vendor/llvm/llvm-trunk-r375505vendor/llvm

5 files changed, 429 insertions, 225 deletions

diff --git a/tools/llvm-objcopy/ELF/ELFConfig.cpp b/tools/llvm-objcopy/ELF/ELFConfig.cpp
new file mode 100644
index 000000000000..40993760add7
--- /dev/null
+++ b/tools/llvm-objcopy/ELF/ELFConfig.cpp
@@ -0,0 +1,133 @@
+//===- ELFConfig.cpp ------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "CopyConfig.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/Errc.h"
+#include "llvm/Support/Error.h"
+
+namespace llvm {
+namespace objcopy {
+namespace elf {
+
+static Expected<NewSymbolInfo> parseNewSymbolInfo(StringRef FlagValue,
+                                                  uint8_t DefaultVisibility) {
+  // Parse value given with --add-symbol option and create the
+  // new symbol if possible. The value format for --add-symbol is:
+  //
+  // <name>=[<section>:]<value>[,<flags>]
+  //
+  // where:
+  // <name> - symbol name, can be empty string
+  // <section> - optional section name. If not given ABS symbol is created
+  // <value> - symbol value, can be decimal or hexadecimal number prefixed
+  //           with 0x.
+  // <flags> - optional flags affecting symbol type, binding or visibility:
+  //           The following are currently supported:
+  //
+  //           global, local, weak, default, hidden, file, section, object,
+  //           indirect-function.
+  //
+  //           The following flags are ignored and provided for GNU
+  //           compatibility only:
+  //
+  //           warning, debug, constructor, indirect, synthetic,
+  //           unique-object, before=<symbol>.
+  NewSymbolInfo SI;
+  StringRef Value;
+  std::tie(SI.SymbolName, Value) = FlagValue.split('=');
+  if (Value.empty())
+    return createStringError(
+        errc::invalid_argument,
+        "bad format for --add-symbol, missing '=' after '%s'",
+        SI.SymbolName.str().c_str());
+
+  if (Value.contains(':')) {
+    std::tie(SI.SectionName, Value) = Value.split(':');
+    if (SI.SectionName.empty() || Value.empty())
+      return createStringError(
+          errc::invalid_argument,
+          "bad format for --add-symbol, missing section name or symbol value");
+  }
+
+  SmallVector<StringRef, 6> Flags;
+  Value.split(Flags, ',');
+  if (Flags[0].getAsInteger(0, SI.Value))
+    return createStringError(errc::invalid_argument, "bad symbol value: '%s'",
+                             Flags[0].str().c_str());
+
+  SI.Visibility = DefaultVisibility;
+
+  using Functor = std::function<void(void)>;
+  SmallVector<StringRef, 6> UnsupportedFlags;
+  for (size_t I = 1, NumFlags = Flags.size(); I < NumFlags; ++I)
+    static_cast<Functor>(
+        StringSwitch<Functor>(Flags[I])
+            .CaseLower("global", [&SI] { SI.Bind = ELF::STB_GLOBAL; })
+            .CaseLower("local", [&SI] { SI.Bind = ELF::STB_LOCAL; })
+            .CaseLower("weak", [&SI] { SI.Bind = ELF::STB_WEAK; })
+            .CaseLower("default", [&SI] { SI.Visibility = ELF::STV_DEFAULT; })
+            .CaseLower("hidden", [&SI] { SI.Visibility = ELF::STV_HIDDEN; })
+            .CaseLower("protected",
+                       [&SI] { SI.Visibility = ELF::STV_PROTECTED; })
+            .CaseLower("file", [&SI] { SI.Type = ELF::STT_FILE; })
+            .CaseLower("section", [&SI] { SI.Type = ELF::STT_SECTION; })
+            .CaseLower("object", [&SI] { SI.Type = ELF::STT_OBJECT; })
+            .CaseLower("function", [&SI] { SI.Type = ELF::STT_FUNC; })
+            .CaseLower("indirect-function",
+                       [&SI] { SI.Type = ELF::STT_GNU_IFUNC; })
+            .CaseLower("debug", [] {})
+            .CaseLower("constructor", [] {})
+            .CaseLower("warning", [] {})
+            .CaseLower("indirect", [] {})
+            .CaseLower("synthetic", [] {})
+            .CaseLower("unique-object", [] {})
+            .StartsWithLower("before", [] {})
+            .Default([&] { UnsupportedFlags.push_back(Flags[I]); }))();
+  if (!UnsupportedFlags.empty())
+    return createStringError(errc::invalid_argument,
+                             "unsupported flag%s for --add-symbol: '%s'",
+                             UnsupportedFlags.size() > 1 ? "s" : "",
+                             join(UnsupportedFlags, "', '").c_str());
+  return SI;
+}
+
+Expected<ELFCopyConfig> parseConfig(const CopyConfig &Config) {
+  ELFCopyConfig ELFConfig;
+  if (Config.NewSymbolVisibility) {
+    const uint8_t Invalid = 0xff;
+    ELFConfig.NewSymbolVisibility =
+        StringSwitch<uint8_t>(*Config.NewSymbolVisibility)
+            .Case("default", ELF::STV_DEFAULT)
+            .Case("hidden", ELF::STV_HIDDEN)
+            .Case("internal", ELF::STV_INTERNAL)
+            .Case("protected", ELF::STV_PROTECTED)
+            .Default(Invalid);
+
+    if (ELFConfig.NewSymbolVisibility == Invalid)
+      return createStringError(errc::invalid_argument,
+                               "'%s' is not a valid symbol visibility",
+                               Config.NewSymbolVisibility->str().c_str());
+  }
+
+  for (StringRef Arg : Config.SymbolsToAdd) {
+    Expected<elf::NewSymbolInfo> NSI = parseNewSymbolInfo(
+        Arg,
+        ELFConfig.NewSymbolVisibility.getValueOr((uint8_t)ELF::STV_DEFAULT));
+    if (!NSI)
+      return NSI.takeError();
+    ELFConfig.SymbolsToAdd.push_back(*NSI);
+  }
+
+  return ELFConfig;
+}
+
+} // end namespace elf
+} // end namespace objcopy
+} // end namespace llvm
diff --git a/tools/llvm-objcopy/ELF/ELFConfig.h b/tools/llvm-objcopy/ELF/ELFConfig.h
new file mode 100644
index 000000000000..977efbc4166f
--- /dev/null
+++ b/tools/llvm-objcopy/ELF/ELFConfig.h
@@ -0,0 +1,44 @@
+//===- ELFConfig.h ----------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_OBJCOPY_ELFCONFIG_H
+#define LLVM_TOOLS_OBJCOPY_ELFCONFIG_H
+
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Object/ELFTypes.h"
+#include "llvm/Support/Error.h"
+#include <vector>
+
+namespace llvm {
+namespace objcopy {
+struct CopyConfig;
+
+namespace elf {
+
+struct NewSymbolInfo {
+  StringRef SymbolName;
+  StringRef SectionName;
+  uint64_t Value = 0;
+  uint8_t Type = ELF::STT_NOTYPE;
+  uint8_t Bind = ELF::STB_GLOBAL;
+  uint8_t Visibility = ELF::STV_DEFAULT;
+};
+
+struct ELFCopyConfig {
+  Optional<uint8_t> NewSymbolVisibility;
+  std::vector<NewSymbolInfo> SymbolsToAdd;
+};
+
+Expected<ELFCopyConfig> parseConfig(const CopyConfig &Config);
+
+} // namespace elf
+} // namespace objcopy
+} // namespace llvm
+
+#endif
diff --git a/tools/llvm-objcopy/ELF/ELFObjcopy.cpp b/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
index b366c6e55987..8bf7e0f88010 100644
--- a/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
+++ b/tools/llvm-objcopy/ELF/ELFObjcopy.cpp
@@ -136,16 +136,16 @@ static std::unique_ptr<Writer> createELFWriter(const CopyConfig &Config,
   // Depending on the initial ELFT and OutputFormat we need a different Writer.
   switch (OutputElfType) {
   case ELFT_ELF32LE:
-    return llvm::make_unique<ELFWriter<ELF32LE>>(Obj, Buf,
+    return std::make_unique<ELFWriter<ELF32LE>>(Obj, Buf,
                                                  !Config.StripSections);
   case ELFT_ELF64LE:
-    return llvm::make_unique<ELFWriter<ELF64LE>>(Obj, Buf,
+    return std::make_unique<ELFWriter<ELF64LE>>(Obj, Buf,
                                                  !Config.StripSections);
   case ELFT_ELF32BE:
-    return llvm::make_unique<ELFWriter<ELF32BE>>(Obj, Buf,
+    return std::make_unique<ELFWriter<ELF32BE>>(Obj, Buf,
                                                  !Config.StripSections);
   case ELFT_ELF64BE:
-    return llvm::make_unique<ELFWriter<ELF64BE>>(Obj, Buf,
+    return std::make_unique<ELFWriter<ELF64BE>>(Obj, Buf,
                                                  !Config.StripSections);
   }
   llvm_unreachable("Invalid output format");
@@ -156,9 +156,9 @@ static std::unique_ptr<Writer> createWriter(const CopyConfig &Config,
                                             ElfType OutputElfType) {
   switch (Config.OutputFormat) {
   case FileFormat::Binary:
-    return llvm::make_unique<BinaryWriter>(Obj, Buf);
+    return std::make_unique<BinaryWriter>(Obj, Buf);
   case FileFormat::IHex:
-    return llvm::make_unique<IHexWriter>(Obj, Buf);
+    return std::make_unique<IHexWriter>(Obj, Buf);
   default:
     return createELFWriter(Config, Obj, Buf, OutputElfType);
   }
@@ -263,7 +263,7 @@ static Error linkToBuildIdDir(const CopyConfig &Config, StringRef ToLink,
 
