame);
     }
 
     if (config->emachine == EM_ARM && !config->relocatable) {
       // The ARMExidxsyntheticsection replaces all the individual .ARM.exidx
       // InputSections.
       part.armExidx = make<ARMExidxSyntheticSection>();
       add(part.armExidx);
     }
   }
 
   if (partitions.size() != 1) {
     // Create the partition end marker. This needs to be in partition number 255
     // so that it is sorted after all other partitions. It also has other
     // special handling (see createPhdrs() and combineEhSections()).
     in.partEnd = make<BssSection>(".part.end", config->maxPageSize, 1);
     in.partEnd->partition = 255;
     add(in.partEnd);
 
     in.partIndex = make<PartitionIndexSection>();
     addOptionalRegular("__part_index_begin", in.partIndex, 0);
     addOptionalRegular("__part_index_end", in.partIndex,
                        in.partIndex->getSize());
     add(in.partIndex);
   }
 
   // Add .got. MIPS' .got is so different from the other archs,
   // it has its own class.
   if (config->emachine == EM_MIPS) {
     in.mipsGot = make<MipsGotSection>();
     add(in.mipsGot);
   } else {
     in.got = make<GotSection>();
     add(in.got);
   }
 
   if (config->emachine == EM_PPC) {
     in.ppc32Got2 = make<PPC32Got2Section>();
     add(in.ppc32Got2);
   }
 
   if (config->emachine == EM_PPC64) {
     in.ppc64LongBranchTarget = make<PPC64LongBranchTargetSection>();
     add(in.ppc64LongBranchTarget);
   }
 
   if (config->emachine == EM_RISCV) {
     in.riscvSdata = make<RISCVSdataSection>();
     add(in.riscvSdata);
   }
 
   in.gotPlt = make<GotPltSection>();
   add(in.gotPlt);
   in.igotPlt = make<IgotPltSection>();
   add(in.igotPlt);
 
   // _GLOBAL_OFFSET_TABLE_ is defined relative to either .got.plt or .got. Treat
   // it as a relocation and ensure the referenced section is created.
   if (ElfSym::globalOffsetTable && config->emachine != EM_MIPS) {
     if (target->gotBaseSymInGotPlt)
       in.gotPlt->hasGotPltOffRel = true;
     else
       in.got->hasGotOffRel = true;
   }
 
   if (config->gdbIndex)
     add(GdbIndexSection::create<ELFT>());
 
   // We always need to add rel[a].plt to output if it has entries.
   // Even for static linking it can contain R_[*]_IRELATIVE relocations.
   in.relaPlt = make<RelocationSection<ELFT>>(
       config->isRela ? ".rela.plt" : ".rel.plt", /*sort=*/false);
   add(in.relaPlt);
 
   // The relaIplt immediately follows .rel.plt (.rel.dyn for ARM) to ensure
   // that the IRelative relocations are processed last by the dynamic loader.
   // We cannot place the iplt section in .rel.dyn when Android relocation
   // packing is enabled because that would cause a section type mismatch.
   // However, because the Android dynamic loader reads .rel.plt after .rel.dyn,
   // we can get the desired behaviour by placing the iplt section in .rel.plt.
   in.relaIplt = make<RelocationSection<ELFT>>(
       (config->emachine == EM_ARM && !config->androidPackDynRelocs)
           ? ".rel.dyn"
           : in.relaPlt->name,
       /*sort=*/false);
   add(in.relaIplt);
 
   in.plt = make<PltSection>(false);
   add(in.plt);
   in.iplt = make<PltSection>(true);
   add(in.iplt);
 
   if (config->andFeatures)
     add(make<GnuPropertySection>());
 
   // .note.GNU-stack is always added when we are creating a re-linkable
   // object file. Other linkers are using the presence of this marker
   // section to control the executable-ness of the stack area, but that
   // is irrelevant these days. Stack area should always be non-executable
   // by default. So we emit this section unconditionally.
   if (config->relocatable)
     add(make<GnuStackSection>());
 
   if (in.symTab)
     add(in.symTab);
   if (in.symTabShndx)
     add(in.symTabShndx);
   add(in.shStrTab);
   if (in.strTab)
     add(in.strTab);
 }
 
 // The main function of the writer.
 template <class ELFT> void Writer<ELFT>::run() {
   // Make copies of any input sections that need to be copied into each
   // partition.
   copySectionsIntoPartitions<ELFT>();
 
   // Create linker-synthesized sections such as .got or .plt.
   // Such sections are of type input section.
   createSyntheticSections<ELFT>();
 
   // Some input sections that are used for exception handling need to be moved
   // into synthetic sections. Do that now so that they aren't assigned to
   // output sections in the usual way.
   if (!config->relocatable)
     combineEhSections<ELFT>();
 
   // We want to process linker script commands. When SECTIONS command
   // is given we let it create sections.
   script->processSectionCommands();
 
   // Linker scripts controls how input sections are assigned to output sections.
   // Input sections that were not handled by scripts are called "orphans", and
   // they are assigned to output sections by the default rule. Process that.
   script->addOrphanSections();
 
   if (config->discard != DiscardPolicy::All)
     copyLocalSymbols();
 
   if (config->copyRelocs)
     addSectionSymbols();
 
   // Now that we have a complete set of output sections. This function
   // completes section contents. For example, we need to add strings
   // to the string table, and add entries to .got and .plt.
   // finalizeSections does that.
   finalizeSections();
   checkExecuteOnly();
   if (errorCount())
     return;
 
   script->assignAddresses();
 
   // If -compressed-debug-sections is specified, we need to compress
   // .debug_* sections. Do it right now because it changes the size of
   // output sections.
   for (OutputSection *sec : outputSections)
     sec->maybeCompress<ELFT>();
 
   script->allocateHeaders(mainPart->phdrs);
 
   // Remove empty PT_LOAD to avoid causing the dynamic linker to try to mmap a
   // 0 sized region. This has to be done late since only after assignAddresses
   // we know the size of the sections.
   for (Partition &part : partitions)
     removeEmptyPTLoad(part.phdrs);
 
   if (!config->oFormatBinary)
     assignFileOffsets();
   else
     assignFileOffsetsBinary();
 
   for (Partition &part : partitions)
     setPhdrs(part);
 
   if (config->relocatable)
     for (OutputSection *sec : outputSections)
       sec->addr = 0;
 
   if (config->checkSections)
     checkSections();
 
   // It does not make sense try to open the file if we have error already.
   if (errorCount())
     return;
   // Write the result down to a file.
   openFile();
   if (errorCount())
     return;
 
   if (!config->oFormatBinary) {
     writeTrapInstr();
     writeHeader();
     writeSections();
   } else {
     writeSectionsBinary();
   }
 
   // Backfill .note.gnu.build-id section content. This is done at last
   // because the content is usually a hash value of the entire output file.
   writeBuildId();
   if (errorCount())
     return;
 
   // Handle -Map and -cref options.
   writeMapFile();
   writeCrossReferenceTable();
   if (errorCount())
     return;
 
   if (auto e = buffer->commit())
     error("failed to write to the output file: " + toString(std::move(e)));
 }
 
 static bool shouldKeepInSymtab(const Defined &sym) {
   if (sym.isSection())
     return false;
 
   if (config->discard == DiscardPolicy::None)
     return true;
 
   // If -emit-reloc is given, all symbols including local ones need to be
   // copied because they may be referenced by relocations.
   if (config->emitRelocs)
     return true;
 
   // In ELF assembly .L symbols are normally discarded by the assembler.
   // If the assembler fails to do so, the linker discards them if
   // * --discard-locals is used.
   // * The symbol is in a SHF_MERGE section, which is normally the reason for
   //   the assembler keeping the .L symbol.
   StringRef name = sym.getName();
   bool isLocal = name.startswith(".L") || name.empty();
   if (!isLocal)
     return true;
 
   if (config->discard == DiscardPolicy::Locals)
     return false;
 
   SectionBase *sec = sym.section;
   return !sec || !(sec->flags & SHF_MERGE);
 }
 
 static bool includeInSymtab(const Symbol &b) {
   if (!b.isLocal() && !b.isUsedInRegularObj)
     return false;
 
   if (auto *d = dyn_cast<Defined>(&b)) {
     // Always include absolute symbols.
     SectionBase *sec = d->section;
     if (!sec)
       return true;
     sec = sec->repl;
 
     // Exclude symbols pointing to garbage-collected sections.
     if (isa<InputSectionBase>(sec) && !sec->isLive())
       return false;
 
     if (auto *s = dyn_cast<MergeInputSection>(sec))
       if (!s->getSectionPiece(d->value)->live)
         return false;
     return true;
   }
   return b.used;
 }
 
 // Local symbols are not in the linker's symbol table. This function scans
 // each object file's symbol table to copy local symbols to the output.
 template <class ELFT> void Writer<ELFT>::copyLocalSymbols() {
   if (!in.symTab)
     return;
   for (InputFile *file : objectFiles) {
     ObjFile<ELFT> *f = cast<ObjFile<ELFT>>(file);
     for (Symbol *b : f->getLocalSymbols()) {
       if (!b->isLocal())
         fatal(toString(f) +
               ": broken object: getLocalSymbols returns a non-local symbol");
       auto *dr = dyn_cast<Defined>(b);
 
       // No reason to keep local undefined symbol in symtab.
       if (!dr)
         continue;
       if (!includeInSymtab(*b))
         continue;
       if (!shouldKeepInSymtab(*dr))
         continue;
       in.symTab->addSymbol(b);
     }
   }
 }
 
 // Create a section symbol for each output section so that we can represent
 // relocations that point to the section. If we know that no relocation is
 // referring to a section (that happens if the section is a synthetic one), we
 // don't create a section symbol for that section.
 template <class ELFT> void Writer<ELFT>::addSectionSymbols() {
   for (BaseCommand *base : script->sectionCommands) {
     auto *sec = dyn_cast<OutputSection>(base);
     if (!sec)
       continue;
     auto i = llvm::find_if(sec->sectionCommands, [](BaseCommand *base) {
       if (auto *isd = dyn_cast<InputSectionDescription>(base))
         return !isd->sections.empty();
       return false;
     });
     if (i == sec->sectionCommands.end())
       continue;
     InputSection *isec = cast<InputSectionDescription>(*i)->sections[0];
 
     // Relocations are not using REL[A] section symbols.
     if (isec->type == SHT_REL || isec->type == SHT_RELA)
       continue;
 
     // Unlike other synthetic sections, mergeable output sections contain data
     // copied from input sections, and there may be a relocation pointing to its
     // contents if -r or -emit-reloc are given.
     if (isa<SyntheticSection>(isec) && !(isec->flags & SHF_MERGE))
       continue;
 
     auto *sym =
         make<Defined>(isec->file, "", STB_LOCAL, /*stOther=*/0, STT_SECTION,
                       /*value=*/0, /*size=*/0, isec);
     in.symTab->addSymbol(sym);
   }
 }
 
 // Today's loaders have a feature to make segments read-only after
 // processing dynamic relocations to enhance security. PT_GNU_RELRO
 // is defined for that.
 //
 // This function returns true if a section needs to be put into a
 // PT_GNU_RELRO segment.
 static bool isRelroSection(const OutputSection *sec) {
   if (!config->zRelro)
     return false;
 
   uint64_t flags = sec->flags;
 
   // Non-allocatable or non-writable sections don't need RELRO because
   // they are not writable or not even mapped to memory in the first place.
   // RELRO is for sections that are essentially read-only but need to
   // be writable only at process startup to allow dynamic linker to
   // apply relocations.
   if (!(flags & SHF_ALLOC) || !(flags & SHF_WRITE))
     return false;
 
   // Once initialized, TLS data segments are used as data templates
   // for a thread-local storage. For each new thread, runtime
   // allocates memory for a TLS and copy templates there. No thread
   // are supposed to use templates directly. Thus, it can be in RELRO.
   if (flags & SHF_TLS)
     return true;
 
   // .init_array, .preinit_array and .fini_array contain pointers to
   // functions that are executed on process startup or exit. These
   // pointers are set by the static linker, and they are not expected
   // to change at runtime. But if you are an attacker, you could do
   // interesting things by manipulating pointers in .fini_array, for
   // example. So they are put into RELRO.
   uint32_t type = sec->type;
   if (type == SHT_INIT_ARRAY || type == SHT_FINI_ARRAY ||
       type == SHT_PREINIT_ARRAY)
     return true;
 
   // .got contains pointers to external symbols. They are resolved by
   // the dynamic linker when a module is loaded into memory, and after
   // that they are not expected to change. So, it can be in RELRO.
   if (in.got && sec == in.got->getParent())
     return true;
 
