vendor/llvm-project/llvmorg-11-init-20887-g2e10b7a39b9vendor/llvm-project/master

12 files changed, 1384 insertions, 472 deletions

diff --git a/llvm/lib/ObjectYAML/COFFEmitter.cpp b/llvm/lib/ObjectYAML/COFFEmitter.cpp
index ec3ec55011f95..734e1be4b2d5c 100644
--- a/llvm/lib/ObjectYAML/COFFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/COFFEmitter.cpp
@@ -187,7 +187,7 @@ toDebugS(ArrayRef<CodeViewYAML::YAMLDebugSubsection> Subsections,
   std::vector<DebugSubsectionRecordBuilder> Builders;
   uint32_t Size = sizeof(uint32_t);
   for (auto &SS : CVSS) {
-    DebugSubsectionRecordBuilder B(SS, CodeViewContainer::ObjectFile);
+    DebugSubsectionRecordBuilder B(SS);
     Size += B.calculateSerializedLength();
     Builders.push_back(std::move(B));
   }
@@ -197,7 +197,7 @@ toDebugS(ArrayRef<CodeViewYAML::YAMLDebugSubsection> Subsections,
 
   Err(Writer.writeInteger<uint32_t>(COFF::DEBUG_SECTION_MAGIC));
   for (const auto &B : Builders) {
-    Err(B.commit(Writer));
+    Err(B.commit(Writer, CodeViewContainer::ObjectFile));
   }
   return {Output};
 }
diff --git a/llvm/lib/ObjectYAML/DWARFEmitter.cpp b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
index b410fed16f09c..ed3732ba29f6c 100644
--- a/llvm/lib/ObjectYAML/DWARFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/DWARFEmitter.cpp
@@ -15,12 +15,15 @@
 #include "DWARFVisitor.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/ObjectYAML/DWARFYAML.h"
+#include "llvm/Support/Errc.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/SwapByteOrder.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
@@ -41,8 +44,8 @@ static void writeInteger(T Integer, raw_ostream &OS, bool IsLittleEndian) {
   OS.write(reinterpret_cast<char *>(&Integer), sizeof(T));
 }
 
-static void writeVariableSizedInteger(uint64_t Integer, size_t Size,
-                                      raw_ostream &OS, bool IsLittleEndian) {
+static Error writeVariableSizedInteger(uint64_t Integer, size_t Size,
+                                       raw_ostream &OS, bool IsLittleEndian) {
   if (8 == Size)
     writeInteger((uint64_t)Integer, OS, IsLittleEndian);
   else if (4 == Size)
@@ -52,7 +55,10 @@ static void writeVariableSizedInteger(uint64_t Integer, size_t Size,
   else if (1 == Size)
     writeInteger((uint8_t)Integer, OS, IsLittleEndian);
   else
-    assert(false && "Invalid integer write size.");
+    return createStringError(errc::not_supported,
+                             "invalid integer write size: %zu", Size);
+
+  return Error::success();
 }
 
 static void ZeroFillBytes(raw_ostream &OS, size_t Size) {
@@ -68,16 +74,31 @@ static void writeInitialLength(const DWARFYAML::InitialLength &Length,
     writeInteger((uint64_t)Length.TotalLength64, OS, IsLittleEndian);
 }
 
-void DWARFYAML::EmitDebugStr(raw_ostream &OS, const DWARFYAML::Data &DI) {
+static void writeInitialLength(const dwarf::DwarfFormat Format,
+                               const uint64_t Length, raw_ostream &OS,
+                               bool IsLittleEndian) {
+  bool IsDWARF64 = Format == dwarf::DWARF64;
+  if (IsDWARF64)
+    cantFail(writeVariableSizedInteger(dwarf::DW_LENGTH_DWARF64, 4, OS,
+                                       IsLittleEndian));
+  cantFail(
+      writeVariableSizedInteger(Length, IsDWARF64 ? 8 : 4, OS, IsLittleEndian));
+}
+
+Error DWARFYAML::emitDebugStr(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (auto Str : DI.DebugStrings) {
     OS.write(Str.data(), Str.size());
     OS.write('\0');
   }
+
+  return Error::success();
 }
 
-void DWARFYAML::EmitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
+Error DWARFYAML::emitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
+  uint64_t AbbrevCode = 0;
   for (auto AbbrevDecl : DI.AbbrevDecls) {
-    encodeULEB128(AbbrevDecl.Code, OS);
+    AbbrevCode = AbbrevDecl.Code ? (uint64_t)*AbbrevDecl.Code : AbbrevCode + 1;
+    encodeULEB128(AbbrevCode, OS);
     encodeULEB128(AbbrevDecl.Tag, OS);
     OS.write(AbbrevDecl.Children);
     for (auto Attr : AbbrevDecl.Attributes) {
@@ -89,14 +110,23 @@ void DWARFYAML::EmitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
     encodeULEB128(0, OS);
     encodeULEB128(0, OS);
   }
+
+  // The abbreviations for a given compilation unit end with an entry consisting
+  // of a 0 byte for the abbreviation code.
+  OS.write_zeros(1);
+
+  return Error::success();
 }
 
-void DWARFYAML::EmitDebugAranges(raw_ostream &OS, const DWARFYAML::Data &DI) {
+Error DWARFYAML::emitDebugAranges(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (auto Range : DI.ARanges) {
     auto HeaderStart = OS.tell();
-    writeInitialLength(Range.Length, OS, DI.IsLittleEndian);
+    writeInitialLength(Range.Format, Range.Length, OS, DI.IsLittleEndian);
     writeInteger((uint16_t)Range.Version, OS, DI.IsLittleEndian);
-    writeInteger((uint32_t)Range.CuOffset, OS, DI.IsLittleEndian);
+    if (Range.Format == dwarf::DWARF64)
+      writeInteger((uint64_t)Range.CuOffset, OS, DI.IsLittleEndian);
+    else
+      writeInteger((uint32_t)Range.CuOffset, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)Range.AddrSize, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)Range.SegSize, OS, DI.IsLittleEndian);
 
@@ -105,29 +135,73 @@ void DWARFYAML::EmitDebugAranges(raw_ostream &OS, const DWARFYAML::Data &DI) {
     ZeroFillBytes(OS, FirstDescriptor - HeaderSize);
 
     for (auto Descriptor : Range.Descriptors) {
-      writeVariableSizedInteger(Descriptor.Address, Range.AddrSize, OS,
-                                DI.IsLittleEndian);
-      writeVariableSizedInteger(Descriptor.Length, Range.AddrSize, OS,
-                                DI.IsLittleEndian);
+      if (Error Err = writeVariableSizedInteger(
+              Descriptor.Address, Range.AddrSize, OS, DI.IsLittleEndian))
+        return createStringError(errc::not_supported,
+                                 "unable to write debug_aranges address: %s",
+                                 toString(std::move(Err)).c_str());
+      cantFail(writeVariableSizedInteger(Descriptor.Length, Range.AddrSize, OS,
+                                         DI.IsLittleEndian));
     }
     ZeroFillBytes(OS, Range.AddrSize * 2);
   }
+
+  return Error::success();
 }
 
-void DWARFYAML::EmitPubSection(raw_ostream &OS,
-                               const DWARFYAML::PubSection &Sect,
-                               bool IsLittleEndian) {
+Error DWARFYAML::emitDebugRanges(raw_ostream &OS, const DWARFYAML::Data &DI) {
+  const size_t RangesOffset = OS.tell();
+  uint64_t EntryIndex = 0;
+  for (auto DebugRanges : DI.DebugRanges) {
+    const size_t CurrOffset = OS.tell() - RangesOffset;
+    if (DebugRanges.Offset && (uint64_t)*DebugRanges.Offset < CurrOffset)
+      return createStringError(errc::invalid_argument,
+                               "'Offset' for 'debug_ranges' with index " +
+                                   Twine(EntryIndex) +
+                                   " must be greater than or equal to the "
+                                   "number of bytes written already (0x" +
+                                   Twine::utohexstr(CurrOffset) + ")");
+    if (DebugRanges.Offset)
+      ZeroFillBytes(OS, *DebugRanges.Offset - CurrOffset);
+
+    uint8_t AddrSize;
+    if (DebugRanges.AddrSize)
+      AddrSize = *DebugRanges.AddrSize;
+    else
+      AddrSize = DI.Is64BitAddrSize ? 8 : 4;
+    for (auto Entry : DebugRanges.Entries) {
+      if (Error Err = writeVariableSizedInteger(Entry.LowOffset, AddrSize, OS,
+                                                DI.IsLittleEndian))
+        return createStringError(
+            errc::not_supported,
+            "unable to write debug_ranges address offset: %s",
+            toString(std::move(Err)).c_str());
+      cantFail(writeVariableSizedInteger(Entry.HighOffset, AddrSize, OS,
+                                         DI.IsLittleEndian));
+    }
+    ZeroFillBytes(OS, AddrSize * 2);
+    ++EntryIndex;
+  }
+
+  return Error::success();
+}
+
+Error DWARFYAML::emitPubSection(raw_ostream &OS,
+                                const DWARFYAML::PubSection &Sect,
+                                bool IsLittleEndian, bool IsGNUPubSec) {
   writeInitialLength(Sect.Length, OS, IsLittleEndian);
   writeInteger((uint16_t)Sect.Version, OS, IsLittleEndian);
   writeInteger((uint32_t)Sect.UnitOffset, OS, IsLittleEndian);
   writeInteger((uint32_t)Sect.UnitSize, OS, IsLittleEndian);
   for (auto Entry : Sect.Entries) {
     writeInteger((uint32_t)Entry.DieOffset, OS, IsLittleEndian);
-    if (Sect.IsGNUStyle)
-      writeInteger((uint32_t)Entry.Descriptor, OS, IsLittleEndian);
+    if (IsGNUPubSec)
+      writeInteger((uint8_t)Entry.Descriptor, OS, IsLittleEndian);
     OS.write(Entry.Name.data(), Entry.Name.size());
     OS.write('\0');
   }
+
+  return Error::success();
 }
 
 namespace {
@@ -138,14 +212,18 @@ class DumpVisitor : public DWARFYAML::ConstVisitor {
 
 protected:
   void onStartCompileUnit(const DWARFYAML::Unit &CU) override {
-    writeInitialLength(CU.Length, OS, DebugInfo.IsLittleEndian);
+    writeInitialLength(CU.Format, CU.Length, OS, DebugInfo.IsLittleEndian);
     writeInteger((uint16_t)CU.Version, OS, DebugInfo.IsLittleEndian);
-    if(CU.Version >= 5) {
+    if (CU.Version >= 5) {
       writeInteger((uint8_t)CU.Type, OS, DebugInfo.IsLittleEndian);
       writeInteger((uint8_t)CU.AddrSize, OS, DebugInfo.IsLittleEndian);
-      writeInteger((uint32_t)CU.AbbrOffset, OS, DebugInfo.IsLittleEndian);
-    }else {
-      writeInteger((uint32_t)CU.AbbrOffset, OS, DebugInfo.IsLittleEndian);
+      cantFail(writeVariableSizedInteger(CU.AbbrOffset,
+                                         CU.Format == dwarf::DWARF64 ? 8 : 4,
+                                         OS, DebugInfo.IsLittleEndian));
+    } else {
+      cantFail(writeVariableSizedInteger(CU.AbbrOffset,
+                                         CU.Format == dwarf::DWARF64 ? 8 : 4,
+                                         OS, DebugInfo.IsLittleEndian));
       writeInteger((uint8_t)CU.AddrSize, OS, DebugInfo.IsLittleEndian);
     }
   }
@@ -196,12 +274,12 @@ public:
 };
 } // namespace
 
-void DWARFYAML::EmitDebugInfo(raw_ostream &OS, const DWARFYAML::Data &DI) {
+Error DWARFYAML::emitDebugInfo(raw_ostream &OS, const DWARFYAML::Data &DI) {
   DumpVisitor Visitor(DI, OS);
-  Visitor.traverseDebugInfo();
+  return Visitor.traverseDebugInfo();
 }
 
-static void EmitFileEntry(raw_ostream &OS, const DWARFYAML::File &File) {
+static void emitFileEntry(raw_ostream &OS, const DWARFYAML::File &File) {
   OS.write(File.Name.data(), File.Name.size());
   OS.write('\0');
   encodeULEB128(File.DirIdx, OS);
@@ -209,13 +287,14 @@ static void EmitFileEntry(raw_ostream &OS, const DWARFYAML::File &File) {
   encodeULEB128(File.Length, OS);
 }
 
-void DWARFYAML::EmitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
+Error DWARFYAML::emitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (const auto &LineTable : DI.DebugLines) {
-    writeInitialLength(LineTable.Length, OS, DI.IsLittleEndian);
-    uint64_t SizeOfPrologueLength = LineTable.Length.isDWARF64() ? 8 : 4;
+    writeInitialLength(LineTable.Format, LineTable.Length, OS,
+                       DI.IsLittleEndian);
+    uint64_t SizeOfPrologueLength = LineTable.Format == dwarf::DWARF64 ? 8 : 4;
     writeInteger((uint16_t)LineTable.Version, OS, DI.IsLittleEndian);
-    writeVariableSizedInteger(LineTable.PrologueLength, SizeOfPrologueLength,
-                              OS, DI.IsLittleEndian);
+    cantFail(writeVariableSizedInteger(
+        LineTable.PrologueLength, SizeOfPrologueLength, OS, DI.IsLittleEndian));
     writeInteger((uint8_t)LineTable.MinInstLength, OS, DI.IsLittleEndian);
     if (LineTable.Version >= 4)
       writeInteger((uint8_t)LineTable.MaxOpsPerInst, OS, DI.IsLittleEndian);
@@ -234,7 +313,7 @@ void DWARFYAML::EmitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
     OS.write('\0');
 
     for (auto File : LineTable.Files)
-      EmitFileEntry(OS, File);
+      emitFileEntry(OS, File);
     OS.write('\0');
 
     for (auto Op : LineTable.Opcodes) {
@@ -245,11 +324,13 @@ void DWARFYAML::EmitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
         switch (Op.SubOpcode) {
         case dwarf::DW_LNE_set_address:
         case dwarf::DW_LNE_set_discriminator:
-          writeVariableSizedInteger(Op.Data, DI.CompileUnits[0].AddrSize, OS,
-                                    DI.IsLittleEndian);
+          // TODO: Test this error.
+          if (Error Err = writeVariableSizedInteger(
+                  Op.Data, DI.CompileUnits[0].AddrSize, OS, DI.IsLittleEndian))
+            return Err;
           break;
         case dwarf::DW_LNE_define_file:
-          EmitFileEntry(OS, Op.FileEntry);
+          emitFileEntry(OS, Op.FileEntry);
           break;
         case dwarf::DW_LNE_end_sequence:
           break;
@@ -290,20 +371,66 @@ void DWARFYAML::EmitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
       }
     }
   }
+
+  return Error::success();
+}
+
+Error DWARFYAML::emitDebugAddr(raw_ostream &OS, const Data &DI) {
+  for (const AddrTableEntry &TableEntry : DI.DebugAddr) {
+    uint8_t AddrSize;
+    if (TableEntry.AddrSize)
+      AddrSize = *TableEntry.AddrSize;
+    else
+      AddrSize = DI.Is64BitAddrSize ? 8 : 4;
+
+    uint64_t Length;
+    if (TableEntry.Length)
+      Length = (uint64_t)*TableEntry.Length;
+    else
+      // 2 (version) + 1 (address_size) + 1 (segment_selector_size) = 4
+      Length = 4 + (AddrSize + TableEntry.SegSelectorSize) *
+                       TableEntry.SegAddrPairs.size();
+
+    writeInitialLength(TableEntry.Format, Length, OS, DI.IsLittleEndian);
+    writeInteger((uint16_t)TableEntry.Version, OS, DI.IsLittleEndian);
+    writeInteger((uint8_t)AddrSize, OS, DI.IsLittleEndian);
+    writeInteger((uint8_t)TableEntry.SegSelectorSize, OS, DI.IsLittleEndian);
+
+    for (const SegAddrPair &Pair : TableEntry.SegAddrPairs) {
+      if (TableEntry.SegSelectorSize != 0)
+        if (Error Err = writeVariableSizedInteger(Pair.Segment,
+                                                  TableEntry.SegSelectorSize,
+                                                  OS, DI.IsLittleEndian))
+          return createStringError(errc::not_supported,
+                                   "unable to write debug_addr segment: %s",
+                                   toString(std::move(Err)).c_str());
+      if (AddrSize != 0)
+        if (Error Err = writeVariableSizedInteger(Pair.Address, AddrSize, OS,
+                                                  DI.IsLittleEndian))
+          return createStringError(errc::not_supported,
+                                   "unable to write debug_addr address: %s",
+                                   toString(std::move(Err)).c_str());
+    }
+  }
+
+  return Error::success();
 }
 
-using EmitFuncType = void (*)(raw_ostream &, const DWARFYAML::Data &);
+using EmitFuncType = Error (*)(raw_ostream &, const DWARFYAML::Data &);
 
-static void
-EmitDebugSectionImpl(const DWARFYAML::Data &DI, EmitFuncType EmitFunc,
+static Error
+emitDebugSectionImpl(const DWARFYAML::Data &DI, EmitFuncType EmitFunc,
                      StringRef Sec,
                      StringMap<std::unique_ptr<MemoryBuffer>> &OutputBuffers) {
   std::string Data;
   raw_string_ostream DebugInfoStream(Data);
-  EmitFunc(DebugInfoStream, DI);
+  if (Error Err = EmitFunc(DebugInfoStream, DI))
+    return Err;
   DebugInfoStream.flush();
   if (!Data.empty())
     OutputBuffers[Sec] = MemoryBuffer::getMemBufferCopy(Data);
+
+  return Error::success();
 }
 
 namespace {
@@ -313,69 +440,84 @@ class DIEFixupVisitor : public DWARFYAML::Visitor {
 public:
   DIEFixupVisitor(DWARFYAML::Data &DI) : DWARFYAML::Visitor(DI){};
 
-private:
-  virtual void onStartCompileUnit(DWARFYAML::Unit &CU) {
+protected:
+  void onStartCompileUnit(DWARFYAML::Unit &CU) override {
     // Size of the unit header, excluding the length field itself.
     Length = CU.Version >= 5 ? 8 : 7;
   }
 
-  virtual void onEndCompileUnit(DWARFYAML::Unit &CU) {
-    CU.Length.setLength(Length);
-  }
+  void onEndCompileUnit(DWARFYAML::Unit &CU) override { CU.Length = Length; }
 