 static Error splitDWOToFile(const CopyConfig &Config, const Reader &Reader,
                             StringRef File, ElfType OutputElfType) {
-  auto DWOFile = Reader.create();
+  auto DWOFile = Reader.create(false);
   auto OnlyKeepDWOPred = [&DWOFile](const SectionBase &Sec) {
     return onlyKeepDWOPred(*DWOFile, Sec);
   };
@@ -305,9 +305,9 @@ static Error dumpSectionToFile(StringRef SecName, StringRef Filename,
                            SecName.str().c_str());
 }
 
-static bool isCompressable(const SectionBase &Section) {
-  return !(Section.Flags & ELF::SHF_COMPRESSED) &&
-         StringRef(Section.Name).startswith(".debug");
+static bool isCompressable(const SectionBase &Sec) {
+  return !(Sec.Flags & ELF::SHF_COMPRESSED) &&
+         StringRef(Sec.Name).startswith(".debug");
 }
 
 static void replaceDebugSections(
@@ -356,7 +356,7 @@ static Error updateAndRemoveSymbols(const CopyConfig &Config, Object &Obj) {
     if (!Sym.isCommon() && Sym.getShndx() != SHN_UNDEF &&
         ((Config.LocalizeHidden &&
           (Sym.Visibility == STV_HIDDEN || Sym.Visibility == STV_INTERNAL)) ||
-         is_contained(Config.SymbolsToLocalize, Sym.Name)))
+         Config.SymbolsToLocalize.matches(Sym.Name)))
       Sym.Binding = STB_LOCAL;
 
     // Note: these two globalize flags have very similar names but different
@@ -370,16 +370,15 @@ static Error updateAndRemoveSymbols(const CopyConfig &Config, Object &Obj) {
     // --keep-global-symbol. Because of that, make sure to check
     // --globalize-symbol second.
     if (!Config.SymbolsToKeepGlobal.empty() &&
-        !is_contained(Config.SymbolsToKeepGlobal, Sym.Name) &&
+        !Config.SymbolsToKeepGlobal.matches(Sym.Name) &&
         Sym.getShndx() != SHN_UNDEF)
       Sym.Binding = STB_LOCAL;
 
-    if (is_contained(Config.SymbolsToGlobalize, Sym.Name) &&
+    if (Config.SymbolsToGlobalize.matches(Sym.Name) &&
         Sym.getShndx() != SHN_UNDEF)
       Sym.Binding = STB_GLOBAL;
 
-    if (is_contained(Config.SymbolsToWeaken, Sym.Name) &&
-        Sym.Binding == STB_GLOBAL)
+    if (Config.SymbolsToWeaken.matches(Sym.Name) && Sym.Binding == STB_GLOBAL)
       Sym.Binding = STB_WEAK;
 
     if (Config.Weaken && Sym.Binding == STB_GLOBAL &&
@@ -399,12 +398,12 @@ static Error updateAndRemoveSymbols(const CopyConfig &Config, Object &Obj) {
   // symbols are still 'needed' and which are not.
   if (Config.StripUnneeded || !Config.UnneededSymbolsToRemove.empty() ||
       !Config.OnlySection.empty()) {
-    for (auto &Section : Obj.sections())
-      Section.markSymbols();
+    for (SectionBase &Sec : Obj.sections())
+      Sec.markSymbols();
   }
 
   auto RemoveSymbolsPred = [&](const Symbol &Sym) {
-    if (is_contained(Config.SymbolsToKeep, Sym.Name) ||
+    if (Config.SymbolsToKeep.matches(Sym.Name) ||
         (Config.KeepFileSymbols && Sym.Type == STT_FILE))
       return false;
 
@@ -418,12 +417,12 @@ static Error updateAndRemoveSymbols(const CopyConfig &Config, Object &Obj) {
     if (Config.StripAll || Config.StripAllGNU)
       return true;
 
-    if (is_contained(Config.SymbolsToRemove, Sym.Name))
+    if (Config.SymbolsToRemove.matches(Sym.Name))
       return true;
 
     if ((Config.StripUnneeded ||
-         is_contained(Config.UnneededSymbolsToRemove, Sym.Name)) &&
-        isUnneededSymbol(Sym))
+         Config.UnneededSymbolsToRemove.matches(Sym.Name)) &&
+        (!Obj.isRelocatable() || isUnneededSymbol(Sym)))
       return true;
 
     // We want to remove undefined symbols if all references have been stripped.
@@ -443,7 +442,7 @@ static Error replaceAndRemoveSections(const CopyConfig &Config, Object &Obj) {
   // Removes:
   if (!Config.ToRemove.empty()) {
     RemovePred = [&Config](const SectionBase &Sec) {
-      return is_contained(Config.ToRemove, Sec.Name);
+      return Config.ToRemove.matches(Sec.Name);
     };
   }
 
@@ -481,7 +480,7 @@ static Error replaceAndRemoveSections(const CopyConfig &Config, Object &Obj) {
     };
   }
 
