Revert "[AIX] Support of Big archive (read)"

This appears to be causing the following build failures on green
dragon during stage2 builds on macOS:

 /System/Volumes/Data/jenkins/workspace/apple-clang-stage2-configure-RA_osceola/clang.roots/BuildRecords/clang-9999.99_install/Objects/obj-llvm/./bin/clang++ -fno-stack-protector -fno-common -Wno-profile-instr-unprofiled -Wno-unknown-warning-option -Werror=unguarded-availability-new -fPIC -fvisibility-inlines-hidden -Werror=date-time -Werror=unguarded-availability-new -fmodules -fmodules-cache-path=/System/Volumes/Data/jenkins/workspace/apple-clang-stage2-configure-RA_osceola/clang.roots/BuildRecords/clang-9999.99_install/Objects/obj-llvm/tools/clang/stage2-bins/module.cache -fcxx-modules -Xclang -fmodules-local-submodule-visibility -gmodules -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wcast-qual -Wmissing-field-initializers -pedantic -Wno-long-long -Wc++98-compat-extra-semi -Wimplicit-fallthrough -Wcovered-switch-default -Wno-class-memaccess -Wno-noexcept-type -Wnon-virtual-dtor -Wdelete-non-virtual-dtor -Wsuggest-override -Wstring-conversion -Wmisleading-indentation -fdiagnostics-color -O2 -gline-tables-only -DNDEBUG -arch x86_64 -arch arm64 -arch arm64e -isysroot /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.0.sdk -mmacosx-version-min=10.10 -Wl,-search_paths_first -Wl,-headerpad_max_install_names -Wl,-dead_strip tools/llvm-cov/CMakeFiles/llvm-cov.dir/llvm-cov.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/gcov.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/CodeCoverage.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/CoverageExporterJson.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/CoverageExporterLcov.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/CoverageFilters.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/CoverageReport.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/CoverageSummaryInfo.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/SourceCoverageView.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/SourceCoverageViewHTML.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/SourceCoverageViewText.cpp.o tools/llvm-cov/CMakeFiles/llvm-cov.dir/TestingSupport.cpp.o -o bin/llvm-cov  -Wl,-rpath,@loader_path/../lib  lib/libLLVMCore.a  lib/libLLVMSupport.a  lib/libLLVMObject.a  lib/libLLVMCoverage.a  lib/libLLVMProfileData.a  lib/libLLVMDebugInfoDWARF.a  lib/libLLVMObject.a  lib/libLLVMBitReader.a  lib/libLLVMCore.a  lib/libLLVMRemarks.a  lib/libLLVMBitstreamReader.a  lib/libLLVMMCParser.a  lib/libLLVMTextAPI.a  lib/libLLVMMC.a  lib/libLLVMBinaryFormat.a  lib/libLLVMDebugInfoCodeView.a  lib/libLLVMSupport.a  -lm  /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.0.sdk/usr/lib/libz.tbd  /Volumes/Xcode/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX12.0.sdk/usr/lib/libcurses.tbd  lib/libLLVMDemangle.a && cd /System/Volumes/Data/jenkins/workspace/apple-clang-stage2-configure-RA_osceola/clang.roots/BuildRecords/clang-9999.99_install/Objects/obj-llvm/tools/clang/stage2-bins/tools/llvm-cov && xcrun dsymutil -o=llvm-cov.dSYM /System/Volumes/Data/jenkins/workspace/apple-clang-stage2-configure-RA_osceola/clang.roots/BuildRecords/clang-9999.99_install/Objects/obj-llvm/tools/clang/stage2-bins/bin/llvm-cov
Undefined symbols for architecture x86_64:
  "llvm::object::CommonArchiveMemberHeader<llvm::object::BigArMemHdrType>::getRawAccessMode() const", referenced from:
      vtable for llvm::object::BigArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::BigArMemHdrType>::getRawUID() const", referenced from:
      vtable for llvm::object::BigArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::BigArMemHdrType>::getRawGID() const", referenced from:
      vtable for llvm::object::BigArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::UnixArMemHdrType>::getRawAccessMode() const", referenced from:
      vtable for llvm::object::ArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::UnixArMemHdrType>::getRawLastModified() const", referenced from:
      vtable for llvm::object::ArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::BigArMemHdrType>::getRawLastModified() const", referenced from:
      vtable for llvm::object::BigArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::BigArMemHdrType>::getOffset() const", referenced from:
      vtable for llvm::object::BigArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::UnixArMemHdrType>::getRawUID() const", referenced from:
      vtable for llvm::object::ArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::UnixArMemHdrType>::getRawGID() const", referenced from:
      vtable for llvm::object::ArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
  "llvm::object::CommonArchiveMemberHeader<llvm::object::UnixArMemHdrType>::getOffset() const", referenced from:
      vtable for llvm::object::ArchiveMemberHeader in libLLVMObject.a(Archive.cpp.o)
ld: symbol(s) not found for architecture x86_64