   // .toc is a GOT-ish section for PowerPC64. Their contents are accessed
   // through r2 register, which is reserved for that purpose. Since r2 is used
   // for accessing .got as well, .got and .toc need to be close enough in the
   // virtual address space. Usually, .toc comes just after .got. Since we place
   // .got into RELRO, .toc needs to be placed into RELRO too.
   if (sec->name.equals(".toc"))
     return true;
 
   // .got.plt contains pointers to external function symbols. They are
   // by default resolved lazily, so we usually cannot put it into RELRO.
   // However, if "-z now" is given, the lazy symbol resolution is
   // disabled, which enables us to put it into RELRO.
   if (sec == in.gotPlt->getParent())
     return config->zNow;
 
   // .dynamic section contains data for the dynamic linker, and
   // there's no need to write to it at runtime, so it's better to put
   // it into RELRO.
   if (sec->name == ".dynamic")
     return true;
 
   // Sections with some special names are put into RELRO. This is a
   // bit unfortunate because section names shouldn't be significant in
   // ELF in spirit. But in reality many linker features depend on
   // magic section names.
   StringRef s = sec->name;
   return s == ".data.rel.ro" || s == ".bss.rel.ro" || s == ".ctors" ||
          s == ".dtors" || s == ".jcr" || s == ".eh_frame" ||
          s == ".openbsd.randomdata";
 }
 
 // We compute a rank for each section. The rank indicates where the
 // section should be placed in the file.  Instead of using simple
 // numbers (0,1,2...), we use a series of flags. One for each decision
 // point when placing the section.
 // Using flags has two key properties:
 // * It is easy to check if a give branch was taken.
 // * It is easy two see how similar two ranks are (see getRankProximity).
 enum RankFlags {
   RF_NOT_ADDR_SET = 1 << 27,
   RF_NOT_ALLOC = 1 << 26,
   RF_PARTITION = 1 << 18, // Partition number (8 bits)
   RF_NOT_PART_EHDR = 1 << 17,
   RF_NOT_PART_PHDR = 1 << 16,
   RF_NOT_INTERP = 1 << 15,
   RF_NOT_NOTE = 1 << 14,
   RF_WRITE = 1 << 13,
   RF_EXEC_WRITE = 1 << 12,
   RF_EXEC = 1 << 11,
   RF_RODATA = 1 << 10,
   RF_NOT_RELRO = 1 << 9,
   RF_NOT_TLS = 1 << 8,
   RF_BSS = 1 << 7,
   RF_PPC_NOT_TOCBSS = 1 << 6,
   RF_PPC_TOCL = 1 << 5,
   RF_PPC_TOC = 1 << 4,
   RF_PPC_GOT = 1 << 3,
   RF_PPC_BRANCH_LT = 1 << 2,
   RF_MIPS_GPREL = 1 << 1,
   RF_MIPS_NOT_GOT = 1 << 0
 };
 
 static unsigned getSectionRank(const OutputSection *sec) {
   unsigned rank = sec->partition * RF_PARTITION;
 
   // We want to put section specified by -T option first, so we
   // can start assigning VA starting from them later.
   if (config->sectionStartMap.count(sec->name))
     return rank;
   rank |= RF_NOT_ADDR_SET;
 
   // Allocatable sections go first to reduce the total PT_LOAD size and
   // so debug info doesn't change addresses in actual code.
   if (!(sec->flags & SHF_ALLOC))
     return rank | RF_NOT_ALLOC;
 
   if (sec->type == SHT_LLVM_PART_EHDR)
     return rank;
   rank |= RF_NOT_PART_EHDR;
 
   if (sec->type == SHT_LLVM_PART_PHDR)
     return rank;
   rank |= RF_NOT_PART_PHDR;
 
   // Put .interp first because some loaders want to see that section
   // on the first page of the executable file when loaded into memory.
   if (sec->name == ".interp")
     return rank;
   rank |= RF_NOT_INTERP;
 
   // Put .note sections (which make up one PT_NOTE) at the beginning so that
   // they are likely to be included in a core file even if core file size is
   // limited. In particular, we want a .note.gnu.build-id and a .note.tag to be
   // included in a core to match core files with executables.
   if (sec->type == SHT_NOTE)
     return rank;
   rank |= RF_NOT_NOTE;
 
   // Sort sections based on their access permission in the following
   // order: R, RX, RWX, RW.  This order is based on the following
   // considerations:
   // * Read-only sections come first such that they go in the
   //   PT_LOAD covering the program headers at the start of the file.
   // * Read-only, executable sections come next.
   // * Writable, executable sections follow such that .plt on
   //   architectures where it needs to be writable will be placed
   //   between .text and .data.
   // * Writable sections come last, such that .bss lands at the very
   //   end of the last PT_LOAD.
   bool isExec = sec->flags & SHF_EXECINSTR;
   bool isWrite = sec->flags & SHF_WRITE;
 
   if (isExec) {
     if (isWrite)
       rank |= RF_EXEC_WRITE;
     else
       rank |= RF_EXEC;
   } else if (isWrite) {
     rank |= RF_WRITE;
   } else if (sec->type == SHT_PROGBITS) {
     // Make non-executable and non-writable PROGBITS sections (e.g .rodata
     // .eh_frame) closer to .text. They likely contain PC or GOT relative
     // relocations and there could be relocation overflow if other huge sections
     // (.dynstr .dynsym) were placed in between.
     rank |= RF_RODATA;
   }
 
   // Place RelRo sections first. After considering SHT_NOBITS below, the
   // ordering is PT_LOAD(PT_GNU_RELRO(.data.rel.ro .bss.rel.ro) | .data .bss),
   // where | marks where page alignment happens. An alternative ordering is
   // PT_LOAD(.data | PT_GNU_RELRO( .data.rel.ro .bss.rel.ro) | .bss), but it may
   // waste more bytes due to 2 alignment places.
   if (!isRelroSection(sec))
     rank |= RF_NOT_RELRO;
 
   // If we got here we know that both A and B are in the same PT_LOAD.
 
   // The TLS initialization block needs to be a single contiguous block in a R/W
   // PT_LOAD, so stick TLS sections directly before the other RelRo R/W
   // sections. Since p_filesz can be less than p_memsz, place NOBITS sections
   // after PROGBITS.
   if (!(sec->flags & SHF_TLS))
     rank |= RF_NOT_TLS;
 
   // Within TLS sections, or within other RelRo sections, or within non-RelRo
   // sections, place non-NOBITS sections first.
   if (sec->type == SHT_NOBITS)
     rank |= RF_BSS;
 
   // Some architectures have additional ordering restrictions for sections
   // within the same PT_LOAD.
   if (config->emachine == EM_PPC64) {
     // PPC64 has a number of special SHT_PROGBITS+SHF_ALLOC+SHF_WRITE sections
     // that we would like to make sure appear is a specific order to maximize
     // their coverage by a single signed 16-bit offset from the TOC base
     // pointer. Conversely, the special .tocbss section should be first among
     // all SHT_NOBITS sections. This will put it next to the loaded special
     // PPC64 sections (and, thus, within reach of the TOC base pointer).
     StringRef name = sec->name;
     if (name != ".tocbss")
       rank |= RF_PPC_NOT_TOCBSS;
 
     if (name == ".toc1")
       rank |= RF_PPC_TOCL;
 
     if (name == ".toc")
       rank |= RF_PPC_TOC;
 
     if (name == ".got")
       rank |= RF_PPC_GOT;
 
     if (name == ".branch_lt")
       rank |= RF_PPC_BRANCH_LT;
   }
 
   if (config->emachine == EM_MIPS) {
     // All sections with SHF_MIPS_GPREL flag should be grouped together
     // because data in these sections is addressable with a gp relative address.
     if (sec->flags & SHF_MIPS_GPREL)
       rank |= RF_MIPS_GPREL;
 
     if (sec->name != ".got")
       rank |= RF_MIPS_NOT_GOT;
   }
 
   return rank;
 }
 
 static bool compareSections(const BaseCommand *aCmd, const BaseCommand *bCmd) {
   const OutputSection *a = cast<OutputSection>(aCmd);
   const OutputSection *b = cast<OutputSection>(bCmd);
 
   if (a->sortRank != b->sortRank)
     return a->sortRank < b->sortRank;
 
   if (!(a->sortRank & RF_NOT_ADDR_SET))
     return config->sectionStartMap.lookup(a->name) <
            config->sectionStartMap.lookup(b->name);
   return false;
 }
 
 void PhdrEntry::add(OutputSection *sec) {
   lastSec = sec;
   if (!firstSec)
     firstSec = sec;
   p_align = std::max(p_align, sec->alignment);
   if (p_type == PT_LOAD)
     sec->ptLoad = this;
 }
 
 // The beginning and the ending of .rel[a].plt section are marked
 // with __rel[a]_iplt_{start,end} symbols if it is a statically linked
 // executable. The runtime needs these symbols in order to resolve
 // all IRELATIVE relocs on startup. For dynamic executables, we don't
 // need these symbols, since IRELATIVE relocs are resolved through GOT
 // and PLT. For details, see http://www.airs.com/blog/archives/403.
 template <class ELFT> void Writer<ELFT>::addRelIpltSymbols() {
   if (config->relocatable || needsInterpSection())
     return;
 
   // By default, __rela_iplt_{start,end} belong to a dummy section 0
   // because .rela.plt might be empty and thus removed from output.
   // We'll override Out::elfHeader with In.relaIplt later when we are
   // sure that .rela.plt exists in output.
   ElfSym::relaIpltStart = addOptionalRegular(
       config->isRela ? "__rela_iplt_start" : "__rel_iplt_start",
       Out::elfHeader, 0, STV_HIDDEN, STB_WEAK);
 
   ElfSym::relaIpltEnd = addOptionalRegular(
       config->isRela ? "__rela_iplt_end" : "__rel_iplt_end",
       Out::elfHeader, 0, STV_HIDDEN, STB_WEAK);
 }
 
 template <class ELFT>
 void Writer<ELFT>::forEachRelSec(
     llvm::function_ref<void(InputSectionBase &)> fn) {
   // Scan all relocations. Each relocation goes through a series
   // of tests to determine if it needs special treatment, such as
   // creating GOT, PLT, copy relocations, etc.
   // Note that relocations for non-alloc sections are directly
   // processed by InputSection::relocateNonAlloc.
   for (InputSectionBase *isec : inputSections)
     if (isec->isLive() && isa<InputSection>(isec) && (isec->flags & SHF_ALLOC))
       fn(*isec);
   for (Partition &part : partitions) {
     for (EhInputSection *es : part.ehFrame->sections)
       fn(*es);
     if (part.armExidx && part.armExidx->isLive())
       for (InputSection *ex : part.armExidx->exidxSections)
         fn(*ex);
   }
 }
 
 // This function generates assignments for predefined symbols (e.g. _end or
 // _etext) and inserts them into the commands sequence to be processed at the
 // appropriate time. This ensures that the value is going to be correct by the
 // time any references to these symbols are processed and is equivalent to
 // defining these symbols explicitly in the linker script.
 template <class ELFT> void Writer<ELFT>::setReservedSymbolSections() {
   if (ElfSym::globalOffsetTable) {
     // The _GLOBAL_OFFSET_TABLE_ symbol is defined by target convention usually
     // to the start of the .got or .got.plt section.
     InputSection *gotSection = in.gotPlt;
     if (!target->gotBaseSymInGotPlt)
       gotSection = in.mipsGot ? cast<InputSection>(in.mipsGot)
                               : cast<InputSection>(in.got);
     ElfSym::globalOffsetTable->section = gotSection;
   }
 
   // .rela_iplt_{start,end} mark the start and the end of .rela.plt section.
   if (ElfSym::relaIpltStart && in.relaIplt->isNeeded()) {
     ElfSym::relaIpltStart->section = in.relaIplt;
     ElfSym::relaIpltEnd->section = in.relaIplt;
     ElfSym::relaIpltEnd->value = in.relaIplt->getSize();
   }
 
   PhdrEntry *last = nullptr;
   PhdrEntry *lastRO = nullptr;
 
   for (Partition &part : partitions) {
     for (PhdrEntry *p : part.phdrs) {
       if (p->p_type != PT_LOAD)
         continue;
       last = p;
       if (!(p->p_flags & PF_W))
         lastRO = p;
     }
   }
 
   if (lastRO) {
     // _etext is the first location after the last read-only loadable segment.
     if (ElfSym::etext1)
       ElfSym::etext1->section = lastRO->lastSec;
     if (ElfSym::etext2)
       ElfSym::etext2->section = lastRO->lastSec;
   }
 
   if (last) {
     // _edata points to the end of the last mapped initialized section.
     OutputSection *edata = nullptr;
     for (OutputSection *os : outputSections) {
       if (os->type != SHT_NOBITS)
         edata = os;
       if (os == last->lastSec)
         break;
     }
 
     if (ElfSym::edata1)
       ElfSym::edata1->section = edata;
     if (ElfSym::edata2)
       ElfSym::edata2->section = edata;
 
