/build/source/lld/ELF/SyntheticSections.cpp

Bug Summary

File:	build/source/lld/ELF/SyntheticSections.cpp
Warning:	line 2025, column 26 1st function call argument is an uninitialized value

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name SyntheticSections.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mframe-pointer=none -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -ffunction-sections -fdata-sections -fcoverage-compilation-dir=/build/source/build-llvm -resource-dir /usr/lib/llvm-17/lib/clang/17 -I tools/lld/ELF -I /build/source/lld/ELF -I /build/source/lld/include -I tools/lld/include -I include -I /build/source/llvm/include -D LLD_VENDOR="Debian" -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -D _FORTIFY_SOURCE=2 -D NDEBUG -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/x86_64-linux-gnu/c++/10 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/backward -internal-isystem /usr/lib/llvm-17/lib/clang/17/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/10/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fmacro-prefix-map=/build/source/build-llvm=build-llvm -fmacro-prefix-map=/build/source/= -fcoverage-prefix-map=/build/source/build-llvm=build-llvm -fcoverage-prefix-map=/build/source/= -source-date-epoch 1675721604 -O3 -Wno-unused-command-line-argument -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-class-memaccess -Wno-redundant-move -Wno-pessimizing-move -Wno-noexcept-type -Wno-comment -Wno-misleading-indentation -std=c++17 -fdeprecated-macro -fdebug-compilation-dir=/build/source/build-llvm -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -fdebug-prefix-map=/build/source/build-llvm=build-llvm -fdebug-prefix-map=/build/source/= -ferror-limit 19 -fvisibility-inlines-hidden -stack-protector 2 -fgnuc-version=4.2.1 -fcolor-diagnostics -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2023-02-07-030702-17298-1 -x c++ /build/source/lld/ELF/SyntheticSections.cpp

/build/source/lld/ELF/SyntheticSections.cpp

→

1//===- SyntheticSections.cpp ----------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file contains linker-synthesized sections. Currently,
10// synthetic sections are created either output sections or input sections,
11// but we are rewriting code so that all synthetic sections are created as
12// input sections.
13//
14//===----------------------------------------------------------------------===//

16#include "SyntheticSections.h"
17#include "Config.h"
18#include "DWARF.h"
19#include "EhFrame.h"
20#include "InputFiles.h"
21#include "LinkerScript.h"
22#include "OutputSections.h"
23#include "SymbolTable.h"
24#include "Symbols.h"
25#include "Target.h"
26#include "Thunks.h"
27#include "Writer.h"
28#include "lld/Common/CommonLinkerContext.h"
29#include "lld/Common/DWARF.h"
30#include "lld/Common/Strings.h"
31#include "lld/Common/Version.h"
32#include "llvm/ADT/STLExtras.h"
33#include "llvm/ADT/SetOperations.h"
34#include "llvm/ADT/StringExtras.h"
35#include "llvm/BinaryFormat/Dwarf.h"
36#include "llvm/BinaryFormat/ELF.h"
37#include "llvm/DebugInfo/DWARF/DWARFDebugPubTable.h"
38#include "llvm/Support/Endian.h"
39#include "llvm/Support/LEB128.h"
40#include "llvm/Support/Parallel.h"
41#include "llvm/Support/TimeProfiler.h"
42#include <cstdlib>

44using namespace llvm;
45using namespace llvm::dwarf;
46using namespace llvm::ELF;
47using namespace llvm::object;
48using namespace llvm::support;
49using namespace lld;
50using namespace lld::elf;

52using llvm::support::endian::read32le;
53using llvm::support::endian::write32le;
54using llvm::support::endian::write64le;

56constexpr size_t MergeNoTailSection::numShards;

58static uint64_t readUint(uint8_t *buf) {
return config->is64 ? read64(buf) : read32(buf);
60}

62static void writeUint(uint8_t *buf, uint64_t val) {
if (config->is64)
  write64(buf, val);
else
  write32(buf, val);
67}

69// Returns an LLD version string.
70static ArrayRef<uint8_t> getVersion() {
// Check LLD_VERSION first for ease of testing.
// You can get consistent output by using the environment variable.
// This is only for testing.
StringRef s = getenv("LLD_VERSION");
if (s.empty())
  s = saver().save(Twine("Linker: ") + getLLDVersion());

// +1 to include the terminating '\0'.
return {(const uint8_t *)s.data(), s.size() + 1};
80}

82// Creates a .comment section containing LLD version info.
83// With this feature, you can identify LLD-generated binaries easily
84// by "readelf --string-dump .comment <file>".
85// The returned object is a mergeable string section.
86MergeInputSection *elf::createCommentSection() {
auto *sec = make<MergeInputSection>(SHF_MERGE | SHF_STRINGS, SHT_PROGBITS, 1,
                                    getVersion(), ".comment");
sec->splitIntoPieces();
return sec;
91}

93// .MIPS.abiflags section.
94template <class ELFT>
95MipsAbiFlagsSection<ELFT>::MipsAbiFlagsSection(Elf_Mips_ABIFlags flags)
  : SyntheticSection(SHF_ALLOC, SHT_MIPS_ABIFLAGS, 8, ".MIPS.abiflags"),
    flags(flags) {
this->entsize = sizeof(Elf_Mips_ABIFlags);
99}

101template <class ELFT> void MipsAbiFlagsSection<ELFT>::writeTo(uint8_t *buf) {
memcpy(buf, &flags, sizeof(flags));
103}

105template <class ELFT>
106std::unique_ptr<MipsAbiFlagsSection<ELFT>> MipsAbiFlagsSection<ELFT>::create() {
Elf_Mips_ABIFlags flags = {};
bool create = false;

for (InputSectionBase *sec : ctx.inputSections) {
  if (sec->type != SHT_MIPS_ABIFLAGS)
    continue;
  sec->markDead();
  create = true;

  std::string filename = toString(sec->file);
  const size_t size = sec->content().size();
  // Older version of BFD (such as the default FreeBSD linker) concatenate
  // .MIPS.abiflags instead of merging. To allow for this case (or potential
  // zero padding) we ignore everything after the first Elf_Mips_ABIFlags
  if (size < sizeof(Elf_Mips_ABIFlags)) {
    error(filename + ": invalid size of .MIPS.abiflags section: got " +
          Twine(size) + " instead of " + Twine(sizeof(Elf_Mips_ABIFlags)));
    return nullptr;
  }
  auto *s =
      reinterpret_cast<const Elf_Mips_ABIFlags *>(sec->content().data());
  if (s->version != 0) {
    error(filename + ": unexpected .MIPS.abiflags version " +
          Twine(s->version));
    return nullptr;
  }

  // LLD checks ISA compatibility in calcMipsEFlags(). Here we just
  // select the highest number of ISA/Rev/Ext.
  flags.isa_level = std::max(flags.isa_level, s->isa_level);
  flags.isa_rev = std::max(flags.isa_rev, s->isa_rev);
  flags.isa_ext = std::max(flags.isa_ext, s->isa_ext);
  flags.gpr_size = std::max(flags.gpr_size, s->gpr_size);
  flags.cpr1_size = std::max(flags.cpr1_size, s->cpr1_size);
  flags.cpr2_size = std::max(flags.cpr2_size, s->cpr2_size);
  flags.ases |= s->ases;
  flags.flags1 |= s->flags1;
  flags.flags2 |= s->flags2;
  flags.fp_abi = elf::getMipsFpAbiFlag(flags.fp_abi, s->fp_abi, filename);
};

if (create)
  return std::make_unique<MipsAbiFlagsSection<ELFT>>(flags);
return nullptr;
151}

153// .MIPS.options section.
154template <class ELFT>
155MipsOptionsSection<ELFT>::MipsOptionsSection(Elf_Mips_RegInfo reginfo)
  : SyntheticSection(SHF_ALLOC, SHT_MIPS_OPTIONS, 8, ".MIPS.options"),
    reginfo(reginfo) {
this->entsize = sizeof(Elf_Mips_Options) + sizeof(Elf_Mips_RegInfo);
159}

161template <class ELFT> void MipsOptionsSection<ELFT>::writeTo(uint8_t *buf) {
auto *options = reinterpret_cast<Elf_Mips_Options *>(buf);
options->kind = ODK_REGINFO;
options->size = getSize();

if (!config->relocatable)
  reginfo.ri_gp_value = in.mipsGot->getGp();
memcpy(buf + sizeof(Elf_Mips_Options), &reginfo, sizeof(reginfo));
169}

171template <class ELFT>
172std::unique_ptr<MipsOptionsSection<ELFT>> MipsOptionsSection<ELFT>::create() {
// N64 ABI only.
if (!ELFT::Is64Bits)
  return nullptr;

SmallVector<InputSectionBase *, 0> sections;
for (InputSectionBase *sec : ctx.inputSections)
  if (sec->type == SHT_MIPS_OPTIONS)
    sections.push_back(sec);

if (sections.empty())
  return nullptr;

Elf_Mips_RegInfo reginfo = {};
for (InputSectionBase *sec : sections) {
  sec->markDead();

  std::string filename = toString(sec->file);
  ArrayRef<uint8_t> d = sec->content();

  while (!d.empty()) {
    if (d.size() < sizeof(Elf_Mips_Options)) {
      error(filename + ": invalid size of .MIPS.options section");
      break;
    }

    auto *opt = reinterpret_cast<const Elf_Mips_Options *>(d.data());
    if (opt->kind == ODK_REGINFO) {
      reginfo.ri_gprmask |= opt->getRegInfo().ri_gprmask;
      sec->getFile<ELFT>()->mipsGp0 = opt->getRegInfo().ri_gp_value;
      break;
    }

    if (!opt->size)
      fatal(filename + ": zero option descriptor size");
    d = d.slice(opt->size);
  }
};

return std::make_unique<MipsOptionsSection<ELFT>>(reginfo);
212}

214// MIPS .reginfo section.
215template <class ELFT>
216MipsReginfoSection<ELFT>::MipsReginfoSection(Elf_Mips_RegInfo reginfo)
  : SyntheticSection(SHF_ALLOC, SHT_MIPS_REGINFO, 4, ".reginfo"),
    reginfo(reginfo) {
this->entsize = sizeof(Elf_Mips_RegInfo);
220}

222template <class ELFT> void MipsReginfoSection<ELFT>::writeTo(uint8_t *buf) {
if (!config->relocatable)
  reginfo.ri_gp_value = in.mipsGot->getGp();
memcpy(buf, &reginfo, sizeof(reginfo));
226}

228template <class ELFT>
229std::unique_ptr<MipsReginfoSection<ELFT>> MipsReginfoSection<ELFT>::create() {
// Section should be alive for O32 and N32 ABIs only.
if (ELFT::Is64Bits)
  return nullptr;

SmallVector<InputSectionBase *, 0> sections;
for (InputSectionBase *sec : ctx.inputSections)
  if (sec->type == SHT_MIPS_REGINFO)
    sections.push_back(sec);

if (sections.empty())
  return nullptr;

Elf_Mips_RegInfo reginfo = {};
for (InputSectionBase *sec : sections) {
  sec->markDead();

  if (sec->content().size() != sizeof(Elf_Mips_RegInfo)) {
    error(toString(sec->file) + ": invalid size of .reginfo section");
    return nullptr;
  }

  auto *r = reinterpret_cast<const Elf_Mips_RegInfo *>(sec->content().data());
  reginfo.ri_gprmask |= r->ri_gprmask;
  sec->getFile<ELFT>()->mipsGp0 = r->ri_gp_value;
};

return std::make_unique<MipsReginfoSection<ELFT>>(reginfo);
257}

259InputSection *elf::createInterpSection() {
// StringSaver guarantees that the returned string ends with '\0'.
StringRef s = saver().save(config->dynamicLinker);
ArrayRef<uint8_t> contents = {(const uint8_t *)s.data(), s.size() + 1};

return make<InputSection>(nullptr, SHF_ALLOC, SHT_PROGBITS, 1, contents,
                          ".interp");
266}

268Defined *elf::addSyntheticLocal(StringRef name, uint8_t type, uint64_t value,
                              uint64_t size, InputSectionBase &section) {
Defined *s = makeDefined(section.file, name, STB_LOCAL, STV_DEFAULT, type,
                         value, size, &section);
if (in.symTab)
  in.symTab->addSymbol(s);
return s;
275}

277static size_t getHashSize() {
switch (config->buildId) {
case BuildIdKind::Fast:
  return 8;
case BuildIdKind::Md5:
case BuildIdKind::Uuid:
  return 16;
case BuildIdKind::Sha1:
  return 20;
case BuildIdKind::Hexstring:
  return config->buildIdVector.size();
default:
  llvm_unreachable("unknown BuildIdKind")::llvm::llvm_unreachable_internal("unknown BuildIdKind", "lld/ELF/SyntheticSections.cpp"
, 289);
}
291}

293// This class represents a linker-synthesized .note.gnu.property section.
294//
295// In x86 and AArch64, object files may contain feature flags indicating the
296// features that they have used. The flags are stored in a .note.gnu.property
297// section.
298//
299// lld reads the sections from input files and merges them by computing AND of
300// the flags. The result is written as a new .note.gnu.property section.
301//
302// If the flag is zero (which indicates that the intersection of the feature
303// sets is empty, or some input files didn't have .note.gnu.property sections),
304// we don't create this section.
305GnuPropertySection::GnuPropertySection()
  : SyntheticSection(llvm::ELF::SHF_ALLOC, llvm::ELF::SHT_NOTE,
                     config->wordsize, ".note.gnu.property") {}

309void GnuPropertySection::writeTo(uint8_t *buf) {
uint32_t featureAndType = config->emachine == EM_AARCH64
                              ? GNU_PROPERTY_AARCH64_FEATURE_1_AND
                              : GNU_PROPERTY_X86_FEATURE_1_AND;

write32(buf, 4);                                   // Name size
write32(buf + 4, config->is64 ? 16 : 12);          // Content size
write32(buf + 8, NT_GNU_PROPERTY_TYPE_0);          // Type
memcpy(buf + 12, "GNU", 4);                        // Name string
write32(buf + 16, featureAndType);                 // Feature type
write32(buf + 20, 4);                              // Feature size
write32(buf + 24, config->andFeatures);            // Feature flags
if (config->is64)
  write32(buf + 28, 0); // Padding
323}

325size_t GnuPropertySection::getSize() const { return config->is64 ? 32 : 28; }

327BuildIdSection::BuildIdSection()
  : SyntheticSection(SHF_ALLOC, SHT_NOTE, 4, ".note.gnu.build-id"),
    hashSize(getHashSize()) {}

331void BuildIdSection::writeTo(uint8_t *buf) {
write32(buf, 4);                      // Name size
write32(buf + 4, hashSize);           // Content size
write32(buf + 8, NT_GNU_BUILD_ID);    // Type
memcpy(buf + 12, "GNU", 4);           // Name string
hashBuf = buf + 16;
337}

339void BuildIdSection::writeBuildId(ArrayRef<uint8_t> buf) {
assert(buf.size() == hashSize)(static_cast <bool> (buf.size() == hashSize) ? void (0)
 : __assert_fail ("buf.size() == hashSize", "lld/ELF/SyntheticSections.cpp"
, 340, __extension__ __PRETTY_FUNCTION__));
memcpy(hashBuf, buf.data(), hashSize);
342}

344BssSection::BssSection(StringRef name, uint64_t size, uint32_t alignment)
  : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_NOBITS, alignment, name) {
this->bss = true;
this->size = size;
348}

350EhFrameSection::EhFrameSection()
  : SyntheticSection(SHF_ALLOC, SHT_PROGBITS, 1, ".eh_frame") {}

353// Search for an existing CIE record or create a new one.
354// CIE records from input object files are uniquified by their contents
355// and where their relocations point to.
356template <class ELFT, class RelTy>
357CieRecord *EhFrameSection::addCie(EhSectionPiece &cie, ArrayRef<RelTy> rels) {
Symbol *personality = nullptr;
unsigned firstRelI = cie.firstRelocation;
if (firstRelI != (unsigned)-1)
  personality =
      &cie.sec->template getFile<ELFT>()->getRelocTargetSym(rels[firstRelI]);

// Search for an existing CIE by CIE contents/relocation target pair.
CieRecord *&rec = cieMap[{cie.data(), personality}];

// If not found, create a new one.
if (!rec) {
  rec = make<CieRecord>();
  rec->cie = &cie;
  cieRecords.push_back(rec);
}
return rec;
374}

376// There is one FDE per function. Returns a non-null pointer to the function
377// symbol if the given FDE points to a live function.
378template <class ELFT, class RelTy>
379Defined *EhFrameSection::isFdeLive(EhSectionPiece &fde, ArrayRef<RelTy> rels) {
auto *sec = cast<EhInputSection>(fde.sec);
unsigned firstRelI = fde.firstRelocation;

// An FDE should point to some function because FDEs are to describe
// functions. That's however not always the case due to an issue of
// ld.gold with -r. ld.gold may discard only functions and leave their
// corresponding FDEs, which results in creating bad .eh_frame sections.
// To deal with that, we ignore such FDEs.
if (firstRelI == (unsigned)-1)
  return nullptr;

const RelTy &rel = rels[firstRelI];
Symbol &b = sec->template getFile<ELFT>()->getRelocTargetSym(rel);

// FDEs for garbage-collected or merged-by-ICF sections, or sections in
// another partition, are dead.
if (auto *d = dyn_cast<Defined>(&b))
  if (!d->folded && d->section && d->section->partition == partition)
    return d;
return nullptr;
400}

402// .eh_frame is a sequence of CIE or FDE records. In general, there
403// is one CIE record per input object file which is followed by
404// a list of FDEs. This function searches an existing CIE or create a new
405// one and associates FDEs to the CIE.
406template <class ELFT, class RelTy>
407void EhFrameSection::addRecords(EhInputSection *sec, ArrayRef<RelTy> rels) {
offsetToCie.clear();
for (EhSectionPiece &cie : sec->cies)
  offsetToCie[cie.inputOff] = addCie<ELFT>(cie, rels);
for (EhSectionPiece &fde : sec->fdes) {
  uint32_t id = endian::read32<ELFT::TargetEndianness>(fde.data().data() + 4);
  CieRecord *rec = offsetToCie[fde.inputOff + 4 - id];
  if (!rec)
    fatal(toString(sec) + ": invalid CIE reference");

  if (!isFdeLive<ELFT>(fde, rels))
    continue;
  rec->fdes.push_back(&fde);
  numFdes++;
}
422}

424template <class ELFT>
425void EhFrameSection::addSectionAux(EhInputSection *sec) {
if (!sec->isLive())
  return;
const RelsOrRelas<ELFT> rels = sec->template relsOrRelas<ELFT>();
if (rels.areRelocsRel())
  addRecords<ELFT>(sec, rels.rels);
else
  addRecords<ELFT>(sec, rels.relas);
433}

435// Used by ICF<ELFT>::handleLSDA(). This function is very similar to
436// EhFrameSection::addRecords().
437template <class ELFT, class RelTy>
438void EhFrameSection::iterateFDEWithLSDAAux(
  EhInputSection &sec, ArrayRef<RelTy> rels, DenseSet<size_t> &ciesWithLSDA,
  llvm::function_ref<void(InputSection &)> fn) {
for (EhSectionPiece &cie : sec.cies)
  if (hasLSDA(cie))
    ciesWithLSDA.insert(cie.inputOff);
for (EhSectionPiece &fde : sec.fdes) {
  uint32_t id = endian::read32<ELFT::TargetEndianness>(fde.data().data() + 4);
  if (!ciesWithLSDA.contains(fde.inputOff + 4 - id))
    continue;

  // The CIE has a LSDA argument. Call fn with d's section.
  if (Defined *d = isFdeLive<ELFT>(fde, rels))
    if (auto *s = dyn_cast_or_null<InputSection>(d->section))
      fn(*s);
}
454}

456template <class ELFT>
457void EhFrameSection::iterateFDEWithLSDA(
  llvm::function_ref<void(InputSection &)> fn) {
DenseSet<size_t> ciesWithLSDA;
for (EhInputSection *sec : sections) {
  ciesWithLSDA.clear();
  const RelsOrRelas<ELFT> rels = sec->template relsOrRelas<ELFT>();
  if (rels.areRelocsRel())
    iterateFDEWithLSDAAux<ELFT>(*sec, rels.rels, ciesWithLSDA, fn);
  else
    iterateFDEWithLSDAAux<ELFT>(*sec, rels.relas, ciesWithLSDA, fn);
}
468}

470static void writeCieFde(uint8_t *buf, ArrayRef<uint8_t> d) {
memcpy(buf, d.data(), d.size());
// Fix the size field. -4 since size does not include the size field itself.
write32(buf, d.size() - 4);
474}

476void EhFrameSection::finalizeContents() {
assert(!this->size)(static_cast <bool> (!this->size) ? void (0) : __assert_fail
 ("!this->size", "lld/ELF/SyntheticSections.cpp", 477, __extension__
 __PRETTY_FUNCTION__)); // Not finalized.

switch (config->ekind) {
case ELFNoneKind:
  llvm_unreachable("invalid ekind")::llvm::llvm_unreachable_internal("invalid ekind", "lld/ELF/SyntheticSections.cpp"
, 481);
case ELF32LEKind:
  for (EhInputSection *sec : sections)
    addSectionAux<ELF32LE>(sec);
  break;
case ELF32BEKind:
  for (EhInputSection *sec : sections)
    addSectionAux<ELF32BE>(sec);
  break;
case ELF64LEKind:
  for (EhInputSection *sec : sections)
    addSectionAux<ELF64LE>(sec);
  break;
case ELF64BEKind:
  for (EhInputSection *sec : sections)
    addSectionAux<ELF64BE>(sec);
  break;
}

size_t off = 0;
for (CieRecord *rec : cieRecords) {
  rec->cie->outputOff = off;
  off += rec->cie->size;

  for (EhSectionPiece *fde : rec->fdes) {
    fde->outputOff = off;
    off += fde->size;
  }
}

// The LSB standard does not allow a .eh_frame section with zero
// Call Frame Information records. glibc unwind-dw2-fde.c
// classify_object_over_fdes expects there is a CIE record length 0 as a
// terminator. Thus we add one unconditionally.
off += 4;

this->size = off;
518}

520// Returns data for .eh_frame_hdr. .eh_frame_hdr is a binary search table
521// to get an FDE from an address to which FDE is applied. This function
522// returns a list of such pairs.
523SmallVector<EhFrameSection::FdeData, 0> EhFrameSection::getFdeData() const {
uint8_t *buf = Out::bufferStart + getParent()->offset + outSecOff;
SmallVector<FdeData, 0> ret;

uint64_t va = getPartition().ehFrameHdr->getVA();
for (CieRecord *rec : cieRecords) {
  uint8_t enc = getFdeEncoding(rec->cie);
  for (EhSectionPiece *fde : rec->fdes) {
    uint64_t pc = getFdePc(buf, fde->outputOff, enc);
    uint64_t fdeVA = getParent()->addr + fde->outputOff;
    if (!isInt<32>(pc - va))
      fatal(toString(fde->sec) + ": PC offset is too large: 0x" +
            Twine::utohexstr(pc - va));
    ret.push_back({uint32_t(pc - va), uint32_t(fdeVA - va)});
  }
}

// Sort the FDE list by their PC and uniqueify. Usually there is only
// one FDE for a PC (i.e. function), but if ICF merges two functions
// into one, there can be more than one FDEs pointing to the address.
auto less = [](const FdeData &a, const FdeData &b) {
  return a.pcRel < b.pcRel;
};
llvm::stable_sort(ret, less);
auto eq = [](const FdeData &a, const FdeData &b) {
  return a.pcRel == b.pcRel;
};
ret.erase(std::unique(ret.begin(), ret.end(), eq), ret.end());

return ret;
553}

555static uint64_t readFdeAddr(uint8_t *buf, int size) {
switch (size) {
case DW_EH_PE_udata2:
  return read16(buf);
case DW_EH_PE_sdata2:
  return (int16_t)read16(buf);
case DW_EH_PE_udata4:
  return read32(buf);
case DW_EH_PE_sdata4:
  return (int32_t)read32(buf);
case DW_EH_PE_udata8:
case DW_EH_PE_sdata8:
  return read64(buf);
case DW_EH_PE_absptr:
  return readUint(buf);
}
fatal("unknown FDE size encoding");
572}

574// Returns the VA to which a given FDE (on a mmap'ed buffer) is applied to.
575// We need it to create .eh_frame_hdr section.
576uint64_t EhFrameSection::getFdePc(uint8_t *buf, size_t fdeOff,
                                uint8_t enc) const {
// The starting address to which this FDE applies is
// stored at FDE + 8 byte.
size_t off = fdeOff + 8;
uint64_t addr = readFdeAddr(buf + off, enc & 0xf);
if ((enc & 0x70) == DW_EH_PE_absptr)
  return addr;
if ((enc & 0x70) == DW_EH_PE_pcrel)
  return addr + getParent()->addr + off;
fatal("unknown FDE size relative encoding");
587}

589void EhFrameSection::writeTo(uint8_t *buf) {
// Write CIE and FDE records.
for (CieRecord *rec : cieRecords) {
  size_t cieOffset = rec->cie->outputOff;
  writeCieFde(buf + cieOffset, rec->cie->data());

  for (EhSectionPiece *fde : rec->fdes) {
    size_t off = fde->outputOff;
    writeCieFde(buf + off, fde->data());

    // FDE's second word should have the offset to an associated CIE.
    // Write it.
    write32(buf + off + 4, off + 4 - cieOffset);
  }
}

// Apply relocations. .eh_frame section contents are not contiguous
// in the output buffer, but relocateAlloc() still works because
// getOffset() takes care of discontiguous section pieces.
for (EhInputSection *s : sections)
  target->relocateAlloc(*s, buf);

if (getPartition().ehFrameHdr && getPartition().ehFrameHdr->getParent())
  getPartition().ehFrameHdr->write();
613}

615GotSection::GotSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS,
                     target->gotEntrySize, ".got") {
numEntries = target->gotHeaderEntriesNum;
619}

621void GotSection::addConstant(const Relocation &r) { relocations.push_back(r); }
622void GotSection::addEntry(Symbol &sym) {
assert(sym.auxIdx == symAux.size() - 1)(static_cast <bool> (sym.auxIdx == symAux.size() - 1) ?
 void (0) : __assert_fail ("sym.auxIdx == symAux.size() - 1",
 "lld/ELF/SyntheticSections.cpp", 623, __extension__ __PRETTY_FUNCTION__
));
symAux.back().gotIdx = numEntries++;
625}

627bool GotSection::addTlsDescEntry(Symbol &sym) {
assert(sym.auxIdx == symAux.size() - 1)(static_cast <bool> (sym.auxIdx == symAux.size() - 1) ?
 void (0) : __assert_fail ("sym.auxIdx == symAux.size() - 1",
 "lld/ELF/SyntheticSections.cpp", 628, __extension__ __PRETTY_FUNCTION__
));
symAux.back().tlsDescIdx = numEntries;
numEntries += 2;
return true;
632}

634bool GotSection::addDynTlsEntry(Symbol &sym) {
assert(sym.auxIdx == symAux.size() - 1)(static_cast <bool> (sym.auxIdx == symAux.size() - 1) ?
 void (0) : __assert_fail ("sym.auxIdx == symAux.size() - 1",
 "lld/ELF/SyntheticSections.cpp", 635, __extension__ __PRETTY_FUNCTION__
));
symAux.back().tlsGdIdx = numEntries;
// Global Dynamic TLS entries take two GOT slots.
numEntries += 2;
return true;
640}

642// Reserves TLS entries for a TLS module ID and a TLS block offset.
643// In total it takes two GOT slots.
644bool GotSection::addTlsIndex() {
if (tlsIndexOff != uint32_t(-1))
  return false;
tlsIndexOff = numEntries * config->wordsize;
numEntries += 2;
return true;
650}

652uint32_t GotSection::getTlsDescOffset(const Symbol &sym) const {
return sym.getTlsDescIdx() * config->wordsize;
654}

656uint64_t GotSection::getTlsDescAddr(const Symbol &sym) const {
return getVA() + getTlsDescOffset(sym);
658}

660uint64_t GotSection::getGlobalDynAddr(const Symbol &b) const {
return this->getVA() + b.getTlsGdIdx() * config->wordsize;
662}

664uint64_t GotSection::getGlobalDynOffset(const Symbol &b) const {
return b.getTlsGdIdx() * config->wordsize;
666}

668void GotSection::finalizeContents() {
if (config->emachine == EM_PPC64 &&
    numEntries <= target->gotHeaderEntriesNum && !ElfSym::globalOffsetTable)
  size = 0;
else
  size = numEntries * config->wordsize;
674}

676bool GotSection::isNeeded() const {
// Needed if the GOT symbol is used or the number of entries is more than just
// the header. A GOT with just the header may not be needed.
return hasGotOffRel || numEntries > target->gotHeaderEntriesNum;
680}

682void GotSection::writeTo(uint8_t *buf) {
// On PPC64 .got may be needed but empty. Skip the write.
if (size == 0)
  return;
target->writeGotHeader(buf);
target->relocateAlloc(*this, buf);
688}

690static uint64_t getMipsPageAddr(uint64_t addr) {
return (addr + 0x8000) & ~0xffff;
692}

694static uint64_t getMipsPageCount(uint64_t size) {
return (size + 0xfffe) / 0xffff + 1;
696}

698MipsGotSection::MipsGotSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE | SHF_MIPS_GPREL, SHT_PROGBITS, 16,
                     ".got") {}

702void MipsGotSection::addEntry(InputFile &file, Symbol &sym, int64_t addend,
                            RelExpr expr) {
FileGot &g = getGot(file);
if (expr == R_MIPS_GOT_LOCAL_PAGE) {
  if (const OutputSection *os = sym.getOutputSection())
    g.pagesMap.insert({os, {}});
  else
    g.local16.insert({{nullptr, getMipsPageAddr(sym.getVA(addend))}, 0});
} else if (sym.isTls())
  g.tls.insert({&sym, 0});
else if (sym.isPreemptible && expr == R_ABS)
  g.relocs.insert({&sym, 0});
else if (sym.isPreemptible)
  g.global.insert({&sym, 0});
else if (expr == R_MIPS_GOT_OFF32)
  g.local32.insert({{&sym, addend}, 0});
else
  g.local16.insert({{&sym, addend}, 0});
720}

722void MipsGotSection::addDynTlsEntry(InputFile &file, Symbol &sym) {
getGot(file).dynTlsSymbols.insert({&sym, 0});
724}

726void MipsGotSection::addTlsIndex(InputFile &file) {
getGot(file).dynTlsSymbols.insert({nullptr, 0});
728}

730size_t MipsGotSection::FileGot::getEntriesNum() const {
return getPageEntriesNum() + local16.size() + global.size() + relocs.size() +
       tls.size() + dynTlsSymbols.size() * 2;
733}

735size_t MipsGotSection::FileGot::getPageEntriesNum() const {
size_t num = 0;
for (const std::pair<const OutputSection *, FileGot::PageBlock> &p : pagesMap)
  num += p.second.count;
return num;
740}

742size_t MipsGotSection::FileGot::getIndexedEntriesNum() const {
size_t count = getPageEntriesNum() + local16.size() + global.size();
// If there are relocation-only entries in the GOT, TLS entries
// are allocated after them. TLS entries should be addressable
// by 16-bit index so count both reloc-only and TLS entries.
if (!tls.empty() || !dynTlsSymbols.empty())
  count += relocs.size() + tls.size() + dynTlsSymbols.size() * 2;
return count;
750}

752MipsGotSection::FileGot &MipsGotSection::getGot(InputFile &f) {
if (f.mipsGotIndex == uint32_t(-1)) {
  gots.emplace_back();
  gots.back().file = &f;
  f.mipsGotIndex = gots.size() - 1;
}
return gots[f.mipsGotIndex];
759}

761uint64_t MipsGotSection::getPageEntryOffset(const InputFile *f,
                                          const Symbol &sym,
                                          int64_t addend) const {
const FileGot &g = gots[f->mipsGotIndex];
uint64_t index = 0;
if (const OutputSection *outSec = sym.getOutputSection()) {
  uint64_t secAddr = getMipsPageAddr(outSec->addr);
  uint64_t symAddr = getMipsPageAddr(sym.getVA(addend));
  index = g.pagesMap.lookup(outSec).firstIndex + (symAddr - secAddr) / 0xffff;
} else {
  index = g.local16.lookup({nullptr, getMipsPageAddr(sym.getVA(addend))});
}
return index * config->wordsize;
774}

776uint64_t MipsGotSection::getSymEntryOffset(const InputFile *f, const Symbol &s,
                                         int64_t addend) const {
const FileGot &g = gots[f->mipsGotIndex];
Symbol *sym = const_cast<Symbol *>(&s);
if (sym->isTls())
  return g.tls.lookup(sym) * config->wordsize;
if (sym->isPreemptible)
  return g.global.lookup(sym) * config->wordsize;
return g.local16.lookup({sym, addend}) * config->wordsize;
785}

787uint64_t MipsGotSection::getTlsIndexOffset(const InputFile *f) const {
const FileGot &g = gots[f->mipsGotIndex];
return g.dynTlsSymbols.lookup(nullptr) * config->wordsize;
790}

792uint64_t MipsGotSection::getGlobalDynOffset(const InputFile *f,
                                          const Symbol &s) const {
const FileGot &g = gots[f->mipsGotIndex];
Symbol *sym = const_cast<Symbol *>(&s);
return g.dynTlsSymbols.lookup(sym) * config->wordsize;
797}

799const Symbol *MipsGotSection::getFirstGlobalEntry() const {
if (gots.empty())
  return nullptr;
const FileGot &primGot = gots.front();
if (!primGot.global.empty())
  return primGot.global.front().first;
if (!primGot.relocs.empty())
  return primGot.relocs.front().first;
return nullptr;
808}

810unsigned MipsGotSection::getLocalEntriesNum() const {
if (gots.empty())
  return headerEntriesNum;
return headerEntriesNum + gots.front().getPageEntriesNum() +
       gots.front().local16.size();
815}

817bool MipsGotSection::tryMergeGots(FileGot &dst, FileGot &src, bool isPrimary) {
FileGot tmp = dst;
set_union(tmp.pagesMap, src.pagesMap);
set_union(tmp.local16, src.local16);
set_union(tmp.global, src.global);
set_union(tmp.relocs, src.relocs);
set_union(tmp.tls, src.tls);
set_union(tmp.dynTlsSymbols, src.dynTlsSymbols);

size_t count = isPrimary ? headerEntriesNum : 0;
count += tmp.getIndexedEntriesNum();

if (count * config->wordsize > config->mipsGotSize)
  return false;

std::swap(tmp, dst);
return true;
834}

836void MipsGotSection::finalizeContents() { updateAllocSize(); }

838bool MipsGotSection::updateAllocSize() {
size = headerEntriesNum * config->wordsize;
for (const FileGot &g : gots)
  size += g.getEntriesNum() * config->wordsize;
return false;
843}

845void MipsGotSection::build() {
if (gots.empty())
  return;

std::vector<FileGot> mergedGots(1);

// For each GOT move non-preemptible symbols from the `Global`
// to `Local16` list. Preemptible symbol might become non-preemptible
// one if, for example, it gets a related copy relocation.
for (FileGot &got : gots) {
  for (auto &p: got.global)
    if (!p.first->isPreemptible)
      got.local16.insert({{p.first, 0}, 0});
  got.global.remove_if([&](const std::pair<Symbol *, size_t> &p) {
    return !p.first->isPreemptible;
  });
}

// For each GOT remove "reloc-only" entry if there is "global"
// entry for the same symbol. And add local entries which indexed
// using 32-bit value at the end of 16-bit entries.
for (FileGot &got : gots) {
  got.relocs.remove_if([&](const std::pair<Symbol *, size_t> &p) {
    return got.global.count(p.first);
  });
  set_union(got.local16, got.local32);
  got.local32.clear();
}

// Evaluate number of "reloc-only" entries in the resulting GOT.
// To do that put all unique "reloc-only" and "global" entries
// from all GOTs to the future primary GOT.
FileGot *primGot = &mergedGots.front();
for (FileGot &got : gots) {
  set_union(primGot->relocs, got.global);
  set_union(primGot->relocs, got.relocs);
  got.relocs.clear();
}

// Evaluate number of "page" entries in each GOT.
for (FileGot &got : gots) {
  for (std::pair<const OutputSection *, FileGot::PageBlock> &p :
       got.pagesMap) {
    const OutputSection *os = p.first;
    uint64_t secSize = 0;
    for (SectionCommand *cmd : os->commands) {
      if (auto *isd = dyn_cast<InputSectionDescription>(cmd))
        for (InputSection *isec : isd->sections) {
          uint64_t off = alignToPowerOf2(secSize, isec->addralign);
          secSize = off + isec->getSize();
        }
    }
    p.second.count = getMipsPageCount(secSize);
  }
}

// Merge GOTs. Try to join as much as possible GOTs but do not exceed
// maximum GOT size. At first, try to fill the primary GOT because
// the primary GOT can be accessed in the most effective way. If it
// is not possible, try to fill the last GOT in the list, and finally
// create a new GOT if both attempts failed.
for (FileGot &srcGot : gots) {
  InputFile *file = srcGot.file;
  if (tryMergeGots(mergedGots.front(), srcGot, true)) {
    file->mipsGotIndex = 0;
  } else {
    // If this is the first time we failed to merge with the primary GOT,
    // MergedGots.back() will also be the primary GOT. We must make sure not
    // to try to merge again with isPrimary=false, as otherwise, if the
    // inputs are just right, we could allow the primary GOT to become 1 or 2
    // words bigger due to ignoring the header size.
    if (mergedGots.size() == 1 ||
        !tryMergeGots(mergedGots.back(), srcGot, false)) {
      mergedGots.emplace_back();
      std::swap(mergedGots.back(), srcGot);
    }
    file->mipsGotIndex = mergedGots.size() - 1;
  }
}
std::swap(gots, mergedGots);