-  if (Config.StripDebug) {
+  if (Config.StripDebug || Config.StripUnneeded) {
     RemovePred = [RemovePred](const SectionBase &Sec) {
       return RemovePred(Sec) || isDebugSection(Sec);
     };
@@ -523,7 +522,7 @@ static Error replaceAndRemoveSections(const CopyConfig &Config, Object &Obj) {
   if (!Config.OnlySection.empty()) {
     RemovePred = [&Config, RemovePred, &Obj](const SectionBase &Sec) {
       // Explicitly keep these sections regardless of previous removes.
-      if (is_contained(Config.OnlySection, Sec.Name))
+      if (Config.OnlySection.matches(Sec.Name))
         return false;
 
       // Allow all implicit removes.
@@ -545,7 +544,7 @@ static Error replaceAndRemoveSections(const CopyConfig &Config, Object &Obj) {
   if (!Config.KeepSection.empty()) {
     RemovePred = [&Config, RemovePred](const SectionBase &Sec) {
       // Explicitly keep these sections regardless of previous removes.
-      if (is_contained(Config.KeepSection, Sec.Name))
+      if (Config.KeepSection.matches(Sec.Name))
         return false;
       // Otherwise defer to RemovePred.
       return RemovePred(Sec);
@@ -614,9 +613,8 @@ static Error handleArgs(const CopyConfig &Config, Object &Obj,
   if (Error E = updateAndRemoveSymbols(Config, Obj))
     return E;
 
-  if (!Config.SectionsToRename.empty() || !Config.AllocSectionsPrefix.empty()) {
-    DenseSet<SectionBase *> PrefixedSections;
-    for (auto &Sec : Obj.sections()) {
+  if (!Config.SectionsToRename.empty()) {
+    for (SectionBase &Sec : Obj.sections()) {
       const auto Iter = Config.SectionsToRename.find(Sec.Name);
       if (Iter != Config.SectionsToRename.end()) {
         const SectionRename &SR = Iter->second;
@@ -624,63 +622,62 @@ static Error handleArgs(const CopyConfig &Config, Object &Obj,
         if (SR.NewFlags.hasValue())
           setSectionFlagsAndType(Sec, SR.NewFlags.getValue());
       }
+    }
+  }
 
-      // Add a prefix to allocated sections and their relocation sections. This
-      // should be done after renaming the section by Config.SectionToRename to
-      // imitate the GNU objcopy behavior.
-      if (!Config.AllocSectionsPrefix.empty()) {
-        if (Sec.Flags & SHF_ALLOC) {
-          Sec.Name = (Config.AllocSectionsPrefix + Sec.Name).str();
-          PrefixedSections.insert(&Sec);
-
-          // Rename relocation sections associated to the allocated sections.
-          // For example, if we rename .text to .prefix.text, we also rename
-          // .rel.text to .rel.prefix.text.
-          //
-          // Dynamic relocation sections (SHT_REL[A] with SHF_ALLOC) are handled
-          // above, e.g., .rela.plt is renamed to .prefix.rela.plt, not
-          // .rela.prefix.plt since GNU objcopy does so.
-        } else if (auto *RelocSec = dyn_cast<RelocationSectionBase>(&Sec)) {
-          auto *TargetSec = RelocSec->getSection();
-          if (TargetSec && (TargetSec->Flags & SHF_ALLOC)) {
-            StringRef prefix;
-            switch (Sec.Type) {
-            case SHT_REL:
-              prefix = ".rel";
-              break;
-            case SHT_RELA:
-              prefix = ".rela";
-              break;
-            default:
-              continue;
-            }
-
-            // If the relocation section comes *after* the target section, we
-            // don't add Config.AllocSectionsPrefix because we've already added
-            // the prefix to TargetSec->Name. Otherwise, if the relocation
-            // section comes *before* the target section, we add the prefix.
-            if (PrefixedSections.count(TargetSec)) {
-              Sec.Name = (prefix + TargetSec->Name).str();
-            } else {
-              const auto Iter = Config.SectionsToRename.find(TargetSec->Name);
-              if (Iter != Config.SectionsToRename.end()) {
-                // Both `--rename-section` and `--prefix-alloc-sections` are
-                // given but the target section is not yet renamed.
-                Sec.Name =
-                    (prefix + Config.AllocSectionsPrefix + Iter->second.NewName)
-                        .str();
-              } else {
-                Sec.Name =
-                    (prefix + Config.AllocSectionsPrefix + TargetSec->Name)
-                        .str();
-              }
-            }
+  // Add a prefix to allocated sections and their relocation sections. This
+  // should be done after renaming the section by Config.SectionToRename to
+  // imitate the GNU objcopy behavior.
+  if (!Config.AllocSectionsPrefix.empty()) {
+    DenseSet<SectionBase *> PrefixedSections;
+    for (SectionBase &Sec : Obj.sections()) {
+      if (Sec.Flags & SHF_ALLOC) {
+        Sec.Name = (Config.AllocSectionsPrefix + Sec.Name).str();
+        PrefixedSections.insert(&Sec);
+      } else if (auto *RelocSec = dyn_cast<RelocationSectionBase>(&Sec)) {
+        // Rename relocation sections associated to the allocated sections.
+        // For example, if we rename .text to .prefix.text, we also rename
+        // .rel.text to .rel.prefix.text.
+        //
+        // Dynamic relocation sections (SHT_REL[A] with SHF_ALLOC) are handled
+        // above, e.g., .rela.plt is renamed to .prefix.rela.plt, not
+        // .rela.prefix.plt since GNU objcopy does so.
+        const SectionBase *TargetSec = RelocSec->getSection();
+        if (TargetSec && (TargetSec->Flags & SHF_ALLOC)) {
+          StringRef prefix;
+          switch (Sec.Type) {
+          case SHT_REL:
+            prefix = ".rel";
+            break;
+          case SHT_RELA:
+            prefix = ".rela";
+            break;
+          default:
+            llvm_unreachable("not a relocation section");
           }
+
+          // If the relocation section comes *after* the target section, we
+          // don't add Config.AllocSectionsPrefix because we've already added
+          // the prefix to TargetSec->Name. Otherwise, if the relocation
+          // section comes *before* the target section, we add the prefix.
+          if (PrefixedSections.count(TargetSec))
+            Sec.Name = (prefix + TargetSec->Name).str();
+          else
+            Sec.Name =
+                (prefix + Config.AllocSectionsPrefix + TargetSec->Name).str();
         }
       }
     }
   }
 
+  if (!Config.SetSectionAlignment.empty()) {
+    for (SectionBase &Sec : Obj.sections()) {
+      auto I = Config.SetSectionAlignment.find(Sec.Name);
+      if (I != Config.SetSectionAlignment.end())
+        Sec.Align = I->second;
+    }
+  }
+
   if (!Config.SetSectionFlags.empty()) {
     for (auto &Sec : Obj.sections()) {
       const auto Iter = Config.SetSectionFlags.find(Sec.Name);
@@ -721,7 +718,7 @@ static Error handleArgs(const CopyConfig &Config, Object &Obj,
     Obj.addSection<GnuDebugLinkSection>(Config.AddGnuDebugLink,
                                         Config.GnuDebugLinkCRC32);
 