     // _end is the first location after the uninitialized data region.
     if (ElfSym::end1)
       ElfSym::end1->section = last->lastSec;
     if (ElfSym::end2)
       ElfSym::end2->section = last->lastSec;
   }
 
   if (ElfSym::bss)
     ElfSym::bss->section = findSection(".bss");
 
   // Setup MIPS _gp_disp/__gnu_local_gp symbols which should
   // be equal to the _gp symbol's value.
   if (ElfSym::mipsGp) {
     // Find GP-relative section with the lowest address
     // and use this address to calculate default _gp value.
     for (OutputSection *os : outputSections) {
       if (os->flags & SHF_MIPS_GPREL) {
         ElfSym::mipsGp->section = os;
         ElfSym::mipsGp->value = 0x7ff0;
         break;
       }
     }
   }
 }
 
 // We want to find how similar two ranks are.
 // The more branches in getSectionRank that match, the more similar they are.
 // Since each branch corresponds to a bit flag, we can just use
 // countLeadingZeros.
 static int getRankProximityAux(OutputSection *a, OutputSection *b) {
   return countLeadingZeros(a->sortRank ^ b->sortRank);
 }
 
 static int getRankProximity(OutputSection *a, BaseCommand *b) {
   auto *sec = dyn_cast<OutputSection>(b);
   return (sec && sec->hasInputSections) ? getRankProximityAux(a, sec) : -1;
 }
 
 // When placing orphan sections, we want to place them after symbol assignments
 // so that an orphan after
 //   begin_foo = .;
 //   foo : { *(foo) }
 //   end_foo = .;
 // doesn't break the intended meaning of the begin/end symbols.
 // We don't want to go over sections since findOrphanPos is the
 // one in charge of deciding the order of the sections.
 // We don't want to go over changes to '.', since doing so in
 //  rx_sec : { *(rx_sec) }
 //  . = ALIGN(0x1000);
 //  /* The RW PT_LOAD starts here*/
 //  rw_sec : { *(rw_sec) }
 // would mean that the RW PT_LOAD would become unaligned.
 static bool shouldSkip(BaseCommand *cmd) {
   if (auto *assign = dyn_cast<SymbolAssignment>(cmd))
     return assign->name != ".";
   return false;
 }
 
 // We want to place orphan sections so that they share as much
 // characteristics with their neighbors as possible. For example, if
 // both are rw, or both are tls.
 static std::vector<BaseCommand *>::iterator
 findOrphanPos(std::vector<BaseCommand *>::iterator b,
               std::vector<BaseCommand *>::iterator e) {
   OutputSection *sec = cast<OutputSection>(*e);
 
   // Find the first element that has as close a rank as possible.
   auto i = std::max_element(b, e, [=](BaseCommand *a, BaseCommand *b) {
     return getRankProximity(sec, a) < getRankProximity(sec, b);
   });
   if (i == e)
     return e;
 
   // Consider all existing sections with the same proximity.
   int proximity = getRankProximity(sec, *i);
   for (; i != e; ++i) {
     auto *curSec = dyn_cast<OutputSection>(*i);
     if (!curSec || !curSec->hasInputSections)
       continue;
     if (getRankProximity(sec, curSec) != proximity ||
         sec->sortRank < curSec->sortRank)
       break;
   }
 
   auto isOutputSecWithInputSections = [](BaseCommand *cmd) {
     auto *os = dyn_cast<OutputSection>(cmd);
     return os && os->hasInputSections;
   };
   auto j = std::find_if(llvm::make_reverse_iterator(i),
                         llvm::make_reverse_iterator(b),
                         isOutputSecWithInputSections);
   i = j.base();
 
   // As a special case, if the orphan section is the last section, put
   // it at the very end, past any other commands.
   // This matches bfd's behavior and is convenient when the linker script fully
   // specifies the start of the file, but doesn't care about the end (the non
   // alloc sections for example).
   auto nextSec = std::find_if(i, e, isOutputSecWithInputSections);
   if (nextSec == e)
     return e;
 
   while (i != e && shouldSkip(*i))
     ++i;
   return i;
 }
 
 // Builds section order for handling --symbol-ordering-file.
 static DenseMap<const InputSectionBase *, int> buildSectionOrder() {
   DenseMap<const InputSectionBase *, int> sectionOrder;
   // Use the rarely used option -call-graph-ordering-file to sort sections.
   if (!config->callGraphProfile.empty())
     return computeCallGraphProfileOrder();
 
   if (config->symbolOrderingFile.empty())
     return sectionOrder;
 
   struct SymbolOrderEntry {
     int priority;
     bool present;
   };
 
   // Build a map from symbols to their priorities. Symbols that didn't
   // appear in the symbol ordering file have the lowest priority 0.
   // All explicitly mentioned symbols have negative (higher) priorities.
   DenseMap<StringRef, SymbolOrderEntry> symbolOrder;
   int priority = -config->symbolOrderingFile.size();
   for (StringRef s : config->symbolOrderingFile)
     symbolOrder.insert({s, {priority++, false}});
 
   // Build a map from sections to their priorities.
   auto addSym = [&](Symbol &sym) {
     auto it = symbolOrder.find(sym.getName());
     if (it == symbolOrder.end())
       return;
     SymbolOrderEntry &ent = it->second;
     ent.present = true;
 
     maybeWarnUnorderableSymbol(&sym);
 
     if (auto *d = dyn_cast<Defined>(&sym)) {
       if (auto *sec = dyn_cast_or_null<InputSectionBase>(d->section)) {
         int &priority = sectionOrder[cast<InputSectionBase>(sec->repl)];
         priority = std::min(priority, ent.priority);
       }
     }
   };
 
   // We want both global and local symbols. We get the global ones from the
   // symbol table and iterate the object files for the local ones.
   symtab->forEachSymbol([&](Symbol *sym) {
     if (!sym->isLazy())
       addSym(*sym);
   });
 
   for (InputFile *file : objectFiles)
     for (Symbol *sym : file->getSymbols())
       if (sym->isLocal())
         addSym(*sym);
 
   if (config->warnSymbolOrdering)
     for (auto orderEntry : symbolOrder)
       if (!orderEntry.second.present)
         warn("symbol ordering file: no such symbol: " + orderEntry.first);
 
   return sectionOrder;
 }
 
 // Sorts the sections in ISD according to the provided section order.
 static void
 sortISDBySectionOrder(InputSectionDescription *isd,
                       const DenseMap<const InputSectionBase *, int> &order) {
   std::vector<InputSection *> unorderedSections;
   std::vector<std::pair<InputSection *, int>> orderedSections;
   uint64_t unorderedSize = 0;
 
   for (InputSection *isec : isd->sections) {
     auto i = order.find(isec);
     if (i == order.end()) {
       unorderedSections.push_back(isec);
       unorderedSize += isec->getSize();
       continue;
     }
     orderedSections.push_back({isec, i->second});
   }
   llvm::sort(orderedSections, [&](std::pair<InputSection *, int> a,
                                   std::pair<InputSection *, int> b) {
     return a.second < b.second;
   });
 
   // Find an insertion point for the ordered section list in the unordered
   // section list. On targets with limited-range branches, this is the mid-point
   // of the unordered section list. This decreases the likelihood that a range
   // extension thunk will be needed to enter or exit the ordered region. If the
   // ordered section list is a list of hot functions, we can generally expect
   // the ordered functions to be called more often than the unordered functions,
   // making it more likely that any particular call will be within range, and
   // therefore reducing the number of thunks required.
   //
   // For example, imagine that you have 8MB of hot code and 32MB of cold code.
   // If the layout is:
   //
   // 8MB hot
   // 32MB cold
   //
   // only the first 8-16MB of the cold code (depending on which hot function it
   // is actually calling) can call the hot code without a range extension thunk.
   // However, if we use this layout:
   //
   // 16MB cold
   // 8MB hot
   // 16MB cold
   //
   // both the last 8-16MB of the first block of cold code and the first 8-16MB
   // of the second block of cold code can call the hot code without a thunk. So
   // we effectively double the amount of code that could potentially call into
   // the hot code without a thunk.
   size_t insPt = 0;
   if (target->getThunkSectionSpacing() && !orderedSections.empty()) {
     uint64_t unorderedPos = 0;
     for (; insPt != unorderedSections.size(); ++insPt) {
       unorderedPos += unorderedSections[insPt]->getSize();
       if (unorderedPos > unorderedSize / 2)
         break;
     }
   }
 
   isd->sections.clear();
   for (InputSection *isec : makeArrayRef(unorderedSections).slice(0, insPt))
     isd->sections.push_back(isec);
   for (std::pair<InputSection *, int> p : orderedSections)
     isd->sections.push_back(p.first);
   for (InputSection *isec : makeArrayRef(unorderedSections).slice(insPt))
     isd->sections.push_back(isec);
 }
 
 static void sortSection(OutputSection *sec,
                         const DenseMap<const InputSectionBase *, int> &order) {
   StringRef name = sec->name;
 
   // Sort input sections by section name suffixes for
   // __attribute__((init_priority(N))).
   if (name == ".init_array" || name == ".fini_array") {
     if (!script->hasSectionsCommand)
       sec->sortInitFini();
     return;
   }
 
   // Sort input sections by the special rule for .ctors and .dtors.
   if (name == ".ctors" || name == ".dtors") {
     if (!script->hasSectionsCommand)
       sec->sortCtorsDtors();
     return;
   }
 
   // Never sort these.
   if (name == ".init" || name == ".fini")
     return;
 
   // .toc is allocated just after .got and is accessed using GOT-relative
   // relocations. Object files compiled with small code model have an
   // addressable range of [.got, .got + 0xFFFC] for GOT-relative relocations.
   // To reduce the risk of relocation overflow, .toc contents are sorted so that
   // sections having smaller relocation offsets are at beginning of .toc
   if (config->emachine == EM_PPC64 && name == ".toc") {
     if (script->hasSectionsCommand)
       return;
     assert(sec->sectionCommands.size() == 1);
     auto *isd = cast<InputSectionDescription>(sec->sectionCommands[0]);
     llvm::stable_sort(isd->sections,
                       [](const InputSection *a, const InputSection *b) -> bool {
                         return a->file->ppc64SmallCodeModelTocRelocs &&
                                !b->file->ppc64SmallCodeModelTocRelocs;
                       });
     return;
   }
 
   // Sort input sections by priority using the list provided
   // by --symbol-ordering-file.
   if (!order.empty())
     for (BaseCommand *b : sec->sectionCommands)
       if (auto *isd = dyn_cast<InputSectionDescription>(b))
         sortISDBySectionOrder(isd, order);
 }
 
 // If no layout was provided by linker script, we want to apply default
 // sorting for special input sections. This also handles --symbol-ordering-file.
 template <class ELFT> void Writer<ELFT>::sortInputSections() {
   // Build the order once since it is expensive.
   DenseMap<const InputSectionBase *, int> order = buildSectionOrder();
   for (BaseCommand *base : script->sectionCommands)
     if (auto *sec = dyn_cast<OutputSection>(base))
       sortSection(sec, order);
 }
 
 template <class ELFT> void Writer<ELFT>::sortSections() {
   script->adjustSectionsBeforeSorting();
 
   // Don't sort if using -r. It is not necessary and we want to preserve the
   // relative order for SHF_LINK_ORDER sections.
   if (config->relocatable)
     return;
 
   sortInputSections();
 
   for (BaseCommand *base : script->sectionCommands) {
     auto *os = dyn_cast<OutputSection>(base);
     if (!os)
       continue;
     os->sortRank = getSectionRank(os);
 
     // We want to assign rude approximation values to outSecOff fields
     // to know the relative order of the input sections. We use it for
     // sorting SHF_LINK_ORDER sections. See resolveShfLinkOrder().
     uint64_t i = 0;
     for (InputSection *sec : getInputSections(os))
       sec->outSecOff = i++;
   }
 
   if (!script->hasSectionsCommand) {
     // We know that all the OutputSections are contiguous in this case.
     auto isSection = [](BaseCommand *base) { return isa<OutputSection>(base); };
     std::stable_sort(
         llvm::find_if(script->sectionCommands, isSection),
         llvm::find_if(llvm::reverse(script->sectionCommands), isSection).base(),
         compareSections);
     return;
   }
 