https://smooshbase.apple.com/ci/job/apple-clang-stage2-configure-RA_osceola/30276/console

1 files changed, 146 insertions, 319 deletions

diff --git a/llvm/lib/Object/Archive.cpp b/llvm/lib/Object/Archive.cpp
index 35cba1a..5492692 100644
--- a/llvm/lib/Object/Archive.cpp
+++ b/llvm/lib/Object/Archive.cpp
@@ -22,7 +22,6 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/ErrorOr.h"
 #include "llvm/Support/FileSystem.h"
-#include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/raw_ostream.h"
@@ -39,6 +38,9 @@ using namespace llvm;
 using namespace object;
 using namespace llvm::support::endian;
 
+const char Magic[] = "!<arch>\n";
+const char ThinMagic[] = "!<thin>\n";
+
 void Archive::anchor() {}
 
 static Error malformedError(Twine Msg) {
@@ -47,59 +49,27 @@ static Error malformedError(Twine Msg) {
                                         object_error::parse_failed);
 }
 
-static Error
-createMemberHeaderParseError(const AbstractArchiveMemberHeader *ArMemHeader,
-                             const char *RawHeaderPtr, uint64_t Size) {
-  StringRef Msg("remaining size of archive too small for next archive "
-                "member header ");
-
-  Expected<StringRef> NameOrErr = ArMemHeader->getName(Size);
-  if (NameOrErr)
-    return malformedError(Msg + "for " + *NameOrErr);
-
-  consumeError(NameOrErr.takeError());
-  uint64_t Offset = RawHeaderPtr - ArMemHeader->Parent->getData().data();
-  return malformedError(Msg + "at offset " + Twine(Offset));
-}
-
-template <class T, std::size_t N>
-StringRef getFieldRawString(const T (&Field)[N]) {
-  return StringRef(Field, N).rtrim(" ");
-}
-
-template <class T>
-StringRef CommonArchiveMemberHeader<T>::getRawAccessMode() const {
-  return getFieldRawString(ArMemHdr->AccessMode);
-}
-
-template <class T>
-StringRef CommonArchiveMemberHeader<T>::getRawLastModified() const {
-  return getFieldRawString(ArMemHdr->LastModified);
-}
-
-template <class T> StringRef CommonArchiveMemberHeader<T>::getRawUID() const {
-  return getFieldRawString(ArMemHdr->UID);
-}
-
-template <class T> StringRef CommonArchiveMemberHeader<T>::getRawGID() const {
-  return getFieldRawString(ArMemHdr->GID);
-}
-
-template <class T> uint64_t CommonArchiveMemberHeader<T>::getOffset() const {
-  return reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
-}
-
 ArchiveMemberHeader::ArchiveMemberHeader(const Archive *Parent,
                                          const char *RawHeaderPtr,
                                          uint64_t Size, Error *Err)
-    : CommonArchiveMemberHeader<UnixArMemHdrType>(
-          Parent, reinterpret_cast<const UnixArMemHdrType *>(RawHeaderPtr)) {
+    : Parent(Parent),
+      ArMemHdr(reinterpret_cast<const ArMemHdrType *>(RawHeaderPtr)) {
   if (RawHeaderPtr == nullptr)
     return;
   ErrorAsOutParameter ErrAsOutParam(Err);
 