-  virtual void onStartDIE(DWARFYAML::Unit &CU, DWARFYAML::Entry &DIE) {
+  void onStartDIE(DWARFYAML::Unit &CU, DWARFYAML::Entry &DIE) override {
     Length += getULEB128Size(DIE.AbbrCode);
   }
 
-  virtual void onValue(const uint8_t U) { Length += 1; }
-  virtual void onValue(const uint16_t U) { Length += 2; }
-  virtual void onValue(const uint32_t U) { Length += 4; }
-  virtual void onValue(const uint64_t U, const bool LEB = false) {
+  void onValue(const uint8_t U) override { Length += 1; }
+  void onValue(const uint16_t U) override { Length += 2; }
+  void onValue(const uint32_t U) override { Length += 4; }
+  void onValue(const uint64_t U, const bool LEB = false) override {
     if (LEB)
       Length += getULEB128Size(U);
     else
       Length += 8;
   }
-  virtual void onValue(const int64_t S, const bool LEB = false) {
+  void onValue(const int64_t S, const bool LEB = false) override {
     if (LEB)
       Length += getSLEB128Size(S);
     else
       Length += 8;
   }
-  virtual void onValue(const StringRef String) { Length += String.size() + 1; }
+  void onValue(const StringRef String) override { Length += String.size() + 1; }
 
-  virtual void onValue(const MemoryBufferRef MBR) {
+  void onValue(const MemoryBufferRef MBR) override {
     Length += MBR.getBufferSize();
   }
 };
 } // namespace
 
 Expected<StringMap<std::unique_ptr<MemoryBuffer>>>
-DWARFYAML::EmitDebugSections(StringRef YAMLString, bool ApplyFixups,
+DWARFYAML::emitDebugSections(StringRef YAMLString, bool ApplyFixups,
                              bool IsLittleEndian) {
-  yaml::Input YIn(YAMLString);
+  auto CollectDiagnostic = [](const SMDiagnostic &Diag, void *DiagContext) {
+    *static_cast<SMDiagnostic *>(DiagContext) = Diag;
+  };
+
+  SMDiagnostic GeneratedDiag;
+  yaml::Input YIn(YAMLString, /*Ctxt=*/nullptr, CollectDiagnostic,
+                  &GeneratedDiag);
 
   DWARFYAML::Data DI;
   DI.IsLittleEndian = IsLittleEndian;
   YIn >> DI;
   if (YIn.error())
-    return errorCodeToError(YIn.error());
+    return createStringError(YIn.error(), GeneratedDiag.getMessage());
 
   if (ApplyFixups) {
     DIEFixupVisitor DIFixer(DI);
-    DIFixer.traverseDebugInfo();
+    if (Error Err = DIFixer.traverseDebugInfo())
+      return std::move(Err);
   }
 
   StringMap<std::unique_ptr<MemoryBuffer>> DebugSections;
-  EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugInfo, "debug_info",
-                       DebugSections);
-  EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugLine, "debug_line",
-                       DebugSections);
-  EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugStr, "debug_str",
-                       DebugSections);
-  EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugAbbrev, "debug_abbrev",
-                       DebugSections);
-  EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugAranges, "debug_aranges",
-                       DebugSections);
+  Error Err = emitDebugSectionImpl(DI, &DWARFYAML::emitDebugInfo, "debug_info",
+                                   DebugSections);
+  Err = joinErrors(std::move(Err),
+                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugLine,
+                                        "debug_line", DebugSections));
+  Err = joinErrors(std::move(Err),
+                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugStr,
+                                        "debug_str", DebugSections));
+  Err = joinErrors(std::move(Err),
+                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugAbbrev,
+                                        "debug_abbrev", DebugSections));
+  Err = joinErrors(std::move(Err),
+                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugAranges,
+                                        "debug_aranges", DebugSections));
+  Err = joinErrors(std::move(Err),
+                   emitDebugSectionImpl(DI, &DWARFYAML::emitDebugRanges,
+                                        "debug_ranges", DebugSections));
+
+  if (Err)
+    return std::move(Err);
   return std::move(DebugSections);
 }
diff --git a/llvm/lib/ObjectYAML/DWARFVisitor.cpp b/llvm/lib/ObjectYAML/DWARFVisitor.cpp
index ecb5967ac532d..a2dd37b5fe324 100644
--- a/llvm/lib/ObjectYAML/DWARFVisitor.cpp
+++ b/llvm/lib/ObjectYAML/DWARFVisitor.cpp
@@ -9,7 +9,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "DWARFVisitor.h"
+#include "llvm/BinaryFormat/Dwarf.h"
 #include "llvm/ObjectYAML/DWARFYAML.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
 
 using namespace llvm;
 
@@ -34,7 +37,7 @@ void DWARFYAML::VisitorImpl<T>::onVariableSizeValue(uint64_t U, unsigned Size) {
 }
 
 static unsigned getOffsetSize(const DWARFYAML::Unit &Unit) {
-  return Unit.Length.isDWARF64() ? 8 : 4;
+  return Unit.Format == dwarf::DWARF64 ? 8 : 4;
 }
 
 static unsigned getRefSize(const DWARFYAML::Unit &Unit) {
@@ -43,16 +46,24 @@ static unsigned getRefSize(const DWARFYAML::Unit &Unit) {
   return getOffsetSize(Unit);
 }
 
-template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
+template <typename T> Error DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
   for (auto &Unit : DebugInfo.CompileUnits) {
     onStartCompileUnit(Unit);
-    auto FirstAbbrevCode = Unit.Entries[0].AbbrCode;
+    if (Unit.Entries.empty())
+      continue;
 
     for (auto &Entry : Unit.Entries) {
       onStartDIE(Unit, Entry);
-      if (Entry.AbbrCode == 0u)
+      uint32_t AbbrCode = Entry.AbbrCode;
+      if (AbbrCode == 0 || Entry.Values.empty())
         continue;
-      auto &Abbrev = DebugInfo.AbbrevDecls[Entry.AbbrCode - FirstAbbrevCode];
+
+      if (AbbrCode > DebugInfo.AbbrevDecls.size())
+        return createStringError(
+            errc::invalid_argument,
+            "abbrev code must be less than or equal to the number of "
+            "entries in abbreviation table");
+      const DWARFYAML::Abbrev &Abbrev = DebugInfo.AbbrevDecls[AbbrCode - 1];
       auto FormVal = Entry.Values.begin();
       auto AbbrForm = Abbrev.Attributes.begin();
       for (;
@@ -105,6 +116,12 @@ template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
                                 ""));
             break;
           }
+          case dwarf::DW_FORM_strx:
+          case dwarf::DW_FORM_addrx:
+          case dwarf::DW_FORM_rnglistx:
+          case dwarf::DW_FORM_loclistx:
+            onValue((uint64_t)FormVal->Value, /*LEB=*/true);
+            break;
           case dwarf::DW_FORM_data1:
           case dwarf::DW_FORM_ref1:
           case dwarf::DW_FORM_flag:
@@ -170,6 +187,8 @@ template <typename T> void DWARFYAML::VisitorImpl<T>::traverseDebugInfo() {
     }
     onEndCompileUnit(Unit);
   }
+
+  return Error::success();
 }
 
 // Explicitly instantiate the two template expansions.
diff --git a/llvm/lib/ObjectYAML/DWARFVisitor.h b/llvm/lib/ObjectYAML/DWARFVisitor.h
index 50e88aa7a26bf..3b2c4303c7f7f 100644
--- a/llvm/lib/ObjectYAML/DWARFVisitor.h
+++ b/llvm/lib/ObjectYAML/DWARFVisitor.h
@@ -16,6 +16,7 @@
 #include "llvm/Support/MemoryBuffer.h"
 
 namespace llvm {
+class Error;
 
 namespace DWARFYAML {
 
@@ -68,7 +69,7 @@ public:
 
   virtual ~VisitorImpl() {}
 
-  void traverseDebugInfo();
+  Error traverseDebugInfo();
 
 private:
   void onVariableSizeValue(uint64_t U, unsigned Size);
diff --git a/llvm/lib/ObjectYAML/DWARFYAML.cpp b/llvm/lib/ObjectYAML/DWARFYAML.cpp
index bb3b1422eb62d..bedf31dc8179f 100644
--- a/llvm/lib/ObjectYAML/DWARFYAML.cpp
+++ b/llvm/lib/ObjectYAML/DWARFYAML.cpp
@@ -12,38 +12,69 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ObjectYAML/DWARFYAML.h"
+#include "llvm/BinaryFormat/Dwarf.h"
 
 namespace llvm {
 
 bool DWARFYAML::Data::isEmpty() const {
-  return 0 == DebugStrings.size() + AbbrevDecls.size();
+  return DebugStrings.empty() && AbbrevDecls.empty() && ARanges.empty() &&
+         DebugRanges.empty() && !PubNames && !PubTypes && !GNUPubNames &&
+         !GNUPubTypes && CompileUnits.empty() && DebugLines.empty();
+}
+
+SetVector<StringRef> DWARFYAML::Data::getUsedSectionNames() const {
+  SetVector<StringRef> SecNames;
+  if (!DebugStrings.empty())
+    SecNames.insert("debug_str");
+  if (!ARanges.empty())
+    SecNames.insert("debug_aranges");
+  if (!DebugRanges.empty())
+    SecNames.insert("debug_ranges");
+  if (!DebugLines.empty())
+    SecNames.insert("debug_line");
+  if (!DebugAddr.empty())
+    SecNames.insert("debug_addr");
+  if (!AbbrevDecls.empty())
+    SecNames.insert("debug_abbrev");
+  if (!CompileUnits.empty())
+    SecNames.insert("debug_info");
+  if (PubNames)
+    SecNames.insert("debug_pubnames");
+  if (PubTypes)
+    SecNames.insert("debug_pubtypes");
+  if (GNUPubNames)
+    SecNames.insert("debug_gnu_pubnames");
+  if (GNUPubTypes)
+    SecNames.insert("debug_gnu_pubtypes");
+  return SecNames;
 }
 
 namespace yaml {
 
 void MappingTraits<DWARFYAML::Data>::mapping(IO &IO, DWARFYAML::Data &DWARF) {
-  auto oldContext = IO.getContext();
-  IO.setContext(&DWARF);
+  void *OldContext = IO.getContext();
+  DWARFYAML::DWARFContext DWARFCtx;
+  IO.setContext(&DWARFCtx);
   IO.mapOptional("debug_str", DWARF.DebugStrings);
   IO.mapOptional("debug_abbrev", DWARF.AbbrevDecls);
   if (!DWARF.ARanges.empty() || !IO.outputting())
     IO.mapOptional("debug_aranges", DWARF.ARanges);
-  if (!DWARF.PubNames.Entries.empty() || !IO.outputting())
-    IO.mapOptional("debug_pubnames", DWARF.PubNames);
-  if (!DWARF.PubTypes.Entries.empty() || !IO.outputting())
-    IO.mapOptional("debug_pubtypes", DWARF.PubTypes);
-  if (!DWARF.GNUPubNames.Entries.empty() || !IO.outputting())
-    IO.mapOptional("debug_gnu_pubnames", DWARF.GNUPubNames);
-  if (!DWARF.GNUPubTypes.Entries.empty() || !IO.outputting())
-    IO.mapOptional("debug_gnu_pubtypes", DWARF.GNUPubTypes);
+  if (!DWARF.DebugRanges.empty() || !IO.outputting())
+    IO.mapOptional("debug_ranges", DWARF.DebugRanges);
+  IO.mapOptional("debug_pubnames", DWARF.PubNames);
+  IO.mapOptional("debug_pubtypes", DWARF.PubTypes);
+  DWARFCtx.IsGNUPubSec = true;
+  IO.mapOptional("debug_gnu_pubnames", DWARF.GNUPubNames);
+  IO.mapOptional("debug_gnu_pubtypes", DWARF.GNUPubTypes);
   IO.mapOptional("debug_info", DWARF.CompileUnits);
   IO.mapOptional("debug_line", DWARF.DebugLines);
-  IO.setContext(&oldContext);
+  IO.mapOptional("debug_addr", DWARF.DebugAddr);
+  IO.setContext(OldContext);
 }
 
 void MappingTraits<DWARFYAML::Abbrev>::mapping(IO &IO,
                                                DWARFYAML::Abbrev &Abbrev) {
-  IO.mapRequired("Code", Abbrev.Code);
+  IO.mapOptional("Code", Abbrev.Code);
   IO.mapRequired("Tag", Abbrev.Tag);
   IO.mapRequired("Children", Abbrev.Children);
   IO.mapRequired("Attributes", Abbrev.Attributes);
@@ -64,38 +95,48 @@ void MappingTraits<DWARFYAML::ARangeDescriptor>::mapping(
 }
 
 void MappingTraits<DWARFYAML::ARange>::mapping(IO &IO,
-                                               DWARFYAML::ARange &Range) {
-  IO.mapRequired("Length", Range.Length);
-  IO.mapRequired("Version", Range.Version);
-  IO.mapRequired("CuOffset", Range.CuOffset);
-  IO.mapRequired("AddrSize", Range.AddrSize);
-  IO.mapRequired("SegSize", Range.SegSize);
-  IO.mapRequired("Descriptors", Range.Descriptors);
+                                               DWARFYAML::ARange &ARange) {
+  IO.mapOptional("Format", ARange.Format, dwarf::DWARF32);
+  IO.mapRequired("Length", ARange.Length);
+  IO.mapRequired("Version", ARange.Version);
+  IO.mapRequired("CuOffset", ARange.CuOffset);
+  IO.mapRequired("AddrSize", ARange.AddrSize);
+  IO.mapRequired("SegSize", ARange.SegSize);
+  IO.mapRequired("Descriptors", ARange.Descriptors);
+}
+
+void MappingTraits<DWARFYAML::RangeEntry>::mapping(
+    IO &IO, DWARFYAML::RangeEntry &Descriptor) {
+  IO.mapRequired("LowOffset", Descriptor.LowOffset);
+  IO.mapRequired("HighOffset", Descriptor.HighOffset);
+}
+
+void MappingTraits<DWARFYAML::Ranges>::mapping(IO &IO,
+                                               DWARFYAML::Ranges &DebugRanges) {
+  IO.mapOptional("Offset", DebugRanges.Offset);
+  IO.mapOptional("AddrSize", DebugRanges.AddrSize);
+  IO.mapRequired("Entries", DebugRanges.Entries);
 }
 
 void MappingTraits<DWARFYAML::PubEntry>::mapping(IO &IO,
                                                  DWARFYAML::PubEntry &Entry) {
   IO.mapRequired("DieOffset", Entry.DieOffset);
-  if (reinterpret_cast<DWARFYAML::PubSection *>(IO.getContext())->IsGNUStyle)
+  if (static_cast<DWARFYAML::DWARFContext *>(IO.getContext())->IsGNUPubSec)
     IO.mapRequired("Descriptor", Entry.Descriptor);
   IO.mapRequired("Name", Entry.Name);
 }
 
 void MappingTraits<DWARFYAML::PubSection>::mapping(
     IO &IO, DWARFYAML::PubSection &Section) {
-  auto OldContext = IO.getContext();
-  IO.setContext(&Section);
-
   IO.mapRequired("Length", Section.Length);
   IO.mapRequired("Version", Section.Version);
   IO.mapRequired("UnitOffset", Section.UnitOffset);
   IO.mapRequired("UnitSize", Section.UnitSize);
   IO.mapRequired("Entries", Section.Entries);
-
-  IO.setContext(OldContext);
 }
 
 void MappingTraits<DWARFYAML::Unit>::mapping(IO &IO, DWARFYAML::Unit &Unit) {
+  IO.mapOptional("Format", Unit.Format, dwarf::DWARF32);
   IO.mapRequired("Length", Unit.Length);
   IO.mapRequired("Version", Unit.Version);
   if (Unit.Version >= 5)
@@ -147,6 +188,7 @@ void MappingTraits<DWARFYAML::LineTableOpcode>::mapping(
 
 void MappingTraits<DWARFYAML::LineTable>::mapping(
     IO &IO, DWARFYAML::LineTable &LineTable) {
+  IO.mapOptional("Format", LineTable.Format, dwarf::DWARF32);
   IO.mapRequired("Length", LineTable.Length);
   IO.mapRequired("Version", LineTable.Version);
   IO.mapRequired("PrologueLength", LineTable.PrologueLength);
@@ -163,6 +205,22 @@ void MappingTraits<DWARFYAML::LineTable>::mapping(
   IO.mapRequired("Opcodes", LineTable.Opcodes);
 }
 
+void MappingTraits<DWARFYAML::SegAddrPair>::mapping(
+    IO &IO, DWARFYAML::SegAddrPair &SegAddrPair) {
+  IO.mapOptional("Segment", SegAddrPair.Segment, 0);
+  IO.mapOptional("Address", SegAddrPair.Address, 0);
+}
+
+void MappingTraits<DWARFYAML::AddrTableEntry>::mapping(
+    IO &IO, DWARFYAML::AddrTableEntry &AddrTable) {
+  IO.mapOptional("Format", AddrTable.Format, dwarf::DWARF32);
+  IO.mapOptional("Length", AddrTable.Length);
+  IO.mapRequired("Version", AddrTable.Version);
+  IO.mapOptional("AddressSize", AddrTable.AddrSize);
+  IO.mapOptional("SegmentSelectorSize", AddrTable.SegSelectorSize, 0);
+  IO.mapOptional("Entries", AddrTable.SegAddrPairs);
+}
+
 void MappingTraits<DWARFYAML::InitialLength>::mapping(
     IO &IO, DWARFYAML::InitialLength &InitialLength) {
   IO.mapRequired("TotalLength", InitialLength.TotalLength);
diff --git a/llvm/lib/ObjectYAML/ELFEmitter.cpp b/llvm/lib/ObjectYAML/ELFEmitter.cpp
index ee7d5f616a737..f9f2f128e2e82 100644
--- a/llvm/lib/ObjectYAML/ELFEmitter.cpp
+++ b/llvm/lib/ObjectYAML/ELFEmitter.cpp
@@ -13,13 +13,18 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/StringSet.h"
 #include "llvm/BinaryFormat/ELF.h"
 #include "llvm/MC/StringTableBuilder.h"
 #include "llvm/Object/ELFObjectFile.h"
+#include "llvm/ObjectYAML/DWARFEmitter.h"
+#include "llvm/ObjectYAML/DWARFYAML.h"
 #include "llvm/ObjectYAML/ELFYAML.h"
 #include "llvm/ObjectYAML/yaml2obj.h"
 #include "llvm/Support/EndianStream.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/WithColor.h"
@@ -31,33 +36,94 @@ using namespace llvm;
 // This class is used to build up a contiguous binary blob while keeping
 // track of an offset in the output (which notionally begins at
 // `InitialOffset`).
+// The blob might be limited to an arbitrary size. All attempts to write data
+// are ignored and the error condition is remembered once the limit is reached.
+// Such an approach allows us to simplify the code by delaying error reporting
+// and doing it at a convenient time.
 namespace {
 class ContiguousBlobAccumulator {
   const uint64_t InitialOffset;
+  const uint64_t MaxSize;
+
   SmallVector<char, 128> Buf;
   raw_svector_ostream OS;
+  Error ReachedLimitErr = Error::success();
+
+  bool checkLimit(uint64_t Size) {
+    if (!ReachedLimitErr && getOffset() + Size <= MaxSize)
+      return true;
+    if (!ReachedLimitErr)
+      ReachedLimitErr = createStringError(errc::invalid_argument,
+                                          "reached the output size limit");
+    return false;
+  }
 
 public:
-  ContiguousBlobAccumulator(uint64_t InitialOffset_)
-      : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
+  ContiguousBlobAccumulator(uint64_t BaseOffset, uint64_t SizeLimit)
+      : InitialOffset(BaseOffset), MaxSize(SizeLimit), OS(Buf) {}
+
+  uint64_t tell() const { return OS.tell(); }
+  uint64_t getOffset() const { return InitialOffset + OS.tell(); }
+  void writeBlobToStream(raw_ostream &Out) const { Out << OS.str(); }
 