// Reduce number of "reloc-only" entries in the primary GOT
// by subtracting "global" entries in the primary GOT.
primGot = &gots.front();
primGot->relocs.remove_if([&](const std::pair<Symbol *, size_t> &p) {
  return primGot->global.count(p.first);
});

// Calculate indexes for each GOT entry.
size_t index = headerEntriesNum;
for (FileGot &got : gots) {
  got.startIndex = &got == primGot ? 0 : index;
  for (std::pair<const OutputSection *, FileGot::PageBlock> &p :
       got.pagesMap) {
    // For each output section referenced by GOT page relocations calculate
    // and save into pagesMap an upper bound of MIPS GOT entries required
    // to store page addresses of local symbols. We assume the worst case -
    // each 64kb page of the output section has at least one GOT relocation
    // against it. And take in account the case when the section intersects
    // page boundaries.
    p.second.firstIndex = index;
    index += p.second.count;
  }
  for (auto &p: got.local16)
    p.second = index++;
  for (auto &p: got.global)
    p.second = index++;
  for (auto &p: got.relocs)
    p.second = index++;
  for (auto &p: got.tls)
    p.second = index++;
  for (auto &p: got.dynTlsSymbols) {
    p.second = index;
    index += 2;
  }
}

// Update SymbolAux::gotIdx field to use this
// value later in the `sortMipsSymbols` function.
for (auto &p : primGot->global) {
  if (p.first->auxIdx == 0)
    p.first->allocateAux();
  symAux.back().gotIdx = p.second;
}
for (auto &p : primGot->relocs) {
  if (p.first->auxIdx == 0)
    p.first->allocateAux();
  symAux.back().gotIdx = p.second;
}

// Create dynamic relocations.
for (FileGot &got : gots) {
  // Create dynamic relocations for TLS entries.
  for (std::pair<Symbol *, size_t> &p : got.tls) {
    Symbol *s = p.first;
    uint64_t offset = p.second * config->wordsize;
    // When building a shared library we still need a dynamic relocation
    // for the TP-relative offset as we don't know how much other data will
    // be allocated before us in the static TLS block.
    if (s->isPreemptible || config->shared)
      mainPart->relaDyn->addReloc({target->tlsGotRel, this, offset,
                                   DynamicReloc::AgainstSymbolWithTargetVA,
                                   *s, 0, R_ABS});
  }
  for (std::pair<Symbol *, size_t> &p : got.dynTlsSymbols) {
    Symbol *s = p.first;
    uint64_t offset = p.second * config->wordsize;
    if (s == nullptr) {
      if (!config->shared)
        continue;
      mainPart->relaDyn->addReloc({target->tlsModuleIndexRel, this, offset});
    } else {
      // When building a shared library we still need a dynamic relocation
      // for the module index. Therefore only checking for
      // S->isPreemptible is not sufficient (this happens e.g. for
      // thread-locals that have been marked as local through a linker script)
      if (!s->isPreemptible && !config->shared)
        continue;
      mainPart->relaDyn->addSymbolReloc(target->tlsModuleIndexRel, *this,
                                        offset, *s);
      // However, we can skip writing the TLS offset reloc for non-preemptible
      // symbols since it is known even in shared libraries
      if (!s->isPreemptible)
        continue;
      offset += config->wordsize;
      mainPart->relaDyn->addSymbolReloc(target->tlsOffsetRel, *this, offset,
                                        *s);
    }
  }

  // Do not create dynamic relocations for non-TLS
  // entries in the primary GOT.
  if (&got == primGot)
    continue;

  // Dynamic relocations for "global" entries.
  for (const std::pair<Symbol *, size_t> &p : got.global) {
    uint64_t offset = p.second * config->wordsize;
    mainPart->relaDyn->addSymbolReloc(target->relativeRel, *this, offset,
                                      *p.first);
  }
  if (!config->isPic)
    continue;
  // Dynamic relocations for "local" entries in case of PIC.
  for (const std::pair<const OutputSection *, FileGot::PageBlock> &l :
       got.pagesMap) {
    size_t pageCount = l.second.count;
    for (size_t pi = 0; pi < pageCount; ++pi) {
      uint64_t offset = (l.second.firstIndex + pi) * config->wordsize;
      mainPart->relaDyn->addReloc({target->relativeRel, this, offset, l.first,
                                   int64_t(pi * 0x10000)});
    }
  }
  for (const std::pair<GotEntry, size_t> &p : got.local16) {
    uint64_t offset = p.second * config->wordsize;
    mainPart->relaDyn->addReloc({target->relativeRel, this, offset,
                                 DynamicReloc::AddendOnlyWithTargetVA,
                                 *p.first.first, p.first.second, R_ABS});
  }
}
1045}

1047bool MipsGotSection::isNeeded() const {
// We add the .got section to the result for dynamic MIPS target because
// its address and properties are mentioned in the .dynamic section.
return !config->relocatable;
1051}

1053uint64_t MipsGotSection::getGp(const InputFile *f) const {
// For files without related GOT or files refer a primary GOT
// returns "common" _gp value. For secondary GOTs calculate
// individual _gp values.
if (!f || f->mipsGotIndex == uint32_t(-1) || f->mipsGotIndex == 0)
  return ElfSym::mipsGp->getVA(0);
return getVA() + gots[f->mipsGotIndex].startIndex * config->wordsize + 0x7ff0;
1060}

1062void MipsGotSection::writeTo(uint8_t *buf) {
// Set the MSB of the second GOT slot. This is not required by any
// MIPS ABI documentation, though.
//
// There is a comment in glibc saying that "The MSB of got[1] of a
// gnu object is set to identify gnu objects," and in GNU gold it
// says "the second entry will be used by some runtime loaders".
// But how this field is being used is unclear.
//
// We are not really willing to mimic other linkers behaviors
// without understanding why they do that, but because all files
// generated by GNU tools have this special GOT value, and because
// we've been doing this for years, it is probably a safe bet to
// keep doing this for now. We really need to revisit this to see
// if we had to do this.
writeUint(buf + config->wordsize, (uint64_t)1 << (config->wordsize * 8 - 1));
for (const FileGot &g : gots) {
  auto write = [&](size_t i, const Symbol *s, int64_t a) {
    uint64_t va = a;
    if (s)
      va = s->getVA(a);
    writeUint(buf + i * config->wordsize, va);
  };
  // Write 'page address' entries to the local part of the GOT.
  for (const std::pair<const OutputSection *, FileGot::PageBlock> &l :
       g.pagesMap) {
    size_t pageCount = l.second.count;
    uint64_t firstPageAddr = getMipsPageAddr(l.first->addr);
    for (size_t pi = 0; pi < pageCount; ++pi)
      write(l.second.firstIndex + pi, nullptr, firstPageAddr + pi * 0x10000);
  }
  // Local, global, TLS, reloc-only  entries.
  // If TLS entry has a corresponding dynamic relocations, leave it
  // initialized by zero. Write down adjusted TLS symbol's values otherwise.
  // To calculate the adjustments use offsets for thread-local storage.
  // http://web.archive.org/web/20190324223224/https://www.linux-mips.org/wiki/NPTL
  for (const std::pair<GotEntry, size_t> &p : g.local16)
    write(p.second, p.first.first, p.first.second);
  // Write VA to the primary GOT only. For secondary GOTs that
  // will be done by REL32 dynamic relocations.
  if (&g == &gots.front())
    for (const std::pair<Symbol *, size_t> &p : g.global)
      write(p.second, p.first, 0);
  for (const std::pair<Symbol *, size_t> &p : g.relocs)
    write(p.second, p.first, 0);
  for (const std::pair<Symbol *, size_t> &p : g.tls)
    write(p.second, p.first,
          p.first->isPreemptible || config->shared ? 0 : -0x7000);
  for (const std::pair<Symbol *, size_t> &p : g.dynTlsSymbols) {
    if (p.first == nullptr && !config->shared)
      write(p.second, nullptr, 1);
    else if (p.first && !p.first->isPreemptible) {
      // If we are emitting a shared library with relocations we mustn't write
      // anything to the GOT here. When using Elf_Rel relocations the value
      // one will be treated as an addend and will cause crashes at runtime
      if (!config->shared)
        write(p.second, nullptr, 1);
      write(p.second + 1, p.first, -0x8000);
    }
  }
}
1123}

1125// On PowerPC the .plt section is used to hold the table of function addresses
1126// instead of the .got.plt, and the type is SHT_NOBITS similar to a .bss
1127// section. I don't know why we have a BSS style type for the section but it is
1128// consistent across both 64-bit PowerPC ABIs as well as the 32-bit PowerPC ABI.
1129GotPltSection::GotPltSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, config->wordsize,
                     ".got.plt") {
if (config->emachine == EM_PPC) {
  name = ".plt";
} else if (config->emachine == EM_PPC64) {
  type = SHT_NOBITS;
  name = ".plt";
}
1138}

1140void GotPltSection::addEntry(Symbol &sym) {
assert(sym.auxIdx == symAux.size() - 1 &&(static_cast <bool> (sym.auxIdx == symAux.size() - 1 &&
 symAux.back().pltIdx == entries.size()) ? void (0) : __assert_fail
 ("sym.auxIdx == symAux.size() - 1 && symAux.back().pltIdx == entries.size()"
, "lld/ELF/SyntheticSections.cpp", 1142, __extension__ __PRETTY_FUNCTION__
))
       symAux.back().pltIdx == entries.size())(static_cast <bool> (sym.auxIdx == symAux.size() - 1 &&
 symAux.back().pltIdx == entries.size()) ? void (0) : __assert_fail
 ("sym.auxIdx == symAux.size() - 1 && symAux.back().pltIdx == entries.size()"
, "lld/ELF/SyntheticSections.cpp", 1142, __extension__ __PRETTY_FUNCTION__
));
entries.push_back(&sym);
1144}

1146size_t GotPltSection::getSize() const {
return (target->gotPltHeaderEntriesNum + entries.size()) *
       target->gotEntrySize;
1149}

1151void GotPltSection::writeTo(uint8_t *buf) {
target->writeGotPltHeader(buf);
buf += target->gotPltHeaderEntriesNum * target->gotEntrySize;
for (const Symbol *b : entries) {
  target->writeGotPlt(buf, *b);
  buf += target->gotEntrySize;
}
1158}

1160bool GotPltSection::isNeeded() const {
// We need to emit GOTPLT even if it's empty if there's a relocation relative
// to it.
return !entries.empty() || hasGotPltOffRel;
1164}

1166static StringRef getIgotPltName() {
// On ARM the IgotPltSection is part of the GotSection.
if (config->emachine == EM_ARM)
  return ".got";

// On PowerPC64 the GotPltSection is renamed to '.plt' so the IgotPltSection
// needs to be named the same.
if (config->emachine == EM_PPC64)
  return ".plt";

return ".got.plt";
1177}

1179// On PowerPC64 the GotPltSection type is SHT_NOBITS so we have to follow suit
1180// with the IgotPltSection.
1181IgotPltSection::IgotPltSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE,
                     config->emachine == EM_PPC64 ? SHT_NOBITS : SHT_PROGBITS,
                     target->gotEntrySize, getIgotPltName()) {}

1186void IgotPltSection::addEntry(Symbol &sym) {
assert(symAux.back().pltIdx == entries.size())(static_cast <bool> (symAux.back().pltIdx == entries.size
()) ? void (0) : __assert_fail ("symAux.back().pltIdx == entries.size()"
, "lld/ELF/SyntheticSections.cpp", 1187, __extension__ __PRETTY_FUNCTION__
));
entries.push_back(&sym);
1189}

1191size_t IgotPltSection::getSize() const {
return entries.size() * target->gotEntrySize;
1193}

1195void IgotPltSection::writeTo(uint8_t *buf) {
for (const Symbol *b : entries) {
  target->writeIgotPlt(buf, *b);
  buf += target->gotEntrySize;
}
1200}

1202StringTableSection::StringTableSection(StringRef name, bool dynamic)
  : SyntheticSection(dynamic ? (uint64_t)SHF_ALLOC : 0, SHT_STRTAB, 1, name),
    dynamic(dynamic) {
// ELF string tables start with a NUL byte.
strings.push_back("");
stringMap.try_emplace(CachedHashStringRef(""), 0);
size = 1;
1209}

1211// Adds a string to the string table. If `hashIt` is true we hash and check for
1212// duplicates. It is optional because the name of global symbols are already
1213// uniqued and hashing them again has a big cost for a small value: uniquing
1214// them with some other string that happens to be the same.
1215unsigned StringTableSection::addString(StringRef s, bool hashIt) {
if (hashIt) {
  auto r = stringMap.try_emplace(CachedHashStringRef(s), size);
  if (!r.second)
    return r.first->second;
}
if (s.empty())
  return 0;
unsigned ret = this->size;
this->size = this->size + s.size() + 1;
strings.push_back(s);
return ret;
1227}

1229void StringTableSection::writeTo(uint8_t *buf) {
for (StringRef s : strings) {
  memcpy(buf, s.data(), s.size());
  buf[s.size()] = '\0';
  buf += s.size() + 1;
}
1235}

1237// Returns the number of entries in .gnu.version_d: the number of
1238// non-VER_NDX_LOCAL-non-VER_NDX_GLOBAL definitions, plus 1.
1239// Note that we don't support vd_cnt > 1 yet.
1240static unsigned getVerDefNum() {
return namedVersionDefs().size() + 1;
1242}

1244template <class ELFT>
1245DynamicSection<ELFT>::DynamicSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_DYNAMIC, config->wordsize,
                     ".dynamic") {
this->entsize = ELFT::Is64Bits ? 16 : 8;

// .dynamic section is not writable on MIPS and on Fuchsia OS
// which passes -z rodynamic.
// See "Special Section" in Chapter 4 in the following document:
// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
if (config->emachine == EM_MIPS || config->zRodynamic)
  this->flags = SHF_ALLOC;
1256}

1258// The output section .rela.dyn may include these synthetic sections:
1259//
1260// - part.relaDyn
1261// - in.relaIplt: this is included if in.relaIplt is named .rela.dyn
1262// - in.relaPlt: this is included if a linker script places .rela.plt inside
1263//   .rela.dyn
1264//
1265// DT_RELASZ is the total size of the included sections.
1266static uint64_t addRelaSz(const RelocationBaseSection &relaDyn) {
size_t size = relaDyn.getSize();
if (in.relaIplt->getParent() == relaDyn.getParent())
  size += in.relaIplt->getSize();
if (in.relaPlt->getParent() == relaDyn.getParent())
  size += in.relaPlt->getSize();
return size;
1273}

1275// A Linker script may assign the RELA relocation sections to the same
1276// output section. When this occurs we cannot just use the OutputSection
1277// Size. Moreover the [DT_JMPREL, DT_JMPREL + DT_PLTRELSZ) is permitted to
1278// overlap with the [DT_RELA, DT_RELA + DT_RELASZ).
1279static uint64_t addPltRelSz() {
size_t size = in.relaPlt->getSize();
if (in.relaIplt->getParent() == in.relaPlt->getParent() &&
    in.relaIplt->name == in.relaPlt->name)
  size += in.relaIplt->getSize();
return size;
1285}

1287// Add remaining entries to complete .dynamic contents.
1288template <class ELFT>
1289std::vector<std::pair<int32_t, uint64_t>>
1290DynamicSection<ELFT>::computeContents() {
elf::Partition &part = getPartition();
bool isMain = part.name.empty();
std::vector<std::pair<int32_t, uint64_t>> entries;

auto addInt = [&](int32_t tag, uint64_t val) {
  entries.emplace_back(tag, val);
};
auto addInSec = [&](int32_t tag, const InputSection &sec) {
  entries.emplace_back(tag, sec.getVA());
};

for (StringRef s : config->filterList)
  addInt(DT_FILTER, part.dynStrTab->addString(s));
for (StringRef s : config->auxiliaryList)
  addInt(DT_AUXILIARY, part.dynStrTab->addString(s));

if (!config->rpath.empty())
  addInt(config->enableNewDtags ? DT_RUNPATH : DT_RPATH,
         part.dynStrTab->addString(config->rpath));

for (SharedFile *file : ctx.sharedFiles)
  if (file->isNeeded)
    addInt(DT_NEEDED, part.dynStrTab->addString(file->soName));

if (isMain) {
  if (!config->soName.empty())
    addInt(DT_SONAME, part.dynStrTab->addString(config->soName));
} else {
  if (!config->soName.empty())
    addInt(DT_NEEDED, part.dynStrTab->addString(config->soName));
  addInt(DT_SONAME, part.dynStrTab->addString(part.name));
}

// Set DT_FLAGS and DT_FLAGS_1.
uint32_t dtFlags = 0;
uint32_t dtFlags1 = 0;
if (config->bsymbolic == BsymbolicKind::All)
  dtFlags |= DF_SYMBOLIC;
if (config->zGlobal)
  dtFlags1 |= DF_1_GLOBAL;
if (config->zInitfirst)
  dtFlags1 |= DF_1_INITFIRST;
if (config->zInterpose)
  dtFlags1 |= DF_1_INTERPOSE;
if (config->zNodefaultlib)
  dtFlags1 |= DF_1_NODEFLIB;
if (config->zNodelete)
  dtFlags1 |= DF_1_NODELETE;
if (config->zNodlopen)
  dtFlags1 |= DF_1_NOOPEN;
if (config->pie)
  dtFlags1 |= DF_1_PIE;
if (config->zNow) {
  dtFlags |= DF_BIND_NOW;
  dtFlags1 |= DF_1_NOW;
}
if (config->zOrigin) {
  dtFlags |= DF_ORIGIN;
  dtFlags1 |= DF_1_ORIGIN;
}
if (!config->zText)
  dtFlags |= DF_TEXTREL;
if (ctx.hasTlsIe && config->shared)
  dtFlags |= DF_STATIC_TLS;

if (dtFlags)
  addInt(DT_FLAGS, dtFlags);
if (dtFlags1)
  addInt(DT_FLAGS_1, dtFlags1);

// DT_DEBUG is a pointer to debug information used by debuggers at runtime. We
// need it for each process, so we don't write it for DSOs. The loader writes
// the pointer into this entry.
//
// DT_DEBUG is the only .dynamic entry that needs to be written to. Some
// systems (currently only Fuchsia OS) provide other means to give the
// debugger this information. Such systems may choose make .dynamic read-only.
// If the target is such a system (used -z rodynamic) don't write DT_DEBUG.
if (!config->shared && !config->relocatable && !config->zRodynamic)
  addInt(DT_DEBUG, 0);

if (part.relaDyn->isNeeded() ||
    (in.relaIplt->isNeeded() &&
     part.relaDyn->getParent() == in.relaIplt->getParent())) {
  addInSec(part.relaDyn->dynamicTag, *part.relaDyn);
  entries.emplace_back(part.relaDyn->sizeDynamicTag,
                       addRelaSz(*part.relaDyn));

  bool isRela = config->isRela;
  addInt(isRela ? DT_RELAENT : DT_RELENT,
         isRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel));

  // MIPS dynamic loader does not support RELCOUNT tag.
  // The problem is in the tight relation between dynamic
  // relocations and GOT. So do not emit this tag on MIPS.
  if (config->emachine != EM_MIPS) {
    size_t numRelativeRels = part.relaDyn->getRelativeRelocCount();
    if (config->zCombreloc && numRelativeRels)
      addInt(isRela ? DT_RELACOUNT : DT_RELCOUNT, numRelativeRels);
  }
}
if (part.relrDyn && part.relrDyn->getParent() &&
    !part.relrDyn->relocs.empty()) {
  addInSec(config->useAndroidRelrTags ? DT_ANDROID_RELR : DT_RELR,
           *part.relrDyn);
  addInt(config->useAndroidRelrTags ? DT_ANDROID_RELRSZ : DT_RELRSZ,
         part.relrDyn->getParent()->size);
  addInt(config->useAndroidRelrTags ? DT_ANDROID_RELRENT : DT_RELRENT,
         sizeof(Elf_Relr));
}
// .rel[a].plt section usually consists of two parts, containing plt and
// iplt relocations. It is possible to have only iplt relocations in the
// output. In that case relaPlt is empty and have zero offset, the same offset
// as relaIplt has. And we still want to emit proper dynamic tags for that
// case, so here we always use relaPlt as marker for the beginning of
// .rel[a].plt section.
if (isMain && (in.relaPlt->isNeeded() || in.relaIplt->isNeeded())) {
  addInSec(DT_JMPREL, *in.relaPlt);
  entries.emplace_back(DT_PLTRELSZ, addPltRelSz());
  switch (config->emachine) {
  case EM_MIPS:
    addInSec(DT_MIPS_PLTGOT, *in.gotPlt);
    break;
  case EM_SPARCV9:
    addInSec(DT_PLTGOT, *in.plt);
    break;
  case EM_AARCH64:
    if (llvm::find_if(in.relaPlt->relocs, [](const DynamicReloc &r) {
         return r.type == target->pltRel &&
                r.sym->stOther & STO_AARCH64_VARIANT_PCS;
        }) != in.relaPlt->relocs.end())
      addInt(DT_AARCH64_VARIANT_PCS, 0);
    addInSec(DT_PLTGOT, *in.gotPlt);
    break;
  case EM_RISCV:
    if (llvm::any_of(in.relaPlt->relocs, [](const DynamicReloc &r) {
          return r.type == target->pltRel &&
                 (r.sym->stOther & STO_RISCV_VARIANT_CC);
        }))
      addInt(DT_RISCV_VARIANT_CC, 0);
    [[fallthrough]];
  default:
    addInSec(DT_PLTGOT, *in.gotPlt);
    break;
  }
  addInt(DT_PLTREL, config->isRela ? DT_RELA : DT_REL);
}

if (config->emachine == EM_AARCH64) {
  if (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)
    addInt(DT_AARCH64_BTI_PLT, 0);
  if (config->zPacPlt)
    addInt(DT_AARCH64_PAC_PLT, 0);
}

addInSec(DT_SYMTAB, *part.dynSymTab);
addInt(DT_SYMENT, sizeof(Elf_Sym));
addInSec(DT_STRTAB, *part.dynStrTab);
addInt(DT_STRSZ, part.dynStrTab->getSize());
if (!config->zText)
  addInt(DT_TEXTREL, 0);
if (part.gnuHashTab && part.gnuHashTab->getParent())
  addInSec(DT_GNU_HASH, *part.gnuHashTab);
if (part.hashTab && part.hashTab->getParent())
  addInSec(DT_HASH, *part.hashTab);

if (isMain) {
  if (Out::preinitArray) {
    addInt(DT_PREINIT_ARRAY, Out::preinitArray->addr);
    addInt(DT_PREINIT_ARRAYSZ, Out::preinitArray->size);
  }
  if (Out::initArray) {
    addInt(DT_INIT_ARRAY, Out::initArray->addr);
    addInt(DT_INIT_ARRAYSZ, Out::initArray->size);
  }
  if (Out::finiArray) {
    addInt(DT_FINI_ARRAY, Out::finiArray->addr);
    addInt(DT_FINI_ARRAYSZ, Out::finiArray->size);
  }

  if (Symbol *b = symtab.find(config->init))
    if (b->isDefined())
      addInt(DT_INIT, b->getVA());
  if (Symbol *b = symtab.find(config->fini))
    if (b->isDefined())
      addInt(DT_FINI, b->getVA());
}

if (part.verSym && part.verSym->isNeeded())
  addInSec(DT_VERSYM, *part.verSym);
if (part.verDef && part.verDef->isLive()) {
  addInSec(DT_VERDEF, *part.verDef);
  addInt(DT_VERDEFNUM, getVerDefNum());
}
if (part.verNeed && part.verNeed->isNeeded()) {
  addInSec(DT_VERNEED, *part.verNeed);
  unsigned needNum = 0;
  for (SharedFile *f : ctx.sharedFiles)
    if (!f->vernauxs.empty())
      ++needNum;
  addInt(DT_VERNEEDNUM, needNum);
}

if (config->emachine == EM_MIPS) {
  addInt(DT_MIPS_RLD_VERSION, 1);
  addInt(DT_MIPS_FLAGS, RHF_NOTPOT);
  addInt(DT_MIPS_BASE_ADDRESS, target->getImageBase());
  addInt(DT_MIPS_SYMTABNO, part.dynSymTab->getNumSymbols());
  addInt(DT_MIPS_LOCAL_GOTNO, in.mipsGot->getLocalEntriesNum());

  if (const Symbol *b = in.mipsGot->getFirstGlobalEntry())
    addInt(DT_MIPS_GOTSYM, b->dynsymIndex);
  else
    addInt(DT_MIPS_GOTSYM, part.dynSymTab->getNumSymbols());
  addInSec(DT_PLTGOT, *in.mipsGot);
  if (in.mipsRldMap) {
    if (!config->pie)
      addInSec(DT_MIPS_RLD_MAP, *in.mipsRldMap);
    // Store the offset to the .rld_map section
    // relative to the address of the tag.
    addInt(DT_MIPS_RLD_MAP_REL,
           in.mipsRldMap->getVA() - (getVA() + entries.size() * entsize));
  }
}

// DT_PPC_GOT indicates to glibc Secure PLT is used. If DT_PPC_GOT is absent,
// glibc assumes the old-style BSS PLT layout which we don't support.
if (config->emachine == EM_PPC)
  addInSec(DT_PPC_GOT, *in.got);

// Glink dynamic tag is required by the V2 abi if the plt section isn't empty.
if (config->emachine == EM_PPC64 && in.plt->isNeeded()) {
  // The Glink tag points to 32 bytes before the first lazy symbol resolution
  // stub, which starts directly after the header.
  addInt(DT_PPC64_GLINK, in.plt->getVA() + target->pltHeaderSize - 32);
}

addInt(DT_NULL, 0);
return entries;
1530}

1532template <class ELFT> void DynamicSection<ELFT>::finalizeContents() {
if (OutputSection *sec = getPartition().dynStrTab->getParent())
  getParent()->link = sec->sectionIndex;
this->size = computeContents().size() * this->entsize;
1536}

1538template <class ELFT> void DynamicSection<ELFT>::writeTo(uint8_t *buf) {
auto *p = reinterpret_cast<Elf_Dyn *>(buf);

for (std::pair<int32_t, uint64_t> kv : computeContents()) {
  p->d_tag = kv.first;
  p->d_un.d_val = kv.second;
  ++p;
}
1546}

1548uint64_t DynamicReloc::getOffset() const {
return inputSec->getVA(offsetInSec);
1550}

1552int64_t DynamicReloc::computeAddend() const {
switch (kind) {
case AddendOnly:
  assert(sym == nullptr)(static_cast <bool> (sym == nullptr) ? void (0) : __assert_fail
 ("sym == nullptr", "lld/ELF/SyntheticSections.cpp", 1555, __extension__
 __PRETTY_FUNCTION__));
  return addend;
case AgainstSymbol:
  assert(sym != nullptr)(static_cast <bool> (sym != nullptr) ? void (0) : __assert_fail
 ("sym != nullptr", "lld/ELF/SyntheticSections.cpp", 1558, __extension__
 __PRETTY_FUNCTION__));
  return addend;
case AddendOnlyWithTargetVA:
case AgainstSymbolWithTargetVA:
  return InputSection::getRelocTargetVA(inputSec->file, type, addend,
                                        getOffset(), *sym, expr);
case MipsMultiGotPage:
  assert(sym == nullptr)(static_cast <bool> (sym == nullptr) ? void (0) : __assert_fail
 ("sym == nullptr", "lld/ELF/SyntheticSections.cpp", 1565, __extension__
 __PRETTY_FUNCTION__));
  return getMipsPageAddr(outputSec->addr) + addend;
}
llvm_unreachable("Unknown DynamicReloc::Kind enum")::llvm::llvm_unreachable_internal("Unknown DynamicReloc::Kind enum"
, "lld/ELF/SyntheticSections.cpp", 1568);
1569}

1571uint32_t DynamicReloc::getSymIndex(SymbolTableBaseSection *symTab) const {
if (!needsDynSymIndex())
  return 0;

size_t index = symTab->getSymbolIndex(sym);
assert((index != 0 || (type != target->gotRel && type != target->pltRel) ||(static_cast <bool> ((index != 0 || (type != target->
gotRel && type != target->pltRel) || !mainPart->
dynSymTab->getParent()) && "GOT or PLT relocation must refer to symbol in dynamic symbol table"
) ? void (0) : __assert_fail ("(index != 0 || (type != target->gotRel && type != target->pltRel) || !mainPart->dynSymTab->getParent()) && \"GOT or PLT relocation must refer to symbol in dynamic symbol table\""
, "lld/ELF/SyntheticSections.cpp", 1578, __extension__ __PRETTY_FUNCTION__
))
        !mainPart->dynSymTab->getParent()) &&(static_cast <bool> ((index != 0 || (type != target->
gotRel && type != target->pltRel) || !mainPart->
dynSymTab->getParent()) && "GOT or PLT relocation must refer to symbol in dynamic symbol table"
) ? void (0) : __assert_fail ("(index != 0 || (type != target->gotRel && type != target->pltRel) || !mainPart->dynSymTab->getParent()) && \"GOT or PLT relocation must refer to symbol in dynamic symbol table\""
, "lld/ELF/SyntheticSections.cpp", 1578, __extension__ __PRETTY_FUNCTION__
))
       "GOT or PLT relocation must refer to symbol in dynamic symbol table")(static_cast <bool> ((index != 0 || (type != target->
gotRel && type != target->pltRel) || !mainPart->
dynSymTab->getParent()) && "GOT or PLT relocation must refer to symbol in dynamic symbol table"
) ? void (0) : __assert_fail ("(index != 0 || (type != target->gotRel && type != target->pltRel) || !mainPart->dynSymTab->getParent()) && \"GOT or PLT relocation must refer to symbol in dynamic symbol table\""
, "lld/ELF/SyntheticSections.cpp", 1578, __extension__ __PRETTY_FUNCTION__
));
return index;
1580}

1582RelocationBaseSection::RelocationBaseSection(StringRef name, uint32_t type,
                                           int32_t dynamicTag,
                                           int32_t sizeDynamicTag,
                                           bool combreloc,
                                           unsigned concurrency)
  : SyntheticSection(SHF_ALLOC, type, config->wordsize, name),
    dynamicTag(dynamicTag), sizeDynamicTag(sizeDynamicTag),
    relocsVec(concurrency), combreloc(combreloc) {}

1591void RelocationBaseSection::addSymbolReloc(
  RelType dynType, InputSectionBase &isec, uint64_t offsetInSec, Symbol &sym,
  int64_t addend, std::optional<RelType> addendRelType) {
addReloc(DynamicReloc::AgainstSymbol, dynType, isec, offsetInSec, sym, addend,
         R_ADDEND, addendRelType ? *addendRelType : target->noneRel);
1596}

1598void RelocationBaseSection::addAddendOnlyRelocIfNonPreemptible(
  RelType dynType, GotSection &sec, uint64_t offsetInSec, Symbol &sym,
  RelType addendRelType) {
// No need to write an addend to the section for preemptible symbols.
if (sym.isPreemptible)
  addReloc({dynType, &sec, offsetInSec, DynamicReloc::AgainstSymbol, sym, 0,
            R_ABS});
else
  addReloc(DynamicReloc::AddendOnlyWithTargetVA, dynType, sec, offsetInSec,
           sym, 0, R_ABS, addendRelType);
1608}

1610void RelocationBaseSection::mergeRels() {
size_t newSize = relocs.size();
for (const auto &v : relocsVec)
  newSize += v.size();
relocs.reserve(newSize);
for (const auto &v : relocsVec)
  llvm::append_range(relocs, v);
relocsVec.clear();
1618}

1620void RelocationBaseSection::partitionRels() {
if (!combreloc)
  return;
const RelType relativeRel = target->relativeRel;
numRelativeRelocs =
    llvm::partition(relocs, [=](auto &r) { return r.type == relativeRel; }) -
    relocs.begin();
1627}

1629void RelocationBaseSection::finalizeContents() {
SymbolTableBaseSection *symTab = getPartition().dynSymTab.get();

// When linking glibc statically, .rel{,a}.plt contains R_*_IRELATIVE
// relocations due to IFUNC (e.g. strcpy). sh_link will be set to 0 in that
// case.
if (symTab && symTab->getParent())
  getParent()->link = symTab->getParent()->sectionIndex;
else
  getParent()->link = 0;

if (in.relaPlt.get() == this && in.gotPlt->getParent()) {
  getParent()->flags |= ELF::SHF_INFO_LINK;
  getParent()->info = in.gotPlt->getParent()->sectionIndex;
}
if (in.relaIplt.get() == this && in.igotPlt->getParent()) {
  getParent()->flags |= ELF::SHF_INFO_LINK;
  getParent()->info = in.igotPlt->getParent()->sectionIndex;
}
1648}

1650void DynamicReloc::computeRaw(SymbolTableBaseSection *symtab) {
r_offset = getOffset();
r_sym = getSymIndex(symtab);
addend = computeAddend();
kind = AddendOnly; // Catch errors
1655}

1657void RelocationBaseSection::computeRels() {
SymbolTableBaseSection *symTab = getPartition().dynSymTab.get();
parallelForEach(relocs,
                [symTab](DynamicReloc &rel) { rel.computeRaw(symTab); });
// Sort by (!IsRelative,SymIndex,r_offset). DT_REL[A]COUNT requires us to
// place R_*_RELATIVE first. SymIndex is to improve locality, while r_offset
// is to make results easier to read.
if (combreloc) {
  auto nonRelative = relocs.begin() + numRelativeRelocs;
  parallelSort(relocs.begin(), nonRelative,
               [&](auto &a, auto &b) { return a.r_offset < b.r_offset; });
  // Non-relative relocations are few, so don't bother with parallelSort.
  llvm::sort(nonRelative, relocs.end(), [&](auto &a, auto &b) {
    return std::tie(a.r_sym, a.r_offset) < std::tie(b.r_sym, b.r_offset);
  });
}
1673}

1675template <class ELFT>
1676RelocationSection<ELFT>::RelocationSection(StringRef name, bool combreloc,
                                         unsigned concurrency)
  : RelocationBaseSection(name, config->isRela ? SHT_RELA : SHT_REL,
                          config->isRela ? DT_RELA : DT_REL,
                          config->isRela ? DT_RELASZ : DT_RELSZ, combreloc,
                          concurrency) {
this->entsize = config->isRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
1683}

1685template <class ELFT> void RelocationSection<ELFT>::writeTo(uint8_t *buf) {
computeRels();
for (const DynamicReloc &rel : relocs) {
  auto *p = reinterpret_cast<Elf_Rela *>(buf);
  p->r_offset = rel.r_offset;
  p->setSymbolAndType(rel.r_sym, rel.type, config->isMips64EL);
  if (config->isRela)
    p->r_addend = rel.addend;
  buf += config->isRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
}
1695}

1697RelrBaseSection::RelrBaseSection(unsigned concurrency)
  : SyntheticSection(SHF_ALLOC,
                     config->useAndroidRelrTags ? SHT_ANDROID_RELR : SHT_RELR,
                     config->wordsize, ".relr.dyn"),
    relocsVec(concurrency) {}

1703void RelrBaseSection::mergeRels() {
size_t newSize = relocs.size();
for (const auto &v : relocsVec)
  newSize += v.size();
relocs.reserve(newSize);
for (const auto &v : relocsVec)
  llvm::append_range(relocs, v);
relocsVec.clear();
1711}

1713template <class ELFT>
1714AndroidPackedRelocationSection<ELFT>::AndroidPackedRelocationSection(
  StringRef name, unsigned concurrency)
  : RelocationBaseSection(
        name, config->isRela ? SHT_ANDROID_RELA : SHT_ANDROID_REL,
        config->isRela ? DT_ANDROID_RELA : DT_ANDROID_REL,
        config->isRela ? DT_ANDROID_RELASZ : DT_ANDROID_RELSZ,
        /*combreloc=*/false, concurrency) {
this->entsize = 1;
1722}

1724template <class ELFT>
1725bool AndroidPackedRelocationSection<ELFT>::updateAllocSize() {
// This function computes the contents of an Android-format packed relocation
// section.
//
// This format compresses relocations by using relocation groups to factor out
// fields that are common between relocations and storing deltas from previous
// relocations in SLEB128 format (which has a short representation for small
// numbers). A good example of a relocation type with common fields is
// R_*_RELATIVE, which is normally used to represent function pointers in
// vtables. In the REL format, each relative relocation has the same r_info
// field, and is only different from other relative relocations in terms of
// the r_offset field. By sorting relocations by offset, grouping them by
// r_info and representing each relocation with only the delta from the
// previous offset, each 8-byte relocation can be compressed to as little as 1
// byte (or less with run-length encoding). This relocation packer was able to
// reduce the size of the relocation section in an Android Chromium DSO from
// 2,911,184 bytes to 174,693 bytes, or 6% of the original size.
//
// A relocation section consists of a header containing the literal bytes
// 'APS2' followed by a sequence of SLEB128-encoded integers. The first two
// elements are the total number of relocations in the section and an initial
// r_offset value. The remaining elements define a sequence of relocation
// groups. Each relocation group starts with a header consisting of the
// following elements:
//
// - the number of relocations in the relocation group
// - flags for the relocation group
// - (if RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG is set) the r_offset delta
//   for each relocation in the group.
// - (if RELOCATION_GROUPED_BY_INFO_FLAG is set) the value of the r_info
//   field for each relocation in the group.
// - (if RELOCATION_GROUP_HAS_ADDEND_FLAG and
//   RELOCATION_GROUPED_BY_ADDEND_FLAG are set) the r_addend delta for
//   each relocation in the group.
//
// Following the relocation group header are descriptions of each of the
// relocations in the group. They consist of the following elements:
//
// - (if RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG is not set) the r_offset
//   delta for this relocation.
// - (if RELOCATION_GROUPED_BY_INFO_FLAG is not set) the value of the r_info
//   field for this relocation.
// - (if RELOCATION_GROUP_HAS_ADDEND_FLAG is set and
//   RELOCATION_GROUPED_BY_ADDEND_FLAG is not set) the r_addend delta for
//   this relocation.