-  if (Size < getSizeOf()) {
-    *Err = createMemberHeaderParseError(this, RawHeaderPtr, Size);
+  if (Size < sizeof(ArMemHdrType)) {
+    if (Err) {
+      std::string Msg("remaining size of archive too small for next archive "
+                      "member header ");
+      Expected<StringRef> NameOrErr = getName(Size);
+      if (!NameOrErr) {
+        consumeError(NameOrErr.takeError());
+        uint64_t Offset = RawHeaderPtr - Parent->getData().data();
+        *Err = malformedError(Msg + "at offset " + Twine(Offset));
+      } else
+        *Err = malformedError(Msg + "for " + NameOrErr.get());
+    }
     return;
   }
   if (ArMemHdr->Terminator[0] != '`' || ArMemHdr->Terminator[1] != '\n') {
@@ -124,19 +94,6 @@ ArchiveMemberHeader::ArchiveMemberHeader(const Archive *Parent,
   }
 }
 
-BigArchiveMemberHeader::BigArchiveMemberHeader(const Archive *Parent,
-                                               const char *RawHeaderPtr,
-                                               uint64_t Size, Error *Err)
-    : CommonArchiveMemberHeader<BigArMemHdrType>(
-          Parent, reinterpret_cast<const BigArMemHdrType *>(RawHeaderPtr)) {
-  if (RawHeaderPtr == nullptr)
-    return;
-  ErrorAsOutParameter ErrAsOutParam(Err);
-
-  if (Size < getSizeOf())
-    *Err = createMemberHeaderParseError(this, RawHeaderPtr, Size);
-}
-
 // This gets the raw name from the ArMemHdr->Name field and checks that it is
 // valid for the kind of archive.  If it is not valid it returns an Error.
 Expected<StringRef> ArchiveMemberHeader::getRawName() const {
@@ -164,69 +121,7 @@ Expected<StringRef> ArchiveMemberHeader::getRawName() const {
   return StringRef(ArMemHdr->Name, end);
 }
 
-Expected<uint64_t>
-getArchiveMemberDecField(Twine FieldName, const StringRef RawField,
-                         const Archive *Parent,
-                         const AbstractArchiveMemberHeader *MemHeader) {
-  uint64_t Value;
-  if (RawField.getAsInteger(10, Value)) {
-    uint64_t Offset = MemHeader->getOffset();
-    return malformedError("characters in " + FieldName +
-                          " field in archive member header are not "
-                          "all decimal numbers: '" +
-                          RawField +
-                          "' for the archive "
-                          "member header at offset " +
-                          Twine(Offset));
-  }
-  return Value;
-}
-
-Expected<uint64_t>
-getArchiveMemberOctField(Twine FieldName, const StringRef RawField,
-                         const Archive *Parent,
-                         const AbstractArchiveMemberHeader *MemHeader) {
-  uint64_t Value;
-  if (RawField.getAsInteger(8, Value)) {
-    uint64_t Offset = MemHeader->getOffset();
-    return malformedError("characters in " + FieldName +
-                          " field in archive member header are not "
-                          "all octal numbers: '" +
-                          RawField +
-                          "' for the archive "
-                          "member header at offset " +
-                          Twine(Offset));
-  }
-  return Value;
-}
-
-Expected<StringRef> BigArchiveMemberHeader::getRawName() const {
-  Expected<uint64_t> NameLenOrErr = getArchiveMemberDecField(
-      "NameLen", getFieldRawString(ArMemHdr->NameLen), Parent, this);
-  if (!NameLenOrErr)
-    // TODO: Out-of-line.
-    return NameLenOrErr.takeError();
-  uint64_t NameLen = NameLenOrErr.get();
-
-  // If the name length is odd, pad with '\0' to get an even length. After
-  // padding, there is the name terminator "`\n".
-  uint64_t NameLenWithPadding = alignTo(NameLen, 2);
-  StringRef NameTerminator = "`\n";
-  StringRef NameStringWithNameTerminator =
-      StringRef(ArMemHdr->Name, NameLenWithPadding + NameTerminator.size());
-  if (!NameStringWithNameTerminator.endswith(NameTerminator)) {
-    uint64_t Offset =
-        reinterpret_cast<const char *>(ArMemHdr->Name + NameLenWithPadding) -
-        Parent->getData().data();
-    // TODO: Out-of-line.
-    return malformedError(
-        "name does not have name terminator \"`\\n\" for archive member"
-        "header at offset " +
-        Twine(Offset));
-  }
-  return StringRef(ArMemHdr->Name, NameLen);
-}
-
+// This gets the name looking up long names. Size is the size of the archive
 // member including the header, so the size of any name following the header
 // is checked to make sure it does not overflow.
 Expected<StringRef> ArchiveMemberHeader::getName(uint64_t Size) const {
@@ -234,7 +129,7 @@ Expected<StringRef> ArchiveMemberHeader::getName(uint64_t Size) const {
   // This can be called from the ArchiveMemberHeader constructor when the
   // archive header is truncated to produce an error message with the name.
   // Make sure the name field is not truncated.
-  if (Size < offsetof(UnixArMemHdrType, Name) + sizeof(ArMemHdr->Name)) {
+  if (Size < offsetof(ArMemHdrType, Name) + sizeof(ArMemHdr->Name)) {
     uint64_t ArchiveOffset =
         reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
     return malformedError("archive header truncated before the name field "
@@ -329,133 +224,126 @@ Expected<StringRef> ArchiveMemberHeader::getName(uint64_t Size) const {
   return Name.drop_back(1);
 }
 