-  template <class Integer>
-  raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
-    Offset = padToAlignment(Align);
-    return OS;
+  Error takeLimitError() {
+    // Request to write 0 bytes to check we did not reach the limit.
+    checkLimit(0);
+    return std::move(ReachedLimitErr);
   }
 
   /// \returns The new offset.
   uint64_t padToAlignment(unsigned Align) {
-    if (Align == 0)
-      Align = 1;
-    uint64_t CurrentOffset = InitialOffset + OS.tell();
-    uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
-    OS.write_zeros(AlignedOffset - CurrentOffset);
-    return AlignedOffset; // == CurrentOffset;
+    uint64_t CurrentOffset = getOffset();
+    if (ReachedLimitErr)
+      return CurrentOffset;
+
+    uint64_t AlignedOffset = alignTo(CurrentOffset, Align == 0 ? 1 : Align);
+    uint64_t PaddingSize = AlignedOffset - CurrentOffset;
+    if (!checkLimit(PaddingSize))
+      return CurrentOffset;
+
+    writeZeros(PaddingSize);
+    return AlignedOffset;
+  }
+
+  raw_ostream *getRawOS(uint64_t Size) {
+    if (checkLimit(Size))
+      return &OS;
+    return nullptr;
+  }
+
+  void writeAsBinary(const yaml::BinaryRef &Bin, uint64_t N = UINT64_MAX) {
+    if (!checkLimit(Bin.binary_size()))
+      return;
+    Bin.writeAsBinary(OS, N);
+  }
+
+  void writeZeros(uint64_t Num) {
+    if (checkLimit(Num))
+      OS.write_zeros(Num);
+  }
+
+  void write(const char *Ptr, size_t Size) {
+    if (checkLimit(Size))
+      OS.write(Ptr, Size);
+  }
+
+  void write(unsigned char C) {
+    if (checkLimit(1))
+      OS.write(C);
+  }
+
+  unsigned writeULEB128(uint64_t Val) {
+    if (!checkLimit(sizeof(uint64_t)))
+      return 0;
+    return encodeULEB128(Val, OS);
   }
 
-  void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
+  template <typename T> void write(T Val, support::endianness E) {
+    if (checkLimit(sizeof(T)))
+      support::endian::write<T>(OS, Val, E);
+  }
 };
 
 // Used to keep track of section and symbol names, so that in the YAML file
@@ -128,9 +194,13 @@ template <class ELFT> class ELFState {
   NameToIdxMap DynSymN2I;
   ELFYAML::Object &Doc;
 
+  StringSet<> ExcludedSectionHeaders;
+
+  uint64_t LocationCounter = 0;
   bool HasError = false;
   yaml::ErrorHandler ErrHandler;
   void reportError(const Twine &Msg);
+  void reportError(Error Err);
 
   std::vector<Elf_Sym> toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
                                     const StringTableBuilder &Strtab);
@@ -151,6 +221,9 @@ template <class ELFT> class ELFState {
                                StringTableBuilder &STB,
                                ContiguousBlobAccumulator &CBA,
                                ELFYAML::Section *YAMLSec);
+  void initDWARFSectionHeader(Elf_Shdr &SHeader, StringRef Name,
+                              ContiguousBlobAccumulator &CBA,
+                              ELFYAML::Section *YAMLSec);
   void setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
                               std::vector<Elf_Shdr> &SHeaders);
 
@@ -159,7 +232,10 @@ template <class ELFT> class ELFState {
                    ArrayRef<typename ELFT::Shdr> SHeaders);
 
   void finalizeStrings();
-  void writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS);
+  void writeELFHeader(raw_ostream &OS, uint64_t SHOff);
+  void writeSectionContent(Elf_Shdr &SHeader,
+                           const ELFYAML::NoBitsSection &Section,
+                           ContiguousBlobAccumulator &CBA);
   void writeSectionContent(Elf_Shdr &SHeader,
                            const ELFYAML::RawContentSection &Section,
                            ContiguousBlobAccumulator &CBA);
@@ -210,14 +286,27 @@ template <class ELFT> class ELFState {
   void writeSectionContent(Elf_Shdr &SHeader,
                            const ELFYAML::DependentLibrariesSection &Section,
                            ContiguousBlobAccumulator &CBA);
+  void writeSectionContent(Elf_Shdr &SHeader,
+                           const ELFYAML::CallGraphProfileSection &Section,
+                           ContiguousBlobAccumulator &CBA);
 
   void writeFill(ELFYAML::Fill &Fill, ContiguousBlobAccumulator &CBA);
 
   ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH);
 
+  void assignSectionAddress(Elf_Shdr &SHeader, ELFYAML::Section *YAMLSec);
+
+  DenseMap<StringRef, size_t> buildSectionHeaderReorderMap();
+
+  BumpPtrAllocator StringAlloc;
+  uint64_t alignToOffset(ContiguousBlobAccumulator &CBA, uint64_t Align,
+                         llvm::Optional<llvm::yaml::Hex64> Offset);
+
+  uint64_t getSectionNameOffset(StringRef Name);
+
 public:
   static bool writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
-                       yaml::ErrorHandler EH);
+                       yaml::ErrorHandler EH, uint64_t MaxSize);
 };
 } // end anonymous namespace
 
@@ -235,11 +324,6 @@ template <class ELFT>
 ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
     : Doc(D), ErrHandler(EH) {
   std::vector<ELFYAML::Section *> Sections = Doc.getSections();
-  StringSet<> DocSections;
-  for (const ELFYAML::Section *Sec : Sections)
-    if (!Sec->Name.empty())
-      DocSections.insert(Sec->Name);
-
   // Insert SHT_NULL section implicitly when it is not defined in YAML.
   if (Sections.empty() || Sections.front()->Type != ELF::SHT_NULL)
     Doc.Chunks.insert(
@@ -247,14 +331,36 @@ ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
         std::make_unique<ELFYAML::Section>(
             ELFYAML::Chunk::ChunkKind::RawContent, /*IsImplicit=*/true));
 
+  // We add a technical suffix for each unnamed section/fill. It does not affect
+  // the output, but allows us to map them by name in the code and report better
+  // error messages.
+  StringSet<> DocSections;
+  for (size_t I = 0; I < Doc.Chunks.size(); ++I) {
+    const std::unique_ptr<ELFYAML::Chunk> &C = Doc.Chunks[I];
+    if (C->Name.empty()) {
+      std::string NewName = ELFYAML::appendUniqueSuffix(
+          /*Name=*/"", "index " + Twine(I));
+      C->Name = StringRef(NewName).copy(StringAlloc);
+      assert(ELFYAML::dropUniqueSuffix(C->Name).empty());
+    }
+
+    if (!DocSections.insert(C->Name).second)
+      reportError("repeated section/fill name: '" + C->Name +
+                  "' at YAML section/fill number " + Twine(I));
+  }
+
   std::vector<StringRef> ImplicitSections;
+  if (Doc.DynamicSymbols)
+    ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
   if (Doc.Symbols)
     ImplicitSections.push_back(".symtab");
+  if (Doc.DWARF)
+    for (StringRef DebugSecName : Doc.DWARF->getUsedSectionNames()) {
+      std::string SecName = ("." + DebugSecName).str();
+      ImplicitSections.push_back(StringRef(SecName).copy(StringAlloc));
+    }
   ImplicitSections.insert(ImplicitSections.end(), {".strtab", ".shstrtab"});
 
-  if (Doc.DynamicSymbols)
-    ImplicitSections.insert(ImplicitSections.end(), {".dynsym", ".dynstr"});
-
   // Insert placeholders for implicit sections that are not
   // defined explicitly in YAML.
   for (StringRef SecName : ImplicitSections) {
@@ -269,7 +375,7 @@ ELFState<ELFT>::ELFState(ELFYAML::Object &D, yaml::ErrorHandler EH)
 }
 
 template <class ELFT>
-void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream &OS) {
+void ELFState<ELFT>::writeELFHeader(raw_ostream &OS, uint64_t SHOff) {
   using namespace llvm::ELF;
 
   Elf_Ehdr Header;
@@ -287,55 +393,134 @@ void ELFState<ELFT>::writeELFHeader(ContiguousBlobAccumulator &CBA, raw_ostream
   Header.e_machine = Doc.Header.Machine;
   Header.e_version = EV_CURRENT;
   Header.e_entry = Doc.Header.Entry;
-  Header.e_phoff = Doc.ProgramHeaders.size() ? sizeof(Header) : 0;
   Header.e_flags = Doc.Header.Flags;
   Header.e_ehsize = sizeof(Elf_Ehdr);
-  Header.e_phentsize = Doc.ProgramHeaders.size() ? sizeof(Elf_Phdr) : 0;
-  Header.e_phnum = Doc.ProgramHeaders.size();
-
-  Header.e_shentsize =
-      Doc.Header.SHEntSize ? (uint16_t)*Doc.Header.SHEntSize : sizeof(Elf_Shdr);
-  // Immediately following the ELF header and program headers.
-  // Align the start of the section header and write the ELF header.
-  uint64_t SHOff;
-  CBA.getOSAndAlignedOffset(SHOff, sizeof(typename ELFT::uint));
-  Header.e_shoff =
-      Doc.Header.SHOff ? typename ELFT::uint(*Doc.Header.SHOff) : SHOff;
-  Header.e_shnum =
-      Doc.Header.SHNum ? (uint16_t)*Doc.Header.SHNum : Doc.getSections().size();
-  Header.e_shstrndx = Doc.Header.SHStrNdx ? (uint16_t)*Doc.Header.SHStrNdx
-                                          : SN2I.get(".shstrtab");
+
+  if (Doc.Header.EPhOff)
+    Header.e_phoff = *Doc.Header.EPhOff;
+  else if (!Doc.ProgramHeaders.empty())
+    Header.e_phoff = sizeof(Header);
+  else
+    Header.e_phoff = 0;
+
+  if (Doc.Header.EPhEntSize)
+    Header.e_phentsize = *Doc.Header.EPhEntSize;
+  else if (!Doc.ProgramHeaders.empty())
+    Header.e_phentsize = sizeof(Elf_Phdr);
+  else
+    Header.e_phentsize = 0;
+
+  if (Doc.Header.EPhNum)
+    Header.e_phnum = *Doc.Header.EPhNum;
+  else if (!Doc.ProgramHeaders.empty())
+    Header.e_phnum = Doc.ProgramHeaders.size();
+  else
+    Header.e_phnum = 0;
+
+  Header.e_shentsize = Doc.Header.EShEntSize ? (uint16_t)*Doc.Header.EShEntSize
+                                             : sizeof(Elf_Shdr);
+
+  const bool NoShdrs =
+      Doc.SectionHeaders && Doc.SectionHeaders->NoHeaders.getValueOr(false);
+
+  if (Doc.Header.EShOff)
+    Header.e_shoff = *Doc.Header.EShOff;
+  else if (NoShdrs)
+    Header.e_shoff = 0;
+  else
+    Header.e_shoff = SHOff;
+
+  if (Doc.Header.EShNum)
+    Header.e_shnum = *Doc.Header.EShNum;
+  else if (!Doc.SectionHeaders)
+    Header.e_shnum = Doc.getSections().size();
+  else if (NoShdrs)
+    Header.e_shnum = 0;
+  else
+    Header.e_shnum =
+        (Doc.SectionHeaders->Sections ? Doc.SectionHeaders->Sections->size()
+                                      : 0) +
+        /*Null section*/ 1;
+
+  if (Doc.Header.EShStrNdx)
+    Header.e_shstrndx = *Doc.Header.EShStrNdx;
+  else if (NoShdrs || ExcludedSectionHeaders.count(".shstrtab"))
+    Header.e_shstrndx = 0;
+  else
+    Header.e_shstrndx = SN2I.get(".shstrtab");
 
   OS.write((const char *)&Header, sizeof(Header));
 }
 
 template <class ELFT>
 void ELFState<ELFT>::initProgramHeaders(std::vector<Elf_Phdr> &PHeaders) {
-  for (const auto &YamlPhdr : Doc.ProgramHeaders) {
+  DenseMap<StringRef, ELFYAML::Fill *> NameToFill;
+  for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks)
+    if (auto S = dyn_cast<ELFYAML::Fill>(D.get()))
+      NameToFill[S->Name] = S;
+
+  std::vector<ELFYAML::Section *> Sections = Doc.getSections();
+  for (ELFYAML::ProgramHeader &YamlPhdr : Doc.ProgramHeaders) {
     Elf_Phdr Phdr;
+    zero(Phdr);
     Phdr.p_type = YamlPhdr.Type;
     Phdr.p_flags = YamlPhdr.Flags;
     Phdr.p_vaddr = YamlPhdr.VAddr;
     Phdr.p_paddr = YamlPhdr.PAddr;
     PHeaders.push_back(Phdr);
+
+    // Map Sections list to corresponding chunks.
+    for (const ELFYAML::SectionName &SecName : YamlPhdr.Sections) {
+      if (ELFYAML::Fill *Fill = NameToFill.lookup(SecName.Section)) {
+        YamlPhdr.Chunks.push_back(Fill);
+        continue;
+      }
+
+      unsigned Index;
+      if (SN2I.lookup(SecName.Section, Index)) {
+        YamlPhdr.Chunks.push_back(Sections[Index]);
+        continue;
+      }
+
+      reportError("unknown section or fill referenced: '" + SecName.Section +
+                  "' by program header");
+    }
   }
 }
 
 template <class ELFT>
 unsigned ELFState<ELFT>::toSectionIndex(StringRef S, StringRef LocSec,
                                         StringRef LocSym) {
+  assert(LocSec.empty() || LocSym.empty());
+
   unsigned Index;
-  if (SN2I.lookup(S, Index) || to_integer(S, Index))
+  if (!SN2I.lookup(S, Index) && !to_integer(S, Index)) {
+    if (!LocSym.empty())
+      reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
+                  LocSym + "'");
+    else
+      reportError("unknown section referenced: '" + S + "' by YAML section '" +
+                  LocSec + "'");
+    return 0;
+  }
+
+  if (!Doc.SectionHeaders || (Doc.SectionHeaders->NoHeaders &&
+                              !Doc.SectionHeaders->NoHeaders.getValue()))
     return Index;
 
-  assert(LocSec.empty() || LocSym.empty());
-  if (!LocSym.empty())
-    reportError("unknown section referenced: '" + S + "' by YAML symbol '" +
-                LocSym + "'");
-  else
-    reportError("unknown section referenced: '" + S + "' by YAML section '" +
-                LocSec + "'");
-  return 0;
+  assert(!Doc.SectionHeaders->NoHeaders.getValueOr(false) ||
+         !Doc.SectionHeaders->Sections);
+  size_t FirstExcluded =
+      Doc.SectionHeaders->Sections ? Doc.SectionHeaders->Sections->size() : 0;
+  if (Index >= FirstExcluded) {
+    if (LocSym.empty())
+      reportError("unable to link '" + LocSec + "' to excluded section '" + S +
+                  "'");
+    else
+      reportError("excluded section referenced: '" + S + "'  by symbol '" +
+                  LocSym + "'");
+  }
+  return Index;
 }
 
 template <class ELFT>
@@ -385,19 +570,53 @@ bool ELFState<ELFT>::initImplicitHeader(ContiguousBlobAccumulator &CBA,
     initSymtabSectionHeader(Header, SymtabType::Dynamic, CBA, YAMLSec);
   else if (SecName == ".dynstr")
     initStrtabSectionHeader(Header, SecName, DotDynstr, CBA, YAMLSec);
-  else
+  else if (SecName.startswith(".debug_")) {
+    // If a ".debug_*" section's type is a preserved one, e.g., SHT_DYNAMIC, we
+    // will not treat it as a debug section.
+    if (YAMLSec && !isa<ELFYAML::RawContentSection>(YAMLSec))
+      return false;
+    initDWARFSectionHeader(Header, SecName, CBA, YAMLSec);
+  } else
     return false;
 
+  LocationCounter += Header.sh_size;
+
   // Override section fields if requested.
   overrideFields<ELFT>(YAMLSec, Header);
   return true;
 }
 
+constexpr char SuffixStart = '(';
+constexpr char SuffixEnd = ')';
+
+std::string llvm::ELFYAML::appendUniqueSuffix(StringRef Name,
+                                              const Twine &Msg) {
+  // Do not add a space when a Name is empty.
+  std::string Ret = Name.empty() ? "" : Name.str() + ' ';
+  return Ret + (Twine(SuffixStart) + Msg + Twine(SuffixEnd)).str();
+}
+
 StringRef llvm::ELFYAML::dropUniqueSuffix(StringRef S) {
-  size_t SuffixPos = S.rfind(" [");
-  if (SuffixPos == StringRef::npos)
+  if (S.empty() || S.back() != SuffixEnd)
     return S;
-  return S.substr(0, SuffixPos);
+
+  // A special case for empty names. See appendUniqueSuffix() above.
+  size_t SuffixPos = S.rfind(SuffixStart);
+  if (SuffixPos == 0)
+    return "";
+
+  if (SuffixPos == StringRef::npos || S[SuffixPos - 1] != ' ')
+    return S;
+  return S.substr(0, SuffixPos - 1);
+}
+
+template <class ELFT>
+uint64_t ELFState<ELFT>::getSectionNameOffset(StringRef Name) {
+  // If a section is excluded from section headers, we do not save its name in
+  // the string table.
+  if (ExcludedSectionHeaders.count(Name))
+    return 0;
+  return DotShStrtab.getOffset(Name);
 }
 
 template <class ELFT>
@@ -407,23 +626,24 @@ void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
   // valid SHN_UNDEF entry since SHT_NULL == 0.
   SHeaders.resize(Doc.getSections().size());
 