size_t oldSize = relocData.size();

relocData = {'A', 'P', 'S', '2'};
raw_svector_ostream os(relocData);
auto add = [&](int64_t v) { encodeSLEB128(v, os); };

// The format header includes the number of relocations and the initial
// offset (we set this to zero because the first relocation group will
// perform the initial adjustment).
add(relocs.size());
add(0);

std::vector<Elf_Rela> relatives, nonRelatives;

for (const DynamicReloc &rel : relocs) {
  Elf_Rela r;
  r.r_offset = rel.getOffset();
  r.setSymbolAndType(rel.getSymIndex(getPartition().dynSymTab.get()),
                     rel.type, false);
  r.r_addend = config->isRela ? rel.computeAddend() : 0;

  if (r.getType(config->isMips64EL) == target->relativeRel)
    relatives.push_back(r);
  else
    nonRelatives.push_back(r);
}

llvm::sort(relatives, [](const Elf_Rel &a, const Elf_Rel &b) {
  return a.r_offset < b.r_offset;
});

// Try to find groups of relative relocations which are spaced one word
// apart from one another. These generally correspond to vtable entries. The
// format allows these groups to be encoded using a sort of run-length
// encoding, but each group will cost 7 bytes in addition to the offset from
// the previous group, so it is only profitable to do this for groups of
// size 8 or larger.
std::vector<Elf_Rela> ungroupedRelatives;
std::vector<std::vector<Elf_Rela>> relativeGroups;
for (auto i = relatives.begin(), e = relatives.end(); i != e;) {
  std::vector<Elf_Rela> group;
  do {
    group.push_back(*i++);
  } while (i != e && (i - 1)->r_offset + config->wordsize == i->r_offset);

  if (group.size() < 8)
    ungroupedRelatives.insert(ungroupedRelatives.end(), group.begin(),
                              group.end());
  else
    relativeGroups.emplace_back(std::move(group));
}

// For non-relative relocations, we would like to:
//   1. Have relocations with the same symbol offset to be consecutive, so
//      that the runtime linker can speed-up symbol lookup by implementing an
//      1-entry cache.
//   2. Group relocations by r_info to reduce the size of the relocation
//      section.
// Since the symbol offset is the high bits in r_info, sorting by r_info
// allows us to do both.
//
// For Rela, we also want to sort by r_addend when r_info is the same. This
// enables us to group by r_addend as well.
llvm::sort(nonRelatives, [](const Elf_Rela &a, const Elf_Rela &b) {
  if (a.r_info != b.r_info)
    return a.r_info < b.r_info;
  if (a.r_addend != b.r_addend)
    return a.r_addend < b.r_addend;
  return a.r_offset < b.r_offset;
});

// Group relocations with the same r_info. Note that each group emits a group
// header and that may make the relocation section larger. It is hard to
// estimate the size of a group header as the encoded size of that varies
// based on r_info. However, we can approximate this trade-off by the number
// of values encoded. Each group header contains 3 values, and each relocation
// in a group encodes one less value, as compared to when it is not grouped.
// Therefore, we only group relocations if there are 3 or more of them with
// the same r_info.
//
// For Rela, the addend for most non-relative relocations is zero, and thus we
// can usually get a smaller relocation section if we group relocations with 0
// addend as well.
std::vector<Elf_Rela> ungroupedNonRelatives;
std::vector<std::vector<Elf_Rela>> nonRelativeGroups;
for (auto i = nonRelatives.begin(), e = nonRelatives.end(); i != e;) {
  auto j = i + 1;
  while (j != e && i->r_info == j->r_info &&
         (!config->isRela || i->r_addend == j->r_addend))
    ++j;
  if (j - i < 3 || (config->isRela && i->r_addend != 0))
    ungroupedNonRelatives.insert(ungroupedNonRelatives.end(), i, j);
  else
    nonRelativeGroups.emplace_back(i, j);
  i = j;
}

// Sort ungrouped relocations by offset to minimize the encoded length.
llvm::sort(ungroupedNonRelatives, [](const Elf_Rela &a, const Elf_Rela &b) {
  return a.r_offset < b.r_offset;
});

unsigned hasAddendIfRela =
    config->isRela ? RELOCATION_GROUP_HAS_ADDEND_FLAG : 0;

uint64_t offset = 0;
uint64_t addend = 0;

// Emit the run-length encoding for the groups of adjacent relative
// relocations. Each group is represented using two groups in the packed
// format. The first is used to set the current offset to the start of the
// group (and also encodes the first relocation), and the second encodes the
// remaining relocations.
for (std::vector<Elf_Rela> &g : relativeGroups) {
  // The first relocation in the group.
  add(1);
  add(RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG |
      RELOCATION_GROUPED_BY_INFO_FLAG | hasAddendIfRela);
  add(g[0].r_offset - offset);
  add(target->relativeRel);
  if (config->isRela) {
    add(g[0].r_addend - addend);
    addend = g[0].r_addend;
  }

  // The remaining relocations.
  add(g.size() - 1);
  add(RELOCATION_GROUPED_BY_OFFSET_DELTA_FLAG |
      RELOCATION_GROUPED_BY_INFO_FLAG | hasAddendIfRela);
  add(config->wordsize);
  add(target->relativeRel);
  if (config->isRela) {
    for (const auto &i : llvm::drop_begin(g)) {
      add(i.r_addend - addend);
      addend = i.r_addend;
    }
  }

  offset = g.back().r_offset;
}

// Now the ungrouped relatives.
if (!ungroupedRelatives.empty()) {
  add(ungroupedRelatives.size());
  add(RELOCATION_GROUPED_BY_INFO_FLAG | hasAddendIfRela);
  add(target->relativeRel);
  for (Elf_Rela &r : ungroupedRelatives) {
    add(r.r_offset - offset);
    offset = r.r_offset;
    if (config->isRela) {
      add(r.r_addend - addend);
      addend = r.r_addend;
    }
  }
}

// Grouped non-relatives.
for (ArrayRef<Elf_Rela> g : nonRelativeGroups) {
  add(g.size());
  add(RELOCATION_GROUPED_BY_INFO_FLAG);
  add(g[0].r_info);
  for (const Elf_Rela &r : g) {
    add(r.r_offset - offset);
    offset = r.r_offset;
  }
  addend = 0;
}

// Finally the ungrouped non-relative relocations.
if (!ungroupedNonRelatives.empty()) {
  add(ungroupedNonRelatives.size());
  add(hasAddendIfRela);
  for (Elf_Rela &r : ungroupedNonRelatives) {
    add(r.r_offset - offset);
    offset = r.r_offset;
    add(r.r_info);
    if (config->isRela) {
      add(r.r_addend - addend);
      addend = r.r_addend;
    }
  }
}

// Don't allow the section to shrink; otherwise the size of the section can
// oscillate infinitely.
if (relocData.size() < oldSize)
  relocData.append(oldSize - relocData.size(), 0);

// Returns whether the section size changed. We need to keep recomputing both
// section layout and the contents of this section until the size converges
// because changing this section's size can affect section layout, which in
// turn can affect the sizes of the LEB-encoded integers stored in this
// section.
return relocData.size() != oldSize;
1965}

1967template <class ELFT>
1968RelrSection<ELFT>::RelrSection(unsigned concurrency)
  : RelrBaseSection(concurrency) {
this->entsize = config->wordsize;
1971}

1973template <class ELFT> bool RelrSection<ELFT>::updateAllocSize() {
// This function computes the contents of an SHT_RELR packed relocation
// section.
//
// Proposal for adding SHT_RELR sections to generic-abi is here:
//   https://groups.google.com/forum/#!topic/generic-abi/bX460iggiKg
//
// The encoded sequence of Elf64_Relr entries in a SHT_RELR section looks
// like [ AAAAAAAA BBBBBBB1 BBBBBBB1 ... AAAAAAAA BBBBBB1 ... ]
//
// i.e. start with an address, followed by any number of bitmaps. The address
// entry encodes 1 relocation. The subsequent bitmap entries encode up to 63
// relocations each, at subsequent offsets following the last address entry.
//
// The bitmap entries must have 1 in the least significant bit. The assumption
// here is that an address cannot have 1 in lsb. Odd addresses are not
// supported.
//
// Excluding the least significant bit in the bitmap, each non-zero bit in
// the bitmap represents a relocation to be applied to a corresponding machine
// word that follows the base address word. The second least significant bit
// represents the machine word immediately following the initial address, and
// each bit that follows represents the next word, in linear order. As such,
// a single bitmap can encode up to 31 relocations in a 32-bit object, and
// 63 relocations in a 64-bit object.
//
// This encoding has a couple of interesting properties:
// 1. Looking at any entry, it is clear whether it's an address or a bitmap:
//    even means address, odd means bitmap.
// 2. Just a simple list of addresses is a valid encoding.

size_t oldSize = relrRelocs.size();
relrRelocs.clear();

// Same as Config->Wordsize but faster because this is a compile-time
// constant.
const size_t wordsize = sizeof(typename ELFT::uint);

// Number of bits to use for the relocation offsets bitmap.
// Must be either 63 or 31.
const size_t nBits = wordsize * 8 - 1;

// Get offsets for all relative relocations and sort them.
std::unique_ptr<uint64_t[]> offsets(new uint64_t[relocs.size()]);
1
Storing uninitialized value→
2
←
Calling constructor for 'unique_ptr<unsigned long[], std::default_delete<unsigned long[]>>'→
7
←
Returning from constructor for 'unique_ptr<unsigned long[], std::default_delete<unsigned long[]>>'→
for (auto [i, r] : llvm::enumerate(relocs))
  offsets[i] = r.getOffset();
llvm::sort(offsets.get(), offsets.get() + relocs.size());
8
←
Calling 'sort<unsigned long *>'→
16
←
Returning from 'sort<unsigned long *>'→

// For each leading relocation, find following ones that can be folded
// as a bitmap and fold them.
for (size_t i = 0, e = relocs.size(); i != e;) {
17
←
'i' initialized to 0→
18
←
Assuming 'i' is not equal to 'e'→
19
←
Loop condition is true.  Entering loop body→
  // Add a leading relocation.
  relrRelocs.push_back(Elf_Relr(offsets[i]));
20
←
Passing the value 0 via 1st parameter '__i'→
21
←
1st function call argument is an uninitialized value
  uint64_t base = offsets[i] + wordsize;
  ++i;

  // Find foldable relocations to construct bitmaps.
  for (;;) {
    uint64_t bitmap = 0;
    for (; i != e; ++i) {
      uint64_t d = offsets[i] - base;
      if (d >= nBits * wordsize || d % wordsize)
        break;
      bitmap |= uint64_t(1) << (d / wordsize);
    }
    if (!bitmap)
      break;
    relrRelocs.push_back(Elf_Relr((bitmap << 1) | 1));
    base += nBits * wordsize;
  }
}

// Don't allow the section to shrink; otherwise the size of the section can
// oscillate infinitely. Trailing 1s do not decode to more relocations.
if (relrRelocs.size() < oldSize) {
  log(".relr.dyn needs " + Twine(oldSize - relrRelocs.size()) +
      " padding word(s)");
  relrRelocs.resize(oldSize, Elf_Relr(1));
}

return relrRelocs.size() != oldSize;
2054}

2056SymbolTableBaseSection::SymbolTableBaseSection(StringTableSection &strTabSec)
  : SyntheticSection(strTabSec.isDynamic() ? (uint64_t)SHF_ALLOC : 0,
                     strTabSec.isDynamic() ? SHT_DYNSYM : SHT_SYMTAB,
                     config->wordsize,
                     strTabSec.isDynamic() ? ".dynsym" : ".symtab"),
    strTabSec(strTabSec) {}

2063// Orders symbols according to their positions in the GOT,
2064// in compliance with MIPS ABI rules.
2065// See "Global Offset Table" in Chapter 5 in the following document
2066// for detailed description:
2067// ftp://www.linux-mips.org/pub/linux/mips/doc/ABI/mipsabi.pdf
2068static bool sortMipsSymbols(const SymbolTableEntry &l,
                          const SymbolTableEntry &r) {
// Sort entries related to non-local preemptible symbols by GOT indexes.
// All other entries go to the beginning of a dynsym in arbitrary order.
if (l.sym->isInGot() && r.sym->isInGot())
  return l.sym->getGotIdx() < r.sym->getGotIdx();
if (!l.sym->isInGot() && !r.sym->isInGot())
  return false;
return !l.sym->isInGot();
2077}

2079void SymbolTableBaseSection::finalizeContents() {
if (OutputSection *sec = strTabSec.getParent())
  getParent()->link = sec->sectionIndex;

if (this->type != SHT_DYNSYM) {
  sortSymTabSymbols();
  return;
}

// If it is a .dynsym, there should be no local symbols, but we need
// to do a few things for the dynamic linker.

// Section's Info field has the index of the first non-local symbol.
// Because the first symbol entry is a null entry, 1 is the first.
getParent()->info = 1;

if (getPartition().gnuHashTab) {
  // NB: It also sorts Symbols to meet the GNU hash table requirements.
  getPartition().gnuHashTab->addSymbols(symbols);
} else if (config->emachine == EM_MIPS) {
  llvm::stable_sort(symbols, sortMipsSymbols);
}

// Only the main partition's dynsym indexes are stored in the symbols
// themselves. All other partitions use a lookup table.
if (this == mainPart->dynSymTab.get()) {
  size_t i = 0;
  for (const SymbolTableEntry &s : symbols)
    s.sym->dynsymIndex = ++i;
}
2109}

2111// The ELF spec requires that all local symbols precede global symbols, so we
2112// sort symbol entries in this function. (For .dynsym, we don't do that because
2113// symbols for dynamic linking are inherently all globals.)
2114//
2115// Aside from above, we put local symbols in groups starting with the STT_FILE
2116// symbol. That is convenient for purpose of identifying where are local symbols
2117// coming from.
2118void SymbolTableBaseSection::sortSymTabSymbols() {
// Move all local symbols before global symbols.
auto e = std::stable_partition(
    symbols.begin(), symbols.end(),
    [](const SymbolTableEntry &s) { return s.sym->isLocal(); });
size_t numLocals = e - symbols.begin();
getParent()->info = numLocals + 1;

// We want to group the local symbols by file. For that we rebuild the local
// part of the symbols vector. We do not need to care about the STT_FILE
// symbols, they are already naturally placed first in each group. That
// happens because STT_FILE is always the first symbol in the object and hence
// precede all other local symbols we add for a file.
MapVector<InputFile *, SmallVector<SymbolTableEntry, 0>> arr;
for (const SymbolTableEntry &s : llvm::make_range(symbols.begin(), e))
  arr[s.sym->file].push_back(s);

auto i = symbols.begin();
for (auto &p : arr)
  for (SymbolTableEntry &entry : p.second)
    *i++ = entry;
2139}

2141void SymbolTableBaseSection::addSymbol(Symbol *b) {
// Adding a local symbol to a .dynsym is a bug.
assert(this->type != SHT_DYNSYM || !b->isLocal())(static_cast <bool> (this->type != SHT_DYNSYM || !b->
isLocal()) ? void (0) : __assert_fail ("this->type != SHT_DYNSYM || !b->isLocal()"
, "lld/ELF/SyntheticSections.cpp", 2143, __extension__ __PRETTY_FUNCTION__
));
symbols.push_back({b, strTabSec.addString(b->getName(), false)});
2145}

2147size_t SymbolTableBaseSection::getSymbolIndex(Symbol *sym) {
if (this == mainPart->dynSymTab.get())
  return sym->dynsymIndex;

// Initializes symbol lookup tables lazily. This is used only for -r,
// --emit-relocs and dynsyms in partitions other than the main one.
llvm::call_once(onceFlag, [&] {
  symbolIndexMap.reserve(symbols.size());
  size_t i = 0;
  for (const SymbolTableEntry &e : symbols) {
    if (e.sym->type == STT_SECTION)
      sectionIndexMap[e.sym->getOutputSection()] = ++i;
    else
      symbolIndexMap[e.sym] = ++i;
  }
});

// Section symbols are mapped based on their output sections
// to maintain their semantics.
if (sym->type == STT_SECTION)
  return sectionIndexMap.lookup(sym->getOutputSection());
return symbolIndexMap.lookup(sym);
2169}

2171template <class ELFT>
2172SymbolTableSection<ELFT>::SymbolTableSection(StringTableSection &strTabSec)
  : SymbolTableBaseSection(strTabSec) {
this->entsize = sizeof(Elf_Sym);
2175}

2177static BssSection *getCommonSec(Symbol *sym) {
if (config->relocatable)
  if (auto *d = dyn_cast<Defined>(sym))
    return dyn_cast_or_null<BssSection>(d->section);
return nullptr;
2182}

2184static uint32_t getSymSectionIndex(Symbol *sym) {
assert(!(sym->hasFlag(NEEDS_COPY) && sym->isObject()))(static_cast <bool> (!(sym->hasFlag(NEEDS_COPY) &&
 sym->isObject())) ? void (0) : __assert_fail ("!(sym->hasFlag(NEEDS_COPY) && sym->isObject())"
, "lld/ELF/SyntheticSections.cpp", 2185, __extension__ __PRETTY_FUNCTION__
));
if (!isa<Defined>(sym) || sym->hasFlag(NEEDS_COPY))
  return SHN_UNDEF;
if (const OutputSection *os = sym->getOutputSection())
  return os->sectionIndex >= SHN_LORESERVE ? (uint32_t)SHN_XINDEX
                                           : os->sectionIndex;
return SHN_ABS;
2192}

2194// Write the internal symbol table contents to the output symbol table.
2195template <class ELFT> void SymbolTableSection<ELFT>::writeTo(uint8_t *buf) {
// The first entry is a null entry as per the ELF spec.
buf += sizeof(Elf_Sym);

auto *eSym = reinterpret_cast<Elf_Sym *>(buf);

for (SymbolTableEntry &ent : symbols) {
  Symbol *sym = ent.sym;
  bool isDefinedHere = type == SHT_SYMTAB || sym->partition == partition;

  // Set st_name, st_info and st_other.
  eSym->st_name = ent.strTabOffset;
  eSym->setBindingAndType(sym->binding, sym->type);
  eSym->st_other = sym->stOther;

  if (BssSection *commonSec = getCommonSec(sym)) {
    // When -r is specified, a COMMON symbol is not allocated. Its st_shndx
    // holds SHN_COMMON and st_value holds the alignment.
    eSym->st_shndx = SHN_COMMON;
    eSym->st_value = commonSec->addralign;
    eSym->st_size = cast<Defined>(sym)->size;
  } else {
    const uint32_t shndx = getSymSectionIndex(sym);
    if (isDefinedHere) {
      eSym->st_shndx = shndx;
      eSym->st_value = sym->getVA();
      // Copy symbol size if it is a defined symbol. st_size is not
      // significant for undefined symbols, so whether copying it or not is up
      // to us if that's the case. We'll leave it as zero because by not
      // setting a value, we can get the exact same outputs for two sets of
      // input files that differ only in undefined symbol size in DSOs.
      eSym->st_size = shndx != SHN_UNDEF ? cast<Defined>(sym)->size : 0;
    } else {
      eSym->st_shndx = 0;
      eSym->st_value = 0;
      eSym->st_size = 0;
    }
  }

  ++eSym;
}

// On MIPS we need to mark symbol which has a PLT entry and requires
// pointer equality by STO_MIPS_PLT flag. That is necessary to help
// dynamic linker distinguish such symbols and MIPS lazy-binding stubs.
// https://sourceware.org/ml/binutils/2008-07/txt00000.txt
if (config->emachine == EM_MIPS) {
  auto *eSym = reinterpret_cast<Elf_Sym *>(buf);

  for (SymbolTableEntry &ent : symbols) {
    Symbol *sym = ent.sym;
    if (sym->isInPlt() && sym->hasFlag(NEEDS_COPY))
      eSym->st_other |= STO_MIPS_PLT;
    if (isMicroMips()) {
      // We already set the less-significant bit for symbols
      // marked by the `STO_MIPS_MICROMIPS` flag and for microMIPS PLT
      // records. That allows us to distinguish such symbols in
      // the `MIPS<ELFT>::relocate()` routine. Now we should
      // clear that bit for non-dynamic symbol table, so tools
      // like `objdump` will be able to deal with a correct
      // symbol position.
      if (sym->isDefined() &&
          ((sym->stOther & STO_MIPS_MICROMIPS) || sym->hasFlag(NEEDS_COPY))) {
        if (!strTabSec.isDynamic())
          eSym->st_value &= ~1;
        eSym->st_other |= STO_MIPS_MICROMIPS;
      }
    }
    if (config->relocatable)
      if (auto *d = dyn_cast<Defined>(sym))
        if (isMipsPIC<ELFT>(d))
          eSym->st_other |= STO_MIPS_PIC;
    ++eSym;
  }
}
2270}

2272SymtabShndxSection::SymtabShndxSection()
  : SyntheticSection(0, SHT_SYMTAB_SHNDX, 4, ".symtab_shndx") {
this->entsize = 4;
2275}

2277void SymtabShndxSection::writeTo(uint8_t *buf) {
// We write an array of 32 bit values, where each value has 1:1 association
// with an entry in .symtab. If the corresponding entry contains SHN_XINDEX,
// we need to write actual index, otherwise, we must write SHN_UNDEF(0).
buf += 4; // Ignore .symtab[0] entry.
for (const SymbolTableEntry &entry : in.symTab->getSymbols()) {
  if (!getCommonSec(entry.sym) && getSymSectionIndex(entry.sym) == SHN_XINDEX)
    write32(buf, entry.sym->getOutputSection()->sectionIndex);
  buf += 4;
}
2287}

2289bool SymtabShndxSection::isNeeded() const {
// SHT_SYMTAB can hold symbols with section indices values up to
// SHN_LORESERVE. If we need more, we want to use extension SHT_SYMTAB_SHNDX
// section. Problem is that we reveal the final section indices a bit too
// late, and we do not know them here. For simplicity, we just always create
// a .symtab_shndx section when the amount of output sections is huge.
size_t size = 0;
for (SectionCommand *cmd : script->sectionCommands)
  if (isa<OutputDesc>(cmd))
    ++size;
return size >= SHN_LORESERVE;
2300}

2302void SymtabShndxSection::finalizeContents() {
getParent()->link = in.symTab->getParent()->sectionIndex;
2304}

2306size_t SymtabShndxSection::getSize() const {
return in.symTab->getNumSymbols() * 4;
2308}

2310// .hash and .gnu.hash sections contain on-disk hash tables that map
2311// symbol names to their dynamic symbol table indices. Their purpose
2312// is to help the dynamic linker resolve symbols quickly. If ELF files
2313// don't have them, the dynamic linker has to do linear search on all
2314// dynamic symbols, which makes programs slower. Therefore, a .hash
2315// section is added to a DSO by default.
2316//
2317// The Unix semantics of resolving dynamic symbols is somewhat expensive.
2318// Each ELF file has a list of DSOs that the ELF file depends on and a
2319// list of dynamic symbols that need to be resolved from any of the
2320// DSOs. That means resolving all dynamic symbols takes O(m)*O(n)
2321// where m is the number of DSOs and n is the number of dynamic
2322// symbols. For modern large programs, both m and n are large.  So
2323// making each step faster by using hash tables substantially
2324// improves time to load programs.
2325//
2326// (Note that this is not the only way to design the shared library.
2327// For instance, the Windows DLL takes a different approach. On
2328// Windows, each dynamic symbol has a name of DLL from which the symbol
2329// has to be resolved. That makes the cost of symbol resolution O(n).
2330// This disables some hacky techniques you can use on Unix such as
2331// LD_PRELOAD, but this is arguably better semantics than the Unix ones.)
2332//
2333// Due to historical reasons, we have two different hash tables, .hash
2334// and .gnu.hash. They are for the same purpose, and .gnu.hash is a new
2335// and better version of .hash. .hash is just an on-disk hash table, but
2336// .gnu.hash has a bloom filter in addition to a hash table to skip
2337// DSOs very quickly. If you are sure that your dynamic linker knows
2338// about .gnu.hash, you want to specify --hash-style=gnu. Otherwise, a
2339// safe bet is to specify --hash-style=both for backward compatibility.
2340GnuHashTableSection::GnuHashTableSection()
  : SyntheticSection(SHF_ALLOC, SHT_GNU_HASH, config->wordsize, ".gnu.hash") {
2342}

2344void GnuHashTableSection::finalizeContents() {
if (OutputSection *sec = getPartition().dynSymTab->getParent())
  getParent()->link = sec->sectionIndex;

// Computes bloom filter size in word size. We want to allocate 12
// bits for each symbol. It must be a power of two.
if (symbols.empty()) {
  maskWords = 1;
} else {
  uint64_t numBits = symbols.size() * 12;
  maskWords = NextPowerOf2(numBits / (config->wordsize * 8));
}

size = 16;                            // Header
size += config->wordsize * maskWords; // Bloom filter
size += nBuckets * 4;                 // Hash buckets
size += symbols.size() * 4;           // Hash values
2361}

2363void GnuHashTableSection::writeTo(uint8_t *buf) {
// Write a header.
write32(buf, nBuckets);
write32(buf + 4, getPartition().dynSymTab->getNumSymbols() - symbols.size());
write32(buf + 8, maskWords);
write32(buf + 12, Shift2);
buf += 16;

// Write the 2-bit bloom filter.
const unsigned c = config->is64 ? 64 : 32;
for (const Entry &sym : symbols) {
  // When C = 64, we choose a word with bits [6:...] and set 1 to two bits in
  // the word using bits [0:5] and [26:31].
  size_t i = (sym.hash / c) & (maskWords - 1);
  uint64_t val = readUint(buf + i * config->wordsize);
  val |= uint64_t(1) << (sym.hash % c);
  val |= uint64_t(1) << ((sym.hash >> Shift2) % c);
  writeUint(buf + i * config->wordsize, val);
}
buf += config->wordsize * maskWords;

// Write the hash table.
uint32_t *buckets = reinterpret_cast<uint32_t *>(buf);
uint32_t oldBucket = -1;
uint32_t *values = buckets + nBuckets;
for (auto i = symbols.begin(), e = symbols.end(); i != e; ++i) {
  // Write a hash value. It represents a sequence of chains that share the
  // same hash modulo value. The last element of each chain is terminated by
  // LSB 1.
  uint32_t hash = i->hash;
  bool isLastInChain = (i + 1) == e || i->bucketIdx != (i + 1)->bucketIdx;
  hash = isLastInChain ? hash | 1 : hash & ~1;
  write32(values++, hash);

  if (i->bucketIdx == oldBucket)
    continue;
  // Write a hash bucket. Hash buckets contain indices in the following hash
  // value table.
  write32(buckets + i->bucketIdx,
          getPartition().dynSymTab->getSymbolIndex(i->sym));
  oldBucket = i->bucketIdx;
}
2405}

2407// Add symbols to this symbol hash table. Note that this function
2408// destructively sort a given vector -- which is needed because
2409// GNU-style hash table places some sorting requirements.
2410void GnuHashTableSection::addSymbols(SmallVectorImpl<SymbolTableEntry> &v) {
// We cannot use 'auto' for Mid because GCC 6.1 cannot deduce
// its type correctly.
auto mid =
    std::stable_partition(v.begin(), v.end(), [&](const SymbolTableEntry &s) {
      return !s.sym->isDefined() || s.sym->partition != partition;
    });

// We chose load factor 4 for the on-disk hash table. For each hash
// collision, the dynamic linker will compare a uint32_t hash value.
// Since the integer comparison is quite fast, we believe we can
// make the load factor even larger. 4 is just a conservative choice.
//
// Note that we don't want to create a zero-sized hash table because
// Android loader as of 2018 doesn't like a .gnu.hash containing such
// table. If that's the case, we create a hash table with one unused
// dummy slot.
nBuckets = std::max<size_t>((v.end() - mid) / 4, 1);

if (mid == v.end())
  return;

for (SymbolTableEntry &ent : llvm::make_range(mid, v.end())) {
  Symbol *b = ent.sym;
  uint32_t hash = hashGnu(b->getName());
  uint32_t bucketIdx = hash % nBuckets;
  symbols.push_back({b, ent.strTabOffset, hash, bucketIdx});
}

llvm::sort(symbols, [](const Entry &l, const Entry &r) {
  return std::tie(l.bucketIdx, l.strTabOffset) <
         std::tie(r.bucketIdx, r.strTabOffset);
});

v.erase(mid, v.end());
for (const Entry &ent : symbols)
  v.push_back({ent.sym, ent.strTabOffset});
2447}

2449HashTableSection::HashTableSection()
  : SyntheticSection(SHF_ALLOC, SHT_HASH, 4, ".hash") {
this->entsize = 4;
2452}

2454void HashTableSection::finalizeContents() {
SymbolTableBaseSection *symTab = getPartition().dynSymTab.get();

if (OutputSection *sec = symTab->getParent())
  getParent()->link = sec->sectionIndex;

unsigned numEntries = 2;               // nbucket and nchain.
numEntries += symTab->getNumSymbols(); // The chain entries.

// Create as many buckets as there are symbols.
numEntries += symTab->getNumSymbols();
this->size = numEntries * 4;
2466}

2468void HashTableSection::writeTo(uint8_t *buf) {
SymbolTableBaseSection *symTab = getPartition().dynSymTab.get();
unsigned numSymbols = symTab->getNumSymbols();

uint32_t *p = reinterpret_cast<uint32_t *>(buf);
write32(p++, numSymbols); // nbucket
write32(p++, numSymbols); // nchain

uint32_t *buckets = p;
uint32_t *chains = p + numSymbols;

for (const SymbolTableEntry &s : symTab->getSymbols()) {
  Symbol *sym = s.sym;
  StringRef name = sym->getName();
  unsigned i = sym->dynsymIndex;
  uint32_t hash = hashSysV(name) % numSymbols;
  chains[i] = buckets[hash];
  write32(buckets + hash, i);
}
2487}

2489PltSection::PltSection()
  : SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16, ".plt"),
    headerSize(target->pltHeaderSize) {
// On PowerPC, this section contains lazy symbol resolvers.
if (config->emachine == EM_PPC64) {
  name = ".glink";
  addralign = 4;
}

// On x86 when IBT is enabled, this section contains the second PLT (lazy
// symbol resolvers).
if ((config->emachine == EM_386 || config->emachine == EM_X86_64) &&
    (config->andFeatures & GNU_PROPERTY_X86_FEATURE_1_IBT))
  name = ".plt.sec";

// The PLT needs to be writable on SPARC as the dynamic linker will
// modify the instructions in the PLT entries.
if (config->emachine == EM_SPARCV9)
  this->flags |= SHF_WRITE;
2508}

2510void PltSection::writeTo(uint8_t *buf) {
// At beginning of PLT, we have code to call the dynamic
// linker to resolve dynsyms at runtime. Write such code.
target->writePltHeader(buf);
size_t off = headerSize;

for (const Symbol *sym : entries) {
  target->writePlt(buf + off, *sym, getVA() + off);
  off += target->pltEntrySize;
}
2520}

2522void PltSection::addEntry(Symbol &sym) {
assert(sym.auxIdx == symAux.size() - 1)(static_cast <bool> (sym.auxIdx == symAux.size() - 1) ?
 void (0) : __assert_fail ("sym.auxIdx == symAux.size() - 1",
 "lld/ELF/SyntheticSections.cpp", 2523, __extension__ __PRETTY_FUNCTION__
));
symAux.back().pltIdx = entries.size();
entries.push_back(&sym);
2526}

2528size_t PltSection::getSize() const {
return headerSize + entries.size() * target->pltEntrySize;
2530}

2532bool PltSection::isNeeded() const {
// For -z retpolineplt, .iplt needs the .plt header.
return !entries.empty() || (config->zRetpolineplt && in.iplt->isNeeded());
2535}

2537// Used by ARM to add mapping symbols in the PLT section, which aid
2538// disassembly.
2539void PltSection::addSymbols() {
target->addPltHeaderSymbols(*this);

size_t off = headerSize;
for (size_t i = 0; i < entries.size(); ++i) {
  target->addPltSymbols(*this, off);
  off += target->pltEntrySize;
}
2547}

2549IpltSection::IpltSection()
  : SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16, ".iplt") {
if (config->emachine == EM_PPC || config->emachine == EM_PPC64) {
  name = ".glink";
  addralign = 4;
}
2555}

2557void IpltSection::writeTo(uint8_t *buf) {
uint32_t off = 0;
for (const Symbol *sym : entries) {
  target->writeIplt(buf + off, *sym, getVA() + off);
  off += target->ipltEntrySize;
}
2563}

2565size_t IpltSection::getSize() const {
return entries.size() * target->ipltEntrySize;
2567}

2569void IpltSection::addEntry(Symbol &sym) {
assert(sym.auxIdx == symAux.size() - 1)(static_cast <bool> (sym.auxIdx == symAux.size() - 1) ?
 void (0) : __assert_fail ("sym.auxIdx == symAux.size() - 1",
 "lld/ELF/SyntheticSections.cpp", 2570, __extension__ __PRETTY_FUNCTION__
));
symAux.back().pltIdx = entries.size();
entries.push_back(&sym);
2573}

2575// ARM uses mapping symbols to aid disassembly.
2576void IpltSection::addSymbols() {
size_t off = 0;
for (size_t i = 0, e = entries.size(); i != e; ++i) {
  target->addPltSymbols(*this, off);
  off += target->pltEntrySize;
}
2582}

2584PPC32GlinkSection::PPC32GlinkSection() {
name = ".glink";
addralign = 4;
2587}

2589void PPC32GlinkSection::writeTo(uint8_t *buf) {
writePPC32GlinkSection(buf, entries.size());
2591}

2593size_t PPC32GlinkSection::getSize() const {
return headerSize + entries.size() * target->pltEntrySize + footerSize;
2595}

2597// This is an x86-only extra PLT section and used only when a security
2598// enhancement feature called CET is enabled. In this comment, I'll explain what
2599// the feature is and why we have two PLT sections if CET is enabled.
2600//
2601// So, what does CET do? CET introduces a new restriction to indirect jump
2602// instructions. CET works this way. Assume that CET is enabled. Then, if you
2603// execute an indirect jump instruction, the processor verifies that a special
2604// "landing pad" instruction (which is actually a repurposed NOP instruction and
2605// now called "endbr32" or "endbr64") is at the jump target. If the jump target
2606// does not start with that instruction, the processor raises an exception
2607// instead of continuing executing code.
2608//
2609// If CET is enabled, the compiler emits endbr to all locations where indirect
2610// jumps may jump to.
2611//
2612// This mechanism makes it extremely hard to transfer the control to a middle of
2613// a function that is not supporsed to be a indirect jump target, preventing
2614// certain types of attacks such as ROP or JOP.
2615//
2616// Note that the processors in the market as of 2019 don't actually support the
2617// feature. Only the spec is available at the moment.
2618//
2619// Now, I'll explain why we have this extra PLT section for CET.
2620//
2621// Since you can indirectly jump to a PLT entry, we have to make PLT entries
2622// start with endbr. The problem is there's no extra space for endbr (which is 4
2623// bytes long), as the PLT entry is only 16 bytes long and all bytes are already
2624// used.
2625//
2626// In order to deal with the issue, we split a PLT entry into two PLT entries.
2627// Remember that each PLT entry contains code to jump to an address read from
2628// .got.plt AND code to resolve a dynamic symbol lazily. With the 2-PLT scheme,
2629// the former code is written to .plt.sec, and the latter code is written to
2630// .plt.
2631//
2632// Lazy symbol resolution in the 2-PLT scheme works in the usual way, except
2633// that the regular .plt is now called .plt.sec and .plt is repurposed to
2634// contain only code for lazy symbol resolution.
2635//
2636// In other words, this is how the 2-PLT scheme works. Application code is
2637// supposed to jump to .plt.sec to call an external function. Each .plt.sec
2638// entry contains code to read an address from a corresponding .got.plt entry
2639// and jump to that address. Addresses in .got.plt initially point to .plt, so
2640// when an application calls an external function for the first time, the
2641// control is transferred to a function that resolves a symbol name from
2642// external shared object files. That function then rewrites a .got.plt entry
2643// with a resolved address, so that the subsequent function calls directly jump
2644// to a desired location from .plt.sec.
2645//
2646// There is an open question as to whether the 2-PLT scheme was desirable or
2647// not. We could have simply extended the PLT entry size to 32-bytes to
2648// accommodate endbr, and that scheme would have been much simpler than the
2649// 2-PLT scheme. One reason to split PLT was, by doing that, we could keep hot
2650// code (.plt.sec) from cold code (.plt). But as far as I know no one proved
2651// that the optimization actually makes a difference.
2652//
2653// That said, the 2-PLT scheme is a part of the ABI, debuggers and other tools
2654// depend on it, so we implement the ABI.
2655IBTPltSection::IBTPltSection()
  : SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS, 16, ".plt") {}

2658void IBTPltSection::writeTo(uint8_t *buf) {
target->writeIBTPlt(buf, in.plt->getNumEntries());
2660}

2662size_t IBTPltSection::getSize() const {
// 16 is the header size of .plt.
return 16 + in.plt->getNumEntries() * target->pltEntrySize;
2665}

2667bool IBTPltSection::isNeeded() const { return in.plt->getNumEntries() > 0; }

2669// The string hash function for .gdb_index.
2670static uint32_t computeGdbHash(StringRef s) {
uint32_t h = 0;
for (uint8_t c : s)
  h = h * 67 + toLower(c) - 113;
return h;
2675}

2677GdbIndexSection::GdbIndexSection()
  : SyntheticSection(0, SHT_PROGBITS, 1, ".gdb_index") {}