-  for (const NewSymbolInfo &SI : Config.SymbolsToAdd) {
+  for (const NewSymbolInfo &SI : Config.ELF->SymbolsToAdd) {
     SectionBase *Sec = Obj.findSection(SI.SectionName);
     uint64_t Value = Sec ? Sec->Addr + SI.Value : SI.Value;
     Obj.SymbolTable->addSymbol(
@@ -746,9 +743,9 @@ static Error writeOutput(const CopyConfig &Config, Object &Obj, Buffer &Out,
 Error executeObjcopyOnIHex(const CopyConfig &Config, MemoryBuffer &In,
                            Buffer &Out) {
   IHexReader Reader(&In);
-  std::unique_ptr<Object> Obj = Reader.create();
+  std::unique_ptr<Object> Obj = Reader.create(true);
   const ElfType OutputElfType =
-      getOutputElfType(Config.OutputArch.getValueOr(Config.BinaryArch));
+    getOutputElfType(Config.OutputArch.getValueOr(MachineInfo()));
   if (Error E = handleArgs(Config, *Obj, Reader, OutputElfType))
     return E;
   return writeOutput(Config, *Obj, Out, OutputElfType);
@@ -756,13 +753,15 @@ Error executeObjcopyOnIHex(const CopyConfig &Config, MemoryBuffer &In,
 
 Error executeObjcopyOnRawBinary(const CopyConfig &Config, MemoryBuffer &In,
                                 Buffer &Out) {
-  BinaryReader Reader(Config.BinaryArch, &In);
-  std::unique_ptr<Object> Obj = Reader.create();
+  uint8_t NewSymbolVisibility =
+      Config.ELF->NewSymbolVisibility.getValueOr((uint8_t)ELF::STV_DEFAULT);
+  BinaryReader Reader(&In, NewSymbolVisibility);
+  std::unique_ptr<Object> Obj = Reader.create(true);
 
   // Prefer OutputArch (-O<format>) if set, otherwise fallback to BinaryArch
   // (-B<arch>).
   const ElfType OutputElfType =
-      getOutputElfType(Config.OutputArch.getValueOr(Config.BinaryArch));
+      getOutputElfType(Config.OutputArch.getValueOr(MachineInfo()));
   if (Error E = handleArgs(Config, *Obj, Reader, OutputElfType))
     return E;
   return writeOutput(Config, *Obj, Out, OutputElfType);
@@ -771,7 +770,7 @@ Error executeObjcopyOnRawBinary(const CopyConfig &Config, MemoryBuffer &In,
 Error executeObjcopyOnBinary(const CopyConfig &Config,
                              object::ELFObjectFileBase &In, Buffer &Out) {
   ELFReader Reader(&In, Config.ExtractPartition);
-  std::unique_ptr<Object> Obj = Reader.create();
+  std::unique_ptr<Object> Obj = Reader.create(!Config.SymbolsToAdd.empty());
   // Prefer OutputArch (-O<format>) if set, otherwise infer it from the input.
   const ElfType OutputElfType =
       Config.OutputArch ? getOutputElfType(Config.OutputArch.getValue())
diff --git a/tools/llvm-objcopy/ELF/Object.cpp b/tools/llvm-objcopy/ELF/Object.cpp
index fa696380e17c..74145dad6e6b 100644
--- a/tools/llvm-objcopy/ELF/Object.cpp
+++ b/tools/llvm-objcopy/ELF/Object.cpp
@@ -397,7 +397,7 @@ void SectionWriter::visit(const OwnedDataSection &Sec) {
   llvm::copy(Sec.Data, Out.getBufferStart() + Sec.Offset);
 }
 
-static const std::vector<uint8_t> ZlibGnuMagic = {'Z', 'L', 'I', 'B'};
+static constexpr std::array<uint8_t, 4> ZlibGnuMagic = {{'Z', 'L', 'I', 'B'}};
 
 static bool isDataGnuCompressed(ArrayRef<uint8_t> Data) {
   return Data.size() > ZlibGnuMagic.size() &&
@@ -665,7 +665,7 @@ void SymbolTableSection::addSymbol(Twine Name, uint8_t Bind, uint8_t Type,
   Sym.Visibility = Visibility;
   Sym.Size = SymbolSize;
   Sym.Index = Symbols.size();
-  Symbols.emplace_back(llvm::make_unique<Symbol>(Sym));
+  Symbols.emplace_back(std::make_unique<Symbol>(Sym));
   Size += this->EntrySize;
 }
 
@@ -1055,29 +1055,28 @@ void GroupSection::accept(MutableSectionVisitor &Visitor) {
 }
 
 // Returns true IFF a section is wholly inside the range of a segment
-static bool sectionWithinSegment(const SectionBase &Section,
-                                 const Segment &Segment) {
+static bool sectionWithinSegment(const SectionBase &Sec, const Segment &Seg) {
   // If a section is empty it should be treated like it has a size of 1. This is
   // to clarify the case when an empty section lies on a boundary between two
   // segments and ensures that the section "belongs" to the second segment and
   // not the first.
-  uint64_t SecSize = Section.Size ? Section.Size : 1;
+  uint64_t SecSize = Sec.Size ? Sec.Size : 1;
 
-  if (Section.Type == SHT_NOBITS) {
-    if (!(Section.Flags & SHF_ALLOC))
+  if (Sec.Type == SHT_NOBITS) {
+    if (!(Sec.Flags & SHF_ALLOC))
       return false;
 
-    bool SectionIsTLS = Section.Flags & SHF_TLS;
-    bool SegmentIsTLS = Segment.Type == PT_TLS;
+    bool SectionIsTLS = Sec.Flags & SHF_TLS;
+    bool SegmentIsTLS = Seg.Type == PT_TLS;
     if (SectionIsTLS != SegmentIsTLS)
       return false;
 
-    return Segment.VAddr <= Section.Addr &&
-           Segment.VAddr + Segment.MemSize >= Section.Addr + SecSize;
+    return Seg.VAddr <= Sec.Addr &&
+           Seg.VAddr + Seg.MemSize >= Sec.Addr + SecSize;
   }
 
-  return Segment.Offset <= Section.OriginalOffset &&
-         Segment.Offset + Segment.FileSize >= Section.OriginalOffset + SecSize;
+  return Seg.Offset <= Sec.OriginalOffset &&
+         Seg.Offset + Seg.FileSize >= Sec.OriginalOffset + SecSize;
 }
 
 // Returns true IFF a segment's original offset is inside of another segment's
@@ -1113,7 +1112,7 @@ void BasicELFBuilder::initFileHeader() {
   Obj->OSABI = ELFOSABI_NONE;
   Obj->ABIVersion = 0;
   Obj->Entry = 0x0;
-  Obj->Machine = EMachine;
+  Obj->Machine = EM_NONE;
   Obj->Version = 1;
 }
 
@@ -1141,8 +1140,8 @@ SymbolTableSection *BasicELFBuilder::addSymTab(StringTableSection *StrTab) {
 }
 
 void BasicELFBuilder::initSections() {
-  for (auto &Section : Obj->sections())
-    Section.initialize(Obj->sections());
+  for (SectionBase &Sec : Obj->sections())
+    Sec.initialize(Obj->sections());
 }
 
 void BinaryELFBuilder::addData(SymbolTableSection *SymTab) {
@@ -1161,11 +1160,12 @@ void BinaryELFBuilder::addData(SymbolTableSection *SymTab) {
   Twine Prefix = Twine("_binary_") + SanitizedFilename;
 