-  size_t SecNdx = -1;
   for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks) {
-    if (auto S = dyn_cast<ELFYAML::Fill>(D.get())) {
+    if (ELFYAML::Fill *S = dyn_cast<ELFYAML::Fill>(D.get())) {
+      S->Offset = alignToOffset(CBA, /*Align=*/1, S->Offset);
       writeFill(*S, CBA);
+      LocationCounter += S->Size;
       continue;
     }
 
-    ++SecNdx;
     ELFYAML::Section *Sec = cast<ELFYAML::Section>(D.get());
-    if (SecNdx == 0 && Sec->IsImplicit)
+    bool IsFirstUndefSection = D == Doc.Chunks.front();
+    if (IsFirstUndefSection && Sec->IsImplicit)
       continue;
 
     // We have a few sections like string or symbol tables that are usually
     // added implicitly to the end. However, if they are explicitly specified
     // in the YAML, we need to write them here. This ensures the file offset
     // remains correct.
-    Elf_Shdr &SHeader = SHeaders[SecNdx];
+    Elf_Shdr &SHeader = SHeaders[SN2I.get(Sec->Name)];
     if (initImplicitHeader(CBA, SHeader, Sec->Name,
                            Sec->IsImplicit ? nullptr : Sec))
       continue;
@@ -432,17 +652,23 @@ void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
                   "implicit sections should already have been handled above.");
 
     SHeader.sh_name =
-        DotShStrtab.getOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
+        getSectionNameOffset(ELFYAML::dropUniqueSuffix(Sec->Name));
     SHeader.sh_type = Sec->Type;
     if (Sec->Flags)
       SHeader.sh_flags = *Sec->Flags;
-    SHeader.sh_addr = Sec->Address;
     SHeader.sh_addralign = Sec->AddressAlign;
 
+    // Set the offset for all sections, except the SHN_UNDEF section with index
+    // 0 when not explicitly requested.
+    if (!IsFirstUndefSection || Sec->Offset)
+      SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign, Sec->Offset);
+
+    assignSectionAddress(SHeader, Sec);
+
     if (!Sec->Link.empty())
       SHeader.sh_link = toSectionIndex(Sec->Link, Sec->Name);
 
-    if (SecNdx == 0) {
+    if (IsFirstUndefSection) {
       if (auto RawSec = dyn_cast<ELFYAML::RawContentSection>(Sec)) {
         // We do not write any content for special SHN_UNDEF section.
         if (RawSec->Size)
@@ -465,11 +691,7 @@ void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
     } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec)) {
       writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec)) {
-      SHeader.sh_entsize = 0;
-      SHeader.sh_size = S->Size;
-      // SHT_NOBITS section does not have content
-      // so just to setup the section offset.
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
+      writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::DynamicSection>(Sec)) {
       writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::SymverSection>(Sec)) {
@@ -492,15 +714,40 @@ void ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
       writeSectionContent(SHeader, *S, CBA);
     } else if (auto S = dyn_cast<ELFYAML::DependentLibrariesSection>(Sec)) {
       writeSectionContent(SHeader, *S, CBA);
+    } else if (auto S = dyn_cast<ELFYAML::CallGraphProfileSection>(Sec)) {
+      writeSectionContent(SHeader, *S, CBA);
     } else {
       llvm_unreachable("Unknown section type");
     }
 
+    LocationCounter += SHeader.sh_size;
+
     // Override section fields if requested.
     overrideFields<ELFT>(Sec, SHeader);
   }
 }
 
+template <class ELFT>
+void ELFState<ELFT>::assignSectionAddress(Elf_Shdr &SHeader,
+                                          ELFYAML::Section *YAMLSec) {
+  if (YAMLSec && YAMLSec->Address) {
+    SHeader.sh_addr = *YAMLSec->Address;
+    LocationCounter = *YAMLSec->Address;
+    return;
+  }
+
+  // sh_addr represents the address in the memory image of a process. Sections
+  // in a relocatable object file or non-allocatable sections do not need
+  // sh_addr assignment.
+  if (Doc.Header.Type.value == ELF::ET_REL ||
+      !(SHeader.sh_flags & ELF::SHF_ALLOC))
+    return;
+
+  LocationCounter =
+      alignTo(LocationCounter, SHeader.sh_addralign ? SHeader.sh_addralign : 1);
+  SHeader.sh_addr = LocationCounter;
+}
+
 static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
   for (size_t I = 0; I < Symbols.size(); ++I)
     if (Symbols[I].Binding.value != ELF::STB_LOCAL)
@@ -508,19 +755,19 @@ static size_t findFirstNonGlobal(ArrayRef<ELFYAML::Symbol> Symbols) {
   return Symbols.size();
 }
 
-static uint64_t writeContent(raw_ostream &OS,
+static uint64_t writeContent(ContiguousBlobAccumulator &CBA,
                              const Optional<yaml::BinaryRef> &Content,
                              const Optional<llvm::yaml::Hex64> &Size) {
   size_t ContentSize = 0;
   if (Content) {
-    Content->writeAsBinary(OS);
+    CBA.writeAsBinary(*Content);
     ContentSize = Content->binary_size();
   }
 
   if (!Size)
     return ContentSize;
 
-  OS.write_zeros(*Size - ContentSize);
+  CBA.writeZeros(*Size - ContentSize);
   return *Size;
 }
 
@@ -538,8 +785,8 @@ ELFState<ELFT>::toELFSymbols(ArrayRef<ELFYAML::Symbol> Symbols,
     // If NameIndex, which contains the name offset, is explicitly specified, we
     // use it. This is useful for preparing broken objects. Otherwise, we add
     // the specified Name to the string table builder to get its offset.
-    if (Sym.NameIndex)
-      Symbol.st_name = *Sym.NameIndex;
+    if (Sym.StName)
+      Symbol.st_name = *Sym.StName;
     else if (!Sym.Name.empty())
       Symbol.st_name = Strtab.getOffset(ELFYAML::dropUniqueSuffix(Sym.Name));
 
@@ -588,7 +835,7 @@ void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
   }
 
   zero(SHeader);
-  SHeader.sh_name = DotShStrtab.getOffset(IsStatic ? ".symtab" : ".dynsym");
+  SHeader.sh_name = getSectionNameOffset(IsStatic ? ".symtab" : ".dynsym");
 
   if (YAMLSec)
     SHeader.sh_type = YAMLSec->Type;
@@ -605,10 +852,13 @@ void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
     // added implicitly and we should be able to leave the Link zeroed if
     // .dynstr is not defined.
     unsigned Link = 0;
-    if (IsStatic)
-      Link = SN2I.get(".strtab");
-    else
-      SN2I.lookup(".dynstr", Link);
+    if (IsStatic) {
+      if (!ExcludedSectionHeaders.count(".strtab"))
+        Link = SN2I.get(".strtab");
+    } else {
+      if (!ExcludedSectionHeaders.count(".dynstr"))
+        SN2I.lookup(".dynstr", Link);
+    }
     SHeader.sh_link = Link;
   }
 
@@ -625,19 +875,21 @@ void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
                            ? (uint64_t)(*YAMLSec->EntSize)
                            : sizeof(Elf_Sym);
   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 8;
-  SHeader.sh_addr = YAMLSec ? (uint64_t)YAMLSec->Address : 0;
 
-  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
+  assignSectionAddress(SHeader, YAMLSec);
+
+  SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign, /*Offset=*/None);
+
   if (RawSec && (RawSec->Content || RawSec->Size)) {
     assert(Symbols.empty());
-    SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
+    SHeader.sh_size = writeContent(CBA, RawSec->Content, RawSec->Size);
     return;
   }
 
   std::vector<Elf_Sym> Syms =
       toELFSymbols(Symbols, IsStatic ? DotStrtab : DotDynstr);
-  writeArrayData(OS, makeArrayRef(Syms));
-  SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
+  SHeader.sh_size = Syms.size() * sizeof(Elf_Sym);
+  CBA.write((const char *)Syms.data(), SHeader.sh_size);
 }
 
 template <class ELFT>
@@ -646,18 +898,20 @@ void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
                                              ContiguousBlobAccumulator &CBA,
                                              ELFYAML::Section *YAMLSec) {
   zero(SHeader);
-  SHeader.sh_name = DotShStrtab.getOffset(Name);
+  SHeader.sh_name = getSectionNameOffset(Name);
   SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_STRTAB;
   SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
 
   ELFYAML::RawContentSection *RawSec =
       dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
 
-  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
+  SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign, /*Offset=*/None);
+
   if (RawSec && (RawSec->Content || RawSec->Size)) {
-    SHeader.sh_size = writeContent(OS, RawSec->Content, RawSec->Size);
+    SHeader.sh_size = writeContent(CBA, RawSec->Content, RawSec->Size);
   } else {
-    STB.write(OS);
+    if (raw_ostream *OS = CBA.getRawOS(STB.getSize()))
+      STB.write(*OS);
     SHeader.sh_size = STB.getSize();
   }
 
@@ -672,10 +926,110 @@ void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
   else if (Name == ".dynstr")
     SHeader.sh_flags = ELF::SHF_ALLOC;
 
-  // If the section is explicitly described in the YAML
-  // then we want to use its section address.
-  if (YAMLSec)
-    SHeader.sh_addr = YAMLSec->Address;
+  assignSectionAddress(SHeader, YAMLSec);
+}
+
+static bool shouldEmitDWARF(DWARFYAML::Data &DWARF, StringRef Name) {
+  SetVector<StringRef> DebugSecNames = DWARF.getUsedSectionNames();
+  return Name.consume_front(".") && DebugSecNames.count(Name);
+}
+
+template <class ELFT>
+Expected<uint64_t> emitDWARF(typename ELFT::Shdr &SHeader, StringRef Name,
+                             const DWARFYAML::Data &DWARF,
+                             ContiguousBlobAccumulator &CBA) {
+  // We are unable to predict the size of debug data, so we request to write 0
+  // bytes. This should always return us an output stream unless CBA is already
+  // in an error state.
+  raw_ostream *OS = CBA.getRawOS(0);
+  if (!OS)
+    return 0;
+
+  uint64_t BeginOffset = CBA.tell();
+  Error Err = Error::success();
+  cantFail(std::move(Err));
+
+  if (Name == ".debug_str")
+    Err = DWARFYAML::emitDebugStr(*OS, DWARF);
+  else if (Name == ".debug_aranges")
+    Err = DWARFYAML::emitDebugAranges(*OS, DWARF);
+  else if (Name == ".debug_ranges")
+    Err = DWARFYAML::emitDebugRanges(*OS, DWARF);
+  else if (Name == ".debug_line")
+    Err = DWARFYAML::emitDebugLine(*OS, DWARF);
+  else if (Name == ".debug_addr")
+    Err = DWARFYAML::emitDebugAddr(*OS, DWARF);
+  else if (Name == ".debug_abbrev")
+    Err = DWARFYAML::emitDebugAbbrev(*OS, DWARF);
+  else if (Name == ".debug_info")
+    Err = DWARFYAML::emitDebugInfo(*OS, DWARF);
+  else if (Name == ".debug_pubnames")
+    Err = DWARFYAML::emitPubSection(*OS, *DWARF.PubNames, DWARF.IsLittleEndian);
+  else if (Name == ".debug_pubtypes")
+    Err = DWARFYAML::emitPubSection(*OS, *DWARF.PubTypes, DWARF.IsLittleEndian);
+  else if (Name == ".debug_gnu_pubnames")
+    Err = DWARFYAML::emitPubSection(*OS, *DWARF.GNUPubNames,
+                                    DWARF.IsLittleEndian, /*IsGNUStyle=*/true);
+  else if (Name == ".debug_gnu_pubtypes")
+    Err = DWARFYAML::emitPubSection(*OS, *DWARF.GNUPubTypes,
+                                    DWARF.IsLittleEndian, /*IsGNUStyle=*/true);
+  else
+    llvm_unreachable("unexpected emitDWARF() call");
+
+  if (Err)
+    return std::move(Err);
+
+  return CBA.tell() - BeginOffset;
+}
+
+template <class ELFT>
+void ELFState<ELFT>::initDWARFSectionHeader(Elf_Shdr &SHeader, StringRef Name,
+                                            ContiguousBlobAccumulator &CBA,
+                                            ELFYAML::Section *YAMLSec) {
+  zero(SHeader);
+  SHeader.sh_name = getSectionNameOffset(ELFYAML::dropUniqueSuffix(Name));
+  SHeader.sh_type = YAMLSec ? YAMLSec->Type : ELF::SHT_PROGBITS;
+  SHeader.sh_addralign = YAMLSec ? (uint64_t)YAMLSec->AddressAlign : 1;
+  SHeader.sh_offset = alignToOffset(CBA, SHeader.sh_addralign,
+                                    YAMLSec ? YAMLSec->Offset : None);
+
+  ELFYAML::RawContentSection *RawSec =
+      dyn_cast_or_null<ELFYAML::RawContentSection>(YAMLSec);
+  if (Doc.DWARF && shouldEmitDWARF(*Doc.DWARF, Name)) {
+    if (RawSec && (RawSec->Content || RawSec->Size))
+      reportError("cannot specify section '" + Name +
+                  "' contents in the 'DWARF' entry and the 'Content' "
+                  "or 'Size' in the 'Sections' entry at the same time");
+    else {
+      if (Expected<uint64_t> ShSizeOrErr =
+              emitDWARF<ELFT>(SHeader, Name, *Doc.DWARF, CBA))
+        SHeader.sh_size = *ShSizeOrErr;
+      else
+        reportError(ShSizeOrErr.takeError());
+    }
+  } else if (RawSec)
+    SHeader.sh_size = writeContent(CBA, RawSec->Content, RawSec->Size);
+  else
+    llvm_unreachable("debug sections can only be initialized via the 'DWARF' "
+                     "entry or a RawContentSection");
+
+  if (YAMLSec && YAMLSec->EntSize)
+    SHeader.sh_entsize = *YAMLSec->EntSize;
+  else if (Name == ".debug_str")
+    SHeader.sh_entsize = 1;
+
+  if (RawSec && RawSec->Info)
+    SHeader.sh_info = *RawSec->Info;
+
+  if (YAMLSec && YAMLSec->Flags)
+    SHeader.sh_flags = *YAMLSec->Flags;
+  else if (Name == ".debug_str")
+    SHeader.sh_flags = ELF::SHF_MERGE | ELF::SHF_STRINGS;
+
+  if (YAMLSec && !YAMLSec->Link.empty())
+    SHeader.sh_link = toSectionIndex(YAMLSec->Link, Name);
+
+  assignSectionAddress(SHeader, YAMLSec);
 }
 
 template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
@@ -683,34 +1037,28 @@ template <class ELFT> void ELFState<ELFT>::reportError(const Twine &Msg) {
   HasError = true;
 }
 
+template <class ELFT> void ELFState<ELFT>::reportError(Error Err) {
+  handleAllErrors(std::move(Err), [&](const ErrorInfoBase &Err) {
+    reportError(Err.message());
+  });
+}
+
 template <class ELFT>
 std::vector<Fragment>
 ELFState<ELFT>::getPhdrFragments(const ELFYAML::ProgramHeader &Phdr,
-                                 ArrayRef<typename ELFT::Shdr> SHeaders) {
-  DenseMap<StringRef, ELFYAML::Fill *> NameToFill;
-  for (const std::unique_ptr<ELFYAML::Chunk> &D : Doc.Chunks)
-    if (auto S = dyn_cast<ELFYAML::Fill>(D.get()))
-      NameToFill[S->Name] = S;
-
+                                 ArrayRef<Elf_Shdr> SHeaders) {
   std::vector<Fragment> Ret;
-  for (const ELFYAML::SectionName &SecName : Phdr.Sections) {
-    unsigned Index;
-    if (SN2I.lookup(SecName.Section, Index)) {
-      const typename ELFT::Shdr &H = SHeaders[Index];
-      Ret.push_back({H.sh_offset, H.sh_size, H.sh_type, H.sh_addralign});
-      continue;
-    }
-
-    if (ELFYAML::Fill *Fill = NameToFill.lookup(SecName.Section)) {
-      Ret.push_back({Fill->ShOffset, Fill->Size, llvm::ELF::SHT_PROGBITS,
+  for (const ELFYAML::Chunk *C : Phdr.Chunks) {
+    if (const ELFYAML::Fill *F = dyn_cast<ELFYAML::Fill>(C)) {
+      Ret.push_back({*F->Offset, F->Size, llvm::ELF::SHT_PROGBITS,
                      /*ShAddrAlign=*/1});
       continue;
     }
 
-    reportError("unknown section or fill referenced: '" + SecName.Section +
-                "' by program header");
+    const ELFYAML::Section *S = cast<ELFYAML::Section>(C);
+    const Elf_Shdr &H = SHeaders[SN2I.get(S->Name)];
+    Ret.push_back({H.sh_offset, H.sh_size, H.sh_type, H.sh_addralign});
   }
-
   return Ret;
 }
 
@@ -721,35 +1069,41 @@ void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
   for (auto &YamlPhdr : Doc.ProgramHeaders) {
     Elf_Phdr &PHeader = PHeaders[PhdrIdx++];
     std::vector<Fragment> Fragments = getPhdrFragments(YamlPhdr, SHeaders);
+    if (!llvm::is_sorted(Fragments, [](const Fragment &A, const Fragment &B) {
+          return A.Offset < B.Offset;
+        }))
+      reportError("sections in the program header with index " +
+                  Twine(PhdrIdx) + " are not sorted by their file offset");
 
     if (YamlPhdr.Offset) {
+      if (!Fragments.empty() && *YamlPhdr.Offset > Fragments.front().Offset)
+        reportError("'Offset' for segment with index " + Twine(PhdrIdx) +
+                    " must be less than or equal to the minimum file offset of "
+                    "all included sections (0x" +
+                    Twine::utohexstr(Fragments.front().Offset) + ")");
       PHeader.p_offset = *YamlPhdr.Offset;
-    } else {
-      if (YamlPhdr.Sections.size())
-        PHeader.p_offset = UINT32_MAX;
-      else
-        PHeader.p_offset = 0;
-
-      // Find the minimum offset for the program header.
-      for (const Fragment &F : Fragments)
-        PHeader.p_offset = std::min((uint64_t)PHeader.p_offset, F.Offset);
+    } else if (!Fragments.empty()) {
+      PHeader.p_offset = Fragments.front().Offset;
     }
 