2680// Returns the desired size of an on-disk hash table for a .gdb_index section.
2681// There's a tradeoff between size and collision rate. We aim 75% utilization.
2682size_t GdbIndexSection::computeSymtabSize() const {
return std::max<size_t>(NextPowerOf2(symbols.size() * 4 / 3), 1024);
2684}

2686static SmallVector<GdbIndexSection::CuEntry, 0>
2687readCuList(DWARFContext &dwarf) {
SmallVector<GdbIndexSection::CuEntry, 0> ret;
for (std::unique_ptr<DWARFUnit> &cu : dwarf.compile_units())
  ret.push_back({cu->getOffset(), cu->getLength() + 4});
return ret;
2692}

2694static SmallVector<GdbIndexSection::AddressEntry, 0>
2695readAddressAreas(DWARFContext &dwarf, InputSection *sec) {
SmallVector<GdbIndexSection::AddressEntry, 0> ret;

uint32_t cuIdx = 0;
for (std::unique_ptr<DWARFUnit> &cu : dwarf.compile_units()) {
  if (Error e = cu->tryExtractDIEsIfNeeded(false)) {
    warn(toString(sec) + ": " + toString(std::move(e)));
    return {};
  }
  Expected<DWARFAddressRangesVector> ranges = cu->collectAddressRanges();
  if (!ranges) {
    warn(toString(sec) + ": " + toString(ranges.takeError()));
    return {};
  }

  ArrayRef<InputSectionBase *> sections = sec->file->getSections();
  for (DWARFAddressRange &r : *ranges) {
    if (r.SectionIndex == -1ULL)
      continue;
    // Range list with zero size has no effect.
    InputSectionBase *s = sections[r.SectionIndex];
    if (s && s != &InputSection::discarded && s->isLive())
      if (r.LowPC != r.HighPC)
        ret.push_back({cast<InputSection>(s), r.LowPC, r.HighPC, cuIdx});
  }
  ++cuIdx;
}

return ret;
2724}

2726template <class ELFT>
2727static SmallVector<GdbIndexSection::NameAttrEntry, 0>
2728readPubNamesAndTypes(const LLDDwarfObj<ELFT> &obj,
                   const SmallVectorImpl<GdbIndexSection::CuEntry> &cus) {
const LLDDWARFSection &pubNames = obj.getGnuPubnamesSection();
const LLDDWARFSection &pubTypes = obj.getGnuPubtypesSection();

SmallVector<GdbIndexSection::NameAttrEntry, 0> ret;
for (const LLDDWARFSection *pub : {&pubNames, &pubTypes}) {
  DWARFDataExtractor data(obj, *pub, config->isLE, config->wordsize);
  DWARFDebugPubTable table;
  table.extract(data, /*GnuStyle=*/true, [&](Error e) {
    warn(toString(pub->sec) + ": " + toString(std::move(e)));
  });
  for (const DWARFDebugPubTable::Set &set : table.getData()) {
    // The value written into the constant pool is kind << 24 | cuIndex. As we
    // don't know how many compilation units precede this object to compute
    // cuIndex, we compute (kind << 24 | cuIndexInThisObject) instead, and add
    // the number of preceding compilation units later.
    uint32_t i = llvm::partition_point(cus,
                                       [&](GdbIndexSection::CuEntry cu) {
                                         return cu.cuOffset < set.Offset;
                                       }) -
                 cus.begin();
    for (const DWARFDebugPubTable::Entry &ent : set.Entries)
      ret.push_back({{ent.Name, computeGdbHash(ent.Name)},
                     (ent.Descriptor.toBits() << 24) | i});
  }
}
return ret;
2756}

2758// Create a list of symbols from a given list of symbol names and types
2759// by uniquifying them by name.
2760static std::pair<SmallVector<GdbIndexSection::GdbSymbol, 0>, size_t>
2761createSymbols(
  ArrayRef<SmallVector<GdbIndexSection::NameAttrEntry, 0>> nameAttrs,
  const SmallVector<GdbIndexSection::GdbChunk, 0> &chunks) {
using GdbSymbol = GdbIndexSection::GdbSymbol;
using NameAttrEntry = GdbIndexSection::NameAttrEntry;

// For each chunk, compute the number of compilation units preceding it.
uint32_t cuIdx = 0;
std::unique_ptr<uint32_t[]> cuIdxs(new uint32_t[chunks.size()]);
for (uint32_t i = 0, e = chunks.size(); i != e; ++i) {
  cuIdxs[i] = cuIdx;
  cuIdx += chunks[i].compilationUnits.size();
}

// The number of symbols we will handle in this function is of the order
// of millions for very large executables, so we use multi-threading to
// speed it up.
constexpr size_t numShards = 32;
const size_t concurrency =
    llvm::bit_floor(std::min<size_t>(config->threadCount, numShards));

// A sharded map to uniquify symbols by name.
auto map =
    std::make_unique<DenseMap<CachedHashStringRef, size_t>[]>(numShards);
size_t shift = 32 - llvm::countr_zero(numShards);

// Instantiate GdbSymbols while uniqufying them by name.
auto symbols = std::make_unique<SmallVector<GdbSymbol, 0>[]>(numShards);

parallelFor(0, concurrency, [&](size_t threadId) {
  uint32_t i = 0;
  for (ArrayRef<NameAttrEntry> entries : nameAttrs) {
    for (const NameAttrEntry &ent : entries) {
      size_t shardId = ent.name.hash() >> shift;
      if ((shardId & (concurrency - 1)) != threadId)
        continue;

      uint32_t v = ent.cuIndexAndAttrs + cuIdxs[i];
      size_t &idx = map[shardId][ent.name];
      if (idx) {
        symbols[shardId][idx - 1].cuVector.push_back(v);
        continue;
      }

      idx = symbols[shardId].size() + 1;
      symbols[shardId].push_back({ent.name, {v}, 0, 0});
    }
    ++i;
  }
});

size_t numSymbols = 0;
for (ArrayRef<GdbSymbol> v : ArrayRef(symbols.get(), numShards))
  numSymbols += v.size();

// The return type is a flattened vector, so we'll copy each vector
// contents to Ret.
SmallVector<GdbSymbol, 0> ret;
ret.reserve(numSymbols);
for (SmallVector<GdbSymbol, 0> &vec :
     MutableArrayRef(symbols.get(), numShards))
  for (GdbSymbol &sym : vec)
    ret.push_back(std::move(sym));

// CU vectors and symbol names are adjacent in the output file.
// We can compute their offsets in the output file now.
size_t off = 0;
for (GdbSymbol &sym : ret) {
  sym.cuVectorOff = off;
  off += (sym.cuVector.size() + 1) * 4;
}
for (GdbSymbol &sym : ret) {
  sym.nameOff = off;
  off += sym.name.size() + 1;
}
// If off overflows, the last symbol's nameOff likely overflows.
if (!isUInt<32>(off))
  errorOrWarn("--gdb-index: constant pool size (" + Twine(off) +
              ") exceeds UINT32_MAX");

return {ret, off};
2842}

2844// Returns a newly-created .gdb_index section.
2845template <class ELFT> GdbIndexSection *GdbIndexSection::create() {
llvm::TimeTraceScope timeScope("Create gdb index");

// Collect InputFiles with .debug_info. See the comment in
// LLDDwarfObj<ELFT>::LLDDwarfObj. If we do lightweight parsing in the future,
// note that isec->data() may uncompress the full content, which should be
// parallelized.
SetVector<InputFile *> files;
for (InputSectionBase *s : ctx.inputSections) {
  InputSection *isec = dyn_cast<InputSection>(s);
  if (!isec)
    continue;
  // .debug_gnu_pub{names,types} are useless in executables.
  // They are present in input object files solely for creating
  // a .gdb_index. So we can remove them from the output.
  if (s->name == ".debug_gnu_pubnames" || s->name == ".debug_gnu_pubtypes")
    s->markDead();
  else if (isec->name == ".debug_info")
    files.insert(isec->file);
}
// Drop .rel[a].debug_gnu_pub{names,types} for --emit-relocs.
llvm::erase_if(ctx.inputSections, [](InputSectionBase *s) {
  if (auto *isec = dyn_cast<InputSection>(s))
    if (InputSectionBase *rel = isec->getRelocatedSection())
      return !rel->isLive();
  return !s->isLive();
});

SmallVector<GdbChunk, 0> chunks(files.size());
SmallVector<SmallVector<NameAttrEntry, 0>, 0> nameAttrs(files.size());

parallelFor(0, files.size(), [&](size_t i) {
  // To keep memory usage low, we don't want to keep cached DWARFContext, so
  // avoid getDwarf() here.
  ObjFile<ELFT> *file = cast<ObjFile<ELFT>>(files[i]);
  DWARFContext dwarf(std::make_unique<LLDDwarfObj<ELFT>>(file));
  auto &dobj = static_cast<const LLDDwarfObj<ELFT> &>(dwarf.getDWARFObj());

  // If the are multiple compile units .debug_info (very rare ld -r --unique),
  // this only picks the last one. Other address ranges are lost.
  chunks[i].sec = dobj.getInfoSection();
  chunks[i].compilationUnits = readCuList(dwarf);
  chunks[i].addressAreas = readAddressAreas(dwarf, chunks[i].sec);
  nameAttrs[i] = readPubNamesAndTypes<ELFT>(dobj, chunks[i].compilationUnits);
});

auto *ret = make<GdbIndexSection>();
ret->chunks = std::move(chunks);
std::tie(ret->symbols, ret->size) = createSymbols(nameAttrs, ret->chunks);

// Count the areas other than the constant pool.
ret->size += sizeof(GdbIndexHeader) + ret->computeSymtabSize() * 8;
for (GdbChunk &chunk : ret->chunks)
  ret->size +=
      chunk.compilationUnits.size() * 16 + chunk.addressAreas.size() * 20;

return ret;
2902}

2904void GdbIndexSection::writeTo(uint8_t *buf) {
// Write the header.
auto *hdr = reinterpret_cast<GdbIndexHeader *>(buf);
uint8_t *start = buf;
hdr->version = 7;
buf += sizeof(*hdr);

// Write the CU list.
hdr->cuListOff = buf - start;
for (GdbChunk &chunk : chunks) {
  for (CuEntry &cu : chunk.compilationUnits) {
    write64le(buf, chunk.sec->outSecOff + cu.cuOffset);
    write64le(buf + 8, cu.cuLength);
    buf += 16;
  }
}

// Write the address area.
hdr->cuTypesOff = buf - start;
hdr->addressAreaOff = buf - start;
uint32_t cuOff = 0;
for (GdbChunk &chunk : chunks) {
  for (AddressEntry &e : chunk.addressAreas) {
    // In the case of ICF there may be duplicate address range entries.
    const uint64_t baseAddr = e.section->repl->getVA(0);
    write64le(buf, baseAddr + e.lowAddress);
    write64le(buf + 8, baseAddr + e.highAddress);
    write32le(buf + 16, e.cuIndex + cuOff);
    buf += 20;
  }
  cuOff += chunk.compilationUnits.size();
}

// Write the on-disk open-addressing hash table containing symbols.
hdr->symtabOff = buf - start;
size_t symtabSize = computeSymtabSize();
uint32_t mask = symtabSize - 1;

for (GdbSymbol &sym : symbols) {
  uint32_t h = sym.name.hash();
  uint32_t i = h & mask;
  uint32_t step = ((h * 17) & mask) | 1;

  while (read32le(buf + i * 8))
    i = (i + step) & mask;

  write32le(buf + i * 8, sym.nameOff);
  write32le(buf + i * 8 + 4, sym.cuVectorOff);
}

buf += symtabSize * 8;

// Write the string pool.
hdr->constantPoolOff = buf - start;
parallelForEach(symbols, [&](GdbSymbol &sym) {
  memcpy(buf + sym.nameOff, sym.name.data(), sym.name.size());
});

// Write the CU vectors.
for (GdbSymbol &sym : symbols) {
  write32le(buf, sym.cuVector.size());
  buf += 4;
  for (uint32_t val : sym.cuVector) {
    write32le(buf, val);
    buf += 4;
  }
}
2971}

2973bool GdbIndexSection::isNeeded() const { return !chunks.empty(); }

2975EhFrameHeader::EhFrameHeader()
  : SyntheticSection(SHF_ALLOC, SHT_PROGBITS, 4, ".eh_frame_hdr") {}

2978void EhFrameHeader::writeTo(uint8_t *buf) {
// Unlike most sections, the EhFrameHeader section is written while writing
// another section, namely EhFrameSection, which calls the write() function
// below from its writeTo() function. This is necessary because the contents
// of EhFrameHeader depend on the relocated contents of EhFrameSection and we
// don't know which order the sections will be written in.
2984}

2986// .eh_frame_hdr contains a binary search table of pointers to FDEs.
2987// Each entry of the search table consists of two values,
2988// the starting PC from where FDEs covers, and the FDE's address.
2989// It is sorted by PC.
2990void EhFrameHeader::write() {
uint8_t *buf = Out::bufferStart + getParent()->offset + outSecOff;
using FdeData = EhFrameSection::FdeData;
SmallVector<FdeData, 0> fdes = getPartition().ehFrame->getFdeData();

buf[0] = 1;
buf[1] = DW_EH_PE_pcrel | DW_EH_PE_sdata4;
buf[2] = DW_EH_PE_udata4;
buf[3] = DW_EH_PE_datarel | DW_EH_PE_sdata4;
write32(buf + 4,
        getPartition().ehFrame->getParent()->addr - this->getVA() - 4);
write32(buf + 8, fdes.size());
buf += 12;

for (FdeData &fde : fdes) {
  write32(buf, fde.pcRel);
  write32(buf + 4, fde.fdeVARel);
  buf += 8;
}
3009}

3011size_t EhFrameHeader::getSize() const {
// .eh_frame_hdr has a 12 bytes header followed by an array of FDEs.
return 12 + getPartition().ehFrame->numFdes * 8;
3014}

3016bool EhFrameHeader::isNeeded() const {
return isLive() && getPartition().ehFrame->isNeeded();
3018}

3020VersionDefinitionSection::VersionDefinitionSection()
  : SyntheticSection(SHF_ALLOC, SHT_GNU_verdef, sizeof(uint32_t),
                     ".gnu.version_d") {}

3024StringRef VersionDefinitionSection::getFileDefName() {
if (!getPartition().name.empty())
  return getPartition().name;
if (!config->soName.empty())
  return config->soName;
return config->outputFile;
3030}

3032void VersionDefinitionSection::finalizeContents() {
fileDefNameOff = getPartition().dynStrTab->addString(getFileDefName());
for (const VersionDefinition &v : namedVersionDefs())
  verDefNameOffs.push_back(getPartition().dynStrTab->addString(v.name));

if (OutputSection *sec = getPartition().dynStrTab->getParent())
  getParent()->link = sec->sectionIndex;

// sh_info should be set to the number of definitions. This fact is missed in
// documentation, but confirmed by binutils community:
// https://sourceware.org/ml/binutils/2014-11/msg00355.html
getParent()->info = getVerDefNum();
3044}

3046void VersionDefinitionSection::writeOne(uint8_t *buf, uint32_t index,
                                      StringRef name, size_t nameOff) {
uint16_t flags = index == 1 ? VER_FLG_BASE : 0;

// Write a verdef.
write16(buf, 1);                  // vd_version
write16(buf + 2, flags);          // vd_flags
write16(buf + 4, index);          // vd_ndx
write16(buf + 6, 1);              // vd_cnt
write32(buf + 8, hashSysV(name)); // vd_hash
write32(buf + 12, 20);            // vd_aux
write32(buf + 16, 28);            // vd_next

// Write a veraux.
write32(buf + 20, nameOff); // vda_name
write32(buf + 24, 0);       // vda_next
3062}

3064void VersionDefinitionSection::writeTo(uint8_t *buf) {
writeOne(buf, 1, getFileDefName(), fileDefNameOff);

auto nameOffIt = verDefNameOffs.begin();
for (const VersionDefinition &v : namedVersionDefs()) {
  buf += EntrySize;
  writeOne(buf, v.id, v.name, *nameOffIt++);
}

// Need to terminate the last version definition.
write32(buf + 16, 0); // vd_next
3075}

3077size_t VersionDefinitionSection::getSize() const {
return EntrySize * getVerDefNum();
3079}

3081// .gnu.version is a table where each entry is 2 byte long.
3082VersionTableSection::VersionTableSection()
  : SyntheticSection(SHF_ALLOC, SHT_GNU_versym, sizeof(uint16_t),
                     ".gnu.version") {
this->entsize = 2;
3086}

3088void VersionTableSection::finalizeContents() {
// At the moment of june 2016 GNU docs does not mention that sh_link field
// should be set, but Sun docs do. Also readelf relies on this field.
getParent()->link = getPartition().dynSymTab->getParent()->sectionIndex;
3092}

3094size_t VersionTableSection::getSize() const {
return (getPartition().dynSymTab->getSymbols().size() + 1) * 2;
3096}

3098void VersionTableSection::writeTo(uint8_t *buf) {
buf += 2;
for (const SymbolTableEntry &s : getPartition().dynSymTab->getSymbols()) {
  // For an unextracted lazy symbol (undefined weak), it must have been
  // converted to Undefined and have VER_NDX_GLOBAL version here.
  assert(!s.sym->isLazy())(static_cast <bool> (!s.sym->isLazy()) ? void (0) : __assert_fail
 ("!s.sym->isLazy()", "lld/ELF/SyntheticSections.cpp", 3103
, __extension__ __PRETTY_FUNCTION__));
  write16(buf, s.sym->versionId);
  buf += 2;
}
3107}

3109bool VersionTableSection::isNeeded() const {
return isLive() &&
       (getPartition().verDef || getPartition().verNeed->isNeeded());
3112}

3114void elf::addVerneed(Symbol *ss) {
auto &file = cast<SharedFile>(*ss->file);
if (ss->verdefIndex == VER_NDX_GLOBAL) {
  ss->versionId = VER_NDX_GLOBAL;
  return;
}

if (file.vernauxs.empty())
  file.vernauxs.resize(file.verdefs.size());

// Select a version identifier for the vernaux data structure, if we haven't
// already allocated one. The verdef identifiers cover the range
// [1..getVerDefNum()]; this causes the vernaux identifiers to start from
// getVerDefNum()+1.
if (file.vernauxs[ss->verdefIndex] == 0)
  file.vernauxs[ss->verdefIndex] = ++SharedFile::vernauxNum + getVerDefNum();

ss->versionId = file.vernauxs[ss->verdefIndex];
3132}

3134template <class ELFT>
3135VersionNeedSection<ELFT>::VersionNeedSection()
  : SyntheticSection(SHF_ALLOC, SHT_GNU_verneed, sizeof(uint32_t),
                     ".gnu.version_r") {}

3139template <class ELFT> void VersionNeedSection<ELFT>::finalizeContents() {
for (SharedFile *f : ctx.sharedFiles) {
  if (f->vernauxs.empty())
    continue;
  verneeds.emplace_back();
  Verneed &vn = verneeds.back();
  vn.nameStrTab = getPartition().dynStrTab->addString(f->soName);
  bool isLibc = config->relrGlibc && f->soName.startswith("libc.so.");
  bool isGlibc2 = false;
  for (unsigned i = 0; i != f->vernauxs.size(); ++i) {
    if (f->vernauxs[i] == 0)
      continue;
    auto *verdef =
        reinterpret_cast<const typename ELFT::Verdef *>(f->verdefs[i]);
    StringRef ver(f->getStringTable().data() + verdef->getAux()->vda_name);
    if (isLibc && ver.startswith("GLIBC_2."))
      isGlibc2 = true;
    vn.vernauxs.push_back({verdef->vd_hash, f->vernauxs[i],
                           getPartition().dynStrTab->addString(ver)});
  }
  if (isGlibc2) {
    const char *ver = "GLIBC_ABI_DT_RELR";
    vn.vernauxs.push_back({hashSysV(ver),
                           ++SharedFile::vernauxNum + getVerDefNum(),
                           getPartition().dynStrTab->addString(ver)});
  }
}

if (OutputSection *sec = getPartition().dynStrTab->getParent())
  getParent()->link = sec->sectionIndex;
getParent()->info = verneeds.size();
3170}

3172template <class ELFT> void VersionNeedSection<ELFT>::writeTo(uint8_t *buf) {
// The Elf_Verneeds need to appear first, followed by the Elf_Vernauxs.
auto *verneed = reinterpret_cast<Elf_Verneed *>(buf);
auto *vernaux = reinterpret_cast<Elf_Vernaux *>(verneed + verneeds.size());

for (auto &vn : verneeds) {
  // Create an Elf_Verneed for this DSO.
  verneed->vn_version = 1;
  verneed->vn_cnt = vn.vernauxs.size();
  verneed->vn_file = vn.nameStrTab;
  verneed->vn_aux =
      reinterpret_cast<char *>(vernaux) - reinterpret_cast<char *>(verneed);
  verneed->vn_next = sizeof(Elf_Verneed);
  ++verneed;

  // Create the Elf_Vernauxs for this Elf_Verneed.
  for (auto &vna : vn.vernauxs) {
    vernaux->vna_hash = vna.hash;
    vernaux->vna_flags = 0;
    vernaux->vna_other = vna.verneedIndex;
    vernaux->vna_name = vna.nameStrTab;
    vernaux->vna_next = sizeof(Elf_Vernaux);
    ++vernaux;
  }

  vernaux[-1].vna_next = 0;
}
verneed[-1].vn_next = 0;
3200}

3202template <class ELFT> size_t VersionNeedSection<ELFT>::getSize() const {
return verneeds.size() * sizeof(Elf_Verneed) +
       SharedFile::vernauxNum * sizeof(Elf_Vernaux);
3205}

3207template <class ELFT> bool VersionNeedSection<ELFT>::isNeeded() const {
return isLive() && SharedFile::vernauxNum != 0;
3209}

3211void MergeSyntheticSection::addSection(MergeInputSection *ms) {
ms->parent = this;
sections.push_back(ms);
assert(addralign == ms->addralign || !(ms->flags & SHF_STRINGS))(static_cast <bool> (addralign == ms->addralign || !
(ms->flags & SHF_STRINGS)) ? void (0) : __assert_fail (
"addralign == ms->addralign || !(ms->flags & SHF_STRINGS)"
, "lld/ELF/SyntheticSections.cpp", 3214, __extension__ __PRETTY_FUNCTION__
));
addralign = std::max(addralign, ms->addralign);
3216}

3218MergeTailSection::MergeTailSection(StringRef name, uint32_t type,
                                 uint64_t flags, uint32_t alignment)
  : MergeSyntheticSection(name, type, flags, alignment),
    builder(StringTableBuilder::RAW, llvm::Align(alignment)) {}

3223size_t MergeTailSection::getSize() const { return builder.getSize(); }

3225void MergeTailSection::writeTo(uint8_t *buf) { builder.write(buf); }

3227void MergeTailSection::finalizeContents() {
// Add all string pieces to the string table builder to create section
// contents.
for (MergeInputSection *sec : sections)
  for (size_t i = 0, e = sec->pieces.size(); i != e; ++i)
    if (sec->pieces[i].live)
      builder.add(sec->getData(i));

// Fix the string table content. After this, the contents will never change.
builder.finalize();

// finalize() fixed tail-optimized strings, so we can now get
// offsets of strings. Get an offset for each string and save it
// to a corresponding SectionPiece for easy access.
for (MergeInputSection *sec : sections)
  for (size_t i = 0, e = sec->pieces.size(); i != e; ++i)
    if (sec->pieces[i].live)
      sec->pieces[i].outputOff = builder.getOffset(sec->getData(i));
3245}

3247void MergeNoTailSection::writeTo(uint8_t *buf) {
parallelFor(0, numShards,
            [&](size_t i) { shards[i].write(buf + shardOffsets[i]); });
3250}

3252// This function is very hot (i.e. it can take several seconds to finish)
3253// because sometimes the number of inputs is in an order of magnitude of
3254// millions. So, we use multi-threading.
3255//
3256// For any strings S and T, we know S is not mergeable with T if S's hash
3257// value is different from T's. If that's the case, we can safely put S and
3258// T into different string builders without worrying about merge misses.
3259// We do it in parallel.
3260void MergeNoTailSection::finalizeContents() {
// Initializes string table builders.
for (size_t i = 0; i < numShards; ++i)
  shards.emplace_back(StringTableBuilder::RAW, llvm::Align(addralign));

// Concurrency level. Must be a power of 2 to avoid expensive modulo
// operations in the following tight loop.
const size_t concurrency =
    llvm::bit_floor(std::min<size_t>(config->threadCount, numShards));

// Add section pieces to the builders.
parallelFor(0, concurrency, [&](size_t threadId) {
  for (MergeInputSection *sec : sections) {
    for (size_t i = 0, e = sec->pieces.size(); i != e; ++i) {
      if (!sec->pieces[i].live)
        continue;
      size_t shardId = getShardId(sec->pieces[i].hash);
      if ((shardId & (concurrency - 1)) == threadId)
        sec->pieces[i].outputOff = shards[shardId].add(sec->getData(i));
    }
  }
});

// Compute an in-section offset for each shard.
size_t off = 0;
for (size_t i = 0; i < numShards; ++i) {
  shards[i].finalizeInOrder();
  if (shards[i].getSize() > 0)
    off = alignToPowerOf2(off, addralign);
  shardOffsets[i] = off;
  off += shards[i].getSize();
}
size = off;

// So far, section pieces have offsets from beginning of shards, but
// we want offsets from beginning of the whole section. Fix them.
parallelForEach(sections, [&](MergeInputSection *sec) {
  for (size_t i = 0, e = sec->pieces.size(); i != e; ++i)
    if (sec->pieces[i].live)
      sec->pieces[i].outputOff +=
          shardOffsets[getShardId(sec->pieces[i].hash)];
});
3302}

3304template <class ELFT> void elf::splitSections() {
llvm::TimeTraceScope timeScope("Split sections");
// splitIntoPieces needs to be called on each MergeInputSection
// before calling finalizeContents().
parallelForEach(ctx.objectFiles, [](ELFFileBase *file) {
  for (InputSectionBase *sec : file->getSections()) {
    if (!sec)
      continue;
    if (auto *s = dyn_cast<MergeInputSection>(sec))
      s->splitIntoPieces();
    else if (auto *eh = dyn_cast<EhInputSection>(sec))
      eh->split<ELFT>();
  }
});
3318}

3320void elf::combineEhSections() {
llvm::TimeTraceScope timeScope("Combine EH sections");
for (EhInputSection *sec : ctx.ehInputSections) {
  EhFrameSection &eh = *sec->getPartition().ehFrame;
  sec->parent = &eh;
  eh.addralign = std::max(eh.addralign, sec->addralign);
  eh.sections.push_back(sec);
  llvm::append_range(eh.dependentSections, sec->dependentSections);
}

if (!mainPart->armExidx)
  return;
llvm::erase_if(ctx.inputSections, [](InputSectionBase *s) {
  // Ignore dead sections and the partition end marker (.part.end),
  // whose partition number is out of bounds.
  if (!s->isLive() || s->partition == 255)
    return false;
  Partition &part = s->getPartition();
  return s->kind() == SectionBase::Regular && part.armExidx &&
         part.armExidx->addSection(cast<InputSection>(s));
});
3341}

3343MipsRldMapSection::MipsRldMapSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, config->wordsize,
                     ".rld_map") {}

3347ARMExidxSyntheticSection::ARMExidxSyntheticSection()
  : SyntheticSection(SHF_ALLOC | SHF_LINK_ORDER, SHT_ARM_EXIDX,
                     config->wordsize, ".ARM.exidx") {}

3351static InputSection *findExidxSection(InputSection *isec) {
for (InputSection *d : isec->dependentSections)
  if (d->type == SHT_ARM_EXIDX && d->isLive())
    return d;
return nullptr;
3356}

3358static bool isValidExidxSectionDep(InputSection *isec) {
return (isec->flags & SHF_ALLOC) && (isec->flags & SHF_EXECINSTR) &&
       isec->getSize() > 0;
3361}

3363bool ARMExidxSyntheticSection::addSection(InputSection *isec) {
if (isec->type == SHT_ARM_EXIDX) {
  if (InputSection *dep = isec->getLinkOrderDep())
    if (isValidExidxSectionDep(dep)) {
      exidxSections.push_back(isec);
      // Every exidxSection is 8 bytes, we need an estimate of
      // size before assignAddresses can be called. Final size
      // will only be known after finalize is called.
      size += 8;
    }
  return true;
}

if (isValidExidxSectionDep(isec)) {
  executableSections.push_back(isec);
  return false;
}

// FIXME: we do not output a relocation section when --emit-relocs is used
// as we do not have relocation sections for linker generated table entries
// and we would have to erase at a late stage relocations from merged entries.
// Given that exception tables are already position independent and a binary
// analyzer could derive the relocations we choose to erase the relocations.
if (config->emitRelocs && isec->type == SHT_REL)
  if (InputSectionBase *ex = isec->getRelocatedSection())
    if (isa<InputSection>(ex) && ex->type == SHT_ARM_EXIDX)
      return true;

return false;
3392}

3394// References to .ARM.Extab Sections have bit 31 clear and are not the
3395// special EXIDX_CANTUNWIND bit-pattern.
3396static bool isExtabRef(uint32_t unwind) {
return (unwind & 0x80000000) == 0 && unwind != 0x1;
3398}

3400// Return true if the .ARM.exidx section Cur can be merged into the .ARM.exidx
3401// section Prev, where Cur follows Prev in the table. This can be done if the
3402// unwinding instructions in Cur are identical to Prev. Linker generated
3403// EXIDX_CANTUNWIND entries are represented by nullptr as they do not have an
3404// InputSection.
3405static bool isDuplicateArmExidxSec(InputSection *prev, InputSection *cur) {

struct ExidxEntry {
  ulittle32_t fn;
  ulittle32_t unwind;
};
// Get the last table Entry from the previous .ARM.exidx section. If Prev is
// nullptr then it will be a synthesized EXIDX_CANTUNWIND entry.
ExidxEntry prevEntry = {ulittle32_t(0), ulittle32_t(1)};
if (prev)
  prevEntry = prev->getDataAs<ExidxEntry>().back();
if (isExtabRef(prevEntry.unwind))
  return false;

// We consider the unwind instructions of an .ARM.exidx table entry
// a duplicate if the previous unwind instructions if:
// - Both are the special EXIDX_CANTUNWIND.
// - Both are the same inline unwind instructions.
// We do not attempt to follow and check links into .ARM.extab tables as
// consecutive identical entries are rare and the effort to check that they
// are identical is high.

// If Cur is nullptr then this is synthesized EXIDX_CANTUNWIND entry.
if (cur == nullptr)
  return prevEntry.unwind == 1;

for (const ExidxEntry entry : cur->getDataAs<ExidxEntry>())
  if (isExtabRef(entry.unwind) || entry.unwind != prevEntry.unwind)
    return false;

// All table entries in this .ARM.exidx Section can be merged into the
// previous Section.
return true;
3438}

3440// The .ARM.exidx table must be sorted in ascending order of the address of the
3441// functions the table describes. std::optionally duplicate adjacent table
3442// entries can be removed. At the end of the function the executableSections
3443// must be sorted in ascending order of address, Sentinel is set to the
3444// InputSection with the highest address and any InputSections that have
3445// mergeable .ARM.exidx table entries are removed from it.
3446void ARMExidxSyntheticSection::finalizeContents() {
// The executableSections and exidxSections that we use to derive the final
// contents of this SyntheticSection are populated before
// processSectionCommands() and ICF. A /DISCARD/ entry in SECTIONS command or
// ICF may remove executable InputSections and their dependent .ARM.exidx
// section that we recorded earlier.
auto isDiscarded = [](const InputSection *isec) { return !isec->isLive(); };
llvm::erase_if(exidxSections, isDiscarded);
// We need to remove discarded InputSections and InputSections without
// .ARM.exidx sections that if we generated the .ARM.exidx it would be out
// of range.
auto isDiscardedOrOutOfRange = [this](InputSection *isec) {
  if (!isec->isLive())
    return true;
  if (findExidxSection(isec))
    return false;
  int64_t off = static_cast<int64_t>(isec->getVA() - getVA());
  return off != llvm::SignExtend64(off, 31);
};
llvm::erase_if(executableSections, isDiscardedOrOutOfRange);

// Sort the executable sections that may or may not have associated
// .ARM.exidx sections by order of ascending address. This requires the
// relative positions of InputSections and OutputSections to be known.
auto compareByFilePosition = [](const InputSection *a,
                                const InputSection *b) {
  OutputSection *aOut = a->getParent();
  OutputSection *bOut = b->getParent();

  if (aOut != bOut)
    return aOut->addr < bOut->addr;
  return a->outSecOff < b->outSecOff;
};
llvm::stable_sort(executableSections, compareByFilePosition);
sentinel = executableSections.back();
// std::optionally merge adjacent duplicate entries.
if (config->mergeArmExidx) {
  SmallVector<InputSection *, 0> selectedSections;
  selectedSections.reserve(executableSections.size());
  selectedSections.push_back(executableSections[0]);
  size_t prev = 0;
  for (size_t i = 1; i < executableSections.size(); ++i) {
    InputSection *ex1 = findExidxSection(executableSections[prev]);
    InputSection *ex2 = findExidxSection(executableSections[i]);
    if (!isDuplicateArmExidxSec(ex1, ex2)) {
      selectedSections.push_back(executableSections[i]);
      prev = i;
    }
  }
  executableSections = std::move(selectedSections);
}

size_t offset = 0;
size = 0;
for (InputSection *isec : executableSections) {
  if (InputSection *d = findExidxSection(isec)) {
    d->outSecOff = offset;
    d->parent = getParent();
    offset += d->getSize();
  } else {
    offset += 8;
  }
}
// Size includes Sentinel.
size = offset + 8;
3511}

3513InputSection *ARMExidxSyntheticSection::getLinkOrderDep() const {
return executableSections.front();
3515}

3517// To write the .ARM.exidx table from the ExecutableSections we have three cases
3518// 1.) The InputSection has a .ARM.exidx InputSection in its dependent sections.
3519//     We write the .ARM.exidx section contents and apply its relocations.
3520// 2.) The InputSection does not have a dependent .ARM.exidx InputSection. We
3521//     must write the contents of an EXIDX_CANTUNWIND directly. We use the
3522//     start of the InputSection as the purpose of the linker generated
3523//     section is to terminate the address range of the previous entry.
3524// 3.) A trailing EXIDX_CANTUNWIND sentinel section is required at the end of
3525//     the table to terminate the address range of the final entry.
3526void ARMExidxSyntheticSection::writeTo(uint8_t *buf) {

const uint8_t cantUnwindData[8] = {0, 0, 0, 0,  // PREL31 to target
                                   1, 0, 0, 0}; // EXIDX_CANTUNWIND

uint64_t offset = 0;
for (InputSection *isec : executableSections) {
  assert(isec->getParent() != nullptr)(static_cast <bool> (isec->getParent() != nullptr) ?
 void (0) : __assert_fail ("isec->getParent() != nullptr",
 "lld/ELF/SyntheticSections.cpp", 3533, __extension__ __PRETTY_FUNCTION__
));
  if (InputSection *d = findExidxSection(isec)) {
    memcpy(buf + offset, d->content().data(), d->content().size());
    target->relocateAlloc(*d, buf + d->outSecOff);
    offset += d->getSize();
  } else {
    // A Linker generated CANTUNWIND section.
    memcpy(buf + offset, cantUnwindData, sizeof(cantUnwindData));
    uint64_t s = isec->getVA();
    uint64_t p = getVA() + offset;
    target->relocateNoSym(buf + offset, R_ARM_PREL31, s - p);
    offset += 8;
  }
}
// Write Sentinel.
memcpy(buf + offset, cantUnwindData, sizeof(cantUnwindData));
uint64_t s = sentinel->getVA(sentinel->getSize());
uint64_t p = getVA() + offset;
target->relocateNoSym(buf + offset, R_ARM_PREL31, s - p);
assert(size == offset + 8)(static_cast <bool> (size == offset + 8) ? void (0) : __assert_fail
 ("size == offset + 8", "lld/ELF/SyntheticSections.cpp", 3552
, __extension__ __PRETTY_FUNCTION__));
3553}

3555bool ARMExidxSyntheticSection::isNeeded() const {
return llvm::any_of(exidxSections,
                    [](InputSection *isec) { return isec->isLive(); });
3558}

3560ThunkSection::ThunkSection(OutputSection *os, uint64_t off)
  : SyntheticSection(SHF_ALLOC | SHF_EXECINSTR, SHT_PROGBITS,
                     config->emachine == EM_PPC64 ? 16 : 4, ".text.thunk") {
this->parent = os;
this->outSecOff = off;
3565}

3567size_t ThunkSection::getSize() const {
if (roundUpSizeForErrata)
  return alignTo(size, 4096);
return size;
3571}

3573void ThunkSection::addThunk(Thunk *t) {
thunks.push_back(t);
t->addSymbols(*this);
3576}

3578void ThunkSection::writeTo(uint8_t *buf) {
for (Thunk *t : thunks)
  t->writeTo(buf + t->offset);
3581}

3583InputSection *ThunkSection::getTargetInputSection() const {
if (thunks.empty())
  return nullptr;
const Thunk *t = thunks.front();
return t->getTargetInputSection();
3588}

3590bool ThunkSection::assignOffsets() {
uint64_t off = 0;
for (Thunk *t : thunks) {
  off = alignToPowerOf2(off, t->alignment);
  t->setOffset(off);
  uint32_t size = t->size();
  t->getThunkTargetSym()->size = size;
  off += size;
}
bool changed = off != size;
size = off;
return changed;
3602}

3604PPC32Got2Section::PPC32Got2Section()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE, SHT_PROGBITS, 4, ".got2") {}