   // Orphan sections are sections present in the input files which are
   // not explicitly placed into the output file by the linker script.
   //
   // The sections in the linker script are already in the correct
   // order. We have to figuere out where to insert the orphan
   // sections.
   //
   // The order of the sections in the script is arbitrary and may not agree with
   // compareSections. This means that we cannot easily define a strict weak
   // ordering. To see why, consider a comparison of a section in the script and
   // one not in the script. We have a two simple options:
   // * Make them equivalent (a is not less than b, and b is not less than a).
   //   The problem is then that equivalence has to be transitive and we can
   //   have sections a, b and c with only b in a script and a less than c
   //   which breaks this property.
   // * Use compareSectionsNonScript. Given that the script order doesn't have
   //   to match, we can end up with sections a, b, c, d where b and c are in the
   //   script and c is compareSectionsNonScript less than b. In which case d
   //   can be equivalent to c, a to b and d < a. As a concrete example:
   //   .a (rx) # not in script
   //   .b (rx) # in script
   //   .c (ro) # in script
   //   .d (ro) # not in script
   //
   // The way we define an order then is:
   // *  Sort only the orphan sections. They are in the end right now.
   // *  Move each orphan section to its preferred position. We try
   //    to put each section in the last position where it can share
   //    a PT_LOAD.
   //
   // There is some ambiguity as to where exactly a new entry should be
   // inserted, because Commands contains not only output section
   // commands but also other types of commands such as symbol assignment
   // expressions. There's no correct answer here due to the lack of the
   // formal specification of the linker script. We use heuristics to
   // determine whether a new output command should be added before or
   // after another commands. For the details, look at shouldSkip
   // function.
 
   auto i = script->sectionCommands.begin();
   auto e = script->sectionCommands.end();
   auto nonScriptI = std::find_if(i, e, [](BaseCommand *base) {
     if (auto *sec = dyn_cast<OutputSection>(base))
       return sec->sectionIndex == UINT32_MAX;
     return false;
   });
 
   // Sort the orphan sections.
   std::stable_sort(nonScriptI, e, compareSections);
 
   // As a horrible special case, skip the first . assignment if it is before any
   // section. We do this because it is common to set a load address by starting
   // the script with ". = 0xabcd" and the expectation is that every section is
   // after that.
   auto firstSectionOrDotAssignment =
       std::find_if(i, e, [](BaseCommand *cmd) { return !shouldSkip(cmd); });
   if (firstSectionOrDotAssignment != e &&
       isa<SymbolAssignment>(**firstSectionOrDotAssignment))
     ++firstSectionOrDotAssignment;
   i = firstSectionOrDotAssignment;
 
   while (nonScriptI != e) {
     auto pos = findOrphanPos(i, nonScriptI);
     OutputSection *orphan = cast<OutputSection>(*nonScriptI);
 
     // As an optimization, find all sections with the same sort rank
     // and insert them with one rotate.
     unsigned rank = orphan->sortRank;
     auto end = std::find_if(nonScriptI + 1, e, [=](BaseCommand *cmd) {
       return cast<OutputSection>(cmd)->sortRank != rank;
     });
     std::rotate(pos, nonScriptI, end);
     nonScriptI = end;
   }
 
   script->adjustSectionsAfterSorting();
 }
 
 static bool compareByFilePosition(InputSection *a, InputSection *b) {
   InputSection *la = a->getLinkOrderDep();
   InputSection *lb = b->getLinkOrderDep();
   OutputSection *aOut = la->getParent();
   OutputSection *bOut = lb->getParent();
 
   if (aOut != bOut)
     return aOut->sectionIndex < bOut->sectionIndex;
   return la->outSecOff < lb->outSecOff;
 }
 
 template <class ELFT> void Writer<ELFT>::resolveShfLinkOrder() {
   for (OutputSection *sec : outputSections) {
     if (!(sec->flags & SHF_LINK_ORDER))
       continue;
 
     // Link order may be distributed across several InputSectionDescriptions
     // but sort must consider them all at once.
     std::vector<InputSection **> scriptSections;
     std::vector<InputSection *> sections;
     for (BaseCommand *base : sec->sectionCommands) {
       if (auto *isd = dyn_cast<InputSectionDescription>(base)) {
         for (InputSection *&isec : isd->sections) {
           scriptSections.push_back(&isec);
           sections.push_back(isec);
         }
       }
     }
 
     // The ARM.exidx section use SHF_LINK_ORDER, but we have consolidated
     // this processing inside the ARMExidxsyntheticsection::finalizeContents().
     if (!config->relocatable && config->emachine == EM_ARM &&
         sec->type == SHT_ARM_EXIDX)
       continue;
 
     llvm::stable_sort(sections, compareByFilePosition);
 
     for (int i = 0, n = sections.size(); i < n; ++i)
       *scriptSections[i] = sections[i];
   }
 }
 
 // We need to generate and finalize the content that depends on the address of
 // InputSections. As the generation of the content may also alter InputSection
 // addresses we must converge to a fixed point. We do that here. See the comment
 // in Writer<ELFT>::finalizeSections().
 template <class ELFT> void Writer<ELFT>::finalizeAddressDependentContent() {
   ThunkCreator tc;
   AArch64Err843419Patcher a64p;
 
   // For some targets, like x86, this loop iterates only once.
   for (;;) {
     bool changed = false;
 
     script->assignAddresses();
 
     if (target->needsThunks)
       changed |= tc.createThunks(outputSections);
 
     if (config->fixCortexA53Errata843419) {
       if (changed)
         script->assignAddresses();
       changed |= a64p.createFixes();
     }
 
     if (in.mipsGot)
       in.mipsGot->updateAllocSize();
 
     for (Partition &part : partitions) {
       changed |= part.relaDyn->updateAllocSize();
       if (part.relrDyn)
         changed |= part.relrDyn->updateAllocSize();
     }
 
     if (!changed)
       return;
   }
 }
 
 static void finalizeSynthetic(SyntheticSection *sec) {
   if (sec && sec->isNeeded() && sec->getParent())
     sec->finalizeContents();
 }
 
 // In order to allow users to manipulate linker-synthesized sections,
 // we had to add synthetic sections to the input section list early,
 // even before we make decisions whether they are needed. This allows
 // users to write scripts like this: ".mygot : { .got }".
 //
 // Doing it has an unintended side effects. If it turns out that we
 // don't need a .got (for example) at all because there's no
 // relocation that needs a .got, we don't want to emit .got.
 //
 // To deal with the above problem, this function is called after
 // scanRelocations is called to remove synthetic sections that turn
 // out to be empty.
 static void removeUnusedSyntheticSections() {
   // All input synthetic sections that can be empty are placed after
   // all regular ones. We iterate over them all and exit at first
   // non-synthetic.
   for (InputSectionBase *s : llvm::reverse(inputSections)) {
     SyntheticSection *ss = dyn_cast<SyntheticSection>(s);
     if (!ss)
       return;
     OutputSection *os = ss->getParent();
     if (!os || ss->isNeeded())
       continue;
 
     // If we reach here, then SS is an unused synthetic section and we want to
     // remove it from corresponding input section description of output section.
     for (BaseCommand *b : os->sectionCommands)
       if (auto *isd = dyn_cast<InputSectionDescription>(b))
         llvm::erase_if(isd->sections,
                        [=](InputSection *isec) { return isec == ss; });
   }
 }
 
 // Returns true if a symbol can be replaced at load-time by a symbol
 // with the same name defined in other ELF executable or DSO.
 static bool computeIsPreemptible(const Symbol &b) {
   assert(!b.isLocal());
 
   // Only symbols that appear in dynsym can be preempted.
   if (!b.includeInDynsym())
     return false;
 
   // Only default visibility symbols can be preempted.
   if (b.visibility != STV_DEFAULT)
     return false;
 
   // At this point copy relocations have not been created yet, so any
   // symbol that is not defined locally is preemptible.
   if (!b.isDefined())
     return true;
 
   // If we have a dynamic list it specifies which local symbols are preemptible.
   if (config->hasDynamicList)
     return false;
 
   if (!config->shared)
     return false;
 
   // -Bsymbolic means that definitions are not preempted.
   if (config->bsymbolic || (config->bsymbolicFunctions && b.isFunc()))
     return false;
   return true;
 }
 
 // Create output section objects and add them to OutputSections.
 template <class ELFT> void Writer<ELFT>::finalizeSections() {
   Out::preinitArray = findSection(".preinit_array");
   Out::initArray = findSection(".init_array");
   Out::finiArray = findSection(".fini_array");
 
   // The linker needs to define SECNAME_start, SECNAME_end and SECNAME_stop
   // symbols for sections, so that the runtime can get the start and end
   // addresses of each section by section name. Add such symbols.
   if (!config->relocatable) {
     addStartEndSymbols();
     for (BaseCommand *base : script->sectionCommands)
       if (auto *sec = dyn_cast<OutputSection>(base))
         addStartStopSymbols(sec);
   }
 
   // Add _DYNAMIC symbol. Unlike GNU gold, our _DYNAMIC symbol has no type.
   // It should be okay as no one seems to care about the type.
   // Even the author of gold doesn't remember why gold behaves that way.
   // https://sourceware.org/ml/binutils/2002-03/msg00360.html
   if (mainPart->dynamic->parent)
     symtab->addSymbol(Defined{/*file=*/nullptr, "_DYNAMIC", STB_WEAK,
                               STV_HIDDEN, STT_NOTYPE,
                               /*value=*/0, /*size=*/0, mainPart->dynamic});
 
   // Define __rel[a]_iplt_{start,end} symbols if needed.
   addRelIpltSymbols();
 
   // RISC-V's gp can address +/- 2 KiB, set it to .sdata + 0x800 if not defined.
   // This symbol should only be defined in an executable.
   if (config->emachine == EM_RISCV && !config->shared)
     ElfSym::riscvGlobalPointer =
         addOptionalRegular("__global_pointer$", findSection(".sdata"), 0x800,
                            STV_DEFAULT, STB_GLOBAL);
 
   if (config->emachine == EM_X86_64) {
     // On targets that support TLSDESC, _TLS_MODULE_BASE_ is defined in such a
     // way that:
     //
     // 1) Without relaxation: it produces a dynamic TLSDESC relocation that
     // computes 0.
     // 2) With LD->LE relaxation: _TLS_MODULE_BASE_@tpoff = 0 (lowest address in
     // the TLS block).
     //
     // 2) is special cased in @tpoff computation. To satisfy 1), we define it as
     // an absolute symbol of zero. This is different from GNU linkers which
     // define _TLS_MODULE_BASE_ relative to the first TLS section.
     Symbol *s = symtab->find("_TLS_MODULE_BASE_");
     if (s && s->isUndefined()) {
       s->resolve(Defined{/*file=*/nullptr, s->getName(), STB_GLOBAL, STV_HIDDEN,
                          STT_TLS, /*value=*/0, 0,
                          /*section=*/nullptr});
       ElfSym::tlsModuleBase = cast<Defined>(s);
     }
   }
 
   // This responsible for splitting up .eh_frame section into
   // pieces. The relocation scan uses those pieces, so this has to be
   // earlier.
   for (Partition &part : partitions)
     finalizeSynthetic(part.ehFrame);
 
   symtab->forEachSymbol([](Symbol *s) {
     if (!s->isPreemptible)
       s->isPreemptible = computeIsPreemptible(*s);
   });
 
   // Scan relocations. This must be done after every symbol is declared so that
   // we can correctly decide if a dynamic relocation is needed.
   if (!config->relocatable) {
     forEachRelSec(scanRelocations<ELFT>);
     reportUndefinedSymbols<ELFT>();
   }
 
   addIRelativeRelocs();
 
   if (in.plt && in.plt->isNeeded())
     in.plt->addSymbols();
   if (in.iplt && in.iplt->isNeeded())
     in.iplt->addSymbols();
 
   if (!config->allowShlibUndefined) {
     // Error on undefined symbols in a shared object, if all of its DT_NEEDED
     // entires are seen. These cases would otherwise lead to runtime errors
     // reported by the dynamic linker.
     //
     // ld.bfd traces all DT_NEEDED to emulate the logic of the dynamic linker to
     // catch more cases. That is too much for us. Our approach resembles the one
     // used in ld.gold, achieves a good balance to be useful but not too smart.
     for (SharedFile *file : sharedFiles)
       file->allNeededIsKnown =
           llvm::all_of(file->dtNeeded, [&](StringRef needed) {
             return symtab->soNames.count(needed);
           });
 
     symtab->forEachSymbol([](Symbol *sym) {
       if (sym->isUndefined() && !sym->isWeak())
         if (auto *f = dyn_cast_or_null<SharedFile>(sym->file))
           if (f->allNeededIsKnown)
             error(toString(f) + ": undefined reference to " + toString(*sym));
     });
   }
 