-    // Find the maximum offset of the end of a section in order to set p_filesz
-    // and p_memsz. When setting p_filesz, trailing SHT_NOBITS sections are not
-    // counted.
-    uint64_t FileOffset = PHeader.p_offset, MemOffset = PHeader.p_offset;
-    for (const Fragment &F : Fragments) {
-      uint64_t End = F.Offset + F.Size;
-      MemOffset = std::max(MemOffset, End);
-
-      if (F.Type != llvm::ELF::SHT_NOBITS)
-        FileOffset = std::max(FileOffset, End);
+    // Set the file size if not set explicitly.
+    if (YamlPhdr.FileSize) {
+      PHeader.p_filesz = *YamlPhdr.FileSize;
+    } else if (!Fragments.empty()) {
+      uint64_t FileSize = Fragments.back().Offset - PHeader.p_offset;
+      // SHT_NOBITS sections occupy no physical space in a file, we should not
+      // take their sizes into account when calculating the file size of a
+      // segment.
+      if (Fragments.back().Type != llvm::ELF::SHT_NOBITS)
+        FileSize += Fragments.back().Size;
+      PHeader.p_filesz = FileSize;
     }
 
-    // Set the file size and the memory size if not set explicitly.
-    PHeader.p_filesz = YamlPhdr.FileSize ? uint64_t(*YamlPhdr.FileSize)
-                                         : FileOffset - PHeader.p_offset;
+    // Find the maximum offset of the end of a section in order to set p_memsz.
+    uint64_t MemOffset = PHeader.p_offset;
+    for (const Fragment &F : Fragments)
+      MemOffset = std::max(MemOffset, F.Offset + F.Size);
+    // Set the memory size if not set explicitly.
     PHeader.p_memsz = YamlPhdr.MemSize ? uint64_t(*YamlPhdr.MemSize)
                                        : MemOffset - PHeader.p_offset;
 
@@ -766,13 +1120,40 @@ void ELFState<ELFT>::setProgramHeaderLayout(std::vector<Elf_Phdr> &PHeaders,
   }
 }
 
+static bool shouldAllocateFileSpace(ArrayRef<ELFYAML::ProgramHeader> Phdrs,
+                                    const ELFYAML::NoBitsSection &S) {
+  for (const ELFYAML::ProgramHeader &PH : Phdrs) {
+    auto It = llvm::find_if(
+        PH.Chunks, [&](ELFYAML::Chunk *C) { return C->Name == S.Name; });
+    if (std::any_of(It, PH.Chunks.end(), [](ELFYAML::Chunk *C) {
+          return (isa<ELFYAML::Fill>(C) ||
+                  cast<ELFYAML::Section>(C)->Type != ELF::SHT_NOBITS);
+        }))
+      return true;
+  }
+  return false;
+}
+
+template <class ELFT>
+void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
+                                         const ELFYAML::NoBitsSection &S,
+                                         ContiguousBlobAccumulator &CBA) {
+  // SHT_NOBITS sections do not have any content to write.
+  SHeader.sh_entsize = 0;
+  SHeader.sh_size = S.Size;
+
+  // When a nobits section is followed by a non-nobits section or fill
+  // in the same segment, we allocate the file space for it. This behavior
+  // matches linkers.
+  if (shouldAllocateFileSpace(Doc.ProgramHeaders, S))
+    CBA.writeZeros(S.Size);
+}
+
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::RawContentSection &Section,
     ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-  SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
+  SHeader.sh_size = writeContent(CBA, Section.Content, Section.Size);
 
   if (Section.EntSize)
     SHeader.sh_entsize = *Section.EntSize;
@@ -796,18 +1177,22 @@ void ELFState<ELFT>::writeSectionContent(
          "Section type is not SHT_REL nor SHT_RELA");
 
   bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
-  SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
-  SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
+  if (Section.EntSize)
+    SHeader.sh_entsize = *Section.EntSize;
+  else
+    SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
+  SHeader.sh_size = (IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel)) *
+                    Section.Relocations.size();
 
   // For relocation section set link to .symtab by default.
   unsigned Link = 0;
-  if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+  if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+      SN2I.lookup(".symtab", Link))
     SHeader.sh_link = Link;
 
   if (!Section.RelocatableSec.empty())
     SHeader.sh_info = toSectionIndex(Section.RelocatableSec, Section.Name);
 
-  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
   for (const auto &Rel : Section.Relocations) {
     unsigned SymIdx = Rel.Symbol ? toSymbolIndex(*Rel.Symbol, Section.Name,
                                                  Section.Link == ".dynsym")
@@ -818,13 +1203,13 @@ void ELFState<ELFT>::writeSectionContent(
       REntry.r_offset = Rel.Offset;
       REntry.r_addend = Rel.Addend;
       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
-      OS.write((const char *)&REntry, sizeof(REntry));
+      CBA.write((const char *)&REntry, sizeof(REntry));
     } else {
       Elf_Rel REntry;
       zero(REntry);
       REntry.r_offset = Rel.Offset;
       REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
-      OS.write((const char *)&REntry, sizeof(REntry));
+      CBA.write((const char *)&REntry, sizeof(REntry));
     }
   }
 }
@@ -833,13 +1218,11 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::RelrSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
   SHeader.sh_entsize =
       Section.EntSize ? uint64_t(*Section.EntSize) : sizeof(Elf_Relr);
 
   if (Section.Content) {
-    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
     return;
   }
 
@@ -850,7 +1233,7 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
     if (!ELFT::Is64Bits && E > UINT32_MAX)
       reportError(Section.Name + ": the value is too large for 32-bits: 0x" +
                   Twine::utohexstr(E));
-    support::endian::write<uintX_t>(OS, E, ELFT::TargetEndianness);
+    CBA.write<uintX_t>(E, ELFT::TargetEndianness);
   }
 
   SHeader.sh_size = sizeof(uintX_t) * Section.Entries->size();
@@ -860,11 +1243,8 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::SymtabShndxSection &Shndx,
     ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   for (uint32_t E : Shndx.Entries)
-    support::endian::write<uint32_t>(OS, E, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(E, ELFT::TargetEndianness);
 
   SHeader.sh_entsize = Shndx.EntSize ? (uint64_t)*Shndx.EntSize : 4;
   SHeader.sh_size = Shndx.Entries.size() * SHeader.sh_entsize;
@@ -878,7 +1258,8 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
          "Section type is not SHT_GROUP");
 
   unsigned Link = 0;
-  if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+  if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+      SN2I.lookup(".symtab", Link))
     SHeader.sh_link = Link;
 
   SHeader.sh_entsize = 4;
@@ -888,16 +1269,13 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
     SHeader.sh_info =
         toSymbolIndex(*Section.Signature, Section.Name, /*IsDynamic=*/false);
 
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   for (const ELFYAML::SectionOrType &Member : Section.Members) {
     unsigned int SectionIndex = 0;
     if (Member.sectionNameOrType == "GRP_COMDAT")
       SectionIndex = llvm::ELF::GRP_COMDAT;
     else
       SectionIndex = toSectionIndex(Member.sectionNameOrType, Section.Name);
-    support::endian::write<uint32_t>(OS, SectionIndex, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(SectionIndex, ELFT::TargetEndianness);
   }
 }
 
@@ -905,10 +1283,8 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::SymverSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
   for (uint16_t Version : Section.Entries)
-    support::endian::write<uint16_t>(OS, Version, ELFT::TargetEndianness);
+    CBA.write<uint16_t>(Version, ELFT::TargetEndianness);
 
   SHeader.sh_entsize = Section.EntSize ? (uint64_t)*Section.EntSize : 2;
   SHeader.sh_size = Section.Entries.size() * SHeader.sh_entsize;
@@ -918,17 +1294,14 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::StackSizesSection &Section,
     ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   if (Section.Content || Section.Size) {
-    SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
+    SHeader.sh_size = writeContent(CBA, Section.Content, Section.Size);
     return;
   }
 
   for (const ELFYAML::StackSizeEntry &E : *Section.Entries) {
-    support::endian::write<uintX_t>(OS, E.Address, ELFT::TargetEndianness);
-    SHeader.sh_size += sizeof(uintX_t) + encodeULEB128(E.Size, OS);
+    CBA.write<uintX_t>(E.Address, ELFT::TargetEndianness);
+    SHeader.sh_size += sizeof(uintX_t) + CBA.writeULEB128(E.Size);
   }
 }
 
@@ -936,11 +1309,8 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::LinkerOptionsSection &Section,
     ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   if (Section.Content) {
-    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
     return;
   }
 
@@ -948,10 +1318,10 @@ void ELFState<ELFT>::writeSectionContent(
     return;
 
   for (const ELFYAML::LinkerOption &LO : *Section.Options) {
-    OS.write(LO.Key.data(), LO.Key.size());
-    OS.write('\0');
-    OS.write(LO.Value.data(), LO.Value.size());
-    OS.write('\0');
+    CBA.write(LO.Key.data(), LO.Key.size());
+    CBA.write('\0');
+    CBA.write(LO.Value.data(), LO.Value.size());
+    CBA.write('\0');
     SHeader.sh_size += (LO.Key.size() + LO.Value.size() + 2);
   }
 }
@@ -960,11 +1330,8 @@ template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(
     Elf_Shdr &SHeader, const ELFYAML::DependentLibrariesSection &Section,
     ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   if (Section.Content) {
-    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
     return;
   }
 
@@ -972,36 +1339,94 @@ void ELFState<ELFT>::writeSectionContent(
     return;
 
   for (StringRef Lib : *Section.Libs) {
-    OS.write(Lib.data(), Lib.size());
-    OS.write('\0');
+    CBA.write(Lib.data(), Lib.size());
+    CBA.write('\0');
     SHeader.sh_size += Lib.size() + 1;
   }
 }
 
 template <class ELFT>
+uint64_t
+ELFState<ELFT>::alignToOffset(ContiguousBlobAccumulator &CBA, uint64_t Align,
+                              llvm::Optional<llvm::yaml::Hex64> Offset) {
+  uint64_t CurrentOffset = CBA.getOffset();
+  uint64_t AlignedOffset;
+
+  if (Offset) {
+    if ((uint64_t)*Offset < CurrentOffset) {
+      reportError("the 'Offset' value (0x" +
+                  Twine::utohexstr((uint64_t)*Offset) + ") goes backward");
+      return CurrentOffset;
+    }
+
+    // We ignore an alignment when an explicit offset has been requested.
+    AlignedOffset = *Offset;
+  } else {
+    AlignedOffset = alignTo(CurrentOffset, std::max(Align, (uint64_t)1));
+  }
+
+  CBA.writeZeros(AlignedOffset - CurrentOffset);
+  return AlignedOffset;
+}
+
+template <class ELFT>
+void ELFState<ELFT>::writeSectionContent(
+    Elf_Shdr &SHeader, const ELFYAML::CallGraphProfileSection &Section,
+    ContiguousBlobAccumulator &CBA) {
+  if (Section.EntSize)
+    SHeader.sh_entsize = *Section.EntSize;
+  else
+    SHeader.sh_entsize = 16;
+
+  unsigned Link = 0;
+  if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+      SN2I.lookup(".symtab", Link))
+    SHeader.sh_link = Link;
+
+  if (Section.Content) {
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
+    return;
+  }
+
+  if (!Section.Entries)
+    return;
+
+  for (const ELFYAML::CallGraphEntry &E : *Section.Entries) {
+    unsigned From = toSymbolIndex(E.From, Section.Name, /*IsDynamic=*/false);
+    unsigned To = toSymbolIndex(E.To, Section.Name, /*IsDynamic=*/false);
+
+    CBA.write<uint32_t>(From, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(To, ELFT::TargetEndianness);
+    CBA.write<uint64_t>(E.Weight, ELFT::TargetEndianness);
+    SHeader.sh_size += 16;
+  }
+}
+
+template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::HashSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   unsigned Link = 0;
-  if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
+  if (Section.Link.empty() && !ExcludedSectionHeaders.count(".dynsym") &&
+      SN2I.lookup(".dynsym", Link))
     SHeader.sh_link = Link;
 
   if (Section.Content || Section.Size) {
-    SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
+    SHeader.sh_size = writeContent(CBA, Section.Content, Section.Size);
     return;
   }
 
-  support::endian::write<uint32_t>(OS, Section.Bucket->size(),
-                                   ELFT::TargetEndianness);
-  support::endian::write<uint32_t>(OS, Section.Chain->size(),
-                                   ELFT::TargetEndianness);
+  CBA.write<uint32_t>(
+      Section.NBucket.getValueOr(llvm::yaml::Hex64(Section.Bucket->size())),
+      ELFT::TargetEndianness);
+  CBA.write<uint32_t>(
+      Section.NChain.getValueOr(llvm::yaml::Hex64(Section.Chain->size())),
+      ELFT::TargetEndianness);
+
   for (uint32_t Val : *Section.Bucket)
-    support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
   for (uint32_t Val : *Section.Chain)
-    support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
 
   SHeader.sh_size = (2 + Section.Bucket->size() + Section.Chain->size()) * 4;
 }
@@ -1012,13 +1437,11 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          ContiguousBlobAccumulator &CBA) {
   typedef typename ELFT::Verdef Elf_Verdef;
   typedef typename ELFT::Verdaux Elf_Verdaux;
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
 
   SHeader.sh_info = Section.Info;
 
   if (Section.Content) {
-    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
     return;
   }
 
@@ -1041,7 +1464,7 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
     else
       VerDef.vd_next =
           sizeof(Elf_Verdef) + E.VerNames.size() * sizeof(Elf_Verdaux);
-    OS.write((const char *)&VerDef, sizeof(Elf_Verdef));
+    CBA.write((const char *)&VerDef, sizeof(Elf_Verdef));
 
     for (size_t J = 0; J < E.VerNames.size(); ++J, ++AuxCnt) {
       Elf_Verdaux VernAux;
@@ -1050,7 +1473,7 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
         VernAux.vda_next = 0;
       else
         VernAux.vda_next = sizeof(Elf_Verdaux);
-      OS.write((const char *)&VernAux, sizeof(Elf_Verdaux));
+      CBA.write((const char *)&VernAux, sizeof(Elf_Verdaux));
     }
   }
 
@@ -1065,11 +1488,10 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   typedef typename ELFT::Verneed Elf_Verneed;
   typedef typename ELFT::Vernaux Elf_Vernaux;
 
-  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
   SHeader.sh_info = Section.Info;
 
   if (Section.Content) {
-    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
     return;
   }
 
@@ -1090,7 +1512,7 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
           sizeof(Elf_Verneed) + VE.AuxV.size() * sizeof(Elf_Vernaux);
     VerNeed.vn_cnt = VE.AuxV.size();
     VerNeed.vn_aux = sizeof(Elf_Verneed);
-    OS.write((const char *)&VerNeed, sizeof(Elf_Verneed));
+    CBA.write((const char *)&VerNeed, sizeof(Elf_Verneed));
 
     for (size_t J = 0; J < VE.AuxV.size(); ++J, ++AuxCnt) {
       const ELFYAML::VernauxEntry &VAuxE = VE.AuxV[J];
@@ -1104,7 +1526,7 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
         VernAux.vna_next = 0;
       else
         VernAux.vna_next = sizeof(Elf_Vernaux);
-      OS.write((const char *)&VernAux, sizeof(Elf_Vernaux));
+      CBA.write((const char *)&VernAux, sizeof(Elf_Vernaux));
     }
   }
 
@@ -1124,7 +1546,6 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   SHeader.sh_entsize = sizeof(Flags);
   SHeader.sh_size = SHeader.sh_entsize;
 
-  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
   Flags.version = Section.Version;
   Flags.isa_level = Section.ISALevel;
   Flags.isa_rev = Section.ISARevision;
@@ -1136,7 +1557,7 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   Flags.ases = Section.ASEs;
   Flags.flags1 = Section.Flags1;
   Flags.flags2 = Section.Flags2;
-  OS.write((const char *)&Flags, sizeof(Flags));
+  CBA.write((const char *)&Flags, sizeof(Flags));
 }
 
 template <class ELFT>
@@ -1160,102 +1581,87 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   else
     SHeader.sh_entsize = sizeof(Elf_Dyn);
 
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
   for (const ELFYAML::DynamicEntry &DE : Section.Entries) {
-    support::endian::write<uintX_t>(OS, DE.Tag, ELFT::TargetEndianness);
-    support::endian::write<uintX_t>(OS, DE.Val, ELFT::TargetEndianness);
+    CBA.write<uintX_t>(DE.Tag, ELFT::TargetEndianness);
+    CBA.write<uintX_t>(DE.Val, ELFT::TargetEndianness);
   }
   if (Section.Content)
-    Section.Content->writeAsBinary(OS);
+    CBA.writeAsBinary(*Section.Content);
 }
 
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::AddrsigSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   unsigned Link = 0;
-  if (Section.Link.empty() && SN2I.lookup(".symtab", Link))
+  if (Section.Link.empty() && !ExcludedSectionHeaders.count(".symtab") &&
+      SN2I.lookup(".symtab", Link))
     SHeader.sh_link = Link;
 
   if (Section.Content || Section.Size) {
-    SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
+    SHeader.sh_size = writeContent(CBA, Section.Content, Section.Size);
     return;
   }
 
-  for (const ELFYAML::AddrsigSymbol &Sym : *Section.Symbols) {
-    uint64_t Val =
-        Sym.Name ? toSymbolIndex(*Sym.Name, Section.Name, /*IsDynamic=*/false)
-                 : (uint32_t)*Sym.Index;
-    SHeader.sh_size += encodeULEB128(Val, OS);
-  }
+  for (StringRef Sym : *Section.Symbols)
+    SHeader.sh_size +=
+        CBA.writeULEB128(toSymbolIndex(Sym, Section.Name, /*IsDynamic=*/false));
 }
 
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::NoteSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-  uint64_t Offset = OS.tell();
-
+  uint64_t Offset = CBA.tell();
   if (Section.Content || Section.Size) {
-    SHeader.sh_size = writeContent(OS, Section.Content, Section.Size);
+    SHeader.sh_size = writeContent(CBA, Section.Content, Section.Size);
     return;
   }
 
   for (const ELFYAML::NoteEntry &NE : *Section.Notes) {
     // Write name size.
     if (NE.Name.empty())
-      support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
+      CBA.write<uint32_t>(0, ELFT::TargetEndianness);
     else
-      support::endian::write<uint32_t>(OS, NE.Name.size() + 1,
-                                       ELFT::TargetEndianness);
+      CBA.write<uint32_t>(NE.Name.size() + 1, ELFT::TargetEndianness);
 