3607bool PPC32Got2Section::isNeeded() const {
// See the comment below. This is not needed if there is no other
// InputSection.
for (SectionCommand *cmd : getParent()->commands)
  if (auto *isd = dyn_cast<InputSectionDescription>(cmd))
    for (InputSection *isec : isd->sections)
      if (isec != this)
        return true;
return false;
3616}

3618void PPC32Got2Section::finalizeContents() {
// PPC32 may create multiple GOT sections for -fPIC/-fPIE, one per file in
// .got2 . This function computes outSecOff of each .got2 to be used in
// PPC32PltCallStub::writeTo(). The purpose of this empty synthetic section is
// to collect input sections named ".got2".
for (SectionCommand *cmd : getParent()->commands)
  if (auto *isd = dyn_cast<InputSectionDescription>(cmd)) {
    for (InputSection *isec : isd->sections) {
      // isec->file may be nullptr for MergeSyntheticSection.
      if (isec != this && isec->file)
        isec->file->ppc32Got2 = isec;
    }
  }
3631}

3633// If linking position-dependent code then the table will store the addresses
3634// directly in the binary so the section has type SHT_PROGBITS. If linking
3635// position-independent code the section has type SHT_NOBITS since it will be
3636// allocated and filled in by the dynamic linker.
3637PPC64LongBranchTargetSection::PPC64LongBranchTargetSection()
  : SyntheticSection(SHF_ALLOC | SHF_WRITE,
                     config->isPic ? SHT_NOBITS : SHT_PROGBITS, 8,
                     ".branch_lt") {}

3642uint64_t PPC64LongBranchTargetSection::getEntryVA(const Symbol *sym,
                                                int64_t addend) {
return getVA() + entry_index.find({sym, addend})->second * 8;
3645}

3647std::optional<uint32_t>
3648PPC64LongBranchTargetSection::addEntry(const Symbol *sym, int64_t addend) {
auto res =
    entry_index.try_emplace(std::make_pair(sym, addend), entries.size());
if (!res.second)
  return std::nullopt;
entries.emplace_back(sym, addend);
return res.first->second;
3655}

3657size_t PPC64LongBranchTargetSection::getSize() const {
return entries.size() * 8;
3659}

3661void PPC64LongBranchTargetSection::writeTo(uint8_t *buf) {
// If linking non-pic we have the final addresses of the targets and they get
// written to the table directly. For pic the dynamic linker will allocate
// the section and fill it.
if (config->isPic)
  return;

for (auto entry : entries) {
  const Symbol *sym = entry.first;
  int64_t addend = entry.second;
  assert(sym->getVA())(static_cast <bool> (sym->getVA()) ? void (0) : __assert_fail
 ("sym->getVA()", "lld/ELF/SyntheticSections.cpp", 3671, __extension__
 __PRETTY_FUNCTION__));
  // Need calls to branch to the local entry-point since a long-branch
  // must be a local-call.
  write64(buf, sym->getVA(addend) +
                   getPPC64GlobalEntryToLocalEntryOffset(sym->stOther));
  buf += 8;
}
3678}

3680bool PPC64LongBranchTargetSection::isNeeded() const {
// `removeUnusedSyntheticSections()` is called before thunk allocation which
// is too early to determine if this section will be empty or not. We need
// Finalized to keep the section alive until after thunk creation. Finalized
// only gets set to true once `finalizeSections()` is called after thunk
// creation. Because of this, if we don't create any long-branch thunks we end
// up with an empty .branch_lt section in the binary.
return !finalized || !entries.empty();
3688}

3690static uint8_t getAbiVersion() {
// MIPS non-PIC executable gets ABI version 1.
if (config->emachine == EM_MIPS) {
  if (!config->isPic && !config->relocatable &&
      (config->eflags & (EF_MIPS_PIC | EF_MIPS_CPIC)) == EF_MIPS_CPIC)
    return 1;
  return 0;
}

if (config->emachine == EM_AMDGPU && !ctx.objectFiles.empty()) {
  uint8_t ver = ctx.objectFiles[0]->abiVersion;
  for (InputFile *file : ArrayRef(ctx.objectFiles).slice(1))
    if (file->abiVersion != ver)
      error("incompatible ABI version: " + toString(file));
  return ver;
}

return 0;
3708}

3710template <typename ELFT> void elf::writeEhdr(uint8_t *buf, Partition &part) {
memcpy(buf, "\177ELF", 4);

auto *eHdr = reinterpret_cast<typename ELFT::Ehdr *>(buf);
eHdr->e_ident[EI_CLASS] = config->is64 ? ELFCLASS64 : ELFCLASS32;
eHdr->e_ident[EI_DATA] = config->isLE ? ELFDATA2LSB : ELFDATA2MSB;
eHdr->e_ident[EI_VERSION] = EV_CURRENT;
eHdr->e_ident[EI_OSABI] = config->osabi;
eHdr->e_ident[EI_ABIVERSION] = getAbiVersion();
eHdr->e_machine = config->emachine;
eHdr->e_version = EV_CURRENT;
eHdr->e_flags = config->eflags;
eHdr->e_ehsize = sizeof(typename ELFT::Ehdr);
eHdr->e_phnum = part.phdrs.size();
eHdr->e_shentsize = sizeof(typename ELFT::Shdr);

if (!config->relocatable) {
  eHdr->e_phoff = sizeof(typename ELFT::Ehdr);
  eHdr->e_phentsize = sizeof(typename ELFT::Phdr);
}
3730}

3732template <typename ELFT> void elf::writePhdrs(uint8_t *buf, Partition &part) {
// Write the program header table.
auto *hBuf = reinterpret_cast<typename ELFT::Phdr *>(buf);
for (PhdrEntry *p : part.phdrs) {
  hBuf->p_type = p->p_type;
  hBuf->p_flags = p->p_flags;
  hBuf->p_offset = p->p_offset;
  hBuf->p_vaddr = p->p_vaddr;
  hBuf->p_paddr = p->p_paddr;
  hBuf->p_filesz = p->p_filesz;
  hBuf->p_memsz = p->p_memsz;
  hBuf->p_align = p->p_align;
  ++hBuf;
}
3746}

3748template <typename ELFT>
3749PartitionElfHeaderSection<ELFT>::PartitionElfHeaderSection()
  : SyntheticSection(SHF_ALLOC, SHT_LLVM_PART_EHDR, 1, "") {}

3752template <typename ELFT>
3753size_t PartitionElfHeaderSection<ELFT>::getSize() const {
return sizeof(typename ELFT::Ehdr);
3755}

3757template <typename ELFT>
3758void PartitionElfHeaderSection<ELFT>::writeTo(uint8_t *buf) {
writeEhdr<ELFT>(buf, getPartition());

// Loadable partitions are always ET_DYN.
auto *eHdr = reinterpret_cast<typename ELFT::Ehdr *>(buf);
eHdr->e_type = ET_DYN;
3764}

3766template <typename ELFT>
3767PartitionProgramHeadersSection<ELFT>::PartitionProgramHeadersSection()
  : SyntheticSection(SHF_ALLOC, SHT_LLVM_PART_PHDR, 1, ".phdrs") {}

3770template <typename ELFT>
3771size_t PartitionProgramHeadersSection<ELFT>::getSize() const {
return sizeof(typename ELFT::Phdr) * getPartition().phdrs.size();
3773}

3775template <typename ELFT>
3776void PartitionProgramHeadersSection<ELFT>::writeTo(uint8_t *buf) {
writePhdrs<ELFT>(buf, getPartition());
3778}

3780PartitionIndexSection::PartitionIndexSection()
  : SyntheticSection(SHF_ALLOC, SHT_PROGBITS, 4, ".rodata") {}

3783size_t PartitionIndexSection::getSize() const {
return 12 * (partitions.size() - 1);
3785}

3787void PartitionIndexSection::finalizeContents() {
for (size_t i = 1; i != partitions.size(); ++i)
  partitions[i].nameStrTab = mainPart->dynStrTab->addString(partitions[i].name);
3790}

3792void PartitionIndexSection::writeTo(uint8_t *buf) {
uint64_t va = getVA();
for (size_t i = 1; i != partitions.size(); ++i) {
  write32(buf, mainPart->dynStrTab->getVA() + partitions[i].nameStrTab - va);
  write32(buf + 4, partitions[i].elfHeader->getVA() - (va + 4));

  SyntheticSection *next = i == partitions.size() - 1
                               ? in.partEnd.get()
                               : partitions[i + 1].elfHeader.get();
  write32(buf + 8, next->getVA() - partitions[i].elfHeader->getVA());

  va += 12;
  buf += 12;
}
3806}

3808void InStruct::reset() {
attributes.reset();
riscvAttributes.reset();
bss.reset();
bssRelRo.reset();
got.reset();
gotPlt.reset();
igotPlt.reset();
ppc64LongBranchTarget.reset();
mipsAbiFlags.reset();
mipsGot.reset();
mipsOptions.reset();
mipsReginfo.reset();
mipsRldMap.reset();
partEnd.reset();
partIndex.reset();
plt.reset();
iplt.reset();
ppc32Got2.reset();
ibtPlt.reset();
relaPlt.reset();
relaIplt.reset();
shStrTab.reset();
strTab.reset();
symTab.reset();
symTabShndx.reset();
3834}

3836constexpr char kMemtagAndroidNoteName[] = "Android";
3837void MemtagAndroidNote::writeTo(uint8_t *buf) {
static_assert(sizeof(kMemtagAndroidNoteName) == 8,
              "ABI check for Android 11 & 12.");
assert((config->androidMemtagStack || config->androidMemtagHeap) &&(static_cast <bool> ((config->androidMemtagStack || config
->androidMemtagHeap) && "Should only be synthesizing a note if heap || stack is enabled."
) ? void (0) : __assert_fail ("(config->androidMemtagStack || config->androidMemtagHeap) && \"Should only be synthesizing a note if heap || stack is enabled.\""
, "lld/ELF/SyntheticSections.cpp", 3841, __extension__ __PRETTY_FUNCTION__
))
       "Should only be synthesizing a note if heap || stack is enabled.")(static_cast <bool> ((config->androidMemtagStack || config
->androidMemtagHeap) && "Should only be synthesizing a note if heap || stack is enabled."
) ? void (0) : __assert_fail ("(config->androidMemtagStack || config->androidMemtagHeap) && \"Should only be synthesizing a note if heap || stack is enabled.\""
, "lld/ELF/SyntheticSections.cpp", 3841, __extension__ __PRETTY_FUNCTION__
));

write32(buf, sizeof(kMemtagAndroidNoteName));
write32(buf + 4, sizeof(uint32_t));
write32(buf + 8, ELF::NT_ANDROID_TYPE_MEMTAG);
memcpy(buf + 12, kMemtagAndroidNoteName, sizeof(kMemtagAndroidNoteName));
buf += 12 + sizeof(kMemtagAndroidNoteName);

uint32_t value = 0;
value |= config->androidMemtagMode;
if (config->androidMemtagHeap)
  value |= ELF::NT_MEMTAG_HEAP;
// Note, MTE stack is an ABI break. Attempting to run an MTE stack-enabled
// binary on Android 11 or 12 will result in a checkfail in the loader.
if (config->androidMemtagStack)
  value |= ELF::NT_MEMTAG_STACK;
write32(buf, value); // note value
3858}

3860size_t MemtagAndroidNote::getSize() const {
return sizeof(llvm::ELF::Elf64_Nhdr) +
       /*namesz=*/sizeof(kMemtagAndroidNoteName) +
       /*descsz=*/sizeof(uint32_t);
3864}

3866void PackageMetadataNote::writeTo(uint8_t *buf) {
write32(buf, 4);
write32(buf + 4, config->packageMetadata.size() + 1);
write32(buf + 8, FDO_PACKAGING_METADATA);
memcpy(buf + 12, "FDO", 4);
memcpy(buf + 16, config->packageMetadata.data(),
       config->packageMetadata.size());
3873}

3875size_t PackageMetadataNote::getSize() const {
return sizeof(llvm::ELF::Elf64_Nhdr) + 4 +
       alignTo(config->packageMetadata.size() + 1, 4);
3878}

3880InStruct elf::in;

3882std::vector<Partition> elf::partitions;
3883Partition *elf::mainPart;

3885template GdbIndexSection *GdbIndexSection::create<ELF32LE>();
3886template GdbIndexSection *GdbIndexSection::create<ELF32BE>();
3887template GdbIndexSection *GdbIndexSection::create<ELF64LE>();
3888template GdbIndexSection *GdbIndexSection::create<ELF64BE>();

3890template void elf::splitSections<ELF32LE>();
3891template void elf::splitSections<ELF32BE>();
3892template void elf::splitSections<ELF64LE>();
3893template void elf::splitSections<ELF64BE>();

3895template class elf::MipsAbiFlagsSection<ELF32LE>;
3896template class elf::MipsAbiFlagsSection<ELF32BE>;
3897template class elf::MipsAbiFlagsSection<ELF64LE>;
3898template class elf::MipsAbiFlagsSection<ELF64BE>;

3900template class elf::MipsOptionsSection<ELF32LE>;
3901template class elf::MipsOptionsSection<ELF32BE>;
3902template class elf::MipsOptionsSection<ELF64LE>;
3903template class elf::MipsOptionsSection<ELF64BE>;

3905template void EhFrameSection::iterateFDEWithLSDA<ELF32LE>(
  function_ref<void(InputSection &)>);
3907template void EhFrameSection::iterateFDEWithLSDA<ELF32BE>(
  function_ref<void(InputSection &)>);
3909template void EhFrameSection::iterateFDEWithLSDA<ELF64LE>(
  function_ref<void(InputSection &)>);
3911template void EhFrameSection::iterateFDEWithLSDA<ELF64BE>(
  function_ref<void(InputSection &)>);

3914template class elf::MipsReginfoSection<ELF32LE>;
3915template class elf::MipsReginfoSection<ELF32BE>;
3916template class elf::MipsReginfoSection<ELF64LE>;
3917template class elf::MipsReginfoSection<ELF64BE>;

3919template class elf::DynamicSection<ELF32LE>;
3920template class elf::DynamicSection<ELF32BE>;
3921template class elf::DynamicSection<ELF64LE>;
3922template class elf::DynamicSection<ELF64BE>;

3924template class elf::RelocationSection<ELF32LE>;
3925template class elf::RelocationSection<ELF32BE>;
3926template class elf::RelocationSection<ELF64LE>;
3927template class elf::RelocationSection<ELF64BE>;

3929template class elf::AndroidPackedRelocationSection<ELF32LE>;
3930template class elf::AndroidPackedRelocationSection<ELF32BE>;
3931template class elf::AndroidPackedRelocationSection<ELF64LE>;
3932template class elf::AndroidPackedRelocationSection<ELF64BE>;

3934template class elf::RelrSection<ELF32LE>;
3935template class elf::RelrSection<ELF32BE>;
3936template class elf::RelrSection<ELF64LE>;
3937template class elf::RelrSection<ELF64BE>;

3939template class elf::SymbolTableSection<ELF32LE>;
3940template class elf::SymbolTableSection<ELF32BE>;
3941template class elf::SymbolTableSection<ELF64LE>;
3942template class elf::SymbolTableSection<ELF64BE>;

3944template class elf::VersionNeedSection<ELF32LE>;
3945template class elf::VersionNeedSection<ELF32BE>;
3946template class elf::VersionNeedSection<ELF64LE>;
3947template class elf::VersionNeedSection<ELF64BE>;

3949template void elf::writeEhdr<ELF32LE>(uint8_t *Buf, Partition &Part);
3950template void elf::writeEhdr<ELF32BE>(uint8_t *Buf, Partition &Part);
3951template void elf::writeEhdr<ELF64LE>(uint8_t *Buf, Partition &Part);
3952template void elf::writeEhdr<ELF64BE>(uint8_t *Buf, Partition &Part);

3954template void elf::writePhdrs<ELF32LE>(uint8_t *Buf, Partition &Part);
3955template void elf::writePhdrs<ELF32BE>(uint8_t *Buf, Partition &Part);
3956template void elf::writePhdrs<ELF64LE>(uint8_t *Buf, Partition &Part);
3957template void elf::writePhdrs<ELF64BE>(uint8_t *Buf, Partition &Part);

3959template class elf::PartitionElfHeaderSection<ELF32LE>;
3960template class elf::PartitionElfHeaderSection<ELF32BE>;
3961template class elf::PartitionElfHeaderSection<ELF64LE>;
3962template class elf::PartitionElfHeaderSection<ELF64BE>;

3964template class elf::PartitionProgramHeadersSection<ELF32LE>;
3965template class elf::PartitionProgramHeadersSection<ELF32BE>;
3966template class elf::PartitionProgramHeadersSection<ELF64LE>;
3967template class elf::PartitionProgramHeadersSection<ELF64BE>;

←

/usr/lib/gcc/x86_64-linux-gnu/10/../../../../include/c++/10/bits/unique_ptr.h

→

1// unique_ptr implementation -*- C++ -*-

3// Copyright (C) 2008-2020 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.

11// This library is distributed in the hope that it will be useful,
12// but WITHOUT ANY WARRANTY; without even the implied warranty of
13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14// GNU General Public License for more details.

16// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.

20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.

25/** @file bits/unique_ptr.h
*  This is an internal header file, included by other library headers.
*  Do not attempt to use it directly. @headername{memory}
*/

30#ifndef _UNIQUE_PTR_H1
31#define _UNIQUE_PTR_H1 1

33#include <bits/c++config.h>
34#include <debug/assertions.h>
35#include <type_traits>
36#include <utility>
37#include <tuple>
38#include <bits/stl_function.h>
39#include <bits/functional_hash.h>
40#if __cplusplus201703L > 201703L
41# include <compare>
42# include <ostream>
43#endif

45namespace std _GLIBCXX_VISIBILITY(default)__attribute__ ((__visibility__ ("default")))
46{
47_GLIBCXX_BEGIN_NAMESPACE_VERSION

/**
 * @addtogroup pointer_abstractions
 * @{
 */

54#if _GLIBCXX_USE_DEPRECATED1
55#pragma GCC diagnostic push
56#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
template<typename> class auto_ptr;
58#pragma GCC diagnostic pop
59#endif

/// Primary template of default_delete, used by unique_ptr for single objects
template<typename _Tp>
  struct default_delete
  {
    /// Default constructor
    constexpr default_delete() noexcept = default;

    /** @brief Converting constructor.
     *
     * Allows conversion from a deleter for objects of another type, `_Up`,
     * only if `_Up*` is convertible to `_Tp*`.
     */
    template<typename _Up,
      typename = _Require<is_convertible<_Up*, _Tp*>>>
      default_delete(const default_delete<_Up>&) noexcept { }

    /// Calls `delete __ptr`
    void
    operator()(_Tp* __ptr) const
    {
static_assert(!is_void<_Tp>::value,
      "can't delete pointer to incomplete type");
static_assert(sizeof(_Tp)>0,
      "can't delete pointer to incomplete type");
delete __ptr;
    }
  };

// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 740 - omit specialization for array objects with a compile time length

/// Specialization of default_delete for arrays, used by `unique_ptr<T[]>`
template<typename _Tp>
  struct default_delete<_Tp[]>
  {
  public:
    /// Default constructor
    constexpr default_delete() noexcept = default;

    /** @brief Converting constructor.
     *
     * Allows conversion from a deleter for arrays of another type, such as
     * a const-qualified version of `_Tp`.
     *
     * Conversions from types derived from `_Tp` are not allowed because
     * it is undefined to `delete[]` an array of derived types through a
     * pointer to the base type.
     */
    template<typename _Up,
      typename = _Require<is_convertible<_Up(*)[], _Tp(*)[]>>>
      default_delete(const default_delete<_Up[]>&) noexcept { }

    /// Calls `delete[] __ptr`
    template<typename _Up>
typename enable_if<is_convertible<_Up(*)[], _Tp(*)[]>::value>::type
operator()(_Up* __ptr) const
{
 static_assert(sizeof(_Tp)>0,
	"can't delete pointer to incomplete type");
 delete [] __ptr;
}
  };

/// @cond undocumented

// Manages the pointer and deleter of a unique_ptr
template <typename _Tp, typename _Dp>
  class __uniq_ptr_impl
  {
    template <typename _Up, typename _Ep, typename = void>
struct _Ptr
{
 using type = _Up*;
};

    template <typename _Up, typename _Ep>
struct
_Ptr<_Up, _Ep, __void_t<typename remove_reference<_Ep>::type::pointer>>
{
 using type = typename remove_reference<_Ep>::type::pointer;
};

  public:
    using _DeleterConstraint = enable_if<
      __and_<__not_<is_pointer<_Dp>>,
      is_default_constructible<_Dp>>::value>;

    using pointer = typename _Ptr<_Tp, _Dp>::type;

    static_assert( !is_rvalue_reference<_Dp>::value,
     "unique_ptr's deleter type must be a function object type"
     " or an lvalue reference type" );

    __uniq_ptr_impl() = default;
    __uniq_ptr_impl(pointer __p) : _M_t() { _M_ptr() = __p; }

    template<typename _Del>
    __uniq_ptr_impl(pointer __p, _Del&& __d)
: _M_t(__p, std::forward<_Del>(__d)) { }

    __uniq_ptr_impl(__uniq_ptr_impl&& __u) noexcept
    : _M_t(std::move(__u._M_t))
    { __u._M_ptr() = nullptr; }

    __uniq_ptr_impl& operator=(__uniq_ptr_impl&& __u) noexcept
    {
reset(__u.release());
_M_deleter() = std::forward<_Dp>(__u._M_deleter());
return *this;
    }

    pointer&   _M_ptr() { return std::get<0>(_M_t); }
    pointer    _M_ptr() const { return std::get<0>(_M_t); }
    _Dp&       _M_deleter() { return std::get<1>(_M_t); }
    const _Dp& _M_deleter() const { return std::get<1>(_M_t); }

    void reset(pointer __p) noexcept
    {
const pointer __old_p = _M_ptr();
_M_ptr() = __p;
if (__old_p)
 _M_deleter()(__old_p);
    }

    pointer release() noexcept
    {
pointer __p = _M_ptr();
_M_ptr() = nullptr;
return __p;
    }

    void
    swap(__uniq_ptr_impl& __rhs) noexcept
    {
using std::swap;
swap(this->_M_ptr(), __rhs._M_ptr());
swap(this->_M_deleter(), __rhs._M_deleter());
    }

  private:
    tuple<pointer, _Dp> _M_t;
  };

// Defines move construction + assignment as either defaulted or deleted.
template <typename _Tp, typename _Dp,
   bool = is_move_constructible<_Dp>::value,
   bool = is_move_assignable<_Dp>::value>
  struct __uniq_ptr_data : __uniq_ptr_impl<_Tp, _Dp>
  {
    using __uniq_ptr_impl<_Tp, _Dp>::__uniq_ptr_impl;
    __uniq_ptr_data(__uniq_ptr_data&&) = default;
    __uniq_ptr_data& operator=(__uniq_ptr_data&&) = default;
  };

template <typename _Tp, typename _Dp>
  struct __uniq_ptr_data<_Tp, _Dp, true, false> : __uniq_ptr_impl<_Tp, _Dp>
  {
    using __uniq_ptr_impl<_Tp, _Dp>::__uniq_ptr_impl;
    __uniq_ptr_data(__uniq_ptr_data&&) = default;
    __uniq_ptr_data& operator=(__uniq_ptr_data&&) = delete;
  };

template <typename _Tp, typename _Dp>
  struct __uniq_ptr_data<_Tp, _Dp, false, true> : __uniq_ptr_impl<_Tp, _Dp>
  {
    using __uniq_ptr_impl<_Tp, _Dp>::__uniq_ptr_impl;
    __uniq_ptr_data(__uniq_ptr_data&&) = delete;
    __uniq_ptr_data& operator=(__uniq_ptr_data&&) = default;
  };

template <typename _Tp, typename _Dp>
  struct __uniq_ptr_data<_Tp, _Dp, false, false> : __uniq_ptr_impl<_Tp, _Dp>
  {
    using __uniq_ptr_impl<_Tp, _Dp>::__uniq_ptr_impl;
    __uniq_ptr_data(__uniq_ptr_data&&) = delete;
    __uniq_ptr_data& operator=(__uniq_ptr_data&&) = delete;
  };
/// @endcond

/// 20.7.1.2 unique_ptr for single objects.
template <typename _Tp, typename _Dp = default_delete<_Tp>>
  class unique_ptr
  {
    template <typename _Up>
using _DeleterConstraint =
 typename __uniq_ptr_impl<_Tp, _Up>::_DeleterConstraint::type;

    __uniq_ptr_data<_Tp, _Dp> _M_t;

  public:
    using pointer	  = typename __uniq_ptr_impl<_Tp, _Dp>::pointer;
    using element_type  = _Tp;
    using deleter_type  = _Dp;

  private:
    // helper template for detecting a safe conversion from another
    // unique_ptr
    template<typename _Up, typename _Ep>
using __safe_conversion_up = __and_<
 is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>,
 __not_<is_array<_Up>>
      >;

  public:
    // Constructors.

    /// Default constructor, creates a unique_ptr that owns nothing.
    template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
constexpr unique_ptr() noexcept
: _M_t()
{ }

    /** Takes ownership of a pointer.
     *
     * @param __p  A pointer to an object of @c element_type
     *
     * The deleter will be value-initialized.
     */
    template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
explicit
unique_ptr(pointer __p) noexcept
: _M_t(__p)
      { }

    /** Takes ownership of a pointer.
     *
     * @param __p  A pointer to an object of @c element_type
     * @param __d  A reference to a deleter.
     *
     * The deleter will be initialized with @p __d
     */
    template<typename _Del = deleter_type,
      typename = _Require<is_copy_constructible<_Del>>>
unique_ptr(pointer __p, const deleter_type& __d) noexcept
: _M_t(__p, __d) { }

    /** Takes ownership of a pointer.
     *
     * @param __p  A pointer to an object of @c element_type
     * @param __d  An rvalue reference to a (non-reference) deleter.
     *
     * The deleter will be initialized with @p std::move(__d)
     */
    template<typename _Del = deleter_type,
      typename = _Require<is_move_constructible<_Del>>>
unique_ptr(pointer __p,
   __enable_if_t<!is_lvalue_reference<_Del>::value,
		 _Del&&> __d) noexcept
: _M_t(__p, std::move(__d))
{ }

    template<typename _Del = deleter_type,
      typename _DelUnref = typename remove_reference<_Del>::type>
unique_ptr(pointer,
   __enable_if_t<is_lvalue_reference<_Del>::value,
		 _DelUnref&&>) = delete;

    /// Creates a unique_ptr that owns nothing.
    template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
constexpr unique_ptr(nullptr_t) noexcept
: _M_t()
{ }

    // Move constructors.

    /// Move constructor.
    unique_ptr(unique_ptr&&) = default;

    /** @brief Converting constructor from another type
     *
     * Requires that the pointer owned by @p __u is convertible to the
     * type of pointer owned by this object, @p __u does not own an array,
     * and @p __u has a compatible deleter type.
     */
    template<typename _Up, typename _Ep, typename = _Require<
             __safe_conversion_up<_Up, _Ep>,
      typename conditional<is_reference<_Dp>::value,
		    is_same<_Ep, _Dp>,
		    is_convertible<_Ep, _Dp>>::type>>
unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
: _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
{ }

344#if _GLIBCXX_USE_DEPRECATED1
345#pragma GCC diagnostic push
346#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
    /// Converting constructor from @c auto_ptr
    template<typename _Up, typename = _Require<
      is_convertible<_Up*, _Tp*>, is_same<_Dp, default_delete<_Tp>>>>
unique_ptr(auto_ptr<_Up>&& __u) noexcept;
351#pragma GCC diagnostic pop
352#endif

    /// Destructor, invokes the deleter if the stored pointer is not null.
    ~unique_ptr() noexcept
    {
static_assert(__is_invocable<deleter_type&, pointer>::value,
      "unique_ptr's deleter must be invocable with a pointer");
auto& __ptr = _M_t._M_ptr();
if (__ptr != nullptr)
 get_deleter()(std::move(__ptr));
__ptr = pointer();
    }

    // Assignment.

    /** @brief Move assignment operator.
     *
     * Invokes the deleter if this object owns a pointer.
     */
    unique_ptr& operator=(unique_ptr&&) = default;

    /** @brief Assignment from another type.
     *
     * @param __u  The object to transfer ownership from, which owns a
     *             convertible pointer to a non-array object.
     *
     * Invokes the deleter if this object owns a pointer.
     */
    template<typename _Up, typename _Ep>
      typename enable_if< __and_<
        __safe_conversion_up<_Up, _Ep>,
        is_assignable<deleter_type&, _Ep&&>
        >::value,
        unique_ptr&>::type
operator=(unique_ptr<_Up, _Ep>&& __u) noexcept
{
 reset(__u.release());
 get_deleter() = std::forward<_Ep>(__u.get_deleter());
 return *this;
}

    /// Reset the %unique_ptr to empty, invoking the deleter if necessary.
    unique_ptr&
    operator=(nullptr_t) noexcept
    {
reset();
return *this;
    }

    // Observers.

    /// Dereference the stored pointer.
    typename add_lvalue_reference<element_type>::type
    operator*() const
    {
__glibcxx_assert(get() != pointer());
return *get();
    }

    /// Return the stored pointer.
    pointer
    operator->() const noexcept
    {
_GLIBCXX_DEBUG_PEDASSERT(get() != pointer());
return get();
    }

    /// Return the stored pointer.
    pointer
    get() const noexcept
    { return _M_t._M_ptr(); }

    /// Return a reference to the stored deleter.
    deleter_type&
    get_deleter() noexcept
    { return _M_t._M_deleter(); }

    /// Return a reference to the stored deleter.
    const deleter_type&
    get_deleter() const noexcept
    { return _M_t._M_deleter(); }

    /// Return @c true if the stored pointer is not null.
    explicit operator bool() const noexcept
    { return get() == pointer() ? false : true; }

    // Modifiers.

    /// Release ownership of any stored pointer.
    pointer
    release() noexcept
    { return _M_t.release(); }

    /** @brief Replace the stored pointer.
     *
     * @param __p  The new pointer to store.
     *
     * The deleter will be invoked if a pointer is already owned.
     */
    void
    reset(pointer __p = pointer()) noexcept
    {
static_assert(__is_invocable<deleter_type&, pointer>::value,
      "unique_ptr's deleter must be invocable with a pointer");
_M_t.reset(std::move(__p));
    }

    /// Exchange the pointer and deleter with another object.
    void
    swap(unique_ptr& __u) noexcept
    {
static_assert(__is_swappable<_Dp>::value, "deleter must be swappable");
_M_t.swap(__u._M_t);
    }

    // Disable copy from lvalue.
    unique_ptr(const unique_ptr&) = delete;
    unique_ptr& operator=(const unique_ptr&) = delete;
};

/// 20.7.1.3 unique_ptr for array objects with a runtime length
// [unique.ptr.runtime]
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 740 - omit specialization for array objects with a compile time length
template<typename _Tp, typename _Dp>
  class unique_ptr<_Tp[], _Dp>
  {
    template <typename _Up>
    using _DeleterConstraint =
typename __uniq_ptr_impl<_Tp, _Up>::_DeleterConstraint::type;

    __uniq_ptr_data<_Tp, _Dp> _M_t;

    template<typename _Up>
using __remove_cv = typename remove_cv<_Up>::type;

    // like is_base_of<_Tp, _Up> but false if unqualified types are the same
    template<typename _Up>
using __is_derived_Tp
 = __and_< is_base_of<_Tp, _Up>,
    __not_<is_same<__remove_cv<_Tp>, __remove_cv<_Up>>> >;

  public:
    using pointer	  = typename __uniq_ptr_impl<_Tp, _Dp>::pointer;
    using element_type  = _Tp;
    using deleter_type  = _Dp;

    // helper template for detecting a safe conversion from another
    // unique_ptr
    template<typename _Up, typename _Ep,
             typename _UPtr = unique_ptr<_Up, _Ep>,
      typename _UP_pointer = typename _UPtr::pointer,
      typename _UP_element_type = typename _UPtr::element_type>
using __safe_conversion_up = __and_<
        is_array<_Up>,
        is_same<pointer, element_type*>,
        is_same<_UP_pointer, _UP_element_type*>,
        is_convertible<_UP_element_type(*)[], element_type(*)[]>
      >;

    // helper template for detecting a safe conversion from a raw pointer
    template<typename _Up>
      using __safe_conversion_raw = __and_<
        __or_<__or_<is_same<_Up, pointer>,
                    is_same<_Up, nullptr_t>>,
              __and_<is_pointer<_Up>,
                     is_same<pointer, element_type*>,
                     is_convertible<
                       typename remove_pointer<_Up>::type(*)[],
                       element_type(*)[]>
              >
        >
      >;

    // Constructors.

    /// Default constructor, creates a unique_ptr that owns nothing.
    template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
constexpr unique_ptr() noexcept
: _M_t()
{ }

    /** Takes ownership of a pointer.
     *
     * @param __p  A pointer to an array of a type safely convertible
     * to an array of @c element_type
     *
     * The deleter will be value-initialized.
     */
    template<typename _Up,
      typename _Vp = _Dp,
      typename = _DeleterConstraint<_Vp>,
      typename = typename enable_if<
               __safe_conversion_raw<_Up>::value, bool>::type>
explicit
unique_ptr(_Up __p) noexcept
: _M_t(__p)
3
←
Calling constructor for '__uniq_ptr_data<unsigned long, std::default_delete<unsigned long[]>, true, true>'→
4
←
Calling constructor for '__uniq_ptr_impl<unsigned long, std::default_delete<unsigned long[]>>'→
5
←
Returning from constructor for '__uniq_ptr_impl<unsigned long, std::default_delete<unsigned long[]>>'→
6
←
Returning from constructor for '__uniq_ptr_data<unsigned long, std::default_delete<unsigned long[]>, true, true>'→
      { }

    /** Takes ownership of a pointer.
     *
     * @param __p  A pointer to an array of a type safely convertible
     * to an array of @c element_type
     * @param __d  A reference to a deleter.
     *
     * The deleter will be initialized with @p __d
     */
    template<typename _Up, typename _Del = deleter_type,
      typename = _Require<__safe_conversion_raw<_Up>,
		   is_copy_constructible<_Del>>>
    unique_ptr(_Up __p, const deleter_type& __d) noexcept
    : _M_t(__p, __d) { }

    /** Takes ownership of a pointer.
     *
     * @param __p  A pointer to an array of a type safely convertible
     * to an array of @c element_type
     * @param __d  A reference to a deleter.
     *
     * The deleter will be initialized with @p std::move(__d)
     */
    template<typename _Up, typename _Del = deleter_type,
      typename = _Require<__safe_conversion_raw<_Up>,
		   is_move_constructible<_Del>>>
unique_ptr(_Up __p,
   __enable_if_t<!is_lvalue_reference<_Del>::value,
		 _Del&&> __d) noexcept
: _M_t(std::move(__p), std::move(__d))
{ }

    template<typename _Up, typename _Del = deleter_type,
      typename _DelUnref = typename remove_reference<_Del>::type,
      typename = _Require<__safe_conversion_raw<_Up>>>
unique_ptr(_Up,
   __enable_if_t<is_lvalue_reference<_Del>::value,
		 _DelUnref&&>) = delete;

    /// Move constructor.
    unique_ptr(unique_ptr&&) = default;

    /// Creates a unique_ptr that owns nothing.
    template<typename _Del = _Dp, typename = _DeleterConstraint<_Del>>
constexpr unique_ptr(nullptr_t) noexcept
: _M_t()
      { }

    template<typename _Up, typename _Ep, typename = _Require<
      __safe_conversion_up<_Up, _Ep>,
      typename conditional<is_reference<_Dp>::value,
		    is_same<_Ep, _Dp>,
		    is_convertible<_Ep, _Dp>>::type>>
unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
: _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
{ }

    /// Destructor, invokes the deleter if the stored pointer is not null.
    ~unique_ptr()
    {
auto& __ptr = _M_t._M_ptr();
if (__ptr != nullptr)
 get_deleter()(__ptr);
__ptr = pointer();
    }

    // Assignment.

    /** @brief Move assignment operator.
     *
     * Invokes the deleter if this object owns a pointer.
     */
    unique_ptr&
    operator=(unique_ptr&&) = default;

    /** @brief Assignment from another type.
     *
     * @param __u  The object to transfer ownership from, which owns a
     *             convertible pointer to an array object.
     *
     * Invokes the deleter if this object owns a pointer.
     */
    template<typename _Up, typename _Ep>
typename
enable_if<__and_<__safe_conversion_up<_Up, _Ep>,
                       is_assignable<deleter_type&, _Ep&&>
                >::value,
                unique_ptr&>::type
operator=(unique_ptr<_Up, _Ep>&& __u) noexcept
{
 reset(__u.release());
 get_deleter() = std::forward<_Ep>(__u.get_deleter());
 return *this;
}

    /// Reset the %unique_ptr to empty, invoking the deleter if necessary.
    unique_ptr&
    operator=(nullptr_t) noexcept
    {
reset();
return *this;
    }

    // Observers.

    /// Access an element of owned array.
    typename std::add_lvalue_reference<element_type>::type
    operator[](size_t __i) const
    {
__glibcxx_assert(get() != pointer());
return get()[__i];
    }

    /// Return the stored pointer.
    pointer
    get() const noexcept
    { return _M_t._M_ptr(); }

    /// Return a reference to the stored deleter.
    deleter_type&
    get_deleter() noexcept
    { return _M_t._M_deleter(); }

    /// Return a reference to the stored deleter.
    const deleter_type&
    get_deleter() const noexcept
    { return _M_t._M_deleter(); }

    /// Return @c true if the stored pointer is not null.
    explicit operator bool() const noexcept
    { return get() == pointer() ? false : true; }

    // Modifiers.