-Expected<StringRef> BigArchiveMemberHeader::getName(uint64_t Size) const {
-  return getRawName();
-}
-
 Expected<uint64_t> ArchiveMemberHeader::getSize() const {
-  return getArchiveMemberDecField("size", getFieldRawString(ArMemHdr->Size),
-                                  Parent, this);
-}
-
-Expected<uint64_t> BigArchiveMemberHeader::getSize() const {
-  Expected<uint64_t> SizeOrErr = getArchiveMemberDecField(
-      "size", getFieldRawString(ArMemHdr->Size), Parent, this);
-  if (!SizeOrErr)
-    return SizeOrErr.takeError();
-
-  Expected<uint64_t> NameLenOrErr = getRawNameSize();
-  if (!NameLenOrErr)
-    return NameLenOrErr.takeError();
-
-  return *SizeOrErr + alignTo(*NameLenOrErr, 2);
-}
-
-Expected<uint64_t> BigArchiveMemberHeader::getRawNameSize() const {
-  return getArchiveMemberDecField(
-      "NameLen", getFieldRawString(ArMemHdr->NameLen), Parent, this);
-}
-
-Expected<uint64_t> BigArchiveMemberHeader::getNextOffset() const {
-  return getArchiveMemberDecField(
-      "NextOffset", getFieldRawString(ArMemHdr->NextOffset), Parent, this);
+  uint64_t Ret;
+  if (StringRef(ArMemHdr->Size, sizeof(ArMemHdr->Size))
+          .rtrim(" ")
+          .getAsInteger(10, Ret)) {
+    std::string Buf;
+    raw_string_ostream OS(Buf);
+    OS.write_escaped(
+        StringRef(ArMemHdr->Size, sizeof(ArMemHdr->Size)).rtrim(" "));
+    OS.flush();
+    uint64_t Offset =
+        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError("characters in size field in archive header are not "
+                          "all decimal numbers: '" +
+                          Buf +
+                          "' for archive "
+                          "member header at offset " +
+                          Twine(Offset));
+  }
+  return Ret;
 }
 
-Expected<sys::fs::perms> AbstractArchiveMemberHeader::getAccessMode() const {
-  Expected<uint64_t> AccessModeOrErr =
-      getArchiveMemberOctField("AccessMode", getRawAccessMode(), Parent, this);
-  if (!AccessModeOrErr)
-    return AccessModeOrErr.takeError();
-  return static_cast<sys::fs::perms>(*AccessModeOrErr);
+Expected<sys::fs::perms> ArchiveMemberHeader::getAccessMode() const {
+  unsigned Ret;
+  if (StringRef(ArMemHdr->AccessMode, sizeof(ArMemHdr->AccessMode))
+          .rtrim(' ')
+          .getAsInteger(8, Ret)) {
+    std::string Buf;
+    raw_string_ostream OS(Buf);
+    OS.write_escaped(
+        StringRef(ArMemHdr->AccessMode, sizeof(ArMemHdr->AccessMode))
+            .rtrim(" "));
+    OS.flush();
+    uint64_t Offset =
+        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError("characters in AccessMode field in archive header "
+                          "are not all decimal numbers: '" +
+                          Buf + "' for the archive member header at offset " +
+                          Twine(Offset));
+  }
+  return static_cast<sys::fs::perms>(Ret);
 }
 