     // Write description size.
     if (NE.Desc.binary_size() == 0)
-      support::endian::write<uint32_t>(OS, 0, ELFT::TargetEndianness);
+      CBA.write<uint32_t>(0, ELFT::TargetEndianness);
     else
-      support::endian::write<uint32_t>(OS, NE.Desc.binary_size(),
-                                       ELFT::TargetEndianness);
+      CBA.write<uint32_t>(NE.Desc.binary_size(), ELFT::TargetEndianness);
 
     // Write type.
-    support::endian::write<uint32_t>(OS, NE.Type, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(NE.Type, ELFT::TargetEndianness);
 
     // Write name, null terminator and padding.
     if (!NE.Name.empty()) {
-      support::endian::write<uint8_t>(OS, arrayRefFromStringRef(NE.Name),
-                                      ELFT::TargetEndianness);
-      support::endian::write<uint8_t>(OS, 0, ELFT::TargetEndianness);
+      CBA.write(NE.Name.data(), NE.Name.size());
+      CBA.write('\0');
       CBA.padToAlignment(4);
     }
 
     // Write description and padding.
     if (NE.Desc.binary_size() != 0) {
-      NE.Desc.writeAsBinary(OS);
+      CBA.writeAsBinary(NE.Desc);
       CBA.padToAlignment(4);
     }
   }
 
-  SHeader.sh_size = OS.tell() - Offset;
+  SHeader.sh_size = CBA.tell() - Offset;
 }
 
 template <class ELFT>
 void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
                                          const ELFYAML::GnuHashSection &Section,
                                          ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS =
-      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
-
   unsigned Link = 0;
-  if (Section.Link.empty() && SN2I.lookup(".dynsym", Link))
+  if (Section.Link.empty() && !ExcludedSectionHeaders.count(".dynsym") &&
+      SN2I.lookup(".dynsym", Link))
     SHeader.sh_link = Link;
 
   if (Section.Content) {
-    SHeader.sh_size = writeContent(OS, Section.Content, None);
+    SHeader.sh_size = writeContent(CBA, Section.Content, None);
     return;
   }
 
@@ -1264,42 +1670,35 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
   // be used to override this field, which is useful for producing broken
   // objects.
   if (Section.Header->NBuckets)
-    support::endian::write<uint32_t>(OS, *Section.Header->NBuckets,
-                                     ELFT::TargetEndianness);
+    CBA.write<uint32_t>(*Section.Header->NBuckets, ELFT::TargetEndianness);
   else
-    support::endian::write<uint32_t>(OS, Section.HashBuckets->size(),
-                                     ELFT::TargetEndianness);
+    CBA.write<uint32_t>(Section.HashBuckets->size(), ELFT::TargetEndianness);
 
   // Write the index of the first symbol in the dynamic symbol table accessible
   // via the hash table.
-  support::endian::write<uint32_t>(OS, Section.Header->SymNdx,
-                                   ELFT::TargetEndianness);
+  CBA.write<uint32_t>(Section.Header->SymNdx, ELFT::TargetEndianness);
 
   // Write the number of words in the Bloom filter. As above, the "MaskWords"
   // property can be used to set this field to any value.
   if (Section.Header->MaskWords)
-    support::endian::write<uint32_t>(OS, *Section.Header->MaskWords,
-                                     ELFT::TargetEndianness);
+    CBA.write<uint32_t>(*Section.Header->MaskWords, ELFT::TargetEndianness);
   else
-    support::endian::write<uint32_t>(OS, Section.BloomFilter->size(),
-                                     ELFT::TargetEndianness);
+    CBA.write<uint32_t>(Section.BloomFilter->size(), ELFT::TargetEndianness);
 
   // Write the shift constant used by the Bloom filter.
-  support::endian::write<uint32_t>(OS, Section.Header->Shift2,
-                                   ELFT::TargetEndianness);
+  CBA.write<uint32_t>(Section.Header->Shift2, ELFT::TargetEndianness);
 
   // We've finished writing the header. Now write the Bloom filter.
   for (llvm::yaml::Hex64 Val : *Section.BloomFilter)
-    support::endian::write<typename ELFT::uint>(OS, Val,
-                                                ELFT::TargetEndianness);
+    CBA.write<uintX_t>(Val, ELFT::TargetEndianness);
 
   // Write an array of hash buckets.
   for (llvm::yaml::Hex32 Val : *Section.HashBuckets)
-    support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
 
   // Write an array of hash values.
   for (llvm::yaml::Hex32 Val : *Section.HashValues)
-    support::endian::write<uint32_t>(OS, Val, ELFT::TargetEndianness);
+    CBA.write<uint32_t>(Val, ELFT::TargetEndianness);
 
   SHeader.sh_size = 16 /*Header size*/ +
                     Section.BloomFilter->size() * sizeof(typename ELFT::uint) +
@@ -1310,42 +1709,91 @@ void ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
 template <class ELFT>
 void ELFState<ELFT>::writeFill(ELFYAML::Fill &Fill,
                                ContiguousBlobAccumulator &CBA) {
-  raw_ostream &OS = CBA.getOSAndAlignedOffset(Fill.ShOffset, /*Align=*/1);
-
   size_t PatternSize = Fill.Pattern ? Fill.Pattern->binary_size() : 0;
   if (!PatternSize) {
-    OS.write_zeros(Fill.Size);
+    CBA.writeZeros(Fill.Size);
     return;
   }
 
   // Fill the content with the specified pattern.
   uint64_t Written = 0;
   for (; Written + PatternSize <= Fill.Size; Written += PatternSize)
-    Fill.Pattern->writeAsBinary(OS);
-  Fill.Pattern->writeAsBinary(OS, Fill.Size - Written);
+    CBA.writeAsBinary(*Fill.Pattern);
+  CBA.writeAsBinary(*Fill.Pattern, Fill.Size - Written);
 }
 
-template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
-  size_t SecNdx = -1;
+template <class ELFT>
+DenseMap<StringRef, size_t> ELFState<ELFT>::buildSectionHeaderReorderMap() {
+  if (!Doc.SectionHeaders || Doc.SectionHeaders->NoHeaders)
+    return DenseMap<StringRef, size_t>();
+
+  DenseMap<StringRef, size_t> Ret;
+  size_t SecNdx = 0;
   StringSet<> Seen;
-  for (size_t I = 0; I < Doc.Chunks.size(); ++I) {
-    const std::unique_ptr<ELFYAML::Chunk> &C = Doc.Chunks[I];
-    bool IsSection = isa<ELFYAML::Section>(C.get());
-    if (IsSection)
-      ++SecNdx;
 
-    if (C->Name.empty())
-      continue;
+  auto AddSection = [&](const ELFYAML::SectionHeader &Hdr) {
+    if (!Ret.try_emplace(Hdr.Name, ++SecNdx).second)
+      reportError("repeated section name: '" + Hdr.Name +
+                  "' in the section header description");
+    Seen.insert(Hdr.Name);
+  };
 
-    if (!Seen.insert(C->Name).second)
-      reportError("repeated section/fill name: '" + C->Name +
-                  "' at YAML section/fill number " + Twine(I));
-    if (!IsSection || HasError)
+  if (Doc.SectionHeaders->Sections)
+    for (const ELFYAML::SectionHeader &Hdr : *Doc.SectionHeaders->Sections)
+      AddSection(Hdr);
+
+  if (Doc.SectionHeaders->Excluded)
+    for (const ELFYAML::SectionHeader &Hdr : *Doc.SectionHeaders->Excluded)
+      AddSection(Hdr);
+
+  for (const ELFYAML::Section *S : Doc.getSections()) {
+    // Ignore special first SHT_NULL section.
+    if (S == Doc.getSections().front())
       continue;
+    if (!Seen.count(S->Name))
+      reportError("section '" + S->Name +
+                  "' should be present in the 'Sections' or 'Excluded' lists");
+    Seen.erase(S->Name);
+  }
 
-    if (!SN2I.addName(C->Name, SecNdx))
+  for (const auto &It : Seen)
+    reportError("section header contains undefined section '" + It.getKey() +
+                "'");
+  return Ret;
+}
+
+template <class ELFT> void ELFState<ELFT>::buildSectionIndex() {
+  // A YAML description can have an explicit section header declaration that
+  // allows to change the order of section headers.
+  DenseMap<StringRef, size_t> ReorderMap = buildSectionHeaderReorderMap();
+
+  if (HasError)
+    return;
+
+  // Build excluded section headers map.
+  std::vector<ELFYAML::Section *> Sections = Doc.getSections();
+  if (Doc.SectionHeaders) {
+    if (Doc.SectionHeaders->Excluded)
+      for (const ELFYAML::SectionHeader &Hdr : *Doc.SectionHeaders->Excluded)
+        if (!ExcludedSectionHeaders.insert(Hdr.Name).second)
+          llvm_unreachable("buildSectionIndex() failed");
+
+    if (Doc.SectionHeaders->NoHeaders.getValueOr(false))
+      for (const ELFYAML::Section *S : Sections)
+        if (!ExcludedSectionHeaders.insert(S->Name).second)
+          llvm_unreachable("buildSectionIndex() failed");
+  }
+
+  size_t SecNdx = -1;
+  for (const ELFYAML::Section *S : Sections) {
+    ++SecNdx;
+
+    size_t Index = ReorderMap.empty() ? SecNdx : ReorderMap.lookup(S->Name);
+    if (!SN2I.addName(S->Name, Index))
       llvm_unreachable("buildSectionIndex() failed");
-    DotShStrtab.add(ELFYAML::dropUniqueSuffix(C->Name));
+
+    if (!ExcludedSectionHeaders.count(S->Name))
+      DotShStrtab.add(ELFYAML::dropUniqueSuffix(S->Name));
   }
 
   DotShStrtab.finalize();
@@ -1402,8 +1850,10 @@ template <class ELFT> void ELFState<ELFT>::finalizeStrings() {
 
 template <class ELFT>
 bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
-                              yaml::ErrorHandler EH) {
+                              yaml::ErrorHandler EH, uint64_t MaxSize) {
   ELFState<ELFT> State(Doc, EH);
+  if (State.HasError)
+    return false;
 
   // Finalize .strtab and .dynstr sections. We do that early because want to
   // finalize the string table builders before writing the content of the
@@ -1411,11 +1861,11 @@ bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
   State.finalizeStrings();
 
   State.buildSectionIndex();
+  State.buildSymbolIndexes();
+
   if (State.HasError)
     return false;
 
-  State.buildSymbolIndexes();
-
   std::vector<Elf_Phdr> PHeaders;
   State.initProgramHeaders(PHeaders);
 
@@ -1423,7 +1873,11 @@ bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
   // things to `OS`.
   const size_t SectionContentBeginOffset =
       sizeof(Elf_Ehdr) + sizeof(Elf_Phdr) * Doc.ProgramHeaders.size();
-  ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
+  // It is quite easy to accidentally create output with yaml2obj that is larger
+  // than intended, for example, due to an issue in the YAML description.
+  // We limit the maximum allowed output size, but also provide a command line
+  // option to change this limitation.
+  ContiguousBlobAccumulator CBA(SectionContentBeginOffset, MaxSize);
 
   std::vector<Elf_Shdr> SHeaders;
   State.initSectionHeaders(SHeaders, CBA);
@@ -1431,10 +1885,26 @@ bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
   // Now we can decide segment offsets.
   State.setProgramHeaderLayout(PHeaders, SHeaders);
 
+  // Align the start of the section header table, which is written after all
+  // section data.
+  uint64_t SHOff =
+      State.alignToOffset(CBA, sizeof(typename ELFT::uint), /*Offset=*/None);
+  bool ReachedLimit = SHOff + arrayDataSize(makeArrayRef(SHeaders)) > MaxSize;
+  if (Error E = CBA.takeLimitError()) {
+    // We report a custom error message instead below.
+    consumeError(std::move(E));
+    ReachedLimit = true;
+  }
+
+  if (ReachedLimit)
+    State.reportError(
+        "the desired output size is greater than permitted. Use the "
+        "--max-size option to change the limit");
+
   if (State.HasError)
     return false;
 
-  State.writeELFHeader(CBA, OS);
+  State.writeELFHeader(OS, SHOff);
   writeArrayData(OS, makeArrayRef(PHeaders));
   CBA.writeBlobToStream(OS);
   writeArrayData(OS, makeArrayRef(SHeaders));
@@ -1444,17 +1914,18 @@ bool ELFState<ELFT>::writeELF(raw_ostream &OS, ELFYAML::Object &Doc,
 namespace llvm {
 namespace yaml {
 
-bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH) {
+bool yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out, ErrorHandler EH,
+              uint64_t MaxSize) {
   bool IsLE = Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
   bool Is64Bit = Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
   if (Is64Bit) {
     if (IsLE)
-      return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH);
-    return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH);
+      return ELFState<object::ELF64LE>::writeELF(Out, Doc, EH, MaxSize);
+    return ELFState<object::ELF64BE>::writeELF(Out, Doc, EH, MaxSize);
   }
   if (IsLE)
-    return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH);
-  return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH);
+    return ELFState<object::ELF32LE>::writeELF(Out, Doc, EH, MaxSize);
+  return ELFState<object::ELF32BE>::writeELF(Out, Doc, EH, MaxSize);
 }
 
 } // namespace yaml
diff --git a/llvm/lib/ObjectYAML/ELFYAML.cpp b/llvm/lib/ObjectYAML/ELFYAML.cpp
index efa7ecb4728b2..2353b34f188b1 100644
--- a/llvm/lib/ObjectYAML/ELFYAML.cpp
+++ b/llvm/lib/ObjectYAML/ELFYAML.cpp
@@ -221,6 +221,7 @@ void ScalarEnumerationTraits<ELFYAML::ELF_EM>::enumeration(
   ECase(EM_RISCV);
   ECase(EM_LANAI);
   ECase(EM_BPF);
+  ECase(EM_VE);
 #undef ECase
   IO.enumFallback<Hex16>(Value);
 }
@@ -349,6 +350,9 @@ void ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset(IO &IO,
     BCase(EF_HEXAGON_MACH_V60);
     BCase(EF_HEXAGON_MACH_V62);
     BCase(EF_HEXAGON_MACH_V65);
+    BCase(EF_HEXAGON_MACH_V66);
+    BCase(EF_HEXAGON_MACH_V67);
+    BCase(EF_HEXAGON_MACH_V67T);
     BCase(EF_HEXAGON_ISA_V2);
     BCase(EF_HEXAGON_ISA_V3);
     BCase(EF_HEXAGON_ISA_V4);
@@ -357,6 +361,8 @@ void ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset(IO &IO,
     BCase(EF_HEXAGON_ISA_V60);
     BCase(EF_HEXAGON_ISA_V62);
     BCase(EF_HEXAGON_ISA_V65);
+    BCase(EF_HEXAGON_ISA_V66);
+    BCase(EF_HEXAGON_ISA_V67);
     break;
   case ELF::EM_AVR:
     BCase(EF_AVR_ARCH_AVR1);
@@ -423,6 +429,7 @@ void ScalarBitSetTraits<ELFYAML::ELF_EF>::bitset(IO &IO,
     BCaseMask(EF_AMDGPU_MACH_AMDGCN_GFX1010, EF_AMDGPU_MACH);
     BCaseMask(EF_AMDGPU_MACH_AMDGCN_GFX1011, EF_AMDGPU_MACH);
     BCaseMask(EF_AMDGPU_MACH_AMDGCN_GFX1012, EF_AMDGPU_MACH);
+    BCaseMask(EF_AMDGPU_MACH_AMDGCN_GFX1030, EF_AMDGPU_MACH);
     BCase(EF_AMDGPU_XNACK);
     BCase(EF_AMDGPU_SRAM_ECC);
     break;
@@ -495,6 +502,9 @@ void ScalarEnumerationTraits<ELFYAML::ELF_SHT>::enumeration(
     ECase(SHT_MIPS_DWARF);
     ECase(SHT_MIPS_ABIFLAGS);
     break;
+  case ELF::EM_RISCV:
+    ECase(SHT_RISCV_ATTRIBUTES);
+    break;
   default:
     // Nothing to do.
     break;
@@ -654,6 +664,9 @@ void ScalarEnumerationTraits<ELFYAML::ELF_REL>::enumeration(
   case ELF::EM_BPF:
 #include "llvm/BinaryFormat/ELFRelocs/BPF.def"
     break;
+  case ELF::EM_VE:
+#include "llvm/BinaryFormat/ELFRelocs/VE.def"
+    break;
   case ELF::EM_PPC64:
 #include "llvm/BinaryFormat/ELFRelocs/PowerPC64.def"
     break;
@@ -820,6 +833,28 @@ void ScalarBitSetTraits<ELFYAML::MIPS_AFL_FLAGS1>::bitset(
 #undef BCase
 }
 
+void MappingTraits<ELFYAML::SectionHeader>::mapping(
+    IO &IO, ELFYAML::SectionHeader &SHdr) {
+  IO.mapRequired("Name", SHdr.Name);
+}
+
+void MappingTraits<ELFYAML::SectionHeaderTable>::mapping(
+    IO &IO, ELFYAML::SectionHeaderTable &SectionHeader) {
+  IO.mapOptional("Sections", SectionHeader.Sections);
+  IO.mapOptional("Excluded", SectionHeader.Excluded);
+  IO.mapOptional("NoHeaders", SectionHeader.NoHeaders);
+}
+
+StringRef MappingTraits<ELFYAML::SectionHeaderTable>::validate(
+    IO &IO, ELFYAML::SectionHeaderTable &SecHdrTable) {
+  if (SecHdrTable.NoHeaders && (SecHdrTable.Sections || SecHdrTable.Excluded))
+    return "NoHeaders can't be used together with Sections/Excluded";
+  if (!SecHdrTable.NoHeaders && !SecHdrTable.Sections && !SecHdrTable.Excluded)
+    return "SectionHeaderTable can't be empty. Use 'NoHeaders' key to drop the "
+           "section header table";
+  return StringRef();
+}
+
 void MappingTraits<ELFYAML::FileHeader>::mapping(IO &IO,
                                                  ELFYAML::FileHeader &FileHdr) {
   IO.mapRequired("Class", FileHdr.Class);
@@ -831,10 +866,16 @@ void MappingTraits<ELFYAML::FileHeader>::mapping(IO &IO,
   IO.mapOptional("Flags", FileHdr.Flags, ELFYAML::ELF_EF(0));
   IO.mapOptional("Entry", FileHdr.Entry, Hex64(0));
 