   // Now that we have defined all possible global symbols including linker-
   // synthesized ones. Visit all symbols to give the finishing touches.
   symtab->forEachSymbol([](Symbol *sym) {
     if (!includeInSymtab(*sym))
       return;
     if (in.symTab)
       in.symTab->addSymbol(sym);
 
     if (sym->includeInDynsym()) {
       partitions[sym->partition - 1].dynSymTab->addSymbol(sym);
       if (auto *file = dyn_cast_or_null<SharedFile>(sym->file))
         if (file->isNeeded && !sym->isUndefined())
           addVerneed(sym);
     }
   });
 
   // We also need to scan the dynamic relocation tables of the other partitions
   // and add any referenced symbols to the partition's dynsym.
   for (Partition &part : MutableArrayRef<Partition>(partitions).slice(1)) {
     DenseSet<Symbol *> syms;
     for (const SymbolTableEntry &e : part.dynSymTab->getSymbols())
       syms.insert(e.sym);
     for (DynamicReloc &reloc : part.relaDyn->relocs)
       if (reloc.sym && !reloc.useSymVA && syms.insert(reloc.sym).second)
         part.dynSymTab->addSymbol(reloc.sym);
   }
 
   // Do not proceed if there was an undefined symbol.
   if (errorCount())
     return;
 
   if (in.mipsGot)
     in.mipsGot->build();
 
   removeUnusedSyntheticSections();
 
   sortSections();
 
   // Now that we have the final list, create a list of all the
   // OutputSections for convenience.
   for (BaseCommand *base : script->sectionCommands)
     if (auto *sec = dyn_cast<OutputSection>(base))
       outputSections.push_back(sec);
 
   // Prefer command line supplied address over other constraints.
   for (OutputSection *sec : outputSections) {
     auto i = config->sectionStartMap.find(sec->name);
     if (i != config->sectionStartMap.end())
       sec->addrExpr = [=] { return i->second; };
   }
 
   // This is a bit of a hack. A value of 0 means undef, so we set it
   // to 1 to make __ehdr_start defined. The section number is not
   // particularly relevant.
   Out::elfHeader->sectionIndex = 1;
 
   for (size_t i = 0, e = outputSections.size(); i != e; ++i) {
     OutputSection *sec = outputSections[i];
     sec->sectionIndex = i + 1;
     sec->shName = in.shStrTab->addString(sec->name);
   }
 
   // Binary and relocatable output does not have PHDRS.
   // The headers have to be created before finalize as that can influence the
   // image base and the dynamic section on mips includes the image base.
   if (!config->relocatable && !config->oFormatBinary) {
     for (Partition &part : partitions) {
       part.phdrs = script->hasPhdrsCommands() ? script->createPhdrs()
                                               : createPhdrs(part);
       if (config->emachine == EM_ARM) {
         // PT_ARM_EXIDX is the ARM EHABI equivalent of PT_GNU_EH_FRAME
         addPhdrForSection(part, SHT_ARM_EXIDX, PT_ARM_EXIDX, PF_R);
       }
       if (config->emachine == EM_MIPS) {
         // Add separate segments for MIPS-specific sections.
         addPhdrForSection(part, SHT_MIPS_REGINFO, PT_MIPS_REGINFO, PF_R);
         addPhdrForSection(part, SHT_MIPS_OPTIONS, PT_MIPS_OPTIONS, PF_R);
         addPhdrForSection(part, SHT_MIPS_ABIFLAGS, PT_MIPS_ABIFLAGS, PF_R);
       }
     }
     Out::programHeaders->size = sizeof(Elf_Phdr) * mainPart->phdrs.size();
 
     // Find the TLS segment. This happens before the section layout loop so that
     // Android relocation packing can look up TLS symbol addresses. We only need
     // to care about the main partition here because all TLS symbols were moved
     // to the main partition (see MarkLive.cpp).
     for (PhdrEntry *p : mainPart->phdrs)
       if (p->p_type == PT_TLS)
         Out::tlsPhdr = p;
   }
 
   // Some symbols are defined in term of program headers. Now that we
   // have the headers, we can find out which sections they point to.
   setReservedSymbolSections();
 
   finalizeSynthetic(in.bss);
   finalizeSynthetic(in.bssRelRo);
   finalizeSynthetic(in.symTabShndx);
   finalizeSynthetic(in.shStrTab);
   finalizeSynthetic(in.strTab);
   finalizeSynthetic(in.got);
   finalizeSynthetic(in.mipsGot);
   finalizeSynthetic(in.igotPlt);
   finalizeSynthetic(in.gotPlt);
   finalizeSynthetic(in.relaIplt);
   finalizeSynthetic(in.relaPlt);
   finalizeSynthetic(in.plt);
   finalizeSynthetic(in.iplt);
   finalizeSynthetic(in.ppc32Got2);
   finalizeSynthetic(in.riscvSdata);
   finalizeSynthetic(in.partIndex);
 
   // Dynamic section must be the last one in this list and dynamic
   // symbol table section (dynSymTab) must be the first one.
   for (Partition &part : partitions) {
     finalizeSynthetic(part.armExidx);
     finalizeSynthetic(part.dynSymTab);
     finalizeSynthetic(part.gnuHashTab);
     finalizeSynthetic(part.hashTab);
     finalizeSynthetic(part.verDef);
     finalizeSynthetic(part.relaDyn);
     finalizeSynthetic(part.relrDyn);
     finalizeSynthetic(part.ehFrameHdr);
     finalizeSynthetic(part.verSym);
     finalizeSynthetic(part.verNeed);
     finalizeSynthetic(part.dynamic);
   }
 
   if (!script->hasSectionsCommand && !config->relocatable)
     fixSectionAlignments();
 
   // SHFLinkOrder processing must be processed after relative section placements are
   // known but before addresses are allocated.
   resolveShfLinkOrder();
 
   // This is used to:
   // 1) Create "thunks":
   //    Jump instructions in many ISAs have small displacements, and therefore
   //    they cannot jump to arbitrary addresses in memory. For example, RISC-V
   //    JAL instruction can target only +-1 MiB from PC. It is a linker's
   //    responsibility to create and insert small pieces of code between
   //    sections to extend the ranges if jump targets are out of range. Such
   //    code pieces are called "thunks".
   //
   //    We add thunks at this stage. We couldn't do this before this point
   //    because this is the earliest point where we know sizes of sections and
   //    their layouts (that are needed to determine if jump targets are in
   //    range).
   //
   // 2) Update the sections. We need to generate content that depends on the
   //    address of InputSections. For example, MIPS GOT section content or
   //    android packed relocations sections content.
   //
   // 3) Assign the final values for the linker script symbols. Linker scripts
   //    sometimes using forward symbol declarations. We want to set the correct
   //    values. They also might change after adding the thunks.
   finalizeAddressDependentContent();
 
   // finalizeAddressDependentContent may have added local symbols to the static symbol table.
   finalizeSynthetic(in.symTab);
   finalizeSynthetic(in.ppc64LongBranchTarget);
 
   // Fill other section headers. The dynamic table is finalized
   // at the end because some tags like RELSZ depend on result
   // of finalizing other sections.
   for (OutputSection *sec : outputSections)
     sec->finalize();
 }
 
 // Ensure data sections are not mixed with executable sections when
 // -execute-only is used. -execute-only is a feature to make pages executable
 // but not readable, and the feature is currently supported only on AArch64.
 template <class ELFT> void Writer<ELFT>::checkExecuteOnly() {
   if (!config->executeOnly)
     return;
 
   for (OutputSection *os : outputSections)
     if (os->flags & SHF_EXECINSTR)
       for (InputSection *isec : getInputSections(os))
         if (!(isec->flags & SHF_EXECINSTR))
           error("cannot place " + toString(isec) + " into " + toString(os->name) +
                 ": -execute-only does not support intermingling data and code");
 }
 
 // The linker is expected to define SECNAME_start and SECNAME_end
 // symbols for a few sections. This function defines them.
 template <class ELFT> void Writer<ELFT>::addStartEndSymbols() {
   // If a section does not exist, there's ambiguity as to how we
   // define _start and _end symbols for an init/fini section. Since
   // the loader assume that the symbols are always defined, we need to
   // always define them. But what value? The loader iterates over all
   // pointers between _start and _end to run global ctors/dtors, so if
   // the section is empty, their symbol values don't actually matter
   // as long as _start and _end point to the same location.
   //
   // That said, we don't want to set the symbols to 0 (which is
   // probably the simplest value) because that could cause some
   // program to fail to link due to relocation overflow, if their
   // program text is above 2 GiB. We use the address of the .text
   // section instead to prevent that failure.
   //
   // In a rare sitaution, .text section may not exist. If that's the
   // case, use the image base address as a last resort.
   OutputSection *Default = findSection(".text");
   if (!Default)
     Default = Out::elfHeader;
 
   auto define = [=](StringRef start, StringRef end, OutputSection *os) {
     if (os) {
       addOptionalRegular(start, os, 0);
       addOptionalRegular(end, os, -1);
     } else {
       addOptionalRegular(start, Default, 0);
       addOptionalRegular(end, Default, 0);
     }
   };
 
   define("__preinit_array_start", "__preinit_array_end", Out::preinitArray);
   define("__init_array_start", "__init_array_end", Out::initArray);
   define("__fini_array_start", "__fini_array_end", Out::finiArray);
 
   if (OutputSection *sec = findSection(".ARM.exidx"))
     define("__exidx_start", "__exidx_end", sec);
 }
 
 // If a section name is valid as a C identifier (which is rare because of
 // the leading '.'), linkers are expected to define __start_<secname> and
 // __stop_<secname> symbols. They are at beginning and end of the section,
 // respectively. This is not requested by the ELF standard, but GNU ld and
 // gold provide the feature, and used by many programs.
 template <class ELFT>
 void Writer<ELFT>::addStartStopSymbols(OutputSection *sec) {
   StringRef s = sec->name;
   if (!isValidCIdentifier(s))
     return;
   addOptionalRegular(saver.save("__start_" + s), sec, 0, STV_PROTECTED);
   addOptionalRegular(saver.save("__stop_" + s), sec, -1, STV_PROTECTED);
 }
 
 static bool needsPtLoad(OutputSection *sec) {
   if (!(sec->flags & SHF_ALLOC) || sec->noload)
     return false;
 
   // Don't allocate VA space for TLS NOBITS sections. The PT_TLS PHDR is
   // responsible for allocating space for them, not the PT_LOAD that
   // contains the TLS initialization image.
   if ((sec->flags & SHF_TLS) && sec->type == SHT_NOBITS)
     return false;
   return true;
 }
 
 // Linker scripts are responsible for aligning addresses. Unfortunately, most
 // linker scripts are designed for creating two PT_LOADs only, one RX and one
 // RW. This means that there is no alignment in the RO to RX transition and we
 // cannot create a PT_LOAD there.
 static uint64_t computeFlags(uint64_t flags) {
   if (config->omagic)
     return PF_R | PF_W | PF_X;
   if (config->executeOnly && (flags & PF_X))
     return flags & ~PF_R;
   if (config->singleRoRx && !(flags & PF_W))
     return flags | PF_X;
   return flags;
 }
 
 // Decide which program headers to create and which sections to include in each
 // one.
 template <class ELFT>
 std::vector<PhdrEntry *> Writer<ELFT>::createPhdrs(Partition &part) {
   std::vector<PhdrEntry *> ret;
   auto addHdr = [&](unsigned type, unsigned flags) -> PhdrEntry * {
     ret.push_back(make<PhdrEntry>(type, flags));
     return ret.back();
   };
 
   unsigned partNo = part.getNumber();
   bool isMain = partNo == 1;
 
   // The first phdr entry is PT_PHDR which describes the program header itself.
   if (isMain)
     addHdr(PT_PHDR, PF_R)->add(Out::programHeaders);
   else
     addHdr(PT_PHDR, PF_R)->add(part.programHeaders->getParent());
 
   // PT_INTERP must be the second entry if exists.
   if (OutputSection *cmd = findSection(".interp", partNo))
     addHdr(PT_INTERP, cmd->getPhdrFlags())->add(cmd);
 