    /// Release ownership of any stored pointer.
    pointer
    release() noexcept
    { return _M_t.release(); }

    /** @brief Replace the stored pointer.
     *
     * @param __p  The new pointer to store.
     *
     * The deleter will be invoked if a pointer is already owned.
     */
    template <typename _Up,
              typename = _Require<
                __or_<is_same<_Up, pointer>,
                      __and_<is_same<pointer, element_type*>,
                             is_pointer<_Up>,
                             is_convertible<
                               typename remove_pointer<_Up>::type(*)[],
                               element_type(*)[]
                             >
                      >
                >
             >>
    void
    reset(_Up __p) noexcept
    { _M_t.reset(std::move(__p)); }

    void reset(nullptr_t = nullptr) noexcept
    { reset(pointer()); }

    /// Exchange the pointer and deleter with another object.
    void
    swap(unique_ptr& __u) noexcept
    {
static_assert(__is_swappable<_Dp>::value, "deleter must be swappable");
_M_t.swap(__u._M_t);
    }

    // Disable copy from lvalue.
    unique_ptr(const unique_ptr&) = delete;
    unique_ptr& operator=(const unique_ptr&) = delete;
  };

/// @relates unique_ptr @{

/// Swap overload for unique_ptr
template<typename _Tp, typename _Dp>
  inline
732#if __cplusplus201703L > 201402L || !defined(__STRICT_ANSI__1) // c++1z or gnu++11
  // Constrained free swap overload, see p0185r1
  typename enable_if<__is_swappable<_Dp>::value>::type
735#else
  void
737#endif
  swap(unique_ptr<_Tp, _Dp>& __x,
unique_ptr<_Tp, _Dp>& __y) noexcept
  { __x.swap(__y); }

742#if __cplusplus201703L > 201402L || !defined(__STRICT_ANSI__1) // c++1z or gnu++11
template<typename _Tp, typename _Dp>
  typename enable_if<!__is_swappable<_Dp>::value>::type
  swap(unique_ptr<_Tp, _Dp>&,
unique_ptr<_Tp, _Dp>&) = delete;
747#endif

/// Equality operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
  typename _Up, typename _Ep>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator==(const unique_ptr<_Tp, _Dp>& __x,
      const unique_ptr<_Up, _Ep>& __y)
  { return __x.get() == __y.get(); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator==(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
  { return !__x; }

763#ifndef __cpp_lib_three_way_comparison
/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator==(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
  { return !__x; }

/// Inequality operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
  typename _Up, typename _Ep>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator!=(const unique_ptr<_Tp, _Dp>& __x,
      const unique_ptr<_Up, _Ep>& __y)
  { return __x.get() != __y.get(); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator!=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t) noexcept
  { return (bool)__x; }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator!=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x) noexcept
  { return (bool)__x; }
789#endif // three way comparison

/// Relational operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
  typename _Up, typename _Ep>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<(const unique_ptr<_Tp, _Dp>& __x,
     const unique_ptr<_Up, _Ep>& __y)
  {
    typedef typename
std::common_type<typename unique_ptr<_Tp, _Dp>::pointer,
                typename unique_ptr<_Up, _Ep>::pointer>::type _CT;
    return std::less<_CT>()(__x.get(), __y.get());
  }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
  {
    return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
						 nullptr);
  }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
  {
    return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
						 __x.get());
  }

/// Relational operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
  typename _Up, typename _Ep>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<=(const unique_ptr<_Tp, _Dp>& __x,
      const unique_ptr<_Up, _Ep>& __y)
  { return !(__y < __x); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
  { return !(nullptr < __x); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator<=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
  { return !(__x < nullptr); }

/// Relational operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
  typename _Up, typename _Ep>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>(const unique_ptr<_Tp, _Dp>& __x,
     const unique_ptr<_Up, _Ep>& __y)
  { return (__y < __x); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
  {
    return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(nullptr,
						 __x.get());
  }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
  {
    return std::less<typename unique_ptr<_Tp, _Dp>::pointer>()(__x.get(),
						 nullptr);
  }

/// Relational operator for unique_ptr objects, compares the owned pointers
template<typename _Tp, typename _Dp,
  typename _Up, typename _Ep>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>=(const unique_ptr<_Tp, _Dp>& __x,
      const unique_ptr<_Up, _Ep>& __y)
  { return !(__x < __y); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>=(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
  { return !(__x < nullptr); }

/// unique_ptr comparison with nullptr
template<typename _Tp, typename _Dp>
  _GLIBCXX_NODISCARD[[__nodiscard__]] inline bool
  operator>=(nullptr_t, const unique_ptr<_Tp, _Dp>& __x)
  { return !(nullptr < __x); }

888#ifdef __cpp_lib_three_way_comparison
template<typename _Tp, typename _Dp, typename _Up, typename _Ep>
  requires three_way_comparable_with<typename unique_ptr<_Tp, _Dp>::pointer,
		       typename unique_ptr<_Up, _Ep>::pointer>
  inline
  compare_three_way_result_t<typename unique_ptr<_Tp, _Dp>::pointer,
	       typename unique_ptr<_Up, _Ep>::pointer>
  operator<=>(const unique_ptr<_Tp, _Dp>& __x,
const unique_ptr<_Up, _Ep>& __y)
  { return compare_three_way()(__x.get(), __y.get()); }

template<typename _Tp, typename _Dp>
  requires three_way_comparable<typename unique_ptr<_Tp, _Dp>::pointer>
  inline
  compare_three_way_result_t<typename unique_ptr<_Tp, _Dp>::pointer>
  operator<=>(const unique_ptr<_Tp, _Dp>& __x, nullptr_t)
  {
    using pointer = typename unique_ptr<_Tp, _Dp>::pointer;
    return compare_three_way()(__x.get(), static_cast<pointer>(nullptr));
  }
908#endif
// @} relates unique_ptr

/// @cond undocumented
template<typename _Up, typename _Ptr = typename _Up::pointer,
  bool = __poison_hash<_Ptr>::__enable_hash_call>
  struct __uniq_ptr_hash
915#if ! _GLIBCXX_INLINE_VERSION0
  : private __poison_hash<_Ptr>
917#endif
  {
    size_t
    operator()(const _Up& __u) const
    noexcept(noexcept(std::declval<hash<_Ptr>>()(std::declval<_Ptr>())))
    { return hash<_Ptr>()(__u.get()); }
  };

template<typename _Up, typename _Ptr>
  struct __uniq_ptr_hash<_Up, _Ptr, false>
  : private __poison_hash<_Ptr>
  { };
/// @endcond

/// std::hash specialization for unique_ptr.
template<typename _Tp, typename _Dp>
  struct hash<unique_ptr<_Tp, _Dp>>
  : public __hash_base<size_t, unique_ptr<_Tp, _Dp>>,
    public __uniq_ptr_hash<unique_ptr<_Tp, _Dp>>
  { };

938#if __cplusplus201703L >= 201402L
/// @relates unique_ptr @{
940#define __cpp_lib_make_unique201304 201304

/// @cond undocumented

template<typename _Tp>
  struct _MakeUniq
  { typedef unique_ptr<_Tp> __single_object; };

template<typename _Tp>
  struct _MakeUniq<_Tp[]>
  { typedef unique_ptr<_Tp[]> __array; };

template<typename _Tp, size_t _Bound>
  struct _MakeUniq<_Tp[_Bound]>
  { struct __invalid_type { }; };

/// @endcond

/// std::make_unique for single objects
template<typename _Tp, typename... _Args>
  inline typename _MakeUniq<_Tp>::__single_object
  make_unique(_Args&&... __args)
  { return unique_ptr<_Tp>(new _Tp(std::forward<_Args>(__args)...)); }

/// std::make_unique for arrays of unknown bound
template<typename _Tp>
  inline typename _MakeUniq<_Tp>::__array
  make_unique(size_t __num)
  { return unique_ptr<_Tp>(new remove_extent_t<_Tp>[__num]()); }

/// Disable std::make_unique for arrays of known bound
template<typename _Tp, typename... _Args>
  inline typename _MakeUniq<_Tp>::__invalid_type
  make_unique(_Args&&...) = delete;
// @} relates unique_ptr
975#endif // C++14

977#if __cplusplus201703L > 201703L && __cpp_concepts
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2948. unique_ptr does not define operator<< for stream output
/// Stream output operator for unique_ptr
template<typename _CharT, typename _Traits, typename _Tp, typename _Dp>
  inline basic_ostream<_CharT, _Traits>&
  operator<<(basic_ostream<_CharT, _Traits>& __os,
      const unique_ptr<_Tp, _Dp>& __p)
  requires requires { __os << __p.get(); }
  {
    __os << __p.get();
    return __os;
  }
990#endif // C++20

// @} group pointer_abstractions

994#if __cplusplus201703L >= 201703L
namespace __detail::__variant
{
  template<typename> struct _Never_valueless_alt; // see <variant>

  // Provide the strong exception-safety guarantee when emplacing a
  // unique_ptr into a variant.
  template<typename _Tp, typename _Del>
    struct _Never_valueless_alt<std::unique_ptr<_Tp, _Del>>
    : std::true_type
    { };
}  // namespace __detail::__variant
1006#endif // C++17