   SymTab->addSymbol(Prefix + "_start", STB_GLOBAL, STT_NOTYPE, &DataSection,
-                    /*Value=*/0, STV_DEFAULT, 0, 0);
+                    /*Value=*/0, NewSymbolVisibility, 0, 0);
   SymTab->addSymbol(Prefix + "_end", STB_GLOBAL, STT_NOTYPE, &DataSection,
-                    /*Value=*/DataSection.Size, STV_DEFAULT, 0, 0);
+                    /*Value=*/DataSection.Size, NewSymbolVisibility, 0, 0);
   SymTab->addSymbol(Prefix + "_size", STB_GLOBAL, STT_NOTYPE, nullptr,
-                    /*Value=*/DataSection.Size, STV_DEFAULT, SHN_ABS, 0);
+                    /*Value=*/DataSection.Size, NewSymbolVisibility, SHN_ABS,
+                    0);
 }
 
 std::unique_ptr<Object> BinaryELFBuilder::build() {
@@ -1255,10 +1255,9 @@ template <class ELFT> void ELFBuilder<ELFT>::findEhdrOffset() {
   if (!ExtractPartition)
     return;
 
-  for (const SectionBase &Section : Obj.sections()) {
-    if (Section.Type == SHT_LLVM_PART_EHDR &&
-        Section.Name == *ExtractPartition) {
-      EhdrOffset = Section.Offset;
+  for (const SectionBase &Sec : Obj.sections()) {
+    if (Sec.Type == SHT_LLVM_PART_EHDR && Sec.Name == *ExtractPartition) {
+      EhdrOffset = Sec.Offset;
       return;
     }
   }
@@ -1287,15 +1286,12 @@ void ELFBuilder<ELFT>::readProgramHeaders(const ELFFile<ELFT> &HeadersFile) {
     Seg.MemSize = Phdr.p_memsz;
     Seg.Align = Phdr.p_align;
     Seg.Index = Index++;
-    for (SectionBase &Section : Obj.sections()) {
-      if (sectionWithinSegment(Section, Seg)) {
-        Seg.addSection(&Section);
-        if (!Section.ParentSegment ||
-            Section.ParentSegment->Offset > Seg.Offset) {
-          Section.ParentSegment = &Seg;
-        }
+    for (SectionBase &Sec : Obj.sections())
+      if (sectionWithinSegment(Sec, Seg)) {
+        Seg.addSection(&Sec);
+        if (!Sec.ParentSegment || Sec.ParentSegment->Offset > Seg.Offset)
+          Sec.ParentSegment = &Seg;
       }
-    }
   }
 
   auto &ElfHdr = Obj.ElfHdrSegment;
@@ -1531,7 +1527,7 @@ template <class ELFT> void ELFBuilder<ELFT>::readSectionHeaders() {
   }
 }
 
-template <class ELFT> void ELFBuilder<ELFT>::readSections() {
+template <class ELFT> void ELFBuilder<ELFT>::readSections(bool EnsureSymtab) {
   // If a section index table exists we'll need to initialize it before we
   // initialize the symbol table because the symbol table might need to
   // reference it.
@@ -1544,16 +1540,37 @@ template <class ELFT> void ELFBuilder<ELFT>::readSections() {
   if (Obj.SymbolTable) {
     Obj.SymbolTable->initialize(Obj.sections());
     initSymbolTable(Obj.SymbolTable);
+  } else if (EnsureSymtab) {
+    // Reuse the existing SHT_STRTAB section if exists.
+    StringTableSection *StrTab = nullptr;
+    for (auto &Sec : Obj.sections()) {
+      if (Sec.Type == ELF::SHT_STRTAB && !(Sec.Flags & SHF_ALLOC)) {
+        StrTab = static_cast<StringTableSection *>(&Sec);
+
+        // Prefer .strtab to .shstrtab.
+        if (Obj.SectionNames != &Sec)
+          break;
+      }
+    }
+    if (!StrTab)
+      StrTab = &Obj.addSection<StringTableSection>();
+
+    SymbolTableSection &SymTab = Obj.addSection<SymbolTableSection>();
+    SymTab.Name = ".symtab";
+    SymTab.Link = StrTab->Index;
+    SymTab.initialize(Obj.sections());
+    SymTab.addSymbol("", 0, 0, nullptr, 0, 0, 0, 0);
+    Obj.SymbolTable = &SymTab;
   }
 
   // Now that all sections and symbols have been added we can add
   // relocations that reference symbols and set the link and info fields for
   // relocation sections.
-  for (auto &Section : Obj.sections()) {
-    if (&Section == Obj.SymbolTable)
+  for (auto &Sec : Obj.sections()) {
+    if (&Sec == Obj.SymbolTable)
       continue;
-    Section.initialize(Obj.sections());
-    if (auto RelSec = dyn_cast<RelocationSection>(&Section)) {
+    Sec.initialize(Obj.sections());
+    if (auto RelSec = dyn_cast<RelocationSection>(&Sec)) {
       auto Shdr = unwrapOrError(ElfFile.sections()).begin() + RelSec->Index;
       if (RelSec->Type == SHT_REL)
         initRelocations(RelSec, Obj.SymbolTable,
@@ -1561,7 +1578,7 @@ template <class ELFT> void ELFBuilder<ELFT>::readSections() {
       else
         initRelocations(RelSec, Obj.SymbolTable,
                         unwrapOrError(ElfFile.relas(Shdr)));
-    } else if (auto GroupSec = dyn_cast<GroupSection>(&Section)) {
+    } else if (auto GroupSec = dyn_cast<GroupSection>(&Sec)) {
       initGroupSection(GroupSec);
     }
   }
@@ -1582,7 +1599,7 @@ template <class ELFT> void ELFBuilder<ELFT>::readSections() {
                 " is not a string table");
 }
 
-template <class ELFT> void ELFBuilder<ELFT>::build() {
+template <class ELFT> void ELFBuilder<ELFT>::build(bool EnsureSymtab) {
   readSectionHeaders();
   findEhdrOffset();
 
@@ -1601,7 +1618,7 @@ template <class ELFT> void ELFBuilder<ELFT>::build() {
   Obj.Entry = Ehdr.e_entry;
   Obj.Flags = Ehdr.e_flags;
 
-  readSections();
+  readSections(EnsureSymtab);
   readProgramHeaders(HeadersFile);
 }
 
@@ -1609,8 +1626,8 @@ Writer::~Writer() {}
 
 Reader::~Reader() {}
 
-std::unique_ptr<Object> BinaryReader::create() const {
-  return BinaryELFBuilder(MInfo.EMachine, MemBuf).build();
+std::unique_ptr<Object> BinaryReader::create(bool /*EnsureSymtab*/) const {
+  return BinaryELFBuilder(MemBuf, NewSymbolVisibility).build();
 }
 
 Expected<std::vector<IHexRecord>> IHexReader::parse() const {
@@ -1639,28 +1656,28 @@ Expected<std::vector<IHexRecord>> IHexReader::parse() const {
   return std::move(Records);
 }
 
-std::unique_ptr<Object> IHexReader::create() const {
+std::unique_ptr<Object> IHexReader::create(bool /*EnsureSymtab*/) const {
   std::vector<IHexRecord> Records = unwrapOrError(parse());
   return IHexELFBuilder(Records).build();
 }
 