 Expected<sys::TimePoint<std::chrono::seconds>>
-AbstractArchiveMemberHeader::getLastModified() const {
-  Expected<uint64_t> SecondsOrErr = getArchiveMemberDecField(
-      "LastModified", getRawLastModified(), Parent, this);
-
-  if (!SecondsOrErr)
-    return SecondsOrErr.takeError();
+ArchiveMemberHeader::getLastModified() const {
+  unsigned Seconds;
+  if (StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
+          .rtrim(' ')
+          .getAsInteger(10, Seconds)) {
+    std::string Buf;
+    raw_string_ostream OS(Buf);
+    OS.write_escaped(
+        StringRef(ArMemHdr->LastModified, sizeof(ArMemHdr->LastModified))
+            .rtrim(" "));
+    OS.flush();
+    uint64_t Offset =
+        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError("characters in LastModified field in archive header "
+                          "are not all decimal numbers: '" +
+                          Buf + "' for the archive member header at offset " +
+                          Twine(Offset));
+  }
 
-  return sys::toTimePoint(*SecondsOrErr);
+  return sys::toTimePoint(Seconds);
 }
 
-Expected<unsigned> AbstractArchiveMemberHeader::getUID() const {
-  StringRef User = getRawUID();
+Expected<unsigned> ArchiveMemberHeader::getUID() const {
+  unsigned Ret;
+  StringRef User = StringRef(ArMemHdr->UID, sizeof(ArMemHdr->UID)).rtrim(' ');
   if (User.empty())
     return 0;
-  return getArchiveMemberDecField("UID", User, Parent, this);
+  if (User.getAsInteger(10, Ret)) {
+    std::string Buf;
+    raw_string_ostream OS(Buf);
+    OS.write_escaped(User);
+    OS.flush();
+    uint64_t Offset =
+        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError("characters in UID field in archive header "
+                          "are not all decimal numbers: '" +
+                          Buf + "' for the archive member header at offset " +
+                          Twine(Offset));
+  }
+  return Ret;
 }
 
-Expected<unsigned> AbstractArchiveMemberHeader::getGID() const {
-  StringRef Group = getRawGID();
+Expected<unsigned> ArchiveMemberHeader::getGID() const {
+  unsigned Ret;
+  StringRef Group = StringRef(ArMemHdr->GID, sizeof(ArMemHdr->GID)).rtrim(' ');
   if (Group.empty())
     return 0;
-  return getArchiveMemberDecField("GID", Group, Parent, this);
-}
-
-Expected<bool> ArchiveMemberHeader::isThin() const {
-  Expected<StringRef> NameOrErr = getRawName();
-  if (!NameOrErr)
-    return NameOrErr.takeError();
-  StringRef Name = NameOrErr.get();
-  return Parent->isThin() && Name != "/" && Name != "//" && Name != "/SYM64/";
-}
-
-Expected<const char *> ArchiveMemberHeader::getNextChildLoc() const {
-  uint64_t Size = getSizeOf();
-  Expected<bool> isThinOrErr = isThin();
-  if (!isThinOrErr)
-    return isThinOrErr.takeError();
-
-  bool isThin = isThinOrErr.get();
-  if (!isThin) {
-    Expected<uint64_t> MemberSize = getSize();
-    if (!MemberSize)
-      return MemberSize.takeError();
-
-    Size += MemberSize.get();
+  if (Group.getAsInteger(10, Ret)) {
+    std::string Buf;
+    raw_string_ostream OS(Buf);
+    OS.write_escaped(Group);
+    OS.flush();
+    uint64_t Offset =
+        reinterpret_cast<const char *>(ArMemHdr) - Parent->getData().data();
+    return malformedError("characters in GID field in archive header "
+                          "are not all decimal numbers: '" +
+                          Buf + "' for the archive member header at offset " +
+                          Twine(Offset));
   }
-
-  // If Size is odd, add 1 to make it even.
-  const char *NextLoc =
-      reinterpret_cast<const char *>(ArMemHdr) + alignTo(Size, 2);
-
-  if (NextLoc == Parent->getMemoryBufferRef().getBufferEnd())
-    return nullptr;
-
-  return NextLoc;
-}
-
-Expected<const char *> BigArchiveMemberHeader::getNextChildLoc() const {
-  if (getOffset() ==
-      static_cast<const BigArchive *>(Parent)->getLastChildOffset())
-    return nullptr;
-
-  Expected<uint64_t> NextOffsetOrErr = getNextOffset();
-  if (!NextOffsetOrErr)
-    return NextOffsetOrErr.takeError();
-  return Parent->getData().data() + NextOffsetOrErr.get();
+  return Ret;
 }
 