1008_GLIBCXX_END_NAMESPACE_VERSION
1009} // namespace

1011#endif /* _UNIQUE_PTR_H */

←

/build/source/llvm/include/llvm/ADT/STLExtras.h

1//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8///
9/// \file
10/// This file contains some templates that are useful if you are working with
11/// the STL at all.
12///
13/// No library is required when using these functions.
14///
15//===----------------------------------------------------------------------===//
16 
17#ifndef LLVM_ADT_STLEXTRAS_H
18#define LLVM_ADT_STLEXTRAS_H
19 
20#include "llvm/ADT/Hashing.h"
21#include "llvm/ADT/STLForwardCompat.h"
22#include "llvm/ADT/STLFunctionalExtras.h"
23#include "llvm/ADT/identity.h"
24#include "llvm/ADT/iterator.h"
25#include "llvm/ADT/iterator_range.h"
26#include "llvm/Config/abi-breaking.h"
27#include "llvm/Support/ErrorHandling.h"
28#include <algorithm>
29#include <cassert>
30#include <cstddef>
31#include <cstdint>
32#include <cstdlib>
33#include <functional>
34#include <initializer_list>
35#include <iterator>
36#include <limits>
37#include <memory>
38#include <optional>
39#include <tuple>
40#include <type_traits>
41#include <utility>
42 
43#ifdef EXPENSIVE_CHECKS
44#include <random> // for std::mt19937
45#endif
46 
47namespace llvm {
48 
49// Only used by compiler if both template types are the same.  Useful when
50// using SFINAE to test for the existence of member functions.
51template <typename T, T> struct SameType;
52 
53namespace detail {
54 
55template <typename RangeT>
56using IterOfRange = decltype(std::begin(std::declval<RangeT &>()));
57 
58template <typename RangeT>
59using ValueOfRange =
60    std::remove_reference_t<decltype(*std::begin(std::declval<RangeT &>()))>;
61 
62} // end namespace detail
63 
64//===----------------------------------------------------------------------===//
65//     Extra additions to <type_traits>
66//===----------------------------------------------------------------------===//
67 
68template <typename T> struct make_const_ptr {
69  using type = std::add_pointer_t<std::add_const_t<T>>;
70};
71 
72template <typename T> struct make_const_ref {
73  using type = std::add_lvalue_reference_t<std::add_const_t<T>>;
74};
75 
76namespace detail {
77template <class, template <class...> class Op, class... Args> struct detector {
78  using value_t = std::false_type;
79};
80template <template <class...> class Op, class... Args>
81struct detector<std::void_t<Op<Args...>>, Op, Args...> {
82  using value_t = std::true_type;
83};
84} // end namespace detail
85 
86/// Detects if a given trait holds for some set of arguments 'Args'.
87/// For example, the given trait could be used to detect if a given type
88/// has a copy assignment operator:
89///   template<class T>
90///   using has_copy_assign_t = decltype(std::declval<T&>()
91///                                                 = std::declval<const T&>());
92///   bool fooHasCopyAssign = is_detected<has_copy_assign_t, FooClass>::value;
93template <template <class...> class Op, class... Args>
94using is_detected = typename detail::detector<void, Op, Args...>::value_t;
95 
96/// This class provides various trait information about a callable object.
97///   * To access the number of arguments: Traits::num_args
98///   * To access the type of an argument: Traits::arg_t<Index>
99///   * To access the type of the result:  Traits::result_t
100template <typename T, bool isClass = std::is_class<T>::value>
101struct function_traits : public function_traits<decltype(&T::operator())> {};
102 
103/// Overload for class function types.
104template <typename ClassType, typename ReturnType, typename... Args>
105struct function_traits<ReturnType (ClassType::*)(Args...) const, false> {
106  /// The number of arguments to this function.
107  enum { num_args = sizeof...(Args) };
108 
109  /// The result type of this function.
110  using result_t = ReturnType;
111 
112  /// The type of an argument to this function.
113  template <size_t Index>
114  using arg_t = std::tuple_element_t<Index, std::tuple<Args...>>;
115};
116/// Overload for class function types.
117template <typename ClassType, typename ReturnType, typename... Args>
118struct function_traits<ReturnType (ClassType::*)(Args...), false>
119    : public function_traits<ReturnType (ClassType::*)(Args...) const> {};
120/// Overload for non-class function types.
121template <typename ReturnType, typename... Args>
122struct function_traits<ReturnType (*)(Args...), false> {
123  /// The number of arguments to this function.
124  enum { num_args = sizeof...(Args) };
125 
126  /// The result type of this function.
127  using result_t = ReturnType;
128 
129  /// The type of an argument to this function.
130  template <size_t i>
131  using arg_t = std::tuple_element_t<i, std::tuple<Args...>>;
132};
133template <typename ReturnType, typename... Args>
134struct function_traits<ReturnType (*const)(Args...), false>
135    : public function_traits<ReturnType (*)(Args...)> {};
136/// Overload for non-class function type references.
137template <typename ReturnType, typename... Args>
138struct function_traits<ReturnType (&)(Args...), false>
139    : public function_traits<ReturnType (*)(Args...)> {};
140 
141/// traits class for checking whether type T is one of any of the given
142/// types in the variadic list.
143template <typename T, typename... Ts>
144using is_one_of = std::disjunction<std::is_same<T, Ts>...>;
145 
146/// traits class for checking whether type T is a base class for all
147///  the given types in the variadic list.
148template <typename T, typename... Ts>
149using are_base_of = std::conjunction<std::is_base_of<T, Ts>...>;
150 
151namespace detail {
152template <typename T, typename... Us> struct TypesAreDistinct;
153template <typename T, typename... Us>
154struct TypesAreDistinct
155    : std::integral_constant<bool, !is_one_of<T, Us...>::value &&
156                                       TypesAreDistinct<Us...>::value> {};
157template <typename T> struct TypesAreDistinct<T> : std::true_type {};
158} // namespace detail
159 
160/// Determine if all types in Ts are distinct.
161///
162/// Useful to statically assert when Ts is intended to describe a non-multi set
163/// of types.
164///
165/// Expensive (currently quadratic in sizeof(Ts...)), and so should only be
166/// asserted once per instantiation of a type which requires it.
167template <typename... Ts> struct TypesAreDistinct;
168template <> struct TypesAreDistinct<> : std::true_type {};
169template <typename... Ts>
170struct TypesAreDistinct
171    : std::integral_constant<bool, detail::TypesAreDistinct<Ts...>::value> {};
172 
173/// Find the first index where a type appears in a list of types.
174///
175/// FirstIndexOfType<T, Us...>::value is the first index of T in Us.
176///
177/// Typically only meaningful when it is otherwise statically known that the
178/// type pack has no duplicate types. This should be guaranteed explicitly with
179/// static_assert(TypesAreDistinct<Us...>::value).
180///
181/// It is a compile-time error to instantiate when T is not present in Us, i.e.
182/// if is_one_of<T, Us...>::value is false.
183template <typename T, typename... Us> struct FirstIndexOfType;
184template <typename T, typename U, typename... Us>
185struct FirstIndexOfType<T, U, Us...>
186    : std::integral_constant<size_t, 1 + FirstIndexOfType<T, Us...>::value> {};
187template <typename T, typename... Us>
188struct FirstIndexOfType<T, T, Us...> : std::integral_constant<size_t, 0> {};
189 
190/// Find the type at a given index in a list of types.
191///
192/// TypeAtIndex<I, Ts...> is the type at index I in Ts.
193template <size_t I, typename... Ts>
194using TypeAtIndex = std::tuple_element_t<I, std::tuple<Ts...>>;
195 
196/// Helper which adds two underlying types of enumeration type.
197/// Implicit conversion to a common type is accepted.
198template <typename EnumTy1, typename EnumTy2,
199          typename UT1 = std::enable_if_t<std::is_enum<EnumTy1>::value,
200                                          std::underlying_type_t<EnumTy1>>,
201          typename UT2 = std::enable_if_t<std::is_enum<EnumTy2>::value,
202                                          std::underlying_type_t<EnumTy2>>>
203constexpr auto addEnumValues(EnumTy1 LHS, EnumTy2 RHS) {
204  return static_cast<UT1>(LHS) + static_cast<UT2>(RHS);
205}
206 
207//===----------------------------------------------------------------------===//
208//     Extra additions to <iterator>
209//===----------------------------------------------------------------------===//
210 
211namespace callable_detail {
212 
213/// Templated storage wrapper for a callable.
214///
215/// This class is consistently default constructible, copy / move
216/// constructible / assignable.
217///
218/// Supported callable types:
219///  - Function pointer
220///  - Function reference
221///  - Lambda
222///  - Function object
223template <typename T,
224          bool = std::is_function_v<std::remove_pointer_t<remove_cvref_t<T>>>>
225class Callable {
226  using value_type = std::remove_reference_t<T>;
227  using reference = value_type &;
228  using const_reference = value_type const &;
229 
230  std::optional<value_type> Obj;
231 
232  static_assert(!std::is_pointer_v<value_type>,
233                "Pointers to non-functions are not callable.");
234 
235public:
236  Callable() = default;
237  Callable(T const &O) : Obj(std::in_place, O) {}
238 
239  Callable(Callable const &Other) = default;
240  Callable(Callable &&Other) = default;
241 
242  Callable &operator=(Callable const &Other) {
243    Obj = std::nullopt;
244    if (Other.Obj)
245      Obj.emplace(*Other.Obj);
246    return *this;
247  }
248 
249  Callable &operator=(Callable &&Other) {
250    Obj = std::nullopt;
251    if (Other.Obj)
252      Obj.emplace(std::move(*Other.Obj));
253    return *this;
254  }
255 
256  template <typename... Pn,
257            std::enable_if_t<std::is_invocable_v<T, Pn...>, int> = 0>
258  decltype(auto) operator()(Pn &&...Params) {
259    return (*Obj)(std::forward<Pn>(Params)...);
260  }
261 
262  template <typename... Pn,
263            std::enable_if_t<std::is_invocable_v<T const, Pn...>, int> = 0>
264  decltype(auto) operator()(Pn &&...Params) const {
265    return (*Obj)(std::forward<Pn>(Params)...);
266  }
267 
268  bool valid() const { return Obj != std::nullopt; }
269  bool reset() { return Obj = std::nullopt; }
270 
271  operator reference() { return *Obj; }
272  operator const_reference() const { return *Obj; }
273};
274 
275// Function specialization.  No need to waste extra space wrapping with a
276// std::optional.
277template <typename T> class Callable<T, true> {
278  static constexpr bool IsPtr = std::is_pointer_v<remove_cvref_t<T>>;
279 
280  using StorageT = std::conditional_t<IsPtr, T, std::remove_reference_t<T> *>;
281  using CastT = std::conditional_t<IsPtr, T, T &>;
282 
283private:
284  StorageT Func = nullptr;
285 
286private:
287  template <typename In> static constexpr auto convertIn(In &&I) {
288    if constexpr (IsPtr) {
289      // Pointer... just echo it back.
290      return I;
291    } else {
292      // Must be a function reference.  Return its address.
293      return &I;
294    }
295  }
296 
297public:
298  Callable() = default;
299 
300  // Construct from a function pointer or reference.
301  //
302  // Disable this constructor for references to 'Callable' so we don't violate
303  // the rule of 0.
304  template < // clang-format off
305    typename FnPtrOrRef,
306    std::enable_if_t<
307      !std::is_same_v<remove_cvref_t<FnPtrOrRef>, Callable>, int
308    > = 0
309  > // clang-format on
310  Callable(FnPtrOrRef &&F) : Func(convertIn(F)) {}
311 
312  template <typename... Pn,
313            std::enable_if_t<std::is_invocable_v<T, Pn...>, int> = 0>
314  decltype(auto) operator()(Pn &&...Params) const {
315    return Func(std::forward<Pn>(Params)...);
316  }
317 
318  bool valid() const { return Func != nullptr; }
319  void reset() { Func = nullptr; }
320 
321  operator T const &() const {
322    if constexpr (IsPtr) {
323      // T is a pointer... just echo it back.
324      return Func;
325    } else {
326      static_assert(std::is_reference_v<T>,
327                    "Expected a reference to a function.");
328      // T is a function reference... dereference the stored pointer.
329      return *Func;
330    }
331  }
332};
333 
334} // namespace callable_detail
335 
336namespace adl_detail {
337 
338using std::begin;
339 
340template <typename ContainerTy>
341decltype(auto) adl_begin(ContainerTy &&container) {
342  return begin(std::forward<ContainerTy>(container));
343}
344 
345using std::end;
346 
347template <typename ContainerTy>
348decltype(auto) adl_end(ContainerTy &&container) {
349  return end(std::forward<ContainerTy>(container));
350}
351 
352using std::swap;
353 
354template <typename T>
355void adl_swap(T &&lhs, T &&rhs) noexcept(noexcept(swap(std::declval<T>(),
356                                                       std::declval<T>()))) {
357  swap(std::forward<T>(lhs), std::forward<T>(rhs));
358}
359 
360} // end namespace adl_detail
361 
362template <typename ContainerTy>
363decltype(auto) adl_begin(ContainerTy &&container) {
364  return adl_detail::adl_begin(std::forward<ContainerTy>(container));
365}
366 
367template <typename ContainerTy>
368decltype(auto) adl_end(ContainerTy &&container) {
369  return adl_detail::adl_end(std::forward<ContainerTy>(container));
370}
371 
372template <typename T>
373void adl_swap(T &&lhs, T &&rhs) noexcept(
374    noexcept(adl_detail::adl_swap(std::declval<T>(), std::declval<T>()))) {
375  adl_detail::adl_swap(std::forward<T>(lhs), std::forward<T>(rhs));
376}
377 
378/// Returns true if the given container only contains a single element.
379template <typename ContainerTy> bool hasSingleElement(ContainerTy &&C) {
380  auto B = std::begin(C), E = std::end(C);
381  return B != E && std::next(B) == E;
382}
383 
384/// Return a range covering \p RangeOrContainer with the first N elements
385/// excluded.
386template <typename T> auto drop_begin(T &&RangeOrContainer, size_t N = 1) {
387  return make_range(std::next(adl_begin(RangeOrContainer), N),
388                    adl_end(RangeOrContainer));
389}
390 
391/// Return a range covering \p RangeOrContainer with the last N elements
392/// excluded.
393template <typename T> auto drop_end(T &&RangeOrContainer, size_t N = 1) {
394  return make_range(adl_begin(RangeOrContainer),
395                    std::prev(adl_end(RangeOrContainer), N));
396}
397 
398// mapped_iterator - This is a simple iterator adapter that causes a function to
399// be applied whenever operator* is invoked on the iterator.
400 
401template <typename ItTy, typename FuncTy,
402          typename ReferenceTy =
403              decltype(std::declval<FuncTy>()(*std::declval<ItTy>()))>
404class mapped_iterator
405    : public iterator_adaptor_base<
406          mapped_iterator<ItTy, FuncTy>, ItTy,
407          typename std::iterator_traits<ItTy>::iterator_category,
408          std::remove_reference_t<ReferenceTy>,
409          typename std::iterator_traits<ItTy>::difference_type,
410          std::remove_reference_t<ReferenceTy> *, ReferenceTy> {
411public:
412  mapped_iterator() = default;
413  mapped_iterator(ItTy U, FuncTy F)
414    : mapped_iterator::iterator_adaptor_base(std::move(U)), F(std::move(F)) {}
415 
416  ItTy getCurrent() { return this->I; }
417 
418  const FuncTy &getFunction() const { return F; }
419 
420  ReferenceTy operator*() const { return F(*this->I); }
421 
422private:
423  callable_detail::Callable<FuncTy> F{};
424};
425 
426// map_iterator - Provide a convenient way to create mapped_iterators, just like
427// make_pair is useful for creating pairs...
428template <class ItTy, class FuncTy>
429inline mapped_iterator<ItTy, FuncTy> map_iterator(ItTy I, FuncTy F) {
430  return mapped_iterator<ItTy, FuncTy>(std::move(I), std::move(F));
431}
432 
433template <class ContainerTy, class FuncTy>
434auto map_range(ContainerTy &&C, FuncTy F) {
435  return make_range(map_iterator(C.begin(), F), map_iterator(C.end(), F));
436}
437 
438/// A base type of mapped iterator, that is useful for building derived
439/// iterators that do not need/want to store the map function (as in
440/// mapped_iterator). These iterators must simply provide a `mapElement` method
441/// that defines how to map a value of the iterator to the provided reference
442/// type.
443template <typename DerivedT, typename ItTy, typename ReferenceTy>
444class mapped_iterator_base
445    : public iterator_adaptor_base<
446          DerivedT, ItTy,
447          typename std::iterator_traits<ItTy>::iterator_category,
448          std::remove_reference_t<ReferenceTy>,
449          typename std::iterator_traits<ItTy>::difference_type,
450          std::remove_reference_t<ReferenceTy> *, ReferenceTy> {
451public:
452  using BaseT = mapped_iterator_base;
453 
454  mapped_iterator_base(ItTy U)
455      : mapped_iterator_base::iterator_adaptor_base(std::move(U)) {}
456 
457  ItTy getCurrent() { return this->I; }
458 
459  ReferenceTy operator*() const {
460    return static_cast<const DerivedT &>(*this).mapElement(*this->I);
461  }
462};
463 
464/// Helper to determine if type T has a member called rbegin().
465template <typename Ty> class has_rbegin_impl {
466  using yes = char[1];
467  using no = char[2];
468 
469  template <typename Inner>
470  static yes& test(Inner *I, decltype(I->rbegin()) * = nullptr);
471 
472  template <typename>
473  static no& test(...);
474 
475public:
476  static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
477};
478 
479/// Metafunction to determine if T& or T has a member called rbegin().
480template <typename Ty>
481struct has_rbegin : has_rbegin_impl<std::remove_reference_t<Ty>> {};
482 
483// Returns an iterator_range over the given container which iterates in reverse.
484template <typename ContainerTy> auto reverse(ContainerTy &&C) {
485  if constexpr (has_rbegin<ContainerTy>::value)
486    return make_range(C.rbegin(), C.rend());
487  else
488    return make_range(std::make_reverse_iterator(std::end(C)),
489                      std::make_reverse_iterator(std::begin(C)));
490}
491 
492/// An iterator adaptor that filters the elements of given inner iterators.
493///
494/// The predicate parameter should be a callable object that accepts the wrapped
495/// iterator's reference type and returns a bool. When incrementing or
496/// decrementing the iterator, it will call the predicate on each element and
497/// skip any where it returns false.
498///
499/// \code
500///   int A[] = { 1, 2, 3, 4 };
501///   auto R = make_filter_range(A, [](int N) { return N % 2 == 1; });
502///   // R contains { 1, 3 }.
503/// \endcode
504///
505/// Note: filter_iterator_base implements support for forward iteration.
506/// filter_iterator_impl exists to provide support for bidirectional iteration,
507/// conditional on whether the wrapped iterator supports it.
508template <typename WrappedIteratorT, typename PredicateT, typename IterTag>
509class filter_iterator_base
510    : public iterator_adaptor_base<
511          filter_iterator_base<WrappedIteratorT, PredicateT, IterTag>,
512          WrappedIteratorT,
513          std::common_type_t<IterTag,
514                             typename std::iterator_traits<
515                                 WrappedIteratorT>::iterator_category>> {
516  using BaseT = typename filter_iterator_base::iterator_adaptor_base;
517 
518protected:
519  WrappedIteratorT End;
520  PredicateT Pred;
521 
522  void findNextValid() {
523    while (this->I != End && !Pred(*this->I))
524      BaseT::operator++();
525  }
526 
527  filter_iterator_base() = default;
528 
529  // Construct the iterator. The begin iterator needs to know where the end
530  // is, so that it can properly stop when it gets there. The end iterator only
531  // needs the predicate to support bidirectional iteration.
532  filter_iterator_base(WrappedIteratorT Begin, WrappedIteratorT End,
533                       PredicateT Pred)
534      : BaseT(Begin), End(End), Pred(Pred) {
535    findNextValid();
536  }
537 
538public:
539  using BaseT::operator++;
540 
541  filter_iterator_base &operator++() {
542    BaseT::operator++();
543    findNextValid();
544    return *this;
545  }
546 
547  decltype(auto) operator*() const {
548    assert(BaseT::wrapped() != End && "Cannot dereference end iterator!")(static_cast <bool> (BaseT::wrapped() != End &&
 "Cannot dereference end iterator!") ? void (0) : __assert_fail
 ("BaseT::wrapped() != End && \"Cannot dereference end iterator!\""
, "llvm/include/llvm/ADT/STLExtras.h", 548, __extension__ __PRETTY_FUNCTION__
));
549    return BaseT::operator*();
550  }
551 
552  decltype(auto) operator->() const {
553    assert(BaseT::wrapped() != End && "Cannot dereference end iterator!")(static_cast <bool> (BaseT::wrapped() != End &&
 "Cannot dereference end iterator!") ? void (0) : __assert_fail
 ("BaseT::wrapped() != End && \"Cannot dereference end iterator!\""
, "llvm/include/llvm/ADT/STLExtras.h", 553, __extension__ __PRETTY_FUNCTION__
));
554    return BaseT::operator->();
555  }
556};
557 
558/// Specialization of filter_iterator_base for forward iteration only.
559template <typename WrappedIteratorT, typename PredicateT,
560          typename IterTag = std::forward_iterator_tag>
561class filter_iterator_impl
562    : public filter_iterator_base<WrappedIteratorT, PredicateT, IterTag> {
563public:
564  filter_iterator_impl() = default;
565 
566  filter_iterator_impl(WrappedIteratorT Begin, WrappedIteratorT End,
567                       PredicateT Pred)
568      : filter_iterator_impl::filter_iterator_base(Begin, End, Pred) {}
569};
570 
571/// Specialization of filter_iterator_base for bidirectional iteration.
572template <typename WrappedIteratorT, typename PredicateT>
573class filter_iterator_impl<WrappedIteratorT, PredicateT,
574                           std::bidirectional_iterator_tag>
575    : public filter_iterator_base<WrappedIteratorT, PredicateT,
576                                  std::bidirectional_iterator_tag> {
577  using BaseT = typename filter_iterator_impl::filter_iterator_base;
578 
579  void findPrevValid() {
580    while (!this->Pred(*this->I))
581      BaseT::operator--();
582  }
583 
584public:
585  using BaseT::operator--;
586 
587  filter_iterator_impl() = default;
588 
589  filter_iterator_impl(WrappedIteratorT Begin, WrappedIteratorT End,
590                       PredicateT Pred)
591      : BaseT(Begin, End, Pred) {}
592 
593  filter_iterator_impl &operator--() {
594    BaseT::operator--();
595    findPrevValid();
596    return *this;
597  }
598};
599 
600namespace detail {
601 
602template <bool is_bidirectional> struct fwd_or_bidi_tag_impl {
603  using type = std::forward_iterator_tag;
604};
605 
606template <> struct fwd_or_bidi_tag_impl<true> {
607  using type = std::bidirectional_iterator_tag;
608};
609 
610/// Helper which sets its type member to forward_iterator_tag if the category
611/// of \p IterT does not derive from bidirectional_iterator_tag, and to
612/// bidirectional_iterator_tag otherwise.
613template <typename IterT> struct fwd_or_bidi_tag {
614  using type = typename fwd_or_bidi_tag_impl<std::is_base_of<
615      std::bidirectional_iterator_tag,
616      typename std::iterator_traits<IterT>::iterator_category>::value>::type;
617};
618 
619} // namespace detail
620 
621/// Defines filter_iterator to a suitable specialization of
622/// filter_iterator_impl, based on the underlying iterator's category.
623template <typename WrappedIteratorT, typename PredicateT>
624using filter_iterator = filter_iterator_impl<
625    WrappedIteratorT, PredicateT,
626    typename detail::fwd_or_bidi_tag<WrappedIteratorT>::type>;
627 
628/// Convenience function that takes a range of elements and a predicate,
629/// and return a new filter_iterator range.
630///
631/// FIXME: Currently if RangeT && is a rvalue reference to a temporary, the
632/// lifetime of that temporary is not kept by the returned range object, and the
633/// temporary is going to be dropped on the floor after the make_iterator_range
634/// full expression that contains this function call.
635template <typename RangeT, typename PredicateT>
636iterator_range<filter_iterator<detail::IterOfRange<RangeT>, PredicateT>>
637make_filter_range(RangeT &&Range, PredicateT Pred) {
638  using FilterIteratorT =
639      filter_iterator<detail::IterOfRange<RangeT>, PredicateT>;
640  return make_range(
641      FilterIteratorT(std::begin(std::forward<RangeT>(Range)),
642                      std::end(std::forward<RangeT>(Range)), Pred),
643      FilterIteratorT(std::end(std::forward<RangeT>(Range)),
644                      std::end(std::forward<RangeT>(Range)), Pred));
645}
646 
647/// A pseudo-iterator adaptor that is designed to implement "early increment"
648/// style loops.
649///
650/// This is *not a normal iterator* and should almost never be used directly. It
651/// is intended primarily to be used with range based for loops and some range
652/// algorithms.
653///
654/// The iterator isn't quite an `OutputIterator` or an `InputIterator` but
655/// somewhere between them. The constraints of these iterators are:
656///
657/// - On construction or after being incremented, it is comparable and
658///   dereferencable. It is *not* incrementable.
659/// - After being dereferenced, it is neither comparable nor dereferencable, it
660///   is only incrementable.
661///
662/// This means you can only dereference the iterator once, and you can only
663/// increment it once between dereferences.
664template <typename WrappedIteratorT>
665class early_inc_iterator_impl
666    : public iterator_adaptor_base<early_inc_iterator_impl<WrappedIteratorT>,
667                                   WrappedIteratorT, std::input_iterator_tag> {
668  using BaseT = typename early_inc_iterator_impl::iterator_adaptor_base;
669 
670  using PointerT = typename std::iterator_traits<WrappedIteratorT>::pointer;
671 
672protected:
673#if LLVM_ENABLE_ABI_BREAKING_CHECKS1
674  bool IsEarlyIncremented = false;
675#endif
676 
677public:
678  early_inc_iterator_impl(WrappedIteratorT I) : BaseT(I) {}
679 
680  using BaseT::operator*;
681  decltype(*std::declval<WrappedIteratorT>()) operator*() {
682#if LLVM_ENABLE_ABI_BREAKING_CHECKS1
683    assert(!IsEarlyIncremented && "Cannot dereference twice!")(static_cast <bool> (!IsEarlyIncremented && "Cannot dereference twice!"
) ? void (0) : __assert_fail ("!IsEarlyIncremented && \"Cannot dereference twice!\""
, "llvm/include/llvm/ADT/STLExtras.h", 683, __extension__ __PRETTY_FUNCTION__
));
684    IsEarlyIncremented = true;
685#endif
686    return *(this->I)++;
687  }
688 
689  using BaseT::operator++;
690  early_inc_iterator_impl &operator++() {
691#if LLVM_ENABLE_ABI_BREAKING_CHECKS1
692    assert(IsEarlyIncremented && "Cannot increment before dereferencing!")(static_cast <bool> (IsEarlyIncremented && "Cannot increment before dereferencing!"
) ? void (0) : __assert_fail ("IsEarlyIncremented && \"Cannot increment before dereferencing!\""
, "llvm/include/llvm/ADT/STLExtras.h", 692, __extension__ __PRETTY_FUNCTION__
));
693    IsEarlyIncremented = false;
694#endif
695    return *this;
696  }
697 
698  friend bool operator==(const early_inc_iterator_impl &LHS,
699                         const early_inc_iterator_impl &RHS) {
700#if LLVM_ENABLE_ABI_BREAKING_CHECKS1
701    assert(!LHS.IsEarlyIncremented && "Cannot compare after dereferencing!")(static_cast <bool> (!LHS.IsEarlyIncremented &&
 "Cannot compare after dereferencing!") ? void (0) : __assert_fail
 ("!LHS.IsEarlyIncremented && \"Cannot compare after dereferencing!\""
, "llvm/include/llvm/ADT/STLExtras.h", 701, __extension__ __PRETTY_FUNCTION__
));
702#endif
703    return (const BaseT &)LHS == (const BaseT &)RHS;
704  }
705};
706 
707/// Make a range that does early increment to allow mutation of the underlying
708/// range without disrupting iteration.
709///
710/// The underlying iterator will be incremented immediately after it is
711/// dereferenced, allowing deletion of the current node or insertion of nodes to
712/// not disrupt iteration provided they do not invalidate the *next* iterator --
713/// the current iterator can be invalidated.
714///
715/// This requires a very exact pattern of use that is only really suitable to
716/// range based for loops and other range algorithms that explicitly guarantee
717/// to dereference exactly once each element, and to increment exactly once each
718/// element.
719template <typename RangeT>
720iterator_range<early_inc_iterator_impl<detail::IterOfRange<RangeT>>>
721make_early_inc_range(RangeT &&Range) {
722  using EarlyIncIteratorT =
723      early_inc_iterator_impl<detail::IterOfRange<RangeT>>;
724  return make_range(EarlyIncIteratorT(std::begin(std::forward<RangeT>(Range))),
725                    EarlyIncIteratorT(std::end(std::forward<RangeT>(Range))));
726}
727 
728// Forward declarations required by zip_shortest/zip_equal/zip_first/zip_longest
729template <typename R, typename UnaryPredicate>
730bool all_of(R &&range, UnaryPredicate P);
731 
732template <typename R, typename UnaryPredicate>
733bool any_of(R &&range, UnaryPredicate P);
734 
735template <typename T> bool all_equal(std::initializer_list<T> Values);
736 
737namespace detail {
738 
739using std::declval;
740 
741// We have to alias this since inlining the actual type at the usage site
742// in the parameter list of iterator_facade_base<> below ICEs MSVC 2017.
743template<typename... Iters> struct ZipTupleType {
744  using type = std::tuple<decltype(*declval<Iters>())...>;
745};
746 
747template <typename ZipType, typename... Iters>
748using zip_traits = iterator_facade_base<
749    ZipType,
750    std::common_type_t<
751        std::bidirectional_iterator_tag,
752        typename std::iterator_traits<Iters>::iterator_category...>,
753    // ^ TODO: Implement random access methods.
754    typename ZipTupleType<Iters...>::type,
755    typename std::iterator_traits<
756        std::tuple_element_t<0, std::tuple<Iters...>>>::difference_type,
757    // ^ FIXME: This follows boost::make_zip_iterator's assumption that all
758    // inner iterators have the same difference_type. It would fail if, for
759    // instance, the second field's difference_type were non-numeric while the
760    // first is.
761    typename ZipTupleType<Iters...>::type *,
762    typename ZipTupleType<Iters...>::type>;
763 
764template <typename ZipType, typename... Iters>
765struct zip_common : public zip_traits<ZipType, Iters...> {
766  using Base = zip_traits<ZipType, Iters...>;
767  using value_type = typename Base::value_type;
768 
769  std::tuple<Iters...> iterators;
770 
771protected:
772  template <size_t... Ns> value_type deref(std::index_sequence<Ns...>) const {
773    return value_type(*std::get<Ns>(iterators)...);
774  }
775 
776  template <size_t... Ns>
777  decltype(iterators) tup_inc(std::index_sequence<Ns...>) const {
778    return std::tuple<Iters...>(std::next(std::get<Ns>(iterators))...);
779  }
780 
781  template <size_t... Ns>
782  decltype(iterators) tup_dec(std::index_sequence<Ns...>) const {
783    return std::tuple<Iters...>(std::prev(std::get<Ns>(iterators))...);
784  }
785 
786  template <size_t... Ns>
787  bool test_all_equals(const zip_common &other,
788            std::index_sequence<Ns...>) const {
789    return ((std::get<Ns>(this->iterators) == std::get<Ns>(other.iterators)) &&
790            ...);
791  }
792 
793public:
794  zip_common(Iters &&... ts) : iterators(std::forward<Iters>(ts)...) {}
795 
796  value_type operator*() const {
797    return deref(std::index_sequence_for<Iters...>{});
798  }
799 
800  ZipType &operator++() {
801    iterators = tup_inc(std::index_sequence_for<Iters...>{});
802    return *reinterpret_cast<ZipType *>(this);
803  }
804 
805  ZipType &operator--() {
806    static_assert(Base::IsBidirectional,
807                  "All inner iterators must be at least bidirectional.");
808    iterators = tup_dec(std::index_sequence_for<Iters...>{});
809    return *reinterpret_cast<ZipType *>(this);
810  }
811 
812  /// Return true if all the iterator are matching `other`'s iterators.
813  bool all_equals(zip_common &other) {
814    return test_all_equals(other, std::index_sequence_for<Iters...>{});
815  }
816};
817 
818template <typename... Iters>
819struct zip_first : public zip_common<zip_first<Iters...>, Iters...> {
820  using Base = zip_common<zip_first<Iters...>, Iters...>;
821 
822  bool operator==(const zip_first<Iters...> &other) const {
823    return std::get<0>(this->iterators) == std::get<0>(other.iterators);
824  }
825 
826  zip_first(Iters &&... ts) : Base(std::forward<Iters>(ts)...) {}
827};
828 
829template <typename... Iters>
830class zip_shortest : public zip_common<zip_shortest<Iters...>, Iters...> {
831  template <size_t... Ns>
832  bool test(const zip_shortest<Iters...> &other,
833            std::index_sequence<Ns...>) const {
834    return ((std::get<Ns>(this->iterators) != std::get<Ns>(other.iterators)) &&
835            ...);
836  }
837 
838public:
839  using Base = zip_common<zip_shortest<Iters...>, Iters...>;
840 
841  zip_shortest(Iters &&... ts) : Base(std::forward<Iters>(ts)...) {}
842 
843  bool operator==(const zip_shortest<Iters...> &other) const {
844    return !test(other, std::index_sequence_for<Iters...>{});
845  }
846};
847 
848template <template <typename...> class ItType, typename... Args> class zippy {
849public:
850  using iterator = ItType<decltype(std::begin(std::declval<Args>()))...>;
851  using iterator_category = typename iterator::iterator_category;
852  using value_type = typename iterator::value_type;
853  using difference_type = typename iterator::difference_type;
854  using pointer = typename iterator::pointer;
855  using reference = typename iterator::reference;
856 
857private:
858  std::tuple<Args...> ts;
859 
860  template <size_t... Ns>
861  iterator begin_impl(std::index_sequence<Ns...>) const {
862    return iterator(std::begin(std::get<Ns>(ts))...);
863  }
864  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
865    return iterator(std::end(std::get<Ns>(ts))...);
866  }
867 
868public:
869  zippy(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
870 
871  iterator begin() const {
872    return begin_impl(std::index_sequence_for<Args...>{});
873  }
874  iterator end() const { return end_impl(std::index_sequence_for<Args...>{}); }
875};
876 
877} // end namespace detail
878 
879/// zip iterator for two or more iteratable types. Iteration continues until the
880/// end of the *shortest* iteratee is reached.
881template <typename T, typename U, typename... Args>
882detail::zippy<detail::zip_shortest, T, U, Args...> zip(T &&t, U &&u,
883                                                       Args &&...args) {
884  return detail::zippy<detail::zip_shortest, T, U, Args...>(
885      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
886}
887 
888/// zip iterator that assumes that all iteratees have the same length.
889/// In builds with assertions on, this assumption is checked before the
890/// iteration starts.
891template <typename T, typename U, typename... Args>
892detail::zippy<detail::zip_first, T, U, Args...> zip_equal(T &&t, U &&u,
893                                                          Args &&...args) {
894  assert(all_equal({std::distance(adl_begin(t), adl_end(t)),(static_cast <bool> (all_equal({std::distance(adl_begin
(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std
::distance(adl_begin(args), adl_end(args))...}) && "Iteratees do not have equal length"
) ? void (0) : __assert_fail ("all_equal({std::distance(adl_begin(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"Iteratees do not have equal length\""
, "llvm/include/llvm/ADT/STLExtras.h", 897, __extension__ __PRETTY_FUNCTION__
))
895                    std::distance(adl_begin(u), adl_end(u)),(static_cast <bool> (all_equal({std::distance(adl_begin
(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std
::distance(adl_begin(args), adl_end(args))...}) && "Iteratees do not have equal length"
) ? void (0) : __assert_fail ("all_equal({std::distance(adl_begin(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"Iteratees do not have equal length\""
, "llvm/include/llvm/ADT/STLExtras.h", 897, __extension__ __PRETTY_FUNCTION__
))
896                    std::distance(adl_begin(args), adl_end(args))...}) &&(static_cast <bool> (all_equal({std::distance(adl_begin
(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std
::distance(adl_begin(args), adl_end(args))...}) && "Iteratees do not have equal length"
) ? void (0) : __assert_fail ("all_equal({std::distance(adl_begin(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"Iteratees do not have equal length\""
, "llvm/include/llvm/ADT/STLExtras.h", 897, __extension__ __PRETTY_FUNCTION__
))
897         "Iteratees do not have equal length")(static_cast <bool> (all_equal({std::distance(adl_begin
(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std
::distance(adl_begin(args), adl_end(args))...}) && "Iteratees do not have equal length"
) ? void (0) : __assert_fail ("all_equal({std::distance(adl_begin(t), adl_end(t)), std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"Iteratees do not have equal length\""
, "llvm/include/llvm/ADT/STLExtras.h", 897, __extension__ __PRETTY_FUNCTION__
));
898  return detail::zippy<detail::zip_first, T, U, Args...>(
899      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
900}
901 
902/// zip iterator that, for the sake of efficiency, assumes the first iteratee to
903/// be the shortest. Iteration continues until the end of the first iteratee is
904/// reached. In builds with assertions on, we check that the assumption about
905/// the first iteratee being the shortest holds.
906template <typename T, typename U, typename... Args>
907detail::zippy<detail::zip_first, T, U, Args...> zip_first(T &&t, U &&u,
908                                                          Args &&...args) {
909  assert(std::distance(adl_begin(t), adl_end(t)) <=(static_cast <bool> (std::distance(adl_begin(t), adl_end
(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)),
 std::distance(adl_begin(args), adl_end(args))...}) &&
 "First iteratee is not the shortest") ? void (0) : __assert_fail
 ("std::distance(adl_begin(t), adl_end(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"First iteratee is not the shortest\""
, "llvm/include/llvm/ADT/STLExtras.h", 912, __extension__ __PRETTY_FUNCTION__
))
910             std::min({std::distance(adl_begin(u), adl_end(u)),(static_cast <bool> (std::distance(adl_begin(t), adl_end
(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)),
 std::distance(adl_begin(args), adl_end(args))...}) &&
 "First iteratee is not the shortest") ? void (0) : __assert_fail
 ("std::distance(adl_begin(t), adl_end(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"First iteratee is not the shortest\""
, "llvm/include/llvm/ADT/STLExtras.h", 912, __extension__ __PRETTY_FUNCTION__
))
911                       std::distance(adl_begin(args), adl_end(args))...}) &&(static_cast <bool> (std::distance(adl_begin(t), adl_end
(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)),
 std::distance(adl_begin(args), adl_end(args))...}) &&
 "First iteratee is not the shortest") ? void (0) : __assert_fail
 ("std::distance(adl_begin(t), adl_end(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"First iteratee is not the shortest\""
, "llvm/include/llvm/ADT/STLExtras.h", 912, __extension__ __PRETTY_FUNCTION__
))
912         "First iteratee is not the shortest")(static_cast <bool> (std::distance(adl_begin(t), adl_end
(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)),
 std::distance(adl_begin(args), adl_end(args))...}) &&
 "First iteratee is not the shortest") ? void (0) : __assert_fail
 ("std::distance(adl_begin(t), adl_end(t)) <= std::min({std::distance(adl_begin(u), adl_end(u)), std::distance(adl_begin(args), adl_end(args))...}) && \"First iteratee is not the shortest\""
, "llvm/include/llvm/ADT/STLExtras.h", 912, __extension__ __PRETTY_FUNCTION__
));
913 
914  return detail::zippy<detail::zip_first, T, U, Args...>(
915      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
916}
917 
918namespace detail {
919template <typename Iter>
920Iter next_or_end(const Iter &I, const Iter &End) {
921  if (I == End)
922    return End;
923  return std::next(I);
924}
925 
926template <typename Iter>
927auto deref_or_none(const Iter &I, const Iter &End) -> std::optional<
928    std::remove_const_t<std::remove_reference_t<decltype(*I)>>> {
929  if (I == End)
930    return std::nullopt;
931  return *I;
932}
933 
934template <typename Iter> struct ZipLongestItemType {
935  using type = std::optional<std::remove_const_t<
936      std::remove_reference_t<decltype(*std::declval<Iter>())>>>;
937};
938 
939template <typename... Iters> struct ZipLongestTupleType {
940  using type = std::tuple<typename ZipLongestItemType<Iters>::type...>;
941};
942 
943template <typename... Iters>
944class zip_longest_iterator
945    : public iterator_facade_base<
946          zip_longest_iterator<Iters...>,
947          std::common_type_t<
948              std::forward_iterator_tag,
949              typename std::iterator_traits<Iters>::iterator_category...>,
950          typename ZipLongestTupleType<Iters...>::type,
951          typename std::iterator_traits<
952              std::tuple_element_t<0, std::tuple<Iters...>>>::difference_type,
953          typename ZipLongestTupleType<Iters...>::type *,
954          typename ZipLongestTupleType<Iters...>::type> {
955public:
956  using value_type = typename ZipLongestTupleType<Iters...>::type;
957 
958private:
959  std::tuple<Iters...> iterators;
960  std::tuple<Iters...> end_iterators;
961 
962  template <size_t... Ns>
963  bool test(const zip_longest_iterator<Iters...> &other,
964            std::index_sequence<Ns...>) const {
965    return ((std::get<Ns>(this->iterators) != std::get<Ns>(other.iterators)) ||
966            ...);
967  }
968 
969  template <size_t... Ns> value_type deref(std::index_sequence<Ns...>) const {
970    return value_type(
971        deref_or_none(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
972  }
973 
974  template <size_t... Ns>
975  decltype(iterators) tup_inc(std::index_sequence<Ns...>) const {
976    return std::tuple<Iters...>(
977        next_or_end(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
978  }
979 
980public:
981  zip_longest_iterator(std::pair<Iters &&, Iters &&>... ts)
982      : iterators(std::forward<Iters>(ts.first)...),
983        end_iterators(std::forward<Iters>(ts.second)...) {}
984 
985  value_type operator*() const {
986    return deref(std::index_sequence_for<Iters...>{});
987  }
988 
989  zip_longest_iterator<Iters...> &operator++() {
990    iterators = tup_inc(std::index_sequence_for<Iters...>{});
991    return *this;
992  }
993 
994  bool operator==(const zip_longest_iterator<Iters...> &other) const {
995    return !test(other, std::index_sequence_for<Iters...>{});
996  }
997};
998 
999template <typename... Args> class zip_longest_range {
1000public:
1001  using iterator =
1002      zip_longest_iterator<decltype(adl_begin(std::declval<Args>()))...>;
1003  using iterator_category = typename iterator::iterator_category;
1004  using value_type = typename iterator::value_type;
1005  using difference_type = typename iterator::difference_type;
1006  using pointer = typename iterator::pointer;
1007  using reference = typename iterator::reference;
1008 
1009private:
1010  std::tuple<Args...> ts;
1011 
1012  template <size_t... Ns>
1013  iterator begin_impl(std::index_sequence<Ns...>) const {
1014    return iterator(std::make_pair(adl_begin(std::get<Ns>(ts)),
1015                                   adl_end(std::get<Ns>(ts)))...);
1016  }
1017 
1018  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
1019    return iterator(std::make_pair(adl_end(std::get<Ns>(ts)),
1020                                   adl_end(std::get<Ns>(ts)))...);
1021  }
1022 
1023public:
1024  zip_longest_range(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
1025 
1026  iterator begin() const {
1027    return begin_impl(std::index_sequence_for<Args...>{});
1028  }
1029  iterator end() const { return end_impl(std::index_sequence_for<Args...>{}); }
1030};
1031} // namespace detail
1032 
1033/// Iterate over two or more iterators at the same time. Iteration continues
1034/// until all iterators reach the end. The std::optional only contains a value
1035/// if the iterator has not reached the end.
1036template <typename T, typename U, typename... Args>
1037detail::zip_longest_range<T, U, Args...> zip_longest(T &&t, U &&u,
1038                                                     Args &&... args) {
1039  return detail::zip_longest_range<T, U, Args...>(
1040      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
1041}
1042 
1043/// Iterator wrapper that concatenates sequences together.
1044///
1045/// This can concatenate different iterators, even with different types, into
1046/// a single iterator provided the value types of all the concatenated
1047/// iterators expose `reference` and `pointer` types that can be converted to
1048/// `ValueT &` and `ValueT *` respectively. It doesn't support more
1049/// interesting/customized pointer or reference types.
1050///
1051/// Currently this only supports forward or higher iterator categories as
1052/// inputs and always exposes a forward iterator interface.
1053template <typename ValueT, typename... IterTs>
1054class concat_iterator
1055    : public iterator_facade_base<concat_iterator<ValueT, IterTs...>,
1056                                  std::forward_iterator_tag, ValueT> {
1057  using BaseT = typename concat_iterator::iterator_facade_base;
1058 
1059  /// We store both the current and end iterators for each concatenated
1060  /// sequence in a tuple of pairs.
1061  ///
1062  /// Note that something like iterator_range seems nice at first here, but the
1063  /// range properties are of little benefit and end up getting in the way
1064  /// because we need to do mutation on the current iterators.
1065  std::tuple<IterTs...> Begins;
1066  std::tuple<IterTs...> Ends;
1067 
1068  /// Attempts to increment a specific iterator.
1069  ///
1070  /// Returns true if it was able to increment the iterator. Returns false if
1071  /// the iterator is already at the end iterator.
1072  template <size_t Index> bool incrementHelper() {
1073    auto &Begin = std::get<Index>(Begins);
1074    auto &End = std::get<Index>(Ends);
1075    if (Begin == End)
1076      return false;
1077 
1078    ++Begin;
1079    return true;
1080  }
1081 
1082  /// Increments the first non-end iterator.
1083  ///
1084  /// It is an error to call this with all iterators at the end.
1085  template <size_t... Ns> void increment(std::index_sequence<Ns...>) {
1086    // Build a sequence of functions to increment each iterator if possible.
1087    bool (concat_iterator::*IncrementHelperFns[])() = {
1088        &concat_iterator::incrementHelper<Ns>...};
1089 
1090    // Loop over them, and stop as soon as we succeed at incrementing one.
1091    for (auto &IncrementHelperFn : IncrementHelperFns)
1092      if ((this->*IncrementHelperFn)())
1093        return;
1094 
1095    llvm_unreachable("Attempted to increment an end concat iterator!")::llvm::llvm_unreachable_internal("Attempted to increment an end concat iterator!"
, "llvm/include/llvm/ADT/STLExtras.h", 1095);
1096  }
1097 
1098  /// Returns null if the specified iterator is at the end. Otherwise,
1099  /// dereferences the iterator and returns the address of the resulting
1100  /// reference.
1101  template <size_t Index> ValueT *getHelper() const {
1102    auto &Begin = std::get<Index>(Begins);
1103    auto &End = std::get<Index>(Ends);
1104    if (Begin == End)
1105      return nullptr;
1106 
1107    return &*Begin;
1108  }
1109 
1110  /// Finds the first non-end iterator, dereferences, and returns the resulting
1111  /// reference.
1112  ///
1113  /// It is an error to call this with all iterators at the end.
1114  template <size_t... Ns> ValueT &get(std::index_sequence<Ns...>) const {
1115    // Build a sequence of functions to get from iterator if possible.
1116    ValueT *(concat_iterator::*GetHelperFns[])() const = {
1117        &concat_iterator::getHelper<Ns>...};
1118 
1119    // Loop over them, and return the first result we find.
1120    for (auto &GetHelperFn : GetHelperFns)
1121      if (ValueT *P = (this->*GetHelperFn)())
1122        return *P;
1123 
1124    llvm_unreachable("Attempted to get a pointer from an end concat iterator!")::llvm::llvm_unreachable_internal("Attempted to get a pointer from an end concat iterator!"
, "llvm/include/llvm/ADT/STLExtras.h", 1124);
1125  }
1126 
1127public:
1128  /// Constructs an iterator from a sequence of ranges.
1129  ///
1130  /// We need the full range to know how to switch between each of the
1131  /// iterators.
1132  template <typename... RangeTs>
1133  explicit concat_iterator(RangeTs &&... Ranges)
1134      : Begins(std::begin(Ranges)...), Ends(std::end(Ranges)...) {}
1135 
1136  using BaseT::operator++;
1137 
1138  concat_iterator &operator++() {
1139    increment(std::index_sequence_for<IterTs...>());
1140    return *this;
1141  }
1142 
1143  ValueT &operator*() const {
1144    return get(std::index_sequence_for<IterTs...>());
1145  }
1146 
1147  bool operator==(const concat_iterator &RHS) const {
1148    return Begins == RHS.Begins && Ends == RHS.Ends;
1149  }
1150};
1151 
1152namespace detail {
1153 
1154/// Helper to store a sequence of ranges being concatenated and access them.
1155///
1156/// This is designed to facilitate providing actual storage when temporaries
1157/// are passed into the constructor such that we can use it as part of range
1158/// based for loops.
1159template <typename ValueT, typename... RangeTs> class concat_range {
1160public:
1161  using iterator =
1162      concat_iterator<ValueT,
1163                      decltype(std::begin(std::declval<RangeTs &>()))...>;
1164 
1165private:
1166  std::tuple<RangeTs...> Ranges;
1167 
1168  template <size_t... Ns>
1169  iterator begin_impl(std::index_sequence<Ns...>) {
1170    return iterator(std::get<Ns>(Ranges)...);
1171  }
1172  template <size_t... Ns>
1173  iterator begin_impl(std::index_sequence<Ns...>) const {
1174    return iterator(std::get<Ns>(Ranges)...);
1175  }
1176  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) {
1177    return iterator(make_range(std::end(std::get<Ns>(Ranges)),
1178                               std::end(std::get<Ns>(Ranges)))...);
1179  }
1180  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
1181    return iterator(make_range(std::end(std::get<Ns>(Ranges)),
1182                               std::end(std::get<Ns>(Ranges)))...);
1183  }
1184 
1185public:
1186  concat_range(RangeTs &&... Ranges)
1187      : Ranges(std::forward<RangeTs>(Ranges)...) {}
1188 
1189  iterator begin() {
1190    return begin_impl(std::index_sequence_for<RangeTs...>{});
1191  }
1192  iterator begin() const {
1193    return begin_impl(std::index_sequence_for<RangeTs...>{});
1194  }
1195  iterator end() {
1196    return end_impl(std::index_sequence_for<RangeTs...>{});
1197  }
1198  iterator end() const {
1199    return end_impl(std::index_sequence_for<RangeTs...>{});
1200  }
1201};
1202 
1203} // end namespace detail
1204 
1205/// Concatenated range across two or more ranges.
1206///
1207/// The desired value type must be explicitly specified.
1208template <typename ValueT, typename... RangeTs>
1209detail::concat_range<ValueT, RangeTs...> concat(RangeTs &&... Ranges) {
1210  static_assert(sizeof...(RangeTs) > 1,
1211                "Need more than one range to concatenate!");
1212  return detail::concat_range<ValueT, RangeTs...>(
1213      std::forward<RangeTs>(Ranges)...);