   // Add the first PT_LOAD segment for regular output sections.
   uint64_t flags = computeFlags(PF_R);
   PhdrEntry *load = nullptr;
 
   // Add the headers. We will remove them if they don't fit.
   // In the other partitions the headers are ordinary sections, so they don't
   // need to be added here.
   if (isMain) {
     load = addHdr(PT_LOAD, flags);
     load->add(Out::elfHeader);
     load->add(Out::programHeaders);
   }
 
   // PT_GNU_RELRO includes all sections that should be marked as
   // read-only by dynamic linker after proccessing relocations.
   // Current dynamic loaders only support one PT_GNU_RELRO PHDR, give
   // an error message if more than one PT_GNU_RELRO PHDR is required.
   PhdrEntry *relRo = make<PhdrEntry>(PT_GNU_RELRO, PF_R);
   bool inRelroPhdr = false;
   OutputSection *relroEnd = nullptr;
   for (OutputSection *sec : outputSections) {
     if (sec->partition != partNo || !needsPtLoad(sec))
       continue;
     if (isRelroSection(sec)) {
       inRelroPhdr = true;
       if (!relroEnd)
         relRo->add(sec);
       else
         error("section: " + sec->name + " is not contiguous with other relro" +
               " sections");
     } else if (inRelroPhdr) {
       inRelroPhdr = false;
       relroEnd = sec;
     }
   }
 
   for (OutputSection *sec : outputSections) {
     if (!(sec->flags & SHF_ALLOC))
       break;
     if (!needsPtLoad(sec))
       continue;
 
     // Normally, sections in partitions other than the current partition are
     // ignored. But partition number 255 is a special case: it contains the
     // partition end marker (.part.end). It needs to be added to the main
     // partition so that a segment is created for it in the main partition,
     // which will cause the dynamic loader to reserve space for the other
     // partitions.
     if (sec->partition != partNo) {
       if (isMain && sec->partition == 255)
         addHdr(PT_LOAD, computeFlags(sec->getPhdrFlags()))->add(sec);
       continue;
     }
 
     // Segments are contiguous memory regions that has the same attributes
     // (e.g. executable or writable). There is one phdr for each segment.
     // Therefore, we need to create a new phdr when the next section has
     // different flags or is loaded at a discontiguous address or memory
     // region using AT or AT> linker script command, respectively. At the same
     // time, we don't want to create a separate load segment for the headers,
     // even if the first output section has an AT or AT> attribute.
     uint64_t newFlags = computeFlags(sec->getPhdrFlags());
     if (!load ||
         ((sec->lmaExpr ||
           (sec->lmaRegion && (sec->lmaRegion != load->firstSec->lmaRegion))) &&
          load->lastSec != Out::programHeaders) ||
         sec->memRegion != load->firstSec->memRegion || flags != newFlags ||
         sec == relroEnd) {
       load = addHdr(PT_LOAD, newFlags);
       flags = newFlags;
     }
 
     load->add(sec);
   }
 
   // Add a TLS segment if any.
   PhdrEntry *tlsHdr = make<PhdrEntry>(PT_TLS, PF_R);
   for (OutputSection *sec : outputSections)
     if (sec->partition == partNo && sec->flags & SHF_TLS)
       tlsHdr->add(sec);
   if (tlsHdr->firstSec)
     ret.push_back(tlsHdr);
 
   // Add an entry for .dynamic.
   if (OutputSection *sec = part.dynamic->getParent())
     addHdr(PT_DYNAMIC, sec->getPhdrFlags())->add(sec);
 
   if (relRo->firstSec)
     ret.push_back(relRo);
 
   // PT_GNU_EH_FRAME is a special section pointing on .eh_frame_hdr.
   if (part.ehFrame->isNeeded() && part.ehFrameHdr &&
       part.ehFrame->getParent() && part.ehFrameHdr->getParent())
     addHdr(PT_GNU_EH_FRAME, part.ehFrameHdr->getParent()->getPhdrFlags())
         ->add(part.ehFrameHdr->getParent());
 
   // PT_OPENBSD_RANDOMIZE is an OpenBSD-specific feature. That makes
   // the dynamic linker fill the segment with random data.
   if (OutputSection *cmd = findSection(".openbsd.randomdata", partNo))
     addHdr(PT_OPENBSD_RANDOMIZE, cmd->getPhdrFlags())->add(cmd);
 
   // PT_GNU_STACK is a special section to tell the loader to make the
   // pages for the stack non-executable. If you really want an executable
   // stack, you can pass -z execstack, but that's not recommended for
   // security reasons.
   unsigned perm = PF_R | PF_W;
   if (config->zExecstack)
     perm |= PF_X;
   addHdr(PT_GNU_STACK, perm)->p_memsz = config->zStackSize;
 
   // PT_OPENBSD_WXNEEDED is a OpenBSD-specific header to mark the executable
   // is expected to perform W^X violations, such as calling mprotect(2) or
   // mmap(2) with PROT_WRITE | PROT_EXEC, which is prohibited by default on
   // OpenBSD.
   if (config->zWxneeded)
     addHdr(PT_OPENBSD_WXNEEDED, PF_X);
 
   // Create one PT_NOTE per a group of contiguous SHT_NOTE sections with the
   // same alignment.
   PhdrEntry *note = nullptr;
   for (OutputSection *sec : outputSections) {
     if (sec->partition != partNo)
       continue;
     if (sec->type == SHT_NOTE && (sec->flags & SHF_ALLOC)) {
       if (!note || sec->lmaExpr || note->lastSec->alignment != sec->alignment)
         note = addHdr(PT_NOTE, PF_R);
       note->add(sec);
     } else {
       note = nullptr;
     }
   }
   return ret;
 }
 
 template <class ELFT>
 void Writer<ELFT>::addPhdrForSection(Partition &part, unsigned shType,
                                      unsigned pType, unsigned pFlags) {
   unsigned partNo = part.getNumber();
   auto i = llvm::find_if(outputSections, [=](OutputSection *cmd) {
     return cmd->partition == partNo && cmd->type == shType;
   });
   if (i == outputSections.end())
     return;
 
   PhdrEntry *entry = make<PhdrEntry>(pType, pFlags);
   entry->add(*i);
   part.phdrs.push_back(entry);
 }
 
 // The first section of each PT_LOAD, the first section in PT_GNU_RELRO and the
 // first section after PT_GNU_RELRO have to be page aligned so that the dynamic
 // linker can set the permissions.
 template <class ELFT> void Writer<ELFT>::fixSectionAlignments() {
   auto pageAlign = [](OutputSection *cmd) {
     if (cmd && !cmd->addrExpr)
       cmd->addrExpr = [=] {
         return alignTo(script->getDot(), config->maxPageSize);
       };
   };
 
   for (Partition &part : partitions) {
     for (const PhdrEntry *p : part.phdrs)
       if (p->p_type == PT_LOAD && p->firstSec)
         pageAlign(p->firstSec);
   }
 }
 
 // Compute an in-file position for a given section. The file offset must be the
 // same with its virtual address modulo the page size, so that the loader can
 // load executables without any address adjustment.
 static uint64_t computeFileOffset(OutputSection *os, uint64_t off) {
-  // File offsets are not significant for .bss sections. By convention, we keep
-  // section offsets monotonically increasing rather than setting to zero.
-  if (os->type == SHT_NOBITS)
-    return off;
-
-  // If the section is not in a PT_LOAD, we just have to align it.
-  if (!os->ptLoad)
-    return alignTo(off, os->alignment);
-
   // The first section in a PT_LOAD has to have congruent offset and address
   // module the page size.
-  OutputSection *first = os->ptLoad->firstSec;
-  if (os == first) {
-    uint64_t alignment = std::max<uint64_t>(os->alignment, config->maxPageSize);
+  if (os->ptLoad && os->ptLoad->firstSec == os) {
+    uint64_t alignment =
+        std::max<uint64_t>(os->ptLoad->p_align, config->maxPageSize);
     return alignTo(off, alignment, os->addr);
   }
 
+  // File offsets are not significant for .bss sections other than the first one
+  // in a PT_LOAD. By convention, we keep section offsets monotonically
+  // increasing rather than setting to zero.
+   if (os->type == SHT_NOBITS)
+     return off;
+
+  // If the section is not in a PT_LOAD, we just have to align it.
+  if (!os->ptLoad)
+    return alignTo(off, os->alignment);
+
   // If two sections share the same PT_LOAD the file offset is calculated
   // using this formula: Off2 = Off1 + (VA2 - VA1).
+  OutputSection *first = os->ptLoad->firstSec;
   return first->offset + os->addr - first->addr;
 }
 
 // Set an in-file position to a given section and returns the end position of
 // the section.
 static uint64_t setFileOffset(OutputSection *os, uint64_t off) {
   off = computeFileOffset(os, off);
   os->offset = off;
 
   if (os->type == SHT_NOBITS)
     return off;
   return off + os->size;
 }
 
 template <class ELFT> void Writer<ELFT>::assignFileOffsetsBinary() {
   uint64_t off = 0;
   for (OutputSection *sec : outputSections)
     if (sec->flags & SHF_ALLOC)
       off = setFileOffset(sec, off);
   fileSize = alignTo(off, config->wordsize);
 }
 
 static std::string rangeToString(uint64_t addr, uint64_t len) {
   return "[0x" + utohexstr(addr) + ", 0x" + utohexstr(addr + len - 1) + "]";
 }
 
 // Assign file offsets to output sections.
 template <class ELFT> void Writer<ELFT>::assignFileOffsets() {
   uint64_t off = 0;
   off = setFileOffset(Out::elfHeader, off);
   off = setFileOffset(Out::programHeaders, off);
 
   PhdrEntry *lastRX = nullptr;
   for (Partition &part : partitions)
     for (PhdrEntry *p : part.phdrs)
       if (p->p_type == PT_LOAD && (p->p_flags & PF_X))
         lastRX = p;
 
   for (OutputSection *sec : outputSections) {
     off = setFileOffset(sec, off);
     if (script->hasSectionsCommand)
       continue;
 
     // If this is a last section of the last executable segment and that
     // segment is the last loadable segment, align the offset of the
     // following section to avoid loading non-segments parts of the file.
     if (lastRX && lastRX->lastSec == sec)
       off = alignTo(off, config->commonPageSize);
   }
 
   sectionHeaderOff = alignTo(off, config->wordsize);
   fileSize = sectionHeaderOff + (outputSections.size() + 1) * sizeof(Elf_Shdr);
 
   // Our logic assumes that sections have rising VA within the same segment.
   // With use of linker scripts it is possible to violate this rule and get file
   // offset overlaps or overflows. That should never happen with a valid script
   // which does not move the location counter backwards and usually scripts do
   // not do that. Unfortunately, there are apps in the wild, for example, Linux
   // kernel, which control segment distribution explicitly and move the counter
   // backwards, so we have to allow doing that to support linking them. We
   // perform non-critical checks for overlaps in checkSectionOverlap(), but here
   // we want to prevent file size overflows because it would crash the linker.
   for (OutputSection *sec : outputSections) {
     if (sec->type == SHT_NOBITS)
       continue;
     if ((sec->offset > fileSize) || (sec->offset + sec->size > fileSize))
       error("unable to place section " + sec->name + " at file offset " +
             rangeToString(sec->offset, sec->size) +
             "; check your linker script for overflows");
   }
 }
 
 // Finalize the program headers. We call this function after we assign
 // file offsets and VAs to all sections.
 template <class ELFT> void Writer<ELFT>::setPhdrs(Partition &part) {
   for (PhdrEntry *p : part.phdrs) {
     OutputSection *first = p->firstSec;
     OutputSection *last = p->lastSec;
 
     if (first) {
       p->p_filesz = last->offset - first->offset;
       if (last->type != SHT_NOBITS)
         p->p_filesz += last->size;
 
       p->p_memsz = last->addr + last->size - first->addr;
       p->p_offset = first->offset;
       p->p_vaddr = first->addr;
 
       // File offsets in partitions other than the main partition are relative
       // to the offset of the ELF headers. Perform that adjustment now.
       if (part.elfHeader)
         p->p_offset -= part.elfHeader->getParent()->offset;
 
       if (!p->hasLMA)
         p->p_paddr = first->getLMA();
     }
 
     if (p->p_type == PT_LOAD) {
       p->p_align = std::max<uint64_t>(p->p_align, config->maxPageSize);
     } else if (p->p_type == PT_GNU_RELRO) {
       p->p_align = 1;
       // The glibc dynamic loader rounds the size down, so we need to round up
       // to protect the last page. This is a no-op on FreeBSD which always
       // rounds up.
       p->p_memsz = alignTo(p->p_memsz, config->commonPageSize);
     }
   }
 }
 