 Archive::Child::Child(const Archive *Parent, StringRef Data,
                       uint16_t StartOfFile)
-    : Parent(Parent), Data(Data), StartOfFile(StartOfFile) {
-  Header = Parent->createArchiveMemberHeader(Data.data(), Data.size(), nullptr);
-}
+    : Parent(Parent), Header(Parent, Data.data(), Data.size(), nullptr),
+      Data(Data), StartOfFile(StartOfFile) {}
 
 Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
-    : Parent(Parent) {
-  if (!Start) {
-    Header = nullptr;
+    : Parent(Parent),
+      Header(Parent, Start,
+             Parent
+                 ? Parent->getData().size() - (Start - Parent->getData().data())
+                 : 0,
+             Err) {
+  if (!Start)
     return;
-  }
-
-  Header = Parent->createArchiveMemberHeader(
-      Start,
-      Parent ? Parent->getData().size() - (Start - Parent->getData().data())
-             : 0,
-      Err);
 
   // If we are pointed to real data, Start is not a nullptr, then there must be
   // a non-null Err pointer available to report malformed data on.  Only in
@@ -470,7 +358,7 @@ Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
   if (*Err)
     return;
 
-  uint64_t Size = Header->getSizeOf();
+  uint64_t Size = Header.getSizeOf();
   Data = StringRef(Start, Size);
   Expected<bool> isThinOrErr = isThinMember();
   if (!isThinOrErr) {
@@ -489,7 +377,7 @@ Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
   }
 
   // Setup StartOfFile and PaddingBytes.
-  StartOfFile = Header->getSizeOf();
+  StartOfFile = Header.getSizeOf();
   // Don't include attached name.
   Expected<StringRef> NameOrErr = getRawName();
   if (!NameOrErr) {
@@ -497,20 +385,17 @@ Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
     return;
   }
   StringRef Name = NameOrErr.get();
-
-  if (Parent->kind() == Archive::K_AIXBIG) {
-    // The actual start of the file is after the name and any necessary
-    // even-alignment padding.
-    StartOfFile += ((Name.size() + 1) >> 1) << 1;
-  } else if (Name.startswith("#1/")) {
+  if (Name.startswith("#1/")) {
     uint64_t NameSize;
-    StringRef RawNameSize = Name.substr(3).rtrim(' ');
-    if (RawNameSize.getAsInteger(10, NameSize)) {
+    if (Name.substr(3).rtrim(' ').getAsInteger(10, NameSize)) {
+      std::string Buf;
+      raw_string_ostream OS(Buf);
+      OS.write_escaped(Name.substr(3).rtrim(' '));
+      OS.flush();
       uint64_t Offset = Start - Parent->getData().data();
       *Err = malformedError("long name length characters after the #1/ are "
                             "not all decimal numbers: '" +
-                            RawNameSize +
-                            "' for archive member header at offset " +
+                            Buf + "' for archive member header at offset " +
                             Twine(Offset));
       return;
     }
@@ -520,15 +405,21 @@ Archive::Child::Child(const Archive *Parent, const char *Start, Error *Err)
 
 Expected<uint64_t> Archive::Child::getSize() const {
   if (Parent->IsThin)
-    return Header->getSize();
+    return Header.getSize();
   return Data.size() - StartOfFile;
 }
 
 Expected<uint64_t> Archive::Child::getRawSize() const {
-  return Header->getSize();
+  return Header.getSize();
 }
 
-Expected<bool> Archive::Child::isThinMember() const { return Header->isThin(); }
+Expected<bool> Archive::Child::isThinMember() const {
+  Expected<StringRef> NameOrErr = Header.getRawName();
+  if (!NameOrErr)
+    return NameOrErr.takeError();
+  StringRef Name = NameOrErr.get();
+  return Parent->IsThin && Name != "/" && Name != "//" && Name != "/SYM64/";
+}
 