-  IO.mapOptional("SHEntSize", FileHdr.SHEntSize);
-  IO.mapOptional("SHOff", FileHdr.SHOff);
-  IO.mapOptional("SHNum", FileHdr.SHNum);
-  IO.mapOptional("SHStrNdx", FileHdr.SHStrNdx);
+  // obj2yaml does not dump these fields.
+  assert(!IO.outputting() ||
+         (!FileHdr.EPhOff && !FileHdr.EPhEntSize && !FileHdr.EPhNum));
+  IO.mapOptional("EPhOff", FileHdr.EPhOff);
+  IO.mapOptional("EPhEntSize", FileHdr.EPhEntSize);
+  IO.mapOptional("EPhNum", FileHdr.EPhNum);
+  IO.mapOptional("EShEntSize", FileHdr.EShEntSize);
+  IO.mapOptional("EShOff", FileHdr.EShOff);
+  IO.mapOptional("EShNum", FileHdr.EShNum);
+  IO.mapOptional("EShStrNdx", FileHdr.EShStrNdx);
 }
 
 void MappingTraits<ELFYAML::ProgramHeader>::mapping(
@@ -843,7 +884,7 @@ void MappingTraits<ELFYAML::ProgramHeader>::mapping(
   IO.mapOptional("Flags", Phdr.Flags, ELFYAML::ELF_PF(0));
   IO.mapOptional("Sections", Phdr.Sections);
   IO.mapOptional("VAddr", Phdr.VAddr, Hex64(0));
-  IO.mapOptional("PAddr", Phdr.PAddr, Hex64(0));
+  IO.mapOptional("PAddr", Phdr.PAddr, Phdr.VAddr);
   IO.mapOptional("Align", Phdr.Align);
   IO.mapOptional("FileSize", Phdr.FileSize);
   IO.mapOptional("MemSize", Phdr.MemSize);
@@ -977,9 +1018,41 @@ struct NormalizedOther {
 
 } // end anonymous namespace
 
+void ScalarTraits<ELFYAML::YAMLIntUInt>::output(const ELFYAML::YAMLIntUInt &Val,
+                                                void *Ctx, raw_ostream &Out) {
+  Out << Val;
+}
+
+StringRef ScalarTraits<ELFYAML::YAMLIntUInt>::input(StringRef Scalar, void *Ctx,
+                                                    ELFYAML::YAMLIntUInt &Val) {
+  const bool Is64 = static_cast<ELFYAML::Object *>(Ctx)->Header.Class ==
+                    ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
+  StringRef ErrMsg = "invalid number";
+  // We do not accept negative hex numbers because their meaning is ambiguous.
+  // For example, would -0xfffffffff mean 1 or INT32_MIN?
+  if (Scalar.empty() || Scalar.startswith("-0x"))
+    return ErrMsg;
+
+  if (Scalar.startswith("-")) {
+    const int64_t MinVal = Is64 ? INT64_MIN : INT32_MIN;
+    long long Int;
+    if (getAsSignedInteger(Scalar, /*Radix=*/0, Int) || (Int < MinVal))
+      return ErrMsg;
+    Val = Int;
+    return "";
+  }
+
+  const uint64_t MaxVal = Is64 ? UINT64_MAX : UINT32_MAX;
+  unsigned long long UInt;
+  if (getAsUnsignedInteger(Scalar, /*Radix=*/0, UInt) || (UInt > MaxVal))
+    return ErrMsg;
+  Val = UInt;
+  return "";
+}
+
 void MappingTraits<ELFYAML::Symbol>::mapping(IO &IO, ELFYAML::Symbol &Symbol) {
   IO.mapOptional("Name", Symbol.Name, StringRef());
-  IO.mapOptional("NameIndex", Symbol.NameIndex);
+  IO.mapOptional("StName", Symbol.StName);
   IO.mapOptional("Type", Symbol.Type, ELFYAML::ELF_STT(0));
   IO.mapOptional("Section", Symbol.Section, StringRef());
   IO.mapOptional("Index", Symbol.Index);
@@ -1001,8 +1074,6 @@ StringRef MappingTraits<ELFYAML::Symbol>::validate(IO &IO,
                                                    ELFYAML::Symbol &Symbol) {
   if (Symbol.Index && Symbol.Section.data())
     return "Index and Section cannot both be specified for Symbol";
-  if (Symbol.NameIndex && !Symbol.Name.empty())
-    return "Name and NameIndex cannot both be specified for Symbol";
   return StringRef();
 }
 
@@ -1010,10 +1081,11 @@ static void commonSectionMapping(IO &IO, ELFYAML::Section &Section) {
   IO.mapOptional("Name", Section.Name, StringRef());
   IO.mapRequired("Type", Section.Type);
   IO.mapOptional("Flags", Section.Flags);
-  IO.mapOptional("Address", Section.Address, Hex64(0));
+  IO.mapOptional("Address", Section.Address);
   IO.mapOptional("Link", Section.Link, StringRef());
   IO.mapOptional("AddressAlign", Section.AddressAlign, Hex64(0));
   IO.mapOptional("EntSize", Section.EntSize);
+  IO.mapOptional("Offset", Section.Offset);
 
   // obj2yaml does not dump these fields. They are expected to be empty when we
   // are producing YAML, because yaml2obj sets appropriate values for them
@@ -1036,6 +1108,17 @@ static void sectionMapping(IO &IO, ELFYAML::DynamicSection &Section) {
 static void sectionMapping(IO &IO, ELFYAML::RawContentSection &Section) {
   commonSectionMapping(IO, Section);
   IO.mapOptional("Content", Section.Content);
+
+  // We also support reading a content as array of bytes using the ContentArray
+  // key. obj2yaml never prints this field.
+  assert(!IO.outputting() || !Section.ContentBuf.hasValue());
+  IO.mapOptional("ContentArray", Section.ContentBuf);
+  if (Section.ContentBuf) {
+    if (Section.Content)
+      IO.setError("Content and ContentArray can't be used together");
+    Section.Content = yaml::BinaryRef(*Section.ContentBuf);
+  }
+
   IO.mapOptional("Size", Section.Size);
   IO.mapOptional("Info", Section.Info);
 }
@@ -1053,6 +1136,13 @@ static void sectionMapping(IO &IO, ELFYAML::HashSection &Section) {
   IO.mapOptional("Bucket", Section.Bucket);
   IO.mapOptional("Chain", Section.Chain);
   IO.mapOptional("Size", Section.Size);
+
+  // obj2yaml does not dump these fields. They can be used to override nchain
+  // and nbucket values for creating broken sections.
+  assert(!IO.outputting() ||
+         (!Section.NBucket.hasValue() && !Section.NChain.hasValue()));
+  IO.mapOptional("NChain", Section.NChain);
+  IO.mapOptional("NBucket", Section.NBucket);
 }
 
 static void sectionMapping(IO &IO, ELFYAML::NoteSection &Section) {
@@ -1128,6 +1218,7 @@ static void sectionMapping(IO &IO, ELFYAML::AddrsigSection &Section) {
 static void fillMapping(IO &IO, ELFYAML::Fill &Fill) {
   IO.mapOptional("Name", Fill.Name, StringRef());
   IO.mapOptional("Pattern", Fill.Pattern);
+  IO.mapOptional("Offset", Fill.Offset);
   IO.mapRequired("Size", Fill.Size);
 }
 
@@ -1144,6 +1235,12 @@ static void sectionMapping(IO &IO,
   IO.mapOptional("Content", Section.Content);
 }
 
+static void sectionMapping(IO &IO, ELFYAML::CallGraphProfileSection &Section) {
+  commonSectionMapping(IO, Section);
+  IO.mapOptional("Entries", Section.Entries);
+  IO.mapOptional("Content", Section.Content);
+}
+
 void MappingTraits<ELFYAML::SectionOrType>::mapping(
     IO &IO, ELFYAML::SectionOrType &sectionOrType) {
   IO.mapRequired("SectionOrType", sectionOrType.sectionNameOrType);
@@ -1277,6 +1374,11 @@ void MappingTraits<std::unique_ptr<ELFYAML::Chunk>>::mapping(
     sectionMapping(IO,
                    *cast<ELFYAML::DependentLibrariesSection>(Section.get()));
     break;
+  case ELF::SHT_LLVM_CALL_GRAPH_PROFILE:
+    if (!IO.outputting())
+      Section.reset(new ELFYAML::CallGraphProfileSection());
+    sectionMapping(IO, *cast<ELFYAML::CallGraphProfileSection>(Section.get()));
+    break;
   default:
     if (!IO.outputting()) {
       StringRef Name;
@@ -1367,11 +1469,6 @@ StringRef MappingTraits<std::unique_ptr<ELFYAML::Chunk>>::validate(
 
     if (!Sec->Symbols)
       return {};
-
-    for (const ELFYAML::AddrsigSymbol &AS : *Sec->Symbols)
-      if (AS.Index && AS.Name)
-        return "\"Index\" and \"Name\" cannot be used together when defining a "
-               "symbol";
     return {};
   }
 
@@ -1458,6 +1555,12 @@ StringRef MappingTraits<std::unique_ptr<ELFYAML::Chunk>>::validate(
     return {};
   }
 
+  if (const auto *CGP = dyn_cast<ELFYAML::CallGraphProfileSection>(C.get())) {
+    if (CGP->Entries && CGP->Content)
+      return "\"Entries\" and \"Content\" can't be used together";
+    return {};
+  }
+
   return {};
 }
 
@@ -1553,7 +1656,7 @@ void MappingTraits<ELFYAML::Relocation>::mapping(IO &IO,
   const auto *Object = static_cast<ELFYAML::Object *>(IO.getContext());
   assert(Object && "The IO context is not initialized");
 
-  IO.mapRequired("Offset", Rel.Offset);
+  IO.mapOptional("Offset", Rel.Offset, (Hex64)0);
   IO.mapOptional("Symbol", Rel.Symbol);
 
   if (Object->Header.Machine == ELFYAML::ELF_EM(ELF::EM_MIPS) &&
@@ -1567,7 +1670,7 @@ void MappingTraits<ELFYAML::Relocation>::mapping(IO &IO,
   } else
     IO.mapRequired("Type", Rel.Type);
 
-  IO.mapOptional("Addend", Rel.Addend, (int64_t)0);
+  IO.mapOptional("Addend", Rel.Addend, (ELFYAML::YAMLIntUInt)0);
 }
 
 void MappingTraits<ELFYAML::Object>::mapping(IO &IO, ELFYAML::Object &Object) {
@@ -1575,19 +1678,21 @@ void MappingTraits<ELFYAML::Object>::mapping(IO &IO, ELFYAML::Object &Object) {
   IO.setContext(&Object);
   IO.mapTag("!ELF", true);
   IO.mapRequired("FileHeader", Object.Header);
+  IO.mapOptional("SectionHeaderTable", Object.SectionHeaders);
   IO.mapOptional("ProgramHeaders", Object.ProgramHeaders);
   IO.mapOptional("Sections", Object.Chunks);
   IO.mapOptional("Symbols", Object.Symbols);
   IO.mapOptional("DynamicSymbols", Object.DynamicSymbols);
+  IO.mapOptional("DWARF", Object.DWARF);
+  if (Object.DWARF) {
+    Object.DWARF->IsLittleEndian =
+        Object.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
+    Object.DWARF->Is64BitAddrSize =
+        Object.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
+  }
   IO.setContext(nullptr);
 }
 
-void MappingTraits<ELFYAML::AddrsigSymbol>::mapping(IO &IO, ELFYAML::AddrsigSymbol &Sym) {
-  assert(IO.getContext() && "The IO context is not initialized");
-  IO.mapOptional("Name", Sym.Name);
-  IO.mapOptional("Index", Sym.Index);
-}
-
 void MappingTraits<ELFYAML::LinkerOption>::mapping(IO &IO,
                                                    ELFYAML::LinkerOption &Opt) {
   assert(IO.getContext() && "The IO context is not initialized");
@@ -1595,6 +1700,14 @@ void MappingTraits<ELFYAML::LinkerOption>::mapping(IO &IO,
   IO.mapRequired("Value", Opt.Value);
 }
 
+void MappingTraits<ELFYAML::CallGraphEntry>::mapping(
+    IO &IO, ELFYAML::CallGraphEntry &E) {
+  assert(IO.getContext() && "The IO context is not initialized");
+  IO.mapRequired("From", E.From);
+  IO.mapRequired("To", E.To);
+  IO.mapRequired("Weight", E.Weight);
+}
+
 LLVM_YAML_STRONG_TYPEDEF(uint8_t, MIPS_AFL_REG)
 LLVM_YAML_STRONG_TYPEDEF(uint8_t, MIPS_ABI_FP)
 LLVM_YAML_STRONG_TYPEDEF(uint32_t, MIPS_AFL_EXT)
diff --git a/llvm/lib/ObjectYAML/MachOEmitter.cpp b/llvm/lib/ObjectYAML/MachOEmitter.cpp
index bda4aed885b48..680264484704b 100644
--- a/llvm/lib/ObjectYAML/MachOEmitter.cpp
+++ b/llvm/lib/ObjectYAML/MachOEmitter.cpp
@@ -15,6 +15,8 @@
 #include "llvm/ObjectYAML/DWARFEmitter.h"
 #include "llvm/ObjectYAML/ObjectYAML.h"
 #include "llvm/ObjectYAML/yaml2obj.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
@@ -33,12 +35,13 @@ public:
     memset(reinterpret_cast<void *>(&Header), 0, sizeof(MachO::mach_header_64));
   }
 
-  void writeMachO(raw_ostream &OS);
+  Error writeMachO(raw_ostream &OS);
 
 private:
   void writeHeader(raw_ostream &OS);
   void writeLoadCommands(raw_ostream &OS);
-  void writeSectionData(raw_ostream &OS);
+  Error writeSectionData(raw_ostream &OS);
+  void writeRelocations(raw_ostream &OS);
   void writeLinkEditData(raw_ostream &OS);
 
   void writeBindOpcodes(raw_ostream &OS,
@@ -58,15 +61,23 @@ private:
   MachOYAML::Object &Obj;
   bool is64Bit;
   uint64_t fileStart;
-
   MachO::mach_header_64 Header;
+
+  // Old PPC Object Files didn't have __LINKEDIT segments, the data was just
+  // stuck at the end of the file.
+  bool FoundLinkEditSeg = false;
 };
 
-void MachOWriter::writeMachO(raw_ostream &OS) {
+Error MachOWriter::writeMachO(raw_ostream &OS) {
   fileStart = OS.tell();
   writeHeader(OS);
   writeLoadCommands(OS);
-  writeSectionData(OS);
+  if (Error Err = writeSectionData(OS))
+    return Err;
+  writeRelocations(OS);
+  if (!FoundLinkEditSeg)
+    writeLinkEditData(OS);
+  return Error::success();
 }
 
 void MachOWriter::writeHeader(raw_ostream &OS) {
@@ -254,8 +265,7 @@ void MachOWriter::writeLoadCommands(raw_ostream &OS) {
   }
 }
 
-void MachOWriter::writeSectionData(raw_ostream &OS) {
-  bool FoundLinkEditSeg = false;
+Error MachOWriter::writeSectionData(raw_ostream &OS) {
   for (auto &LC : Obj.LoadCommands) {
     switch (LC.Data.load_command_data.cmd) {
     case MachO::LC_SEGMENT:
@@ -271,27 +281,37 @@ void MachOWriter::writeSectionData(raw_ostream &OS) {
         ZeroToOffset(OS, Sec.offset);
         // Zero Fill any data between the end of the last thing we wrote and the
         // start of this section.
-        assert((OS.tell() - fileStart <= Sec.offset ||
-                Sec.offset == (uint32_t)0) &&
-               "Wrote too much data somewhere, section offsets don't line up.");
+        if (OS.tell() - fileStart > Sec.offset && Sec.offset != (uint32_t)0)
+          return createStringError(
+              errc::invalid_argument,
+              "wrote too much data somewhere, section offsets don't line up");
         if (0 == strncmp(&Sec.segname[0], "__DWARF", 16)) {
-          if (0 == strncmp(&Sec.sectname[0], "__debug_str", 16)) {
-            DWARFYAML::EmitDebugStr(OS, Obj.DWARF);
-          } else if (0 == strncmp(&Sec.sectname[0], "__debug_abbrev", 16)) {
-            DWARFYAML::EmitDebugAbbrev(OS, Obj.DWARF);
-          } else if (0 == strncmp(&Sec.sectname[0], "__debug_aranges", 16)) {
-            DWARFYAML::EmitDebugAranges(OS, Obj.DWARF);
-          } else if (0 == strncmp(&Sec.sectname[0], "__debug_pubnames", 16)) {
-            DWARFYAML::EmitPubSection(OS, Obj.DWARF.PubNames,
-                                      Obj.IsLittleEndian);
+          Error Err = Error::success();
+          cantFail(std::move(Err));
+
+          if (0 == strncmp(&Sec.sectname[0], "__debug_str", 16))
+            Err = DWARFYAML::emitDebugStr(OS, Obj.DWARF);
+          else if (0 == strncmp(&Sec.sectname[0], "__debug_abbrev", 16))
+            Err = DWARFYAML::emitDebugAbbrev(OS, Obj.DWARF);
+          else if (0 == strncmp(&Sec.sectname[0], "__debug_aranges", 16))
+            Err = DWARFYAML::emitDebugAranges(OS, Obj.DWARF);
+          else if (0 == strncmp(&Sec.sectname[0], "__debug_ranges", 16))
+            Err = DWARFYAML::emitDebugRanges(OS, Obj.DWARF);
+          else if (0 == strncmp(&Sec.sectname[0], "__debug_pubnames", 16)) {
+            if (Obj.DWARF.PubNames)
+              Err = DWARFYAML::emitPubSection(OS, *Obj.DWARF.PubNames,
+                                              Obj.IsLittleEndian);
           } else if (0 == strncmp(&Sec.sectname[0], "__debug_pubtypes", 16)) {
-            DWARFYAML::EmitPubSection(OS, Obj.DWARF.PubTypes,
-                                      Obj.IsLittleEndian);
-          } else if (0 == strncmp(&Sec.sectname[0], "__debug_info", 16)) {
-            DWARFYAML::EmitDebugInfo(OS, Obj.DWARF);
-          } else if (0 == strncmp(&Sec.sectname[0], "__debug_line", 16)) {
-            DWARFYAML::EmitDebugLine(OS, Obj.DWARF);
-          }
+            if (Obj.DWARF.PubTypes)
+              Err = DWARFYAML::emitPubSection(OS, *Obj.DWARF.PubTypes,
+                                              Obj.IsLittleEndian);
+          } else if (0 == strncmp(&Sec.sectname[0], "__debug_info", 16))
+            Err = DWARFYAML::emitDebugInfo(OS, Obj.DWARF);
+          else if (0 == strncmp(&Sec.sectname[0], "__debug_line", 16))
+            Err = DWARFYAML::emitDebugLine(OS, Obj.DWARF);
+
+          if (Err)
+            return Err;
 