 // A helper struct for checkSectionOverlap.
 namespace {
 struct SectionOffset {
   OutputSection *sec;
   uint64_t offset;
 };
 } // namespace
 
 // Check whether sections overlap for a specific address range (file offsets,
 // load and virtual adresses).
 static void checkOverlap(StringRef name, std::vector<SectionOffset> &sections,
                          bool isVirtualAddr) {
   llvm::sort(sections, [=](const SectionOffset &a, const SectionOffset &b) {
     return a.offset < b.offset;
   });
 
   // Finding overlap is easy given a vector is sorted by start position.
   // If an element starts before the end of the previous element, they overlap.
   for (size_t i = 1, end = sections.size(); i < end; ++i) {
     SectionOffset a = sections[i - 1];
     SectionOffset b = sections[i];
     if (b.offset >= a.offset + a.sec->size)
       continue;
 
     // If both sections are in OVERLAY we allow the overlapping of virtual
     // addresses, because it is what OVERLAY was designed for.
     if (isVirtualAddr && a.sec->inOverlay && b.sec->inOverlay)
       continue;
 
     errorOrWarn("section " + a.sec->name + " " + name +
                 " range overlaps with " + b.sec->name + "\n>>> " + a.sec->name +
                 " range is " + rangeToString(a.offset, a.sec->size) + "\n>>> " +
                 b.sec->name + " range is " +
                 rangeToString(b.offset, b.sec->size));
   }
 }
 
 // Check for overlapping sections and address overflows.
 //
 // In this function we check that none of the output sections have overlapping
 // file offsets. For SHF_ALLOC sections we also check that the load address
 // ranges and the virtual address ranges don't overlap
 template <class ELFT> void Writer<ELFT>::checkSections() {
   // First, check that section's VAs fit in available address space for target.
   for (OutputSection *os : outputSections)
     if ((os->addr + os->size < os->addr) ||
         (!ELFT::Is64Bits && os->addr + os->size > UINT32_MAX))
       errorOrWarn("section " + os->name + " at 0x" + utohexstr(os->addr) +
                   " of size 0x" + utohexstr(os->size) +
                   " exceeds available address space");
 
   // Check for overlapping file offsets. In this case we need to skip any
   // section marked as SHT_NOBITS. These sections don't actually occupy space in
   // the file so Sec->Offset + Sec->Size can overlap with others. If --oformat
   // binary is specified only add SHF_ALLOC sections are added to the output
   // file so we skip any non-allocated sections in that case.
   std::vector<SectionOffset> fileOffs;
   for (OutputSection *sec : outputSections)
     if (sec->size > 0 && sec->type != SHT_NOBITS &&
         (!config->oFormatBinary || (sec->flags & SHF_ALLOC)))
       fileOffs.push_back({sec, sec->offset});
   checkOverlap("file", fileOffs, false);
 
   // When linking with -r there is no need to check for overlapping virtual/load
   // addresses since those addresses will only be assigned when the final
   // executable/shared object is created.
   if (config->relocatable)
     return;
 
   // Checking for overlapping virtual and load addresses only needs to take
   // into account SHF_ALLOC sections since others will not be loaded.
   // Furthermore, we also need to skip SHF_TLS sections since these will be
   // mapped to other addresses at runtime and can therefore have overlapping
   // ranges in the file.
   std::vector<SectionOffset> vmas;
   for (OutputSection *sec : outputSections)
     if (sec->size > 0 && (sec->flags & SHF_ALLOC) && !(sec->flags & SHF_TLS))
       vmas.push_back({sec, sec->addr});
   checkOverlap("virtual address", vmas, true);
 
   // Finally, check that the load addresses don't overlap. This will usually be
   // the same as the virtual addresses but can be different when using a linker
   // script with AT().
   std::vector<SectionOffset> lmas;
   for (OutputSection *sec : outputSections)
     if (sec->size > 0 && (sec->flags & SHF_ALLOC) && !(sec->flags & SHF_TLS))
       lmas.push_back({sec, sec->getLMA()});
   checkOverlap("load address", lmas, false);
 }
 
 // The entry point address is chosen in the following ways.
 //
 // 1. the '-e' entry command-line option;
 // 2. the ENTRY(symbol) command in a linker control script;
 // 3. the value of the symbol _start, if present;
 // 4. the number represented by the entry symbol, if it is a number;
 // 5. the address of the first byte of the .text section, if present;
 // 6. the address 0.
 static uint64_t getEntryAddr() {
   // Case 1, 2 or 3
   if (Symbol *b = symtab->find(config->entry))
     return b->getVA();
 
   // Case 4
   uint64_t addr;
   if (to_integer(config->entry, addr))
     return addr;
 
   // Case 5
   if (OutputSection *sec = findSection(".text")) {
     if (config->warnMissingEntry)
       warn("cannot find entry symbol " + config->entry + "; defaulting to 0x" +
            utohexstr(sec->addr));
     return sec->addr;
   }
 
   // Case 6
   if (config->warnMissingEntry)
     warn("cannot find entry symbol " + config->entry +
          "; not setting start address");
   return 0;
 }
 
 static uint16_t getELFType() {
   if (config->isPic)
     return ET_DYN;
   if (config->relocatable)
     return ET_REL;
   return ET_EXEC;
 }
 
 template <class ELFT> void Writer<ELFT>::writeHeader() {
   writeEhdr<ELFT>(Out::bufferStart, *mainPart);
   writePhdrs<ELFT>(Out::bufferStart + sizeof(Elf_Ehdr), *mainPart);
 
   auto *eHdr = reinterpret_cast<Elf_Ehdr *>(Out::bufferStart);
   eHdr->e_type = getELFType();
   eHdr->e_entry = getEntryAddr();
   eHdr->e_shoff = sectionHeaderOff;
 
   // Write the section header table.
   //
   // The ELF header can only store numbers up to SHN_LORESERVE in the e_shnum
   // and e_shstrndx fields. When the value of one of these fields exceeds
   // SHN_LORESERVE ELF requires us to put sentinel values in the ELF header and
   // use fields in the section header at index 0 to store
   // the value. The sentinel values and fields are:
   // e_shnum = 0, SHdrs[0].sh_size = number of sections.
   // e_shstrndx = SHN_XINDEX, SHdrs[0].sh_link = .shstrtab section index.
   auto *sHdrs = reinterpret_cast<Elf_Shdr *>(Out::bufferStart + eHdr->e_shoff);
   size_t num = outputSections.size() + 1;
   if (num >= SHN_LORESERVE)
     sHdrs->sh_size = num;
   else
     eHdr->e_shnum = num;
 
   uint32_t strTabIndex = in.shStrTab->getParent()->sectionIndex;
   if (strTabIndex >= SHN_LORESERVE) {
     sHdrs->sh_link = strTabIndex;
     eHdr->e_shstrndx = SHN_XINDEX;
   } else {
     eHdr->e_shstrndx = strTabIndex;
   }
 
   for (OutputSection *sec : outputSections)
     sec->writeHeaderTo<ELFT>(++sHdrs);
 }
 
 // Open a result file.
 template <class ELFT> void Writer<ELFT>::openFile() {
   uint64_t maxSize = config->is64 ? INT64_MAX : UINT32_MAX;
   if (fileSize != size_t(fileSize) || maxSize < fileSize) {
     error("output file too large: " + Twine(fileSize) + " bytes");
     return;
   }
 
   unlinkAsync(config->outputFile);
   unsigned flags = 0;
   if (!config->relocatable)
     flags = FileOutputBuffer::F_executable;
   Expected<std::unique_ptr<FileOutputBuffer>> bufferOrErr =
       FileOutputBuffer::create(config->outputFile, fileSize, flags);
 
   if (!bufferOrErr) {
     error("failed to open " + config->outputFile + ": " +
           llvm::toString(bufferOrErr.takeError()));
     return;
   }
   buffer = std::move(*bufferOrErr);
   Out::bufferStart = buffer->getBufferStart();
 }
 
 template <class ELFT> void Writer<ELFT>::writeSectionsBinary() {
   for (OutputSection *sec : outputSections)
     if (sec->flags & SHF_ALLOC)
       sec->writeTo<ELFT>(Out::bufferStart + sec->offset);
 }
 
 static void fillTrap(uint8_t *i, uint8_t *end) {
   for (; i + 4 <= end; i += 4)
     memcpy(i, &target->trapInstr, 4);
 }
 
 // Fill the last page of executable segments with trap instructions
 // instead of leaving them as zero. Even though it is not required by any
 // standard, it is in general a good thing to do for security reasons.
 //
 // We'll leave other pages in segments as-is because the rest will be
 // overwritten by output sections.
 template <class ELFT> void Writer<ELFT>::writeTrapInstr() {
   if (script->hasSectionsCommand)
     return;
 
   for (Partition &part : partitions) {
     // Fill the last page.
     for (PhdrEntry *p : part.phdrs)
       if (p->p_type == PT_LOAD && (p->p_flags & PF_X))
         fillTrap(Out::bufferStart + alignDown(p->firstSec->offset + p->p_filesz,
                                               config->commonPageSize),
                  Out::bufferStart + alignTo(p->firstSec->offset + p->p_filesz,
                                             config->commonPageSize));
 
     // Round up the file size of the last segment to the page boundary iff it is
     // an executable segment to ensure that other tools don't accidentally
     // trim the instruction padding (e.g. when stripping the file).
     PhdrEntry *last = nullptr;
     for (PhdrEntry *p : part.phdrs)
       if (p->p_type == PT_LOAD)
         last = p;
 
     if (last && (last->p_flags & PF_X))
       last->p_memsz = last->p_filesz =
           alignTo(last->p_filesz, config->commonPageSize);
   }
 }
 
 // Write section contents to a mmap'ed file.
 template <class ELFT> void Writer<ELFT>::writeSections() {
   // In -r or -emit-relocs mode, write the relocation sections first as in
   // ELf_Rel targets we might find out that we need to modify the relocated
   // section while doing it.
   for (OutputSection *sec : outputSections)
     if (sec->type == SHT_REL || sec->type == SHT_RELA)
       sec->writeTo<ELFT>(Out::bufferStart + sec->offset);
 
   for (OutputSection *sec : outputSections)
     if (sec->type != SHT_REL && sec->type != SHT_RELA)
       sec->writeTo<ELFT>(Out::bufferStart + sec->offset);
 }
 
 // Split one uint8 array into small pieces of uint8 arrays.
 static std::vector<ArrayRef<uint8_t>> split(ArrayRef<uint8_t> arr,
                                             size_t chunkSize) {
   std::vector<ArrayRef<uint8_t>> ret;
   while (arr.size() > chunkSize) {
     ret.push_back(arr.take_front(chunkSize));
     arr = arr.drop_front(chunkSize);
   }
   if (!arr.empty())
     ret.push_back(arr);
   return ret;
 }
 
 // Computes a hash value of Data using a given hash function.
 // In order to utilize multiple cores, we first split data into 1MB
 // chunks, compute a hash for each chunk, and then compute a hash value
 // of the hash values.
 static void
 computeHash(llvm::MutableArrayRef<uint8_t> hashBuf,
             llvm::ArrayRef<uint8_t> data,
             std::function<void(uint8_t *dest, ArrayRef<uint8_t> arr)> hashFn) {
   std::vector<ArrayRef<uint8_t>> chunks = split(data, 1024 * 1024);
   std::vector<uint8_t> hashes(chunks.size() * hashBuf.size());
 
   // Compute hash values.
   parallelForEachN(0, chunks.size(), [&](size_t i) {
     hashFn(hashes.data() + i * hashBuf.size(), chunks[i]);
   });
 
   // Write to the final output buffer.
   hashFn(hashBuf.data(), hashes);
 }
 
 template <class ELFT> void Writer<ELFT>::writeBuildId() {
   if (!mainPart->buildId || !mainPart->buildId->getParent())
     return;
 
   if (config->buildId == BuildIdKind::Hexstring) {
     for (Partition &part : partitions)
       part.buildId->writeBuildId(config->buildIdVector);
     return;
   }
 