-std::unique_ptr<Object> ELFReader::create() const {
-  auto Obj = llvm::make_unique<Object>();
+std::unique_ptr<Object> ELFReader::create(bool EnsureSymtab) const {
+  auto Obj = std::make_unique<Object>();
   if (auto *O = dyn_cast<ELFObjectFile<ELF32LE>>(Bin)) {
     ELFBuilder<ELF32LE> Builder(*O, *Obj, ExtractPartition);
-    Builder.build();
+    Builder.build(EnsureSymtab);
     return Obj;
   } else if (auto *O = dyn_cast<ELFObjectFile<ELF64LE>>(Bin)) {
     ELFBuilder<ELF64LE> Builder(*O, *Obj, ExtractPartition);
-    Builder.build();
+    Builder.build(EnsureSymtab);
     return Obj;
   } else if (auto *O = dyn_cast<ELFObjectFile<ELF32BE>>(Bin)) {
     ELFBuilder<ELF32BE> Builder(*O, *Obj, ExtractPartition);
-    Builder.build();
+    Builder.build(EnsureSymtab);
     return Obj;
   } else if (auto *O = dyn_cast<ELFObjectFile<ELF64BE>>(Bin)) {
     ELFBuilder<ELF64BE> Builder(*O, *Obj, ExtractPartition);
-    Builder.build();
+    Builder.build(EnsureSymtab);
     return Obj;
   }
   error("invalid file type");
@@ -1693,7 +1710,7 @@ template <class ELFT> void ELFWriter<ELFT>::writeEhdr() {
   Ehdr.e_ehsize = sizeof(Elf_Ehdr);
   if (WriteSectionHeaders && Obj.sections().size() != 0) {
     Ehdr.e_shentsize = sizeof(Elf_Shdr);
-    Ehdr.e_shoff = Obj.SHOffset;
+    Ehdr.e_shoff = Obj.SHOff;
     // """
     // If the number of sections is greater than or equal to
     // SHN_LORESERVE (0xff00), this member has the value zero and the actual
@@ -1732,7 +1749,7 @@ template <class ELFT> void ELFWriter<ELFT>::writeShdrs() {
   // This reference serves to write the dummy section header at the begining
   // of the file. It is not used for anything else
   Elf_Shdr &Shdr =
-      *reinterpret_cast<Elf_Shdr *>(Buf.getBufferStart() + Obj.SHOffset);
+      *reinterpret_cast<Elf_Shdr *>(Buf.getBufferStart() + Obj.SHOff);
   Shdr.sh_name = 0;
   Shdr.sh_type = SHT_NULL;
   Shdr.sh_flags = 0;
@@ -1862,26 +1879,13 @@ void Object::sortSections() {
   });
 }
 
-static uint64_t alignToAddr(uint64_t Offset, uint64_t Addr, uint64_t Align) {
-  // Calculate Diff such that (Offset + Diff) & -Align == Addr & -Align.
-  if (Align == 0)
-    Align = 1;
-  auto Diff =
-      static_cast<int64_t>(Addr % Align) - static_cast<int64_t>(Offset % Align);
-  // We only want to add to Offset, however, so if Diff < 0 we can add Align and
-  // (Offset + Diff) & -Align == Addr & -Align will still hold.
-  if (Diff < 0)
-    Diff += Align;
-  return Offset + Diff;
-}
-
 // Orders segments such that if x = y->ParentSegment then y comes before x.
 static void orderSegments(std::vector<Segment *> &Segments) {
   llvm::stable_sort(Segments, compareSegmentsByOffset);
 }
 
 // This function finds a consistent layout for a list of segments starting from
-// an Offset. It assumes that Segments have been sorted by OrderSegments and
+// an Offset. It assumes that Segments have been sorted by orderSegments and
 // returns an Offset one past the end of the last segment.
 static uint64_t layoutSegments(std::vector<Segment *> &Segments,
                                uint64_t Offset) {
@@ -1902,8 +1906,8 @@ static uint64_t layoutSegments(std::vector<Segment *> &Segments,
       Seg->Offset =
           Parent->Offset + Seg->OriginalOffset - Parent->OriginalOffset;
     } else {
-      Offset = alignToAddr(Offset, Seg->VAddr, Seg->Align);
-      Seg->Offset = Offset;
+      Seg->Offset =
+          alignTo(Offset, std::max<uint64_t>(Seg->Align, 1), Seg->VAddr);
     }
     Offset = std::max(Offset, Seg->Offset + Seg->FileSize);
   }
@@ -1925,17 +1929,17 @@ static uint64_t layoutSections(Range Sections, uint64_t Offset) {
   // of the segment we can assign a new offset to the section. For sections not
   // covered by segments we can just bump Offset to the next valid location.
   uint32_t Index = 1;
-  for (auto &Section : Sections) {
-    Section.Index = Index++;
-    if (Section.ParentSegment != nullptr) {
-      auto Segment = *Section.ParentSegment;
-      Section.Offset =
-          Segment.Offset + (Section.OriginalOffset - Segment.OriginalOffset);
+  for (auto &Sec : Sections) {
+    Sec.Index = Index++;
+    if (Sec.ParentSegment != nullptr) {
+      auto Segment = *Sec.ParentSegment;
+      Sec.Offset =
+          Segment.Offset + (Sec.OriginalOffset - Segment.OriginalOffset);
     } else {
-      Offset = alignTo(Offset, Section.Align == 0 ? 1 : Section.Align);
-      Section.Offset = Offset;
-      if (Section.Type != SHT_NOBITS)
-        Offset += Section.Size;
+      Offset = alignTo(Offset, Sec.Align == 0 ? 1 : Sec.Align);
+      Sec.Offset = Offset;
+      if (Sec.Type != SHT_NOBITS)
+        Offset += Sec.Size;
     }
   }
   return Offset;
@@ -1971,16 +1975,16 @@ template <class ELFT> void ELFWriter<ELFT>::assignOffsets() {
   // Offset so that SHOffset is valid.
   if (WriteSectionHeaders)
     Offset = alignTo(Offset, sizeof(Elf_Addr));
-  Obj.SHOffset = Offset;
+  Obj.SHOff = Offset;
 }
 
 template <class ELFT> size_t ELFWriter<ELFT>::totalSize() const {
   // We already have the section header offset so we can calculate the total
   // size by just adding up the size of each section header.
   if (!WriteSectionHeaders)
-    return Obj.SHOffset;
+    return Obj.SHOff;
   size_t ShdrCount = Obj.sections().size() + 1; // Includes null shdr.
-  return Obj.SHOffset + ShdrCount * sizeof(Elf_Shdr);
+  return Obj.SHOff + ShdrCount * sizeof(Elf_Shdr);
 }
 
 template <class ELFT> Error ELFWriter<ELFT>::write() {
@@ -1995,6 +1999,25 @@ template <class ELFT> Error ELFWriter<ELFT>::write() {
   return Buf.commit();
 }
 
+static Error removeUnneededSections(Object &Obj) {
+  // We can remove an empty symbol table from non-relocatable objects.
+  // Relocatable objects typically have relocation sections whose
+  // sh_link field points to .symtab, so we can't remove .symtab
+  // even if it is empty.
+  if (Obj.isRelocatable() || Obj.SymbolTable == nullptr ||
+      !Obj.SymbolTable->empty())
+    return Error::success();
+
+  // .strtab can be used for section names. In such a case we shouldn't
+  // remove it.
+  auto *StrTab = Obj.SymbolTable->getStrTab() == Obj.SectionNames
+                     ? nullptr
+                     : Obj.SymbolTable->getStrTab();
+  return Obj.removeSections(false, [&](const SectionBase &Sec) {
+    return &Sec == Obj.SymbolTable || &Sec == StrTab;
+  });
+}
+
 template <class ELFT> Error ELFWriter<ELFT>::finalize() {
   // It could happen that SectionNames has been removed and yet the user wants
   // a section header table output. We need to throw an error if a user tries
@@ -2004,6 +2027,8 @@ template <class ELFT> Error ELFWriter<ELFT>::finalize() {
                              "cannot write section header table because "
                              "section header string table was removed");
 