1214}
1215 
1216/// A utility class used to implement an iterator that contains some base object
1217/// and an index. The iterator moves the index but keeps the base constant.
1218template <typename DerivedT, typename BaseT, typename T,
1219          typename PointerT = T *, typename ReferenceT = T &>
1220class indexed_accessor_iterator
1221    : public llvm::iterator_facade_base<DerivedT,
1222                                        std::random_access_iterator_tag, T,
1223                                        std::ptrdiff_t, PointerT, ReferenceT> {
1224public:
1225  ptrdiff_t operator-(const indexed_accessor_iterator &rhs) const {
1226    assert(base == rhs.base && "incompatible iterators")(static_cast <bool> (base == rhs.base && "incompatible iterators"
) ? void (0) : __assert_fail ("base == rhs.base && \"incompatible iterators\""
, "llvm/include/llvm/ADT/STLExtras.h", 1226, __extension__ __PRETTY_FUNCTION__
));
1227    return index - rhs.index;
1228  }
1229  bool operator==(const indexed_accessor_iterator &rhs) const {
1230    return base == rhs.base && index == rhs.index;
1231  }
1232  bool operator<(const indexed_accessor_iterator &rhs) const {
1233    assert(base == rhs.base && "incompatible iterators")(static_cast <bool> (base == rhs.base && "incompatible iterators"
) ? void (0) : __assert_fail ("base == rhs.base && \"incompatible iterators\""
, "llvm/include/llvm/ADT/STLExtras.h", 1233, __extension__ __PRETTY_FUNCTION__
));
1234    return index < rhs.index;
1235  }
1236 
1237  DerivedT &operator+=(ptrdiff_t offset) {
1238    this->index += offset;
1239    return static_cast<DerivedT &>(*this);
1240  }
1241  DerivedT &operator-=(ptrdiff_t offset) {
1242    this->index -= offset;
1243    return static_cast<DerivedT &>(*this);
1244  }
1245 
1246  /// Returns the current index of the iterator.
1247  ptrdiff_t getIndex() const { return index; }
1248 
1249  /// Returns the current base of the iterator.
1250  const BaseT &getBase() const { return base; }
1251 
1252protected:
1253  indexed_accessor_iterator(BaseT base, ptrdiff_t index)
1254      : base(base), index(index) {}
1255  BaseT base;
1256  ptrdiff_t index;
1257};
1258 
1259namespace detail {
1260/// The class represents the base of a range of indexed_accessor_iterators. It
1261/// provides support for many different range functionalities, e.g.
1262/// drop_front/slice/etc.. Derived range classes must implement the following
1263/// static methods:
1264///   * ReferenceT dereference_iterator(const BaseT &base, ptrdiff_t index)
1265///     - Dereference an iterator pointing to the base object at the given
1266///       index.
1267///   * BaseT offset_base(const BaseT &base, ptrdiff_t index)
1268///     - Return a new base that is offset from the provide base by 'index'
1269///       elements.
1270template <typename DerivedT, typename BaseT, typename T,
1271          typename PointerT = T *, typename ReferenceT = T &>
1272class indexed_accessor_range_base {
1273public:
1274  using RangeBaseT = indexed_accessor_range_base;
1275 
1276  /// An iterator element of this range.
1277  class iterator : public indexed_accessor_iterator<iterator, BaseT, T,
1278                                                    PointerT, ReferenceT> {
1279  public:
1280    // Index into this iterator, invoking a static method on the derived type.
1281    ReferenceT operator*() const {
1282      return DerivedT::dereference_iterator(this->getBase(), this->getIndex());
1283    }
1284 
1285  private:
1286    iterator(BaseT owner, ptrdiff_t curIndex)
1287        : iterator::indexed_accessor_iterator(owner, curIndex) {}
1288 
1289    /// Allow access to the constructor.
1290    friend indexed_accessor_range_base<DerivedT, BaseT, T, PointerT,
1291                                       ReferenceT>;
1292  };
1293 
1294  indexed_accessor_range_base(iterator begin, iterator end)
1295      : base(offset_base(begin.getBase(), begin.getIndex())),
1296        count(end.getIndex() - begin.getIndex()) {}
1297  indexed_accessor_range_base(const iterator_range<iterator> &range)
1298      : indexed_accessor_range_base(range.begin(), range.end()) {}
1299  indexed_accessor_range_base(BaseT base, ptrdiff_t count)
1300      : base(base), count(count) {}
1301 
1302  iterator begin() const { return iterator(base, 0); }
1303  iterator end() const { return iterator(base, count); }
1304  ReferenceT operator[](size_t Index) const {
1305    assert(Index < size() && "invalid index for value range")(static_cast <bool> (Index < size() && "invalid index for value range"
) ? void (0) : __assert_fail ("Index < size() && \"invalid index for value range\""
, "llvm/include/llvm/ADT/STLExtras.h", 1305, __extension__ __PRETTY_FUNCTION__
));
1306    return DerivedT::dereference_iterator(base, static_cast<ptrdiff_t>(Index));
1307  }
1308  ReferenceT front() const {
1309    assert(!empty() && "expected non-empty range")(static_cast <bool> (!empty() && "expected non-empty range"
) ? void (0) : __assert_fail ("!empty() && \"expected non-empty range\""
, "llvm/include/llvm/ADT/STLExtras.h", 1309, __extension__ __PRETTY_FUNCTION__
));
1310    return (*this)[0];
1311  }
1312  ReferenceT back() const {
1313    assert(!empty() && "expected non-empty range")(static_cast <bool> (!empty() && "expected non-empty range"
) ? void (0) : __assert_fail ("!empty() && \"expected non-empty range\""
, "llvm/include/llvm/ADT/STLExtras.h", 1313, __extension__ __PRETTY_FUNCTION__
));
1314    return (*this)[size() - 1];
1315  }
1316 
1317  /// Compare this range with another.
1318  template <typename OtherT>
1319  friend bool operator==(const indexed_accessor_range_base &lhs,
1320                         const OtherT &rhs) {
1321    return std::equal(lhs.begin(), lhs.end(), rhs.begin(), rhs.end());
1322  }
1323  template <typename OtherT>
1324  friend bool operator!=(const indexed_accessor_range_base &lhs,
1325                         const OtherT &rhs) {
1326    return !(lhs == rhs);
1327  }
1328 
1329  /// Return the size of this range.
1330  size_t size() const { return count; }
1331 
1332  /// Return if the range is empty.
1333  bool empty() const { return size() == 0; }
1334 
1335  /// Drop the first N elements, and keep M elements.
1336  DerivedT slice(size_t n, size_t m) const {
1337    assert(n + m <= size() && "invalid size specifiers")(static_cast <bool> (n + m <= size() && "invalid size specifiers"
) ? void (0) : __assert_fail ("n + m <= size() && \"invalid size specifiers\""
, "llvm/include/llvm/ADT/STLExtras.h", 1337, __extension__ __PRETTY_FUNCTION__
));
1338    return DerivedT(offset_base(base, n), m);
1339  }
1340 
1341  /// Drop the first n elements.
1342  DerivedT drop_front(size_t n = 1) const {
1343    assert(size() >= n && "Dropping more elements than exist")(static_cast <bool> (size() >= n && "Dropping more elements than exist"
) ? void (0) : __assert_fail ("size() >= n && \"Dropping more elements than exist\""
, "llvm/include/llvm/ADT/STLExtras.h", 1343, __extension__ __PRETTY_FUNCTION__
));
1344    return slice(n, size() - n);
1345  }
1346  /// Drop the last n elements.
1347  DerivedT drop_back(size_t n = 1) const {
1348    assert(size() >= n && "Dropping more elements than exist")(static_cast <bool> (size() >= n && "Dropping more elements than exist"
) ? void (0) : __assert_fail ("size() >= n && \"Dropping more elements than exist\""
, "llvm/include/llvm/ADT/STLExtras.h", 1348, __extension__ __PRETTY_FUNCTION__
));
1349    return DerivedT(base, size() - n);
1350  }
1351 
1352  /// Take the first n elements.
1353  DerivedT take_front(size_t n = 1) const {
1354    return n < size() ? drop_back(size() - n)
1355                      : static_cast<const DerivedT &>(*this);
1356  }
1357 
1358  /// Take the last n elements.
1359  DerivedT take_back(size_t n = 1) const {
1360    return n < size() ? drop_front(size() - n)
1361                      : static_cast<const DerivedT &>(*this);
1362  }
1363 
1364  /// Allow conversion to any type accepting an iterator_range.
1365  template <typename RangeT, typename = std::enable_if_t<std::is_constructible<
1366                                 RangeT, iterator_range<iterator>>::value>>
1367  operator RangeT() const {
1368    return RangeT(iterator_range<iterator>(*this));
1369  }
1370 
1371  /// Returns the base of this range.
1372  const BaseT &getBase() const { return base; }
1373 
1374private:
1375  /// Offset the given base by the given amount.
1376  static BaseT offset_base(const BaseT &base, size_t n) {
1377    return n == 0 ? base : DerivedT::offset_base(base, n);
1378  }
1379 
1380protected:
1381  indexed_accessor_range_base(const indexed_accessor_range_base &) = default;
1382  indexed_accessor_range_base(indexed_accessor_range_base &&) = default;
1383  indexed_accessor_range_base &
1384  operator=(const indexed_accessor_range_base &) = default;
1385 
1386  /// The base that owns the provided range of values.
1387  BaseT base;
1388  /// The size from the owning range.
1389  ptrdiff_t count;
1390};
1391} // end namespace detail
1392 
1393/// This class provides an implementation of a range of
1394/// indexed_accessor_iterators where the base is not indexable. Ranges with
1395/// bases that are offsetable should derive from indexed_accessor_range_base
1396/// instead. Derived range classes are expected to implement the following
1397/// static method:
1398///   * ReferenceT dereference(const BaseT &base, ptrdiff_t index)
1399///     - Dereference an iterator pointing to a parent base at the given index.
1400template <typename DerivedT, typename BaseT, typename T,
1401          typename PointerT = T *, typename ReferenceT = T &>
1402class indexed_accessor_range
1403    : public detail::indexed_accessor_range_base<
1404          DerivedT, std::pair<BaseT, ptrdiff_t>, T, PointerT, ReferenceT> {
1405public:
1406  indexed_accessor_range(BaseT base, ptrdiff_t startIndex, ptrdiff_t count)
1407      : detail::indexed_accessor_range_base<
1408            DerivedT, std::pair<BaseT, ptrdiff_t>, T, PointerT, ReferenceT>(
1409            std::make_pair(base, startIndex), count) {}
1410  using detail::indexed_accessor_range_base<
1411      DerivedT, std::pair<BaseT, ptrdiff_t>, T, PointerT,
1412      ReferenceT>::indexed_accessor_range_base;
1413 
1414  /// Returns the current base of the range.
1415  const BaseT &getBase() const { return this->base.first; }
1416 
1417  /// Returns the current start index of the range.
1418  ptrdiff_t getStartIndex() const { return this->base.second; }
1419 
1420  /// See `detail::indexed_accessor_range_base` for details.
1421  static std::pair<BaseT, ptrdiff_t>
1422  offset_base(const std::pair<BaseT, ptrdiff_t> &base, ptrdiff_t index) {
1423    // We encode the internal base as a pair of the derived base and a start
1424    // index into the derived base.
1425    return std::make_pair(base.first, base.second + index);
1426  }
1427  /// See `detail::indexed_accessor_range_base` for details.
1428  static ReferenceT
1429  dereference_iterator(const std::pair<BaseT, ptrdiff_t> &base,
1430                       ptrdiff_t index) {
1431    return DerivedT::dereference(base.first, base.second + index);
1432  }
1433};
1434 
1435namespace detail {
1436/// Return a reference to the first or second member of a reference. Otherwise,
1437/// return a copy of the member of a temporary.
1438///
1439/// When passing a range whose iterators return values instead of references,
1440/// the reference must be dropped from `decltype((elt.first))`, which will
1441/// always be a reference, to avoid returning a reference to a temporary.
1442template <typename EltTy, typename FirstTy> class first_or_second_type {
1443public:
1444  using type = std::conditional_t<std::is_reference<EltTy>::value, FirstTy,
1445                                  std::remove_reference_t<FirstTy>>;
1446};
1447} // end namespace detail
1448 
1449/// Given a container of pairs, return a range over the first elements.
1450template <typename ContainerTy> auto make_first_range(ContainerTy &&c) {
1451  using EltTy = decltype((*std::begin(c)));
1452  return llvm::map_range(std::forward<ContainerTy>(c),
1453                         [](EltTy elt) -> typename detail::first_or_second_type<
1454                                           EltTy, decltype((elt.first))>::type {
1455                           return elt.first;
1456                         });
1457}
1458 
1459/// Given a container of pairs, return a range over the second elements.
1460template <typename ContainerTy> auto make_second_range(ContainerTy &&c) {
1461  using EltTy = decltype((*std::begin(c)));
1462  return llvm::map_range(
1463      std::forward<ContainerTy>(c),
1464      [](EltTy elt) ->
1465      typename detail::first_or_second_type<EltTy,
1466                                            decltype((elt.second))>::type {
1467        return elt.second;
1468      });
1469}
1470 
1471//===----------------------------------------------------------------------===//
1472//     Extra additions to <utility>
1473//===----------------------------------------------------------------------===//
1474 
1475/// Function object to check whether the first component of a std::pair
1476/// compares less than the first component of another std::pair.
1477struct less_first {
1478  template <typename T> bool operator()(const T &lhs, const T &rhs) const {
1479    return std::less<>()(lhs.first, rhs.first);
1480  }
1481};
1482 
1483/// Function object to check whether the second component of a std::pair
1484/// compares less than the second component of another std::pair.
1485struct less_second {
1486  template <typename T> bool operator()(const T &lhs, const T &rhs) const {
1487    return std::less<>()(lhs.second, rhs.second);
1488  }
1489};
1490 
1491/// \brief Function object to apply a binary function to the first component of
1492/// a std::pair.
1493template<typename FuncTy>
1494struct on_first {
1495  FuncTy func;
1496 
1497  template <typename T>
1498  decltype(auto) operator()(const T &lhs, const T &rhs) const {
1499    return func(lhs.first, rhs.first);
1500  }
1501};
1502 
1503/// Utility type to build an inheritance chain that makes it easy to rank
1504/// overload candidates.
1505template <int N> struct rank : rank<N - 1> {};
1506template <> struct rank<0> {};
1507 
1508/// traits class for checking whether type T is one of any of the given
1509/// types in the variadic list.
1510template <typename T, typename... Ts>
1511using is_one_of = std::disjunction<std::is_same<T, Ts>...>;
1512 
1513/// traits class for checking whether type T is a base class for all
1514///  the given types in the variadic list.
1515template <typename T, typename... Ts>
1516using are_base_of = std::conjunction<std::is_base_of<T, Ts>...>;
1517 
1518namespace detail {
1519template <typename... Ts> struct Visitor;
1520 
1521template <typename HeadT, typename... TailTs>
1522struct Visitor<HeadT, TailTs...> : remove_cvref_t<HeadT>, Visitor<TailTs...> {
1523  explicit constexpr Visitor(HeadT &&Head, TailTs &&...Tail)
1524      : remove_cvref_t<HeadT>(std::forward<HeadT>(Head)),
1525        Visitor<TailTs...>(std::forward<TailTs>(Tail)...) {}
1526  using remove_cvref_t<HeadT>::operator();
1527  using Visitor<TailTs...>::operator();
1528};
1529 
1530template <typename HeadT> struct Visitor<HeadT> : remove_cvref_t<HeadT> {
1531  explicit constexpr Visitor(HeadT &&Head)
1532      : remove_cvref_t<HeadT>(std::forward<HeadT>(Head)) {}
1533  using remove_cvref_t<HeadT>::operator();
1534};
1535} // namespace detail
1536 
1537/// Returns an opaquely-typed Callable object whose operator() overload set is
1538/// the sum of the operator() overload sets of each CallableT in CallableTs.
1539///
1540/// The type of the returned object derives from each CallableT in CallableTs.
1541/// The returned object is constructed by invoking the appropriate copy or move
1542/// constructor of each CallableT, as selected by overload resolution on the
1543/// corresponding argument to makeVisitor.
1544///
1545/// Example:
1546///
1547/// \code
1548/// auto visitor = makeVisitor([](auto) { return "unhandled type"; },
1549///                            [](int i) { return "int"; },
1550///                            [](std::string s) { return "str"; });
1551/// auto a = visitor(42);    // `a` is now "int".
1552/// auto b = visitor("foo"); // `b` is now "str".
1553/// auto c = visitor(3.14f); // `c` is now "unhandled type".
1554/// \endcode
1555///
1556/// Example of making a visitor with a lambda which captures a move-only type:
1557///
1558/// \code
1559/// std::unique_ptr<FooHandler> FH = /* ... */;
1560/// auto visitor = makeVisitor(
1561///     [FH{std::move(FH)}](Foo F) { return FH->handle(F); },
1562///     [](int i) { return i; },
1563///     [](std::string s) { return atoi(s); });
1564/// \endcode
1565template <typename... CallableTs>
1566constexpr decltype(auto) makeVisitor(CallableTs &&...Callables) {
1567  return detail::Visitor<CallableTs...>(std::forward<CallableTs>(Callables)...);
1568}
1569 
1570//===----------------------------------------------------------------------===//
1571//     Extra additions to <algorithm>
1572//===----------------------------------------------------------------------===//
1573 
1574// We have a copy here so that LLVM behaves the same when using different
1575// standard libraries.
1576template <class Iterator, class RNG>
1577void shuffle(Iterator first, Iterator last, RNG &&g) {
1578  // It would be better to use a std::uniform_int_distribution,
1579  // but that would be stdlib dependent.
1580  typedef
1581      typename std::iterator_traits<Iterator>::difference_type difference_type;
1582  for (auto size = last - first; size > 1; ++first, (void)--size) {
1583    difference_type offset = g() % size;
1584    // Avoid self-assignment due to incorrect assertions in libstdc++
1585    // containers (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85828).
1586    if (offset != difference_type(0))
1587      std::iter_swap(first, first + offset);
1588  }
1589}
1590 
1591/// Adapt std::less<T> for array_pod_sort.
1592template<typename T>
1593inline int array_pod_sort_comparator(const void *P1, const void *P2) {
1594  if (std::less<T>()(*reinterpret_cast<const T*>(P1),
1595                     *reinterpret_cast<const T*>(P2)))
1596    return -1;
1597  if (std::less<T>()(*reinterpret_cast<const T*>(P2),
1598                     *reinterpret_cast<const T*>(P1)))
1599    return 1;
1600  return 0;
1601}
1602 
1603/// get_array_pod_sort_comparator - This is an internal helper function used to
1604/// get type deduction of T right.
1605template<typename T>
1606inline int (*get_array_pod_sort_comparator(const T &))
1607             (const void*, const void*) {
1608  return array_pod_sort_comparator<T>;
1609}
1610 
1611#ifdef EXPENSIVE_CHECKS
1612namespace detail {
1613 
1614inline unsigned presortShuffleEntropy() {
1615  static unsigned Result(std::random_device{}());
1616  return Result;
1617}
1618 
1619template <class IteratorTy>
1620inline void presortShuffle(IteratorTy Start, IteratorTy End) {
1621  std::mt19937 Generator(presortShuffleEntropy());
1622  llvm::shuffle(Start, End, Generator);
1623}
1624 
1625} // end namespace detail
1626#endif
1627 
1628/// array_pod_sort - This sorts an array with the specified start and end
1629/// extent.  This is just like std::sort, except that it calls qsort instead of
1630/// using an inlined template.  qsort is slightly slower than std::sort, but
1631/// most sorts are not performance critical in LLVM and std::sort has to be
1632/// template instantiated for each type, leading to significant measured code
1633/// bloat.  This function should generally be used instead of std::sort where
1634/// possible.
1635///
1636/// This function assumes that you have simple POD-like types that can be
1637/// compared with std::less and can be moved with memcpy.  If this isn't true,
1638/// you should use std::sort.
1639///
1640/// NOTE: If qsort_r were portable, we could allow a custom comparator and
1641/// default to std::less.
1642template<class IteratorTy>
1643inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
1644  // Don't inefficiently call qsort with one element or trigger undefined
1645  // behavior with an empty sequence.
1646  auto NElts = End - Start;
1647  if (NElts <= 1) return;
11
←
Assuming 'NElts' is <= 1→
12
←
Taking true branch→
13
←
Returning without writing to '*Start'→
1648#ifdef EXPENSIVE_CHECKS
1649  detail::presortShuffle<IteratorTy>(Start, End);
1650#endif
1651  qsort(&*Start, NElts, sizeof(*Start), get_array_pod_sort_comparator(*Start));
1652}
1653 
1654template <class IteratorTy>
1655inline void array_pod_sort(
1656    IteratorTy Start, IteratorTy End,
1657    int (*Compare)(
1658        const typename std::iterator_traits<IteratorTy>::value_type *,
1659        const typename std::iterator_traits<IteratorTy>::value_type *)) {
1660  // Don't inefficiently call qsort with one element or trigger undefined
1661  // behavior with an empty sequence.
1662  auto NElts = End - Start;
1663  if (NElts <= 1) return;
1664#ifdef EXPENSIVE_CHECKS
1665  detail::presortShuffle<IteratorTy>(Start, End);
1666#endif
1667  qsort(&*Start, NElts, sizeof(*Start),
1668        reinterpret_cast<int (*)(const void *, const void *)>(Compare));
1669}
1670 
1671namespace detail {
1672template <typename T>
1673// We can use qsort if the iterator type is a pointer and the underlying value
1674// is trivially copyable.
1675using sort_trivially_copyable = std::conjunction<
1676    std::is_pointer<T>,
1677    std::is_trivially_copyable<typename std::iterator_traits<T>::value_type>>;
1678} // namespace detail
1679 
1680// Provide wrappers to std::sort which shuffle the elements before sorting
1681// to help uncover non-deterministic behavior (PR35135).
1682template <typename IteratorTy>
1683inline void sort(IteratorTy Start, IteratorTy End) {
1684  if constexpr (detail::sort_trivially_copyable<IteratorTy>::value8.1
'value' is true
8.1
'value' is true
8.1
'value' is true
) {
9
←
Taking true branch→
1685    // Forward trivially copyable types to array_pod_sort. This avoids a large
1686    // amount of code bloat for a minor performance hit.
1687    array_pod_sort(Start, End);
10
←
Calling 'array_pod_sort<unsigned long *>'→
14
←
Returning from 'array_pod_sort<unsigned long *>'→
1688  } else {
1689#ifdef EXPENSIVE_CHECKS
1690    detail::presortShuffle<IteratorTy>(Start, End);
1691#endif
1692    std::sort(Start, End);
1693  }
1694}
15
←
Returning without writing to '*Start'→
1695 
1696template <typename Container> inline void sort(Container &&C) {
1697  llvm::sort(adl_begin(C), adl_end(C));
1698}
1699 
1700template <typename IteratorTy, typename Compare>
1701inline void sort(IteratorTy Start, IteratorTy End, Compare Comp) {
1702#ifdef EXPENSIVE_CHECKS
1703  detail::presortShuffle<IteratorTy>(Start, End);
1704#endif
1705  std::sort(Start, End, Comp);
1706}
1707 
1708template <typename Container, typename Compare>
1709inline void sort(Container &&C, Compare Comp) {
1710  llvm::sort(adl_begin(C), adl_end(C), Comp);
1711}
1712 
1713/// Get the size of a range. This is a wrapper function around std::distance
1714/// which is only enabled when the operation is O(1).
1715template <typename R>
1716auto size(R &&Range,
1717          std::enable_if_t<
1718              std::is_base_of<std::random_access_iterator_tag,
1719                              typename std::iterator_traits<decltype(
1720                                  Range.begin())>::iterator_category>::value,
1721              void> * = nullptr) {
1722  return std::distance(Range.begin(), Range.end());
1723}
1724 
1725/// Provide wrappers to std::for_each which take ranges instead of having to
1726/// pass begin/end explicitly.
1727template <typename R, typename UnaryFunction>
1728UnaryFunction for_each(R &&Range, UnaryFunction F) {
1729  return std::for_each(adl_begin(Range), adl_end(Range), F);
1730}
1731 
1732/// Provide wrappers to std::all_of which take ranges instead of having to pass
1733/// begin/end explicitly.
1734template <typename R, typename UnaryPredicate>
1735bool all_of(R &&Range, UnaryPredicate P) {
1736  return std::all_of(adl_begin(Range), adl_end(Range), P);
1737}
1738 
1739/// Provide wrappers to std::any_of which take ranges instead of having to pass
1740/// begin/end explicitly.
1741template <typename R, typename UnaryPredicate>
1742bool any_of(R &&Range, UnaryPredicate P) {
1743  return std::any_of(adl_begin(Range), adl_end(Range), P);
1744}
1745 
1746/// Provide wrappers to std::none_of which take ranges instead of having to pass
1747/// begin/end explicitly.
1748template <typename R, typename UnaryPredicate>
1749bool none_of(R &&Range, UnaryPredicate P) {
1750  return std::none_of(adl_begin(Range), adl_end(Range), P);
1751}
1752 
1753/// Provide wrappers to std::find which take ranges instead of having to pass
1754/// begin/end explicitly.
1755template <typename R, typename T> auto find(R &&Range, const T &Val) {
1756  return std::find(adl_begin(Range), adl_end(Range), Val);
1757}
1758 
1759/// Provide wrappers to std::find_if which take ranges instead of having to pass
1760/// begin/end explicitly.
1761template <typename R, typename UnaryPredicate>
1762auto find_if(R &&Range, UnaryPredicate P) {
1763  return std::find_if(adl_begin(Range), adl_end(Range), P);
1764}
1765 
1766template <typename R, typename UnaryPredicate>
1767auto find_if_not(R &&Range, UnaryPredicate P) {
1768  return std::find_if_not(adl_begin(Range), adl_end(Range), P);
1769}
1770 
1771/// Provide wrappers to std::remove_if which take ranges instead of having to
1772/// pass begin/end explicitly.
1773template <typename R, typename UnaryPredicate>
1774auto remove_if(R &&Range, UnaryPredicate P) {
1775  return std::remove_if(adl_begin(Range), adl_end(Range), P);
1776}
1777 
1778/// Provide wrappers to std::copy_if which take ranges instead of having to
1779/// pass begin/end explicitly.
1780template <typename R, typename OutputIt, typename UnaryPredicate>
1781OutputIt copy_if(R &&Range, OutputIt Out, UnaryPredicate P) {
1782  return std::copy_if(adl_begin(Range), adl_end(Range), Out, P);
1783}
1784 
1785/// Return the single value in \p Range that satisfies
1786/// \p P(<member of \p Range> *, AllowRepeats)->T * returning nullptr
1787/// when no values or multiple values were found.
1788/// When \p AllowRepeats is true, multiple values that compare equal
1789/// are allowed.
1790template <typename T, typename R, typename Predicate>
1791T *find_singleton(R &&Range, Predicate P, bool AllowRepeats = false) {
1792  T *RC = nullptr;
1793  for (auto *A : Range) {
1794    if (T *PRC = P(A, AllowRepeats)) {
1795      if (RC) {
1796        if (!AllowRepeats || PRC != RC)
1797          return nullptr;
1798      } else
1799        RC = PRC;
1800    }
1801  }
1802  return RC;
1803}
1804 
1805/// Return a pair consisting of the single value in \p Range that satisfies
1806/// \p P(<member of \p Range> *, AllowRepeats)->std::pair<T*, bool> returning
1807/// nullptr when no values or multiple values were found, and a bool indicating
1808/// whether multiple values were found to cause the nullptr.
1809/// When \p AllowRepeats is true, multiple values that compare equal are
1810/// allowed.  The predicate \p P returns a pair<T *, bool> where T is the
1811/// singleton while the bool indicates whether multiples have already been
1812/// found.  It is expected that first will be nullptr when second is true.
1813/// This allows using find_singleton_nested within the predicate \P.
1814template <typename T, typename R, typename Predicate>
1815std::pair<T *, bool> find_singleton_nested(R &&Range, Predicate P,
1816                                           bool AllowRepeats = false) {
1817  T *RC = nullptr;
1818  for (auto *A : Range) {
1819    std::pair<T *, bool> PRC = P(A, AllowRepeats);
1820    if (PRC.second) {
1821      assert(PRC.first == nullptr &&(static_cast <bool> (PRC.first == nullptr && "Inconsistent return values in find_singleton_nested."
) ? void (0) : __assert_fail ("PRC.first == nullptr && \"Inconsistent return values in find_singleton_nested.\""
, "llvm/include/llvm/ADT/STLExtras.h", 1822, __extension__ __PRETTY_FUNCTION__
))
1822             "Inconsistent return values in find_singleton_nested.")(static_cast <bool> (PRC.first == nullptr && "Inconsistent return values in find_singleton_nested."
) ? void (0) : __assert_fail ("PRC.first == nullptr && \"Inconsistent return values in find_singleton_nested.\""
, "llvm/include/llvm/ADT/STLExtras.h", 1822, __extension__ __PRETTY_FUNCTION__
));
1823      return PRC;
1824    }
1825    if (PRC.first) {
1826      if (RC) {
1827        if (!AllowRepeats || PRC.first != RC)
1828          return {nullptr, true};
1829      } else
1830        RC = PRC.first;
1831    }
1832  }
1833  return {RC, false};
1834}
1835 
1836template <typename R, typename OutputIt>
1837OutputIt copy(R &&Range, OutputIt Out) {
1838  return std::copy(adl_begin(Range), adl_end(Range), Out);
1839}
1840 
1841/// Provide wrappers to std::replace_copy_if which take ranges instead of having
1842/// to pass begin/end explicitly.
1843template <typename R, typename OutputIt, typename UnaryPredicate, typename T>
1844OutputIt replace_copy_if(R &&Range, OutputIt Out, UnaryPredicate P,
1845                         const T &NewValue) {
1846  return std::replace_copy_if(adl_begin(Range), adl_end(Range), Out, P,
1847                              NewValue);
1848}
1849 
1850/// Provide wrappers to std::replace_copy which take ranges instead of having to
1851/// pass begin/end explicitly.
1852template <typename R, typename OutputIt, typename T>
1853OutputIt replace_copy(R &&Range, OutputIt Out, const T &OldValue,
1854                      const T &NewValue) {
1855  return std::replace_copy(adl_begin(Range), adl_end(Range), Out, OldValue,
1856                           NewValue);
1857}
1858 
1859/// Provide wrappers to std::move which take ranges instead of having to
1860/// pass begin/end explicitly.
1861template <typename R, typename OutputIt>
1862OutputIt move(R &&Range, OutputIt Out) {
1863  return std::move(adl_begin(Range), adl_end(Range), Out);
1864}
1865 
1866/// Wrapper function around std::find to detect if an element exists
1867/// in a container.
1868template <typename R, typename E>
1869bool is_contained(R &&Range, const E &Element) {
1870  return std::find(adl_begin(Range), adl_end(Range), Element) != adl_end(Range);
1871}
1872 
1873template <typename T>
1874constexpr bool is_contained(std::initializer_list<T> Set, T Value) {
1875  // TODO: Use std::find when we switch to C++20.
1876  for (T V : Set)
1877    if (V == Value)
1878      return true;
1879  return false;
1880}
1881 
1882/// Wrapper function around std::is_sorted to check if elements in a range \p R
1883/// are sorted with respect to a comparator \p C.
1884template <typename R, typename Compare> bool is_sorted(R &&Range, Compare C) {
1885  return std::is_sorted(adl_begin(Range), adl_end(Range), C);
1886}
1887 
1888/// Wrapper function around std::is_sorted to check if elements in a range \p R
1889/// are sorted in non-descending order.
1890template <typename R> bool is_sorted(R &&Range) {
1891  return std::is_sorted(adl_begin(Range), adl_end(Range));
1892}
1893 
1894/// Wrapper function around std::count to count the number of times an element
1895/// \p Element occurs in the given range \p Range.
1896template <typename R, typename E> auto count(R &&Range, const E &Element) {
1897  return std::count(adl_begin(Range), adl_end(Range), Element);
1898}
1899 
1900/// Wrapper function around std::count_if to count the number of times an
1901/// element satisfying a given predicate occurs in a range.
1902template <typename R, typename UnaryPredicate>
1903auto count_if(R &&Range, UnaryPredicate P) {
1904  return std::count_if(adl_begin(Range), adl_end(Range), P);
1905}
1906 
1907/// Wrapper function around std::transform to apply a function to a range and
1908/// store the result elsewhere.
1909template <typename R, typename OutputIt, typename UnaryFunction>
1910OutputIt transform(R &&Range, OutputIt d_first, UnaryFunction F) {
1911  return std::transform(adl_begin(Range), adl_end(Range), d_first, F);
1912}
1913 
1914/// Provide wrappers to std::partition which take ranges instead of having to
1915/// pass begin/end explicitly.
1916template <typename R, typename UnaryPredicate>
1917auto partition(R &&Range, UnaryPredicate P) {
1918  return std::partition(adl_begin(Range), adl_end(Range), P);
1919}
1920 
1921/// Provide wrappers to std::lower_bound which take ranges instead of having to
1922/// pass begin/end explicitly.
1923template <typename R, typename T> auto lower_bound(R &&Range, T &&Value) {
1924  return std::lower_bound(adl_begin(Range), adl_end(Range),
1925                          std::forward<T>(Value));
1926}
1927 
1928template <typename R, typename T, typename Compare>
1929auto lower_bound(R &&Range, T &&Value, Compare C) {
1930  return std::lower_bound(adl_begin(Range), adl_end(Range),
1931                          std::forward<T>(Value), C);
1932}
1933 
1934/// Provide wrappers to std::upper_bound which take ranges instead of having to
1935/// pass begin/end explicitly.
1936template <typename R, typename T> auto upper_bound(R &&Range, T &&Value) {
1937  return std::upper_bound(adl_begin(Range), adl_end(Range),
1938                          std::forward<T>(Value));
1939}
1940 
1941template <typename R, typename T, typename Compare>
1942auto upper_bound(R &&Range, T &&Value, Compare C) {
1943  return std::upper_bound(adl_begin(Range), adl_end(Range),
1944                          std::forward<T>(Value), C);
1945}
1946 
1947template <typename R>
1948void stable_sort(R &&Range) {
1949  std::stable_sort(adl_begin(Range), adl_end(Range));
1950}
1951 
1952template <typename R, typename Compare>
1953void stable_sort(R &&Range, Compare C) {
1954  std::stable_sort(adl_begin(Range), adl_end(Range), C);
1955}
1956 
1957/// Binary search for the first iterator in a range where a predicate is false.
1958/// Requires that C is always true below some limit, and always false above it.
1959template <typename R, typename Predicate,
1960          typename Val = decltype(*adl_begin(std::declval<R>()))>
1961auto partition_point(R &&Range, Predicate P) {
1962  return std::partition_point(adl_begin(Range), adl_end(Range), P);
1963}
1964 
1965template<typename Range, typename Predicate>
1966auto unique(Range &&R, Predicate P) {
1967  return std::unique(adl_begin(R), adl_end(R), P);
1968}
1969 
1970/// Wrapper function around std::equal to detect if pair-wise elements between
1971/// two ranges are the same.
1972template <typename L, typename R> bool equal(L &&LRange, R &&RRange) {
1973  return std::equal(adl_begin(LRange), adl_end(LRange), adl_begin(RRange),
1974                    adl_end(RRange));
1975}
1976 
1977/// Returns true if all elements in Range are equal or when the Range is empty.
1978template <typename R> bool all_equal(R &&Range) {
1979  auto Begin = adl_begin(Range);
1980  auto End = adl_end(Range);
1981  return Begin == End || std::equal(Begin + 1, End, Begin);
1982}
1983 
1984/// Returns true if all Values in the initializer lists are equal or the list
1985// is empty.
1986template <typename T> bool all_equal(std::initializer_list<T> Values) {
1987  return all_equal<std::initializer_list<T>>(std::move(Values));
1988}
1989 
1990/// Provide a container algorithm similar to C++ Library Fundamentals v2's
1991/// `erase_if` which is equivalent to:
1992///
1993///   C.erase(remove_if(C, pred), C.end());
1994///
1995/// This version works for any container with an erase method call accepting
1996/// two iterators.
1997template <typename Container, typename UnaryPredicate>
1998void erase_if(Container &C, UnaryPredicate P) {
1999  C.erase(remove_if(C, P), C.end());
2000}
2001 
2002/// Wrapper function to remove a value from a container:
2003///
2004/// C.erase(remove(C.begin(), C.end(), V), C.end());
2005template <typename Container, typename ValueType>
2006void erase_value(Container &C, ValueType V) {
2007  C.erase(std::remove(C.begin(), C.end(), V), C.end());
2008}
2009 
2010/// Wrapper function to append a range to a container.
2011///
2012/// C.insert(C.end(), R.begin(), R.end());
2013template <typename Container, typename Range>
2014inline void append_range(Container &C, Range &&R) {
2015  C.insert(C.end(), R.begin(), R.end());
2016}
2017 
2018/// Given a sequence container Cont, replace the range [ContIt, ContEnd) with
2019/// the range [ValIt, ValEnd) (which is not from the same container).
2020template<typename Container, typename RandomAccessIterator>
2021void replace(Container &Cont, typename Container::iterator ContIt,
2022             typename Container::iterator ContEnd, RandomAccessIterator ValIt,
2023             RandomAccessIterator ValEnd) {
2024  while (true) {
2025    if (ValIt == ValEnd) {
2026      Cont.erase(ContIt, ContEnd);
2027      return;
2028    } else if (ContIt == ContEnd) {
2029      Cont.insert(ContIt, ValIt, ValEnd);
2030      return;
2031    }
2032    *ContIt++ = *ValIt++;
2033  }
2034}
2035 
2036/// Given a sequence container Cont, replace the range [ContIt, ContEnd) with
2037/// the range R.
2038template<typename Container, typename Range = std::initializer_list<
2039                                 typename Container::value_type>>
2040void replace(Container &Cont, typename Container::iterator ContIt,
2041             typename Container::iterator ContEnd, Range R) {
2042  replace(Cont, ContIt, ContEnd, R.begin(), R.end());
2043}
2044 
2045/// An STL-style algorithm similar to std::for_each that applies a second
2046/// functor between every pair of elements.
2047///
2048/// This provides the control flow logic to, for example, print a
2049/// comma-separated list:
2050/// \code
2051///   interleave(names.begin(), names.end(),
2052///              [&](StringRef name) { os << name; },
2053///              [&] { os << ", "; });
2054/// \endcode
2055template <typename ForwardIterator, typename UnaryFunctor,
2056          typename NullaryFunctor,
2057          typename = std::enable_if_t<
2058              !std::is_constructible<StringRef, UnaryFunctor>::value &&
2059              !std::is_constructible<StringRef, NullaryFunctor>::value>>
2060inline void interleave(ForwardIterator begin, ForwardIterator end,
2061                       UnaryFunctor each_fn, NullaryFunctor between_fn) {
2062  if (begin == end)
2063    return;
2064  each_fn(*begin);
2065  ++begin;
2066  for (; begin != end; ++begin) {
2067    between_fn();
2068    each_fn(*begin);
2069  }
2070}
2071 
2072template <typename Container, typename UnaryFunctor, typename NullaryFunctor,
2073          typename = std::enable_if_t<
2074              !std::is_constructible<StringRef, UnaryFunctor>::value &&
2075              !std::is_constructible<StringRef, NullaryFunctor>::value>>
2076inline void interleave(const Container &c, UnaryFunctor each_fn,
2077                       NullaryFunctor between_fn) {
2078  interleave(c.begin(), c.end(), each_fn, between_fn);
2079}
2080 
2081/// Overload of interleave for the common case of string separator.
2082template <typename Container, typename UnaryFunctor, typename StreamT,
2083          typename T = detail::ValueOfRange<Container>>
2084inline void interleave(const Container &c, StreamT &os, UnaryFunctor each_fn,
2085                       const StringRef &separator) {
2086  interleave(c.begin(), c.end(), each_fn, [&] { os << separator; });
2087}
2088template <typename Container, typename StreamT,
2089          typename T = detail::ValueOfRange<Container>>
2090inline void interleave(const Container &c, StreamT &os,
2091                       const StringRef &separator) {
2092  interleave(
2093      c, os, [&](const T &a) { os << a; }, separator);
2094}
2095 
2096template <typename Container, typename UnaryFunctor, typename StreamT,
2097          typename T = detail::ValueOfRange<Container>>
2098inline void interleaveComma(const Container &c, StreamT &os,
2099                            UnaryFunctor each_fn) {
2100  interleave(c, os, each_fn, ", ");
2101}
2102template <typename Container, typename StreamT,
2103          typename T = detail::ValueOfRange<Container>>
2104inline void interleaveComma(const Container &c, StreamT &os) {
2105  interleaveComma(c, os, [&](const T &a) { os << a; });
2106}
2107 
2108//===----------------------------------------------------------------------===//
2109//     Extra additions to <memory>
2110//===----------------------------------------------------------------------===//
2111 
2112struct FreeDeleter {
2113  void operator()(void* v) {
2114    ::free(v);
2115  }
2116};
2117 
2118template<typename First, typename Second>
2119struct pair_hash {
2120  size_t operator()(const std::pair<First, Second> &P) const {
2121    return std::hash<First>()(P.first) * 31 + std::hash<Second>()(P.second);
2122  }
2123};
2124 
2125/// Binary functor that adapts to any other binary functor after dereferencing
2126/// operands.
2127template <typename T> struct deref {
2128  T func;
2129 
2130  // Could be further improved to cope with non-derivable functors and
2131  // non-binary functors (should be a variadic template member function
2132  // operator()).
2133  template <typename A, typename B> auto operator()(A &lhs, B &rhs) const {
2134    assert(lhs)(static_cast <bool> (lhs) ? void (0) : __assert_fail ("lhs"
, "llvm/include/llvm/ADT/STLExtras.h", 2134, __extension__ __PRETTY_FUNCTION__
));
2135    assert(rhs)(static_cast <bool> (rhs) ? void (0) : __assert_fail ("rhs"
, "llvm/include/llvm/ADT/STLExtras.h", 2135, __extension__ __PRETTY_FUNCTION__
));
2136    return func(*lhs, *rhs);
2137  }
2138};
2139 
2140namespace detail {
2141 
2142template <typename R> class enumerator_iter;
2143 
2144template <typename R> struct result_pair {
2145  using value_reference =
2146      typename std::iterator_traits<IterOfRange<R>>::reference;
2147 
2148  friend class enumerator_iter<R>;
2149 
2150  result_pair() = default;
2151  result_pair(std::size_t Index, IterOfRange<R> Iter)
2152      : Index(Index), Iter(Iter) {}
2153 
2154  result_pair(const result_pair<R> &Other)
2155      : Index(Other.Index), Iter(Other.Iter) {}
2156  result_pair &operator=(const result_pair &Other) {
2157    Index = Other.Index;
2158    Iter = Other.Iter;
2159    return *this;
2160  }
2161 
2162  std::size_t index() const { return Index; }
2163  value_reference value() const { return *Iter; }
2164 
2165private:
2166  std::size_t Index = std::numeric_limits<std::size_t>::max();
2167  IterOfRange<R> Iter;
2168};
2169 
2170template <std::size_t i, typename R>
2171decltype(auto) get(const result_pair<R> &Pair) {
2172  static_assert(i < 2);
2173  if constexpr (i == 0) {
2174    return Pair.index();
2175  } else {
2176    return Pair.value();
2177  }
2178}
2179 
2180template <typename R>
2181class enumerator_iter
2182    : public iterator_facade_base<enumerator_iter<R>, std::forward_iterator_tag,
2183                                  const result_pair<R>> {
2184  using result_type = result_pair<R>;
2185 
2186public:
2187  explicit enumerator_iter(IterOfRange<R> EndIter)
2188      : Result(std::numeric_limits<size_t>::max(), EndIter) {}
2189 
2190  enumerator_iter(std::size_t Index, IterOfRange<R> Iter)
2191      : Result(Index, Iter) {}
2192 
2193  const result_type &operator*() const { return Result; }
2194 
2195  enumerator_iter &operator++() {
2196    assert(Result.Index != std::numeric_limits<size_t>::max())(static_cast <bool> (Result.Index != std::numeric_limits
<size_t>::max()) ? void (0) : __assert_fail ("Result.Index != std::numeric_limits<size_t>::max()"
, "llvm/include/llvm/ADT/STLExtras.h", 2196, __extension__ __PRETTY_FUNCTION__
));
2197    ++Result.Iter;
2198    ++Result.Index;
2199    return *this;
2200  }
2201 
2202  bool operator==(const enumerator_iter &RHS) const {
2203    // Don't compare indices here, only iterators.  It's possible for an end
2204    // iterator to have different indices depending on whether it was created
2205    // by calling std::end() versus incrementing a valid iterator.
2206    return Result.Iter == RHS.Result.Iter;
2207  }
2208 
2209  enumerator_iter(const enumerator_iter &Other) : Result(Other.Result) {}
2210  enumerator_iter &operator=(const enumerator_iter &Other) {
2211    Result = Other.Result;
2212    return *this;
2213  }
2214 
2215private:
2216  result_type Result;
2217};
2218 
2219template <typename R> class enumerator {
2220public:
2221  explicit enumerator(R &&Range) : TheRange(std::forward<R>(Range)) {}
2222 
2223  enumerator_iter<R> begin() {
2224    return enumerator_iter<R>(0, std::begin(TheRange));
2225  }
2226  enumerator_iter<R> begin() const {
2227    return enumerator_iter<R>(0, std::begin(TheRange));
2228  }
2229 
2230  enumerator_iter<R> end() {
2231    return enumerator_iter<R>(std::end(TheRange));
2232  }
2233  enumerator_iter<R> end() const {
2234    return enumerator_iter<R>(std::end(TheRange));
2235  }
2236 
2237private:
2238  R TheRange;
2239};
2240 
2241} // end namespace detail
2242 
2243/// Given an input range, returns a new range whose values are are pair (A,B)
2244/// such that A is the 0-based index of the item in the sequence, and B is
2245/// the value from the original sequence.  Example:
2246///
2247/// std::vector<char> Items = {'A', 'B', 'C', 'D'};
2248/// for (auto X : enumerate(Items)) {
2249///   printf("Item %d - %c\n", X.index(), X.value());
2250/// }
2251///
2252/// or using structured bindings:
2253///
2254/// for (auto [Index, Value] : enumerate(Items)) {
2255///   printf("Item %d - %c\n", Index, Value);
2256/// }
2257///
2258/// Output:
2259///   Item 0 - A
2260///   Item 1 - B
2261///   Item 2 - C
2262///   Item 3 - D
2263///
2264template <typename R> detail::enumerator<R> enumerate(R &&TheRange) {
2265  return detail::enumerator<R>(std::forward<R>(TheRange));
2266}
2267 
2268namespace detail {
2269 
2270template <typename Predicate, typename... Args>
2271bool all_of_zip_predicate_first(Predicate &&P, Args &&...args) {
2272  auto z = zip(args...);
2273  auto it = z.begin();
2274  auto end = z.end();
2275  while (it != end) {
2276    if (!std::apply([&](auto &&...args) { return P(args...); }, *it))
2277      return false;
2278    ++it;
2279  }
2280  return it.all_equals(end);
2281}
2282 
2283// Just an adaptor to switch the order of argument and have the predicate before
2284// the zipped inputs.
2285template <typename... ArgsThenPredicate, size_t... InputIndexes>
2286bool all_of_zip_predicate_last(
2287    std::tuple<ArgsThenPredicate...> argsThenPredicate,
2288    std::index_sequence<InputIndexes...>) {
2289  auto constexpr OutputIndex =
2290      std::tuple_size<decltype(argsThenPredicate)>::value - 1;
2291  return all_of_zip_predicate_first(std::get<OutputIndex>(argsThenPredicate),
2292                             std::get<InputIndexes>(argsThenPredicate)...);
2293}
2294 
2295} // end namespace detail
2296 
2297/// Compare two zipped ranges using the provided predicate (as last argument).
2298/// Return true if all elements satisfy the predicate and false otherwise.
2299//  Return false if the zipped iterator aren't all at end (size mismatch).
2300template <typename... ArgsAndPredicate>
2301bool all_of_zip(ArgsAndPredicate &&...argsAndPredicate) {
2302  return detail::all_of_zip_predicate_last(
2303      std::forward_as_tuple(argsAndPredicate...),
2304      std::make_index_sequence<sizeof...(argsAndPredicate) - 1>{});
2305}
2306 
2307/// Return true if the sequence [Begin, End) has exactly N items. Runs in O(N)
2308/// time. Not meant for use with random-access iterators.
2309/// Can optionally take a predicate to filter lazily some items.
2310template <typename IterTy,
2311          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
2312bool hasNItems(
2313    IterTy &&Begin, IterTy &&End, unsigned N,
2314    Pred &&ShouldBeCounted =
2315        [](const decltype(*std::declval<IterTy>()) &) { return true; },
2316    std::enable_if_t<
2317        !std::is_base_of<std::random_access_iterator_tag,
2318                         typename std::iterator_traits<std::remove_reference_t<
2319                             decltype(Begin)>>::iterator_category>::value,
2320        void> * = nullptr) {
2321  for (; N; ++Begin) {
2322    if (Begin == End)
2323      return false; // Too few.
2324    N -= ShouldBeCounted(*Begin);
2325  }
2326  for (; Begin != End; ++Begin)
2327    if (ShouldBeCounted(*Begin))
2328      return false; // Too many.
2329  return true;
2330}
2331 
2332/// Return true if the sequence [Begin, End) has N or more items. Runs in O(N)
2333/// time. Not meant for use with random-access iterators.
2334/// Can optionally take a predicate to lazily filter some items.
2335template <typename IterTy,
2336          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
2337bool hasNItemsOrMore(
2338    IterTy &&Begin, IterTy &&End, unsigned N,
2339    Pred &&ShouldBeCounted =
2340        [](const decltype(*std::declval<IterTy>()) &) { return true; },
2341    std::enable_if_t<
2342        !std::is_base_of<std::random_access_iterator_tag,
2343                         typename std::iterator_traits<std::remove_reference_t<
2344                             decltype(Begin)>>::iterator_category>::value,
2345        void> * = nullptr) {
2346  for (; N; ++Begin) {
2347    if (Begin == End)
2348      return false; // Too few.
2349    N -= ShouldBeCounted(*Begin);
2350  }
2351  return true;
2352}
2353 
2354/// Returns true if the sequence [Begin, End) has N or less items. Can
2355/// optionally take a predicate to lazily filter some items.
2356template <typename IterTy,
2357          typename Pred = bool (*)(const decltype(*std::declval<IterTy>()) &)>
2358bool hasNItemsOrLess(
2359    IterTy &&Begin, IterTy &&End, unsigned N,
2360    Pred &&ShouldBeCounted = [](const decltype(*std::declval<IterTy>()) &) {
2361      return true;
2362    }) {
2363  assert(N != std::numeric_limits<unsigned>::max())(static_cast <bool> (N != std::numeric_limits<unsigned
>::max()) ? void (0) : __assert_fail ("N != std::numeric_limits<unsigned>::max()"
, "llvm/include/llvm/ADT/STLExtras.h", 2363, __extension__ __PRETTY_FUNCTION__
));
2364  return !hasNItemsOrMore(Begin, End, N + 1, ShouldBeCounted);
2365}
2366 
2367/// Returns true if the given container has exactly N items
2368template <typename ContainerTy> bool hasNItems(ContainerTy &&C, unsigned N) {
2369  return hasNItems(std::begin(C), std::end(C), N);
2370}
2371 
2372/// Returns true if the given container has N or more items
2373template <typename ContainerTy>
2374bool hasNItemsOrMore(ContainerTy &&C, unsigned N) {
2375  return hasNItemsOrMore(std::begin(C), std::end(C), N);
2376}
2377 
2378/// Returns true if the given container has N or less items
2379template <typename ContainerTy>
2380bool hasNItemsOrLess(ContainerTy &&C, unsigned N) {
2381  return hasNItemsOrLess(std::begin(C), std::end(C), N);
2382}
2383 
2384/// Returns a raw pointer that represents the same address as the argument.
2385///
2386/// This implementation can be removed once we move to C++20 where it's defined
2387/// as std::to_address().
2388///
2389/// The std::pointer_traits<>::to_address(p) variations of these overloads has
2390/// not been implemented.
2391template <class Ptr> auto to_address(const Ptr &P) { return P.operator->(); }
2392template <class T> constexpr T *to_address(T *P) { return P; }
2393 
2394} // end namespace llvm
2395 
2396namespace std {
2397template <typename R>
2398struct tuple_size<llvm::detail::result_pair<R>>
2399    : std::integral_constant<std::size_t, 2> {};
2400 
2401template <std::size_t i, typename R>
2402struct tuple_element<i, llvm::detail::result_pair<R>>
2403    : std::conditional<i == 0, std::size_t,
2404                       typename llvm::detail::result_pair<R>::value_reference> {
2405};
2406 
2407} // namespace std
2408 
2409#endif // LLVM_ADT_STLEXTRAS_H