   // Compute a hash of all sections of the output file.
   size_t hashSize = mainPart->buildId->hashSize;
   std::vector<uint8_t> buildId(hashSize);
   llvm::ArrayRef<uint8_t> buf{Out::bufferStart, size_t(fileSize)};
 
   switch (config->buildId) {
   case BuildIdKind::Fast:
     computeHash(buildId, buf, [](uint8_t *dest, ArrayRef<uint8_t> arr) {
       write64le(dest, xxHash64(arr));
     });
     break;
   case BuildIdKind::Md5:
     computeHash(buildId, buf, [&](uint8_t *dest, ArrayRef<uint8_t> arr) {
       memcpy(dest, MD5::hash(arr).data(), hashSize);
     });
     break;
   case BuildIdKind::Sha1:
     computeHash(buildId, buf, [&](uint8_t *dest, ArrayRef<uint8_t> arr) {
       memcpy(dest, SHA1::hash(arr).data(), hashSize);
     });
     break;
   case BuildIdKind::Uuid:
     if (auto ec = llvm::getRandomBytes(buildId.data(), hashSize))
       error("entropy source failure: " + ec.message());
     break;
   default:
     llvm_unreachable("unknown BuildIdKind");
   }
   for (Partition &part : partitions)
     part.buildId->writeBuildId(buildId);
 }
 
 template void elf::writeResult<ELF32LE>();
 template void elf::writeResult<ELF32BE>();
 template void elf::writeResult<ELF64LE>();
 template void elf::writeResult<ELF64BE>();
Index: vendor/lld/dist-release_90/docs/ReleaseNotes.rst
===================================================================
--- vendor/lld/dist-release_90/docs/ReleaseNotes.rst	(revision 351986)
+++ vendor/lld/dist-release_90/docs/ReleaseNotes.rst	(revision 351987)
@@ -1,88 +1,231 @@
 =======================
 lld 9.0.0 Release Notes
 =======================
 
 .. contents::
     :local:
 
 Introduction
 ============
 
-This document contains the release notes for the lld linker, release 9.0.0.
-Here we describe the status of lld, including major improvements
-from the previous release. All lld releases may be downloaded
-from the `LLVM releases web site <https://llvm.org/releases/>`_.
+lld is a high-performance linker that supports ELF (Unix), COFF
+(Windows), Mach-O (macOS), MinGW and WebAssembly. lld is
+command-line-compatible with GNU linkers and Microsoft link.exe and is
+significantly faster than the system default linkers.
 
+lld 9 has lots of feature improvements and bug fixes.
+
 Non-comprehensive list of changes in this release
 =================================================
 
 ELF Improvements
 ----------------
 
 * ld.lld now has typo suggestions for flags:
   ``$ ld.lld --call-shared`` now prints
   ``unknown argument '--call-shared', did you mean '--call_shared'``.
+  (`r361518 <https://reviews.llvm.org/rL361518>`_)
 
+* ``--allow-shlib-undefined`` and ``--no-allow-shlib-undefined``
+  options are added. ``--no-allow-shlib-undefined`` is the default for
+  executables.
+  (`r352826 <https://reviews.llvm.org/rL352826>`_)
+
+* ``-nmagic`` and ``-omagic`` options are fully supported.
+  (`r360593 <https://reviews.llvm.org/rL360593>`_)
+
+* Segment layout has changed. PT_GNU_RELRO, which was previously
+  placed in the middle of readable/writable PT_LOAD segments, is now
+  placed at the beginning of them. This change permits lld-produced
+  ELF files to be read correctly by GNU strip older than 2.31, which
+  has a bug to discard a PT_GNU_RELRO in the former layout.
+
+* ``-z common-page-size`` is supported.
+  (`r360593 <https://reviews.llvm.org/rL360593>`_)
+
+* Diagnostics messages have improved. A new flag ``--vs-diagnostics``
+  alters the format of diagnostic output to enable source hyperlinks
+  in Microsoft Visual Studio IDE.
+
+* Linker script compatibility with GNU BFD linker has generally improved.
+
+* The clang ``--dependent-library`` form of autolinking is supported.
+
+  This feature is added to implement the Windows-style autolinking for
+  Unix. On Unix, in order to use a library, you usually have to
+  include a header file provided by the library and then explicitly
+  link the library with the linker ``-l`` option. On Windows, header
+  files usually contain pragmas that list needed libraries. Compilers
+  copy that information to object files, so that linkers can
+  automatically link needed libraries. ``--dependent-library`` is
+  added for implementing that Windows semantics on Unix.
+  (`r360984 <https://reviews.llvm.org/rL360984>`_)
+
+* AArch64 BTI and PAC are supported.
+  (`r362793 <https://reviews.llvm.org/rL362793>`_)
+
 * lld now supports replacing ``JAL`` with ``JALX`` instructions in case
-  of MIPS - microMIPS cross-mode jumps.
+  of MIPS-microMIPS cross-mode jumps.
+  (`r354311 <https://reviews.llvm.org/rL354311>`_)
 
 * lld now creates LA25 thunks for MIPS R6 code.
+  (`r354312 <https://reviews.llvm.org/rL354312>`_)
 
 * Put MIPS-specific .reginfo, .MIPS.options, and .MIPS.abiflags sections
   into corresponding PT_MIPS_REGINFO, PT_MIPS_OPTIONS, and PT_MIPS_ABIFLAGS
   segments.
 
+* The quality of RISC-V and PowerPC ports have greatly improved. Many
+  applications can now be linked by lld. PowerPC64 is now almost
+  production ready.
+
+* The Linux kernel for arm32_7, arm64, ppc64le and x86_64 can now be
+  linked by lld.
+
+* x86-64 TLSDESC is supported.
+  (`r361911 <https://reviews.llvm.org/rL361911>`_,
+  `r362078 <https://reviews.llvm.org/rL362078>`_)
+
+* DF_STATIC_TLS flag is set for i386 and x86-64 when needed.
+  (`r353293 <https://reviews.llvm.org/rL353293>`_,
+  `r353378 <https://reviews.llvm.org/rL353378>`_)
+
+* The experimental partitioning feature is added to allow a program to
+  be split into multiple pieces.
+
+  The feature allows you to semi-automatically split a single program
+  into multiple ELF files called "partitions". Since all partitions
+  share the same memory address space and don't use PLT/GOT, split
+  programs run as fast as regular programs.
+
+  With the mechanism, you can start a program only with a "main"
+  partition and load remaining partitions on-demand. For example, you
+  can split a web browser into a main partition and a PDF reader
+  sub-partition and load the PDF reader partition only when a user
+  tries to open a PDF file.
+
+  See `the documentation <Partitions.html>`_ for more information.
+
+* If "-" is given as an output filename, lld writes the final result
+  to the standard output. Previously, it created a file "-" in the
+  current directory.
+  (`r351852 <https://reviews.llvm.org/rL351852>`_)
+
+* ``-z ifunc-noplt`` option is added to reduce IFunc function call
+  overhead in a freestanding environment such as the OS kernel.
+
+  Functions resolved by the IFunc mechanism are usually dispatched via
+  PLT and thus slower than regular functions because of the cost of
+  indirection. With ``-z ifunc-noplt``, you can eliminate it by doing
+  text relocations at load-time. You need a special loader to utilize
+  this feature. This feature is added for the FreeBSD kernel but can
+  be used by any operating systems.
+  (`r360685 <https://reviews.llvm.org/rL360685>`_)
+
+* ``--undefined-glob`` option is added. The new option is an extension
+  to ``--undefined`` to take a glob pattern instead of a single symbol
+  name.
+  (`r363396 <https://reviews.llvm.org/rL363396>`_)
+
+
 COFF Improvements
 -----------------
 
 * Like the ELF driver, lld-link now has typo suggestions for flags.
+  (`r361518 <https://reviews.llvm.org/rL361518>`_)
 
-* lld-link now correctly reports duplicate symbol errors for obj files
-  that were compiled with /Gy.
+* lld-link now correctly reports duplicate symbol errors for object
+  files that were compiled with ``/Gy``.
+  (`r352590 <https://reviews.llvm.org/rL352590>`_)
 
-* lld-link now correctly reports duplicate symbol errors when several res
-  input files define resources with the same type, name, and language.
-  This can be demoted to a warning using ``/force:multipleres``.
+* lld-link now correctly reports duplicate symbol errors when several
+  resource (.res) input files define resources with the same type,
+  name and language.  This can be demoted to a warning using
+  ``/force:multipleres``.
+  (`r359829 <https://reviews.llvm.org/rL359829>`_)
 
-* lld-link now rejects more than one resource obj input files, matching
-  link.exe. Previously, lld-link would silently ignore all but one.
-  If you hit this: Don't pass resource obj files to the linker, instead pass
-  res files to the linker directly. Don't put res files in static libraries,
-  pass them on the command line.
+* lld-link now rejects more than one resource object input files,
+  matching link.exe. Previously, lld-link would silently ignore all
+  but one.  If you hit this: Don't pass resource object files to the
+  linker, instead pass res files to the linker directly. Don't put
+  resource files in static libraries, pass them on the command line.
+  (`r359749 <https://reviews.llvm.org/rL359749>`_)
 
 * Having more than two ``/natvis:`` now works correctly; it used to not
   work for larger binaries before.
+  (`r327895 <https://reviews.llvm.org/rL327895>`_)
 
 * Undefined symbols are now printed only in demangled form. Pass
   ``/demangle:no`` to see raw symbol names instead.
+  (`r355878 <https://reviews.llvm.org/rL355878>`_)
 
-* The following flags have been added: ``/functionpadmin``, ``/swaprun:``,
-  ``/threads:no``
-
 * Several speed and memory usage improvements.
 
-* Range extension thunks are now created for ARM64, if needed
-
 * lld-link now supports resource object files created by GNU windres and
-  MS cvtres, not only llvm-cvtres
+  MS cvtres, not only llvm-cvtres.
 
 * The generated thunks for delayimports now share the majority of code
-  among thunks, significantly reducing the overhead of using delayimport
+  among thunks, significantly reducing the overhead of using delayimport.
+  (`r365823 <https://reviews.llvm.org/rL365823>`_)
 
+* ``IMAGE_REL_ARM{,64}_REL32`` relocations are supported.
+  (`r352325 <https://reviews.llvm.org/rL352325>`_)
+
+* Range extension thunks for AArch64 are now supported, so lld can
+  create large executables for Windows/ARM64.
+  (`r352929 <https://reviews.llvm.org/rL352929>`_)
+
+* The following flags have been added:
+  ``/functionpadmin`` (`r354716 <https://reviews.llvm.org/rL354716>`_),
+  ``/swaprun:`` (`r359192 <https://reviews.llvm.org/rL359192>`_),
+  ``/threads:no`` (`r355029 <https://reviews.llvm.org/rL355029>`_),
+  ``/filealign`` (`r361634 <https://reviews.llvm.org/rL361634>`_)
+
+WebAssembly Improvements
+------------------------
+
+* Imports from custom module names are supported.
+  (`r352828 <https://reviews.llvm.org/rL352828>`_)
+
+* Symbols that are in llvm.used are now exported by default.
+  (`r353364 <https://reviews.llvm.org/rL353364>`_)
+
+* Initial support for PIC and dynamic linking has landed.
+  (`r357022 <https://reviews.llvm.org/rL357022>`_)
+
+* wasm-ld now add ``__start_``/``__stop_`` symbols for data sections.
+  (`r361236 <https://reviews.llvm.org/rL361236>`_)
+
+* wasm-ld now doesn't report an error on archives without a symbol index.
+  (`r364338 <https://reviews.llvm.org/rL364338>`_)
+
+* The following flags have been added:
+  ``--emit-relocs`` (`r361635 <https://reviews.llvm.org/rL361635>`_),
+  ``--wrap`` (`r361639 <https://reviews.llvm.org/rL361639>`_),
+  ``--trace`` and ``--trace-symbol``
+  (`r353264 <https://reviews.llvm.org/rL353264>`_).
+
+
 MinGW Improvements
 ------------------
 
 * lld now correctly links crtend.o as the last object file, handling
   terminators for the sections such as .eh_frame properly, fixing
   DWARF exception handling with libgcc and gcc's crtend.o.
 
 * lld now also handles DWARF unwind info generated by GCC, when linking
-  with libgcc
+  with libgcc.
 
-* Many more GNU ld options are now supported, which e.g. allows the lld
-  MinGW frontend to be called by GCC
-
 * PDB output can be requested without manually specifying the PDB file
   name, with the new option ``-pdb=`` with an empty value to the option.
   (The old existing syntax ``-pdb <filename>`` was more cumbersome to use
   with an empty parameter value.)
+
+* ``--no-insert-timestamp`` option is added as an alias to ``/timestamp:0``.
+  (`r353145 <https://reviews.llvm.org/rL353145>`_)
+
+* Many more GNU ld options are now supported, which e.g. allows the lld
+  MinGW frontend to be called by GCC.
+
+* The following options are added: ``--exclude-all-symbols``,
+  ``--appcontainer``, ``--undefined``