+  if (Error E = removeUnneededSections(Obj))
+    return E;
   Obj.sortSections();
 
   // We need to assign indexes before we perform layout because we need to know
@@ -2045,9 +2070,8 @@ template <class ELFT> Error ELFWriter<ELFT>::finalize() {
   // Make sure we add the names of all the sections. Importantly this must be
   // done after we decide to add or remove SectionIndexes.
   if (Obj.SectionNames != nullptr)
-    for (const auto &Section : Obj.sections()) {
-      Obj.SectionNames->addString(Section.Name);
-    }
+    for (const SectionBase &Sec : Obj.sections())
+      Obj.SectionNames->addString(Sec.Name);
 
   initEhdrSegment();
 
@@ -2055,8 +2079,8 @@ template <class ELFT> Error ELFWriter<ELFT>::finalize() {
   // Also, the output arch may not be the same as the input arch, so fix up
   // size-related fields before doing layout calculations.
   uint64_t Index = 0;
-  auto SecSizer = llvm::make_unique<ELFSectionSizer<ELFT>>();
-  for (auto &Sec : Obj.sections()) {
+  auto SecSizer = std::make_unique<ELFSectionSizer<ELFT>>();
+  for (SectionBase &Sec : Obj.sections()) {
     Sec.Index = Index++;
     Sec.accept(*SecSizer);
   }
@@ -2082,40 +2106,36 @@ template <class ELFT> Error ELFWriter<ELFT>::finalize() {
 
   // Finally now that all offsets and indexes have been set we can finalize any
   // remaining issues.
-  uint64_t Offset = Obj.SHOffset + sizeof(Elf_Shdr);
-  for (SectionBase &Section : Obj.sections()) {
-    Section.HeaderOffset = Offset;
+  uint64_t Offset = Obj.SHOff + sizeof(Elf_Shdr);
+  for (SectionBase &Sec : Obj.sections()) {
+    Sec.HeaderOffset = Offset;
     Offset += sizeof(Elf_Shdr);
     if (WriteSectionHeaders)
-      Section.NameIndex = Obj.SectionNames->findIndex(Section.Name);
-    Section.finalize();
+      Sec.NameIndex = Obj.SectionNames->findIndex(Sec.Name);
+    Sec.finalize();
   }
 
   if (Error E = Buf.allocate(totalSize()))
     return E;
-  SecWriter = llvm::make_unique<ELFSectionWriter<ELFT>>(Buf);
+  SecWriter = std::make_unique<ELFSectionWriter<ELFT>>(Buf);
   return Error::success();
 }
 
 Error BinaryWriter::write() {
-  for (auto &Section : Obj.sections())
-    if (Section.Flags & SHF_ALLOC)
-      Section.accept(*SecWriter);
+  for (const SectionBase &Sec : Obj.allocSections())
+    Sec.accept(*SecWriter);
   return Buf.commit();
 }
 
 Error BinaryWriter::finalize() {
-  // TODO: Create a filter range to construct OrderedSegments from so that this
-  // code can be deduped with assignOffsets above. This should also solve the
-  // todo below for LayoutSections.
   // We need a temporary list of segments that has a special order to it
   // so that we know that anytime ->ParentSegment is set that segment has
   // already had it's offset properly set. We only want to consider the segments
   // that will affect layout of allocated sections so we only add those.
   std::vector<Segment *> OrderedSegments;
-  for (SectionBase &Section : Obj.sections())
-    if ((Section.Flags & SHF_ALLOC) != 0 && Section.ParentSegment != nullptr)
-      OrderedSegments.push_back(Section.ParentSegment);
+  for (const SectionBase &Sec : Obj.allocSections())
+    if (Sec.ParentSegment != nullptr)
+      OrderedSegments.push_back(Sec.ParentSegment);
 
   // For binary output, we're going to use physical addresses instead of
   // virtual addresses, since a binary output is used for cases like ROM
@@ -2130,7 +2150,7 @@ Error BinaryWriter::finalize() {
   llvm::stable_sort(OrderedSegments, compareSegmentsByPAddr);
 
   // Because we add a ParentSegment for each section we might have duplicate
-  // segments in OrderedSegments. If there were duplicates then LayoutSegments
+  // segments in OrderedSegments. If there were duplicates then layoutSegments
   // would do very strange things.
   auto End =
       std::unique(std::begin(OrderedSegments), std::end(OrderedSegments));
@@ -2158,28 +2178,20 @@ Error BinaryWriter::finalize() {
     }
   }
 
-  // TODO: generalize LayoutSections to take a range. Pass a special range
-  // constructed from an iterator that skips values for which a predicate does
-  // not hold. Then pass such a range to LayoutSections instead of constructing
-  // AllocatedSections here.
-  std::vector<SectionBase *> AllocatedSections;
-  for (SectionBase &Section : Obj.sections())
-    if (Section.Flags & SHF_ALLOC)
-      AllocatedSections.push_back(&Section);
-  layoutSections(make_pointee_range(AllocatedSections), Offset);
+  layoutSections(Obj.allocSections(), Offset);
 
   // Now that every section has been laid out we just need to compute the total
   // file size. This might not be the same as the offset returned by
-  // LayoutSections, because we want to truncate the last segment to the end of
+  // layoutSections, because we want to truncate the last segment to the end of
   // its last section, to match GNU objcopy's behaviour.
   TotalSize = 0;
-  for (SectionBase *Section : AllocatedSections)
-    if (Section->Type != SHT_NOBITS)
-      TotalSize = std::max(TotalSize, Section->Offset + Section->Size);
+  for (const SectionBase &Sec : Obj.allocSections())
+    if (Sec.Type != SHT_NOBITS)
+      TotalSize = std::max(TotalSize, Sec.Offset + Sec.Size);
 
   if (Error E = Buf.allocate(TotalSize))
     return E;
-  SecWriter = llvm::make_unique<BinarySectionWriter>(Buf);
+  SecWriter = std::make_unique<BinarySectionWriter>(Buf);
   return Error::success();
 }
 
@@ -2259,17 +2271,17 @@ Error IHexWriter::finalize() {
   // If any section we're to write has segment then we
   // switch to using physical addresses. Otherwise we
   // use section virtual address.
-  for (auto &Section : Obj.sections())
-    if (ShouldWrite(Section) && IsInPtLoad(Section)) {
+  for (const SectionBase &Sec : Obj.sections())
+    if (ShouldWrite(Sec) && IsInPtLoad(Sec)) {
       UseSegments = true;
       break;
     }
 
-  for (auto &Section : Obj.sections())
-    if (ShouldWrite(Section) && (!UseSegments || IsInPtLoad(Section))) {
-      if (Error E = checkSection(Section))
+  for (const SectionBase &Sec : Obj.sections())
+    if (ShouldWrite(Sec) && (!UseSegments || IsInPtLoad(Sec))) {
+      if (Error E = checkSection(Sec))
         return E;
-      Sections.insert(&Section);
+      Sections.insert(&Sec);
     }
 