           continue;
         }
@@ -315,10 +335,62 @@ void MachOWriter::writeSectionData(raw_ostream &OS) {
       break;
     }
   }
-  // Old PPC Object Files didn't have __LINKEDIT segments, the data was just
-  // stuck at the end of the file.
-  if (!FoundLinkEditSeg)
-    writeLinkEditData(OS);
+
+  return Error::success();
+}
+
+// The implementation of makeRelocationInfo and makeScatteredRelocationInfo is
+// consistent with how libObject parses MachO binary files. For the reference
+// see getStruct, getRelocation, getPlainRelocationPCRel,
+// getPlainRelocationLength and related methods in MachOObjectFile.cpp
+static MachO::any_relocation_info
+makeRelocationInfo(const MachOYAML::Relocation &R, bool IsLE) {
+  assert(!R.is_scattered && "non-scattered relocation expected");
+  MachO::any_relocation_info MRE;
+  MRE.r_word0 = R.address;
+  if (IsLE)
+    MRE.r_word1 = ((unsigned)R.symbolnum << 0) | ((unsigned)R.is_pcrel << 24) |
+                  ((unsigned)R.length << 25) | ((unsigned)R.is_extern << 27) |
+                  ((unsigned)R.type << 28);
+  else
+    MRE.r_word1 = ((unsigned)R.symbolnum << 8) | ((unsigned)R.is_pcrel << 7) |
+                  ((unsigned)R.length << 5) | ((unsigned)R.is_extern << 4) |
+                  ((unsigned)R.type << 0);
+  return MRE;
+}
+
+static MachO::any_relocation_info
+makeScatteredRelocationInfo(const MachOYAML::Relocation &R) {
+  assert(R.is_scattered && "scattered relocation expected");
+  MachO::any_relocation_info MRE;
+  MRE.r_word0 = (((unsigned)R.address << 0) | ((unsigned)R.type << 24) |
+                 ((unsigned)R.length << 28) | ((unsigned)R.is_pcrel << 30) |
+                 MachO::R_SCATTERED);
+  MRE.r_word1 = R.value;
+  return MRE;
+}
+
+void MachOWriter::writeRelocations(raw_ostream &OS) {
+  for (const MachOYAML::LoadCommand &LC : Obj.LoadCommands) {
+    switch (LC.Data.load_command_data.cmd) {
+    case MachO::LC_SEGMENT:
+    case MachO::LC_SEGMENT_64:
+      for (const MachOYAML::Section &Sec : LC.Sections) {
+        if (Sec.relocations.empty())
+          continue;
+        ZeroToOffset(OS, Sec.reloff);
+        for (const MachOYAML::Relocation &R : Sec.relocations) {
+          MachO::any_relocation_info MRE =
+              R.is_scattered ? makeScatteredRelocationInfo(R)
+                             : makeRelocationInfo(R, Obj.IsLittleEndian);
+          if (Obj.IsLittleEndian != sys::IsLittleEndianHost)
+            MachO::swapStruct(MRE);
+          OS.write(reinterpret_cast<const char *>(&MRE),
+                   sizeof(MachO::any_relocation_info));
+        }
+      }
+    }
+  }
 }
 
 void MachOWriter::writeBindOpcodes(
@@ -470,7 +542,7 @@ public:
   UniversalWriter(yaml::YamlObjectFile &ObjectFile)
       : ObjectFile(ObjectFile), fileStart(0) {}
 
-  void writeMachO(raw_ostream &OS);
+  Error writeMachO(raw_ostream &OS);
 
 private:
   void writeFatHeader(raw_ostream &OS);
@@ -482,28 +554,33 @@ private:
   uint64_t fileStart;
 };
 
-void UniversalWriter::writeMachO(raw_ostream &OS) {
+Error UniversalWriter::writeMachO(raw_ostream &OS) {
   fileStart = OS.tell();
   if (ObjectFile.MachO) {
     MachOWriter Writer(*ObjectFile.MachO);
-    Writer.writeMachO(OS);
-    return;
+    return Writer.writeMachO(OS);
   }
 
   writeFatHeader(OS);
   writeFatArchs(OS);
 
   auto &FatFile = *ObjectFile.FatMachO;
-  assert(FatFile.FatArchs.size() >= FatFile.Slices.size() &&
-         "Cannot write Slices if not decribed in FatArches");
+  if (FatFile.FatArchs.size() < FatFile.Slices.size())
+    return createStringError(
+        errc::invalid_argument,
+        "cannot write 'Slices' if not described in 'FatArches'");
+
   for (size_t i = 0; i < FatFile.Slices.size(); i++) {
     ZeroToOffset(OS, FatFile.FatArchs[i].offset);
     MachOWriter Writer(FatFile.Slices[i]);
-    Writer.writeMachO(OS);
+    if (Error Err = Writer.writeMachO(OS))
+      return Err;
 
     auto SliceEnd = FatFile.FatArchs[i].offset + FatFile.FatArchs[i].size;
     ZeroToOffset(OS, SliceEnd);
   }
+
+  return Error::success();
 }
 
 void UniversalWriter::writeFatHeader(raw_ostream &OS) {
@@ -571,9 +648,13 @@ void UniversalWriter::ZeroToOffset(raw_ostream &OS, size_t Offset) {
 namespace llvm {
 namespace yaml {
 
-bool yaml2macho(YamlObjectFile &Doc, raw_ostream &Out, ErrorHandler /*EH*/) {
+bool yaml2macho(YamlObjectFile &Doc, raw_ostream &Out, ErrorHandler EH) {
   UniversalWriter Writer(Doc);
-  Writer.writeMachO(Out);
+  if (Error Err = Writer.writeMachO(Out)) {
+    handleAllErrors(std::move(Err),
+                    [&](const ErrorInfoBase &Err) { EH(Err.message()); });
+    return false;
+  }
   return true;
 }
 
diff --git a/llvm/lib/ObjectYAML/MachOYAML.cpp b/llvm/lib/ObjectYAML/MachOYAML.cpp
index 0f7cd1e1495cb..86aad0233767e 100644
--- a/llvm/lib/ObjectYAML/MachOYAML.cpp
+++ b/llvm/lib/ObjectYAML/MachOYAML.cpp
@@ -107,6 +107,8 @@ void MappingTraits<MachOYAML::Object>::mapping(IO &IO,
   Object.DWARF.IsLittleEndian = Object.IsLittleEndian;
 
   IO.mapRequired("FileHeader", Object.Header);
+  Object.DWARF.Is64BitAddrSize = Object.Header.magic == MachO::MH_MAGIC_64 ||
+                                 Object.Header.magic == MachO::MH_CIGAM_64;
   IO.mapOptional("LoadCommands", Object.LoadCommands);
   if(!Object.LinkEdit.isEmpty() || !IO.outputting())
     IO.mapOptional("LinkEditData", Object.LinkEdit);
@@ -273,6 +275,18 @@ void MappingTraits<MachO::dyld_info_command>::mapping(
   IO.mapRequired("export_size", LoadCommand.export_size);
 }
 
+void MappingTraits<MachOYAML::Relocation>::mapping(
+    IO &IO, MachOYAML::Relocation &Relocation) {
+  IO.mapRequired("address", Relocation.address);
+  IO.mapRequired("symbolnum", Relocation.symbolnum);
+  IO.mapRequired("pcrel", Relocation.is_pcrel);
+  IO.mapRequired("length", Relocation.length);
+  IO.mapRequired("extern", Relocation.is_extern);
+  IO.mapRequired("type", Relocation.type);
+  IO.mapRequired("scattered", Relocation.is_scattered);
+  IO.mapRequired("value", Relocation.value);
+}
+
 void MappingTraits<MachOYAML::Section>::mapping(IO &IO,
                                                 MachOYAML::Section &Section) {
   IO.mapRequired("sectname", Section.sectname);
@@ -288,6 +302,7 @@ void MappingTraits<MachOYAML::Section>::mapping(IO &IO,
   IO.mapRequired("reserved2", Section.reserved2);
   IO.mapOptional("reserved3", Section.reserved3);
   IO.mapOptional("content", Section.content);
+  IO.mapOptional("relocations", Section.relocations);
 }
 
 StringRef
diff --git a/llvm/lib/ObjectYAML/WasmEmitter.cpp b/llvm/lib/ObjectYAML/WasmEmitter.cpp
index debc040587a87..cbb062d87ae63 100644
--- a/llvm/lib/ObjectYAML/WasmEmitter.cpp
+++ b/llvm/lib/ObjectYAML/WasmEmitter.cpp
@@ -41,8 +41,8 @@ private:
   void writeSectionContent(raw_ostream &OS, WasmYAML::FunctionSection &Section);
   void writeSectionContent(raw_ostream &OS, WasmYAML::TableSection &Section);
   void writeSectionContent(raw_ostream &OS, WasmYAML::MemorySection &Section);
-  void writeSectionContent(raw_ostream &OS, WasmYAML::GlobalSection &Section);
   void writeSectionContent(raw_ostream &OS, WasmYAML::EventSection &Section);
+  void writeSectionContent(raw_ostream &OS, WasmYAML::GlobalSection &Section);
   void writeSectionContent(raw_ostream &OS, WasmYAML::ExportSection &Section);
   void writeSectionContent(raw_ostream &OS, WasmYAML::StartSection &Section);
   void writeSectionContent(raw_ostream &OS, WasmYAML::ElemSection &Section);
@@ -415,6 +415,21 @@ void WasmWriter::writeSectionContent(raw_ostream &OS,
 }
 
 void WasmWriter::writeSectionContent(raw_ostream &OS,
+                                     WasmYAML::EventSection &Section) {
+  encodeULEB128(Section.Events.size(), OS);
+  uint32_t ExpectedIndex = NumImportedEvents;
+  for (auto &Event : Section.Events) {
+    if (Event.Index != ExpectedIndex) {
+      reportError("unexpected event index: " + Twine(Event.Index));
+      return;
+    }
+    ++ExpectedIndex;
+    encodeULEB128(Event.Attribute, OS);
+    encodeULEB128(Event.SigIndex, OS);
+  }
+}
+
+void WasmWriter::writeSectionContent(raw_ostream &OS,
                                      WasmYAML::GlobalSection &Section) {
   encodeULEB128(Section.Globals.size(), OS);
   uint32_t ExpectedIndex = NumImportedGlobals;
@@ -431,21 +446,6 @@ void WasmWriter::writeSectionContent(raw_ostream &OS,
 }
 
 void WasmWriter::writeSectionContent(raw_ostream &OS,
-                                    WasmYAML::EventSection &Section) {
-  encodeULEB128(Section.Events.size(), OS);
-  uint32_t ExpectedIndex = NumImportedEvents;
-  for (auto &Event : Section.Events) {
-    if (Event.Index != ExpectedIndex) {
-      reportError("unexpected event index: " + Twine(Event.Index));
-      return;
-    }
-    ++ExpectedIndex;
-    encodeULEB128(Event.Attribute, OS);
-    encodeULEB128(Event.SigIndex, OS);
-  }
-}
-
-void WasmWriter::writeSectionContent(raw_ostream &OS,
                                      WasmYAML::ElemSection &Section) {
   encodeULEB128(Section.Segments.size(), OS);
   for (auto &Segment : Section.Segments) {
@@ -532,8 +532,11 @@ void WasmWriter::writeRelocSection(raw_ostream &OS, WasmYAML::Section &Sec,
     encodeULEB128(Reloc.Index, OS);
     switch (Reloc.Type) {
     case wasm::R_WASM_MEMORY_ADDR_LEB:
+    case wasm::R_WASM_MEMORY_ADDR_LEB64:
     case wasm::R_WASM_MEMORY_ADDR_SLEB:
+    case wasm::R_WASM_MEMORY_ADDR_SLEB64:
     case wasm::R_WASM_MEMORY_ADDR_I32:
+    case wasm::R_WASM_MEMORY_ADDR_I64:
     case wasm::R_WASM_FUNCTION_OFFSET_I32:
     case wasm::R_WASM_SECTION_OFFSET_I32:
       encodeULEB128(Reloc.Addend, OS);
@@ -571,10 +574,10 @@ bool WasmWriter::writeWasm(raw_ostream &OS) {
       writeSectionContent(StringStream, *S);
     else if (auto S = dyn_cast<WasmYAML::MemorySection>(Sec.get()))
       writeSectionContent(StringStream, *S);
-    else if (auto S = dyn_cast<WasmYAML::GlobalSection>(Sec.get()))
-      writeSectionContent(StringStream, *S);
     else if (auto S = dyn_cast<WasmYAML::EventSection>(Sec.get()))
       writeSectionContent(StringStream, *S);
+    else if (auto S = dyn_cast<WasmYAML::GlobalSection>(Sec.get()))
+      writeSectionContent(StringStream, *S);
     else if (auto S = dyn_cast<WasmYAML::ExportSection>(Sec.get()))
       writeSectionContent(StringStream, *S);
     else if (auto S = dyn_cast<WasmYAML::StartSection>(Sec.get()))
diff --git a/llvm/lib/ObjectYAML/WasmYAML.cpp b/llvm/lib/ObjectYAML/WasmYAML.cpp
index 232d5122004a7..d1aa1181a3445 100644
--- a/llvm/lib/ObjectYAML/WasmYAML.cpp
+++ b/llvm/lib/ObjectYAML/WasmYAML.cpp
@@ -118,14 +118,14 @@ static void sectionMapping(IO &IO, WasmYAML::MemorySection &Section) {
   IO.mapOptional("Memories", Section.Memories);
 }
 
-static void sectionMapping(IO &IO, WasmYAML::GlobalSection &Section) {
+static void sectionMapping(IO &IO, WasmYAML::EventSection &Section) {
   commonSectionMapping(IO, Section);
-  IO.mapOptional("Globals", Section.Globals);
+  IO.mapOptional("Events", Section.Events);
 }
 
-static void sectionMapping(IO &IO, WasmYAML::EventSection &Section) {
+static void sectionMapping(IO &IO, WasmYAML::GlobalSection &Section) {
   commonSectionMapping(IO, Section);
-  IO.mapOptional("Events", Section.Events);
+  IO.mapOptional("Globals", Section.Globals);
 }
 
 static void sectionMapping(IO &IO, WasmYAML::ExportSection &Section) {
@@ -227,16 +227,16 @@ void MappingTraits<std::unique_ptr<WasmYAML::Section>>::mapping(
       Section.reset(new WasmYAML::MemorySection());
     sectionMapping(IO, *cast<WasmYAML::MemorySection>(Section.get()));
     break;
-  case wasm::WASM_SEC_GLOBAL:
-    if (!IO.outputting())
-      Section.reset(new WasmYAML::GlobalSection());
-    sectionMapping(IO, *cast<WasmYAML::GlobalSection>(Section.get()));
-    break;
   case wasm::WASM_SEC_EVENT:
     if (!IO.outputting())
       Section.reset(new WasmYAML::EventSection());
     sectionMapping(IO, *cast<WasmYAML::EventSection>(Section.get()));
     break;
+  case wasm::WASM_SEC_GLOBAL:
+    if (!IO.outputting())
+      Section.reset(new WasmYAML::GlobalSection());
+    sectionMapping(IO, *cast<WasmYAML::GlobalSection>(Section.get()));
+    break;
   case wasm::WASM_SEC_EXPORT:
     if (!IO.outputting())
       Section.reset(new WasmYAML::ExportSection());
@@ -433,6 +433,11 @@ void MappingTraits<wasm::WasmInitExpr>::mapping(IO &IO,
   case wasm::WASM_OPCODE_GLOBAL_GET:
     IO.mapRequired("Index", Expr.Value.Global);
     break;
+  case wasm::WASM_OPCODE_REF_NULL: {
+    WasmYAML::ValueType Ty = wasm::WASM_TYPE_EXTERNREF;
+    IO.mapRequired("Type", Ty);
+    break;
+  }
   }
 }
 
@@ -517,6 +522,7 @@ void ScalarBitSetTraits<WasmYAML::LimitFlags>::bitset(
 #define BCase(X) IO.bitSetCase(Value, #X, wasm::WASM_LIMITS_FLAG_##X)
   BCase(HAS_MAX);
   BCase(IS_SHARED);
+  BCase(IS_64);
 #undef BCase
 }
 
@@ -559,6 +565,8 @@ void ScalarEnumerationTraits<WasmYAML::ValueType>::enumeration(
   ECase(F64);
   ECase(V128);
   ECase(FUNCREF);
+  ECase(EXNREF);
+  ECase(EXTERNREF);
   ECase(FUNC);
 #undef ECase
 }
@@ -583,6 +591,7 @@ void ScalarEnumerationTraits<WasmYAML::Opcode>::enumeration(
   ECase(F64_CONST);
   ECase(F32_CONST);
   ECase(GLOBAL_GET);
+  ECase(REF_NULL);
 #undef ECase
 }
 
diff --git a/llvm/lib/ObjectYAML/yaml2obj.cpp b/llvm/lib/ObjectYAML/yaml2obj.cpp
index c18fa5cfdb5e7..a04345f1294a2 100644
--- a/llvm/lib/ObjectYAML/yaml2obj.cpp
+++ b/llvm/lib/ObjectYAML/yaml2obj.cpp
@@ -19,7 +19,7 @@ namespace llvm {
 namespace yaml {
 
 bool convertYAML(yaml::Input &YIn, raw_ostream &Out, ErrorHandler ErrHandler,
-                 unsigned DocNum) {
+                 unsigned DocNum, uint64_t MaxSize) {
   unsigned CurDocNum = 0;
   do {
     if (++CurDocNum != DocNum)
@@ -33,7 +33,7 @@ bool convertYAML(yaml::Input &YIn, raw_ostream &Out, ErrorHandler ErrHandler,
     }
 
     if (Doc.Elf)
-      return yaml2elf(*Doc.Elf, Out, ErrHandler);
+      return yaml2elf(*Doc.Elf, Out, ErrHandler, MaxSize);
     if (Doc.Coff)
       return yaml2coff(*Doc.Coff, Out, ErrHandler);
     if (Doc.MachO || Doc.FatMachO)