   IHexSectionWriterBase LengthCalc(Buf);
diff --git a/tools/llvm-objcopy/ELF/Object.h b/tools/llvm-objcopy/ELF/Object.h
index f3df93b9662f..eeacb014e4dc 100644
--- a/tools/llvm-objcopy/ELF/Object.h
+++ b/tools/llvm-objcopy/ELF/Object.h
@@ -57,8 +57,8 @@ public:
       : Sections(Secs) {}
   SectionTableRef(const SectionTableRef &) = default;
 
-  iterator begin() { return iterator(Sections.data()); }
-  iterator end() { return iterator(Sections.data() + Sections.size()); }
+  iterator begin() const { return iterator(Sections.data()); }
+  iterator end() const { return iterator(Sections.data() + Sections.size()); }
   size_t size() const { return Sections.size(); }
 
   SectionBase *getSection(uint32_t Index, Twine ErrMsg);
@@ -863,7 +863,7 @@ public:
 class Reader {
 public:
   virtual ~Reader();
-  virtual std::unique_ptr<Object> create() const = 0;
+  virtual std::unique_ptr<Object> create(bool EnsureSymtab) const = 0;
 };
 
 using object::Binary;
@@ -873,7 +873,6 @@ using object::OwningBinary;
 
 class BasicELFBuilder {
 protected:
-  uint16_t EMachine;
   std::unique_ptr<Object> Obj;
 
   void initFileHeader();
@@ -883,17 +882,18 @@ protected:
   void initSections();
 
 public:
-  BasicELFBuilder(uint16_t EM)
-      : EMachine(EM), Obj(llvm::make_unique<Object>()) {}
+  BasicELFBuilder() : Obj(std::make_unique<Object>()) {}
 };
 
 class BinaryELFBuilder : public BasicELFBuilder {
   MemoryBuffer *MemBuf;
+  uint8_t NewSymbolVisibility;
   void addData(SymbolTableSection *SymTab);
 
 public:
-  BinaryELFBuilder(uint16_t EM, MemoryBuffer *MB)
-      : BasicELFBuilder(EM), MemBuf(MB) {}
+  BinaryELFBuilder(MemoryBuffer *MB, uint8_t NewSymbolVisibility)
+      : BasicELFBuilder(), MemBuf(MB),
+        NewSymbolVisibility(NewSymbolVisibility) {}
 
   std::unique_ptr<Object> build();
 };
@@ -905,7 +905,7 @@ class IHexELFBuilder : public BasicELFBuilder {
 
 public:
   IHexELFBuilder(const std::vector<IHexRecord> &Records)
-      : BasicELFBuilder(ELF::EM_386), Records(Records) {}
+      : BasicELFBuilder(), Records(Records) {}
 
   std::unique_ptr<Object> build();
 };
@@ -926,7 +926,7 @@ private:
   void initGroupSection(GroupSection *GroupSec);
   void initSymbolTable(SymbolTableSection *SymTab);
   void readSectionHeaders();
-  void readSections();
+  void readSections(bool EnsureSymtab);
   void findEhdrOffset();
   SectionBase &makeSection(const Elf_Shdr &Shdr);
 
@@ -936,17 +936,17 @@ public:
       : ElfFile(*ElfObj.getELFFile()), Obj(Obj),
         ExtractPartition(ExtractPartition) {}
 
-  void build();
+  void build(bool EnsureSymtab);
 };
 
 class BinaryReader : public Reader {
-  const MachineInfo &MInfo;
   MemoryBuffer *MemBuf;
+  uint8_t NewSymbolVisibility;
 
 public:
-  BinaryReader(const MachineInfo &MI, MemoryBuffer *MB)
-      : MInfo(MI), MemBuf(MB) {}
-  std::unique_ptr<Object> create() const override;
+  BinaryReader(MemoryBuffer *MB, const uint8_t NewSymbolVisibility)
+      : MemBuf(MB), NewSymbolVisibility(NewSymbolVisibility) {}
+  std::unique_ptr<Object> create(bool EnsureSymtab) const override;
 };
 
 class IHexReader : public Reader {
@@ -968,7 +968,7 @@ class IHexReader : public Reader {
 public:
   IHexReader(MemoryBuffer *MB) : MemBuf(MB) {}
 
-  std::unique_ptr<Object> create() const override;
+  std::unique_ptr<Object> create(bool EnsureSymtab) const override;
 };
 
 class ELFReader : public Reader {
@@ -976,7 +976,7 @@ class ELFReader : public Reader {
   Optional<StringRef> ExtractPartition;
 
 public:
-  std::unique_ptr<Object> create() const override;
+  std::unique_ptr<Object> create(bool EnsureSymtab) const override;
   explicit ELFReader(Binary *B, Optional<StringRef> ExtractPartition)
       : Bin(B), ExtractPartition(ExtractPartition) {}
 };
@@ -990,6 +990,10 @@ private:
   std::vector<SegPtr> Segments;
   std::vector<SecPtr> RemovedSections;
 
+  static bool sectionIsAlloc(const SectionBase &Sec) {
+    return Sec.Flags & ELF::SHF_ALLOC;
+  };
+
 public:
   template <class T>
   using Range = iterator_range<
@@ -1011,13 +1015,14 @@ public:
   uint8_t OSABI;
   uint8_t ABIVersion;
   uint64_t Entry;
-  uint64_t SHOffset;
+  uint64_t SHOff;
   uint32_t Type;
   uint32_t Machine;
   uint32_t Version;
   uint32_t Flags;
 
   bool HadShdrs = true;
+  bool MustBeRelocatable = false;
   StringTableSection *SectionNames = nullptr;
   SymbolTableSection *SymbolTable = nullptr;
   SectionIndexSection *SectionIndexTable = nullptr;
@@ -1027,6 +1032,13 @@ public:
   ConstRange<SectionBase> sections() const {
     return make_pointee_range(Sections);
   }
+  iterator_range<
+      filter_iterator<pointee_iterator<std::vector<SecPtr>::const_iterator>,
+                      decltype(&sectionIsAlloc)>>
+  allocSections() const {
+    return make_filter_range(make_pointee_range(Sections), sectionIsAlloc);
+  }
+
   SectionBase *findSection(StringRef Name) {
     auto SecIt =
         find_if(Sections, [&](const SecPtr &Sec) { return Sec->Name == Name; });
@@ -1041,16 +1053,20 @@ public:
                        std::function<bool(const SectionBase &)> ToRemove);
   Error removeSymbols(function_ref<bool(const Symbol &)> ToRemove);
   template <class T, class... Ts> T &addSection(Ts &&... Args) {
-    auto Sec = llvm::make_unique<T>(std::forward<Ts>(Args)...);
+    auto Sec = std::make_unique<T>(std::forward<Ts>(Args)...);
     auto Ptr = Sec.get();
+    MustBeRelocatable |= isa<RelocationSection>(*Ptr);
     Sections.emplace_back(std::move(Sec));
     Ptr->Index = Sections.size();
     return *Ptr;
   }
   Segment &addSegment(ArrayRef<uint8_t> Data) {
-    Segments.emplace_back(llvm::make_unique<Segment>(Data));
+    Segments.emplace_back(std::make_unique<Segment>(Data));
     return *Segments.back();
   }
+  bool isRelocatable() const {
+    return (Type != ELF::ET_DYN && Type != ELF::ET_EXEC) || MustBeRelocatable;
+  }
 };
 
 } // end namespace elf