 Expected<std::string> Archive::Child::getFullName() const {
   Expected<bool> isThin = isThinMember();
@@ -571,14 +462,15 @@ Expected<StringRef> Archive::Child::getBuffer() const {
 }
 
 Expected<Archive::Child> Archive::Child::getNext() const {
-  Expected<const char *> NextLocOrErr = Header->getNextChildLoc();
-  if (!NextLocOrErr)
-    return NextLocOrErr.takeError();
+  size_t SpaceToSkip = Data.size();
+  // If it's odd, add 1 to make it even.
+  if (SpaceToSkip & 1)
+    ++SpaceToSkip;
 
-  const char *NextLoc = *NextLocOrErr;
+  const char *NextLoc = Data.data() + SpaceToSkip;
 
   // Check to see if this is at the end of the archive.
-  if (NextLoc == nullptr)
+  if (NextLoc == Parent->Data.getBufferEnd())
     return Child(nullptr, nullptr, nullptr);
 
   // Check to see if this is past the end of the archive.
@@ -613,8 +505,7 @@ Expected<StringRef> Archive::Child::getName() const {
   if (!RawSizeOrErr)
     return RawSizeOrErr.takeError();
   uint64_t RawSize = RawSizeOrErr.get();
-  Expected<StringRef> NameOrErr =
-      Header->getName(Header->getSizeOf() + RawSize);
+  Expected<StringRef> NameOrErr = Header.getName(Header.getSizeOf() + RawSize);
   if (!NameOrErr)
     return NameOrErr.takeError();
   StringRef Name = NameOrErr.get();
@@ -646,39 +537,12 @@ Archive::Child::getAsBinary(LLVMContext *Context) const {
 
 Expected<std::unique_ptr<Archive>> Archive::create(MemoryBufferRef Source) {
   Error Err = Error::success();
-  std::unique_ptr<Archive> Ret;
-  StringRef Buffer = Source.getBuffer();
-
-  if (Buffer.startswith(BigArchiveMagic))
-    Ret = std::make_unique<BigArchive>(Source, Err);
-  else
-    Ret = std::make_unique<Archive>(Source, Err);
-
+  std::unique_ptr<Archive> Ret(new Archive(Source, Err));
   if (Err)
     return std::move(Err);
   return std::move(Ret);
 }
 
-std::unique_ptr<AbstractArchiveMemberHeader>
-Archive::createArchiveMemberHeader(const char *RawHeaderPtr, uint64_t Size,
-                                   Error *Err) const {
-  ErrorAsOutParameter ErrAsOutParam(Err);
-  if (kind() != K_AIXBIG)
-    return std::make_unique<ArchiveMemberHeader>(this, RawHeaderPtr, Size, Err);
-  return std::make_unique<BigArchiveMemberHeader>(this, RawHeaderPtr, Size,
-                                                  Err);
-}
-
-uint64_t Archive::getArchiveMagicLen() const {
-  if (isThin())
-    return sizeof(ThinArchiveMagic) - 1;
-
-  if (Kind() == K_AIXBIG)
-    return sizeof(BigArchiveMagic) - 1;
-
-  return sizeof(ArchiveMagic) - 1;
-}
-
 void Archive::setFirstRegular(const Child &C) {
   FirstRegularData = C.Data;
   FirstRegularStartOfFile = C.StartOfFile;
@@ -689,14 +553,10 @@ Archive::Archive(MemoryBufferRef Source, Error &Err)
   ErrorAsOutParameter ErrAsOutParam(&Err);
   StringRef Buffer = Data.getBuffer();
   // Check for sufficient magic.
-  if (Buffer.startswith(ThinArchiveMagic)) {
+  if (Buffer.startswith(ThinMagic)) {
     IsThin = true;
-  } else if (Buffer.startswith(ArchiveMagic)) {
-    IsThin = false;
-  } else if (Buffer.startswith(BigArchiveMagic)) {
-    Format = K_AIXBIG;
+  } else if (Buffer.startswith(Magic)) {
     IsThin = false;
-    return;
   } else {
     Err = make_error<GenericBinaryError>("file too small to be an archive",
                                          object_error::invalid_file_type);
@@ -928,7 +788,7 @@ Archive::child_iterator Archive::child_begin(Error &Err,
     return child_iterator::itr(
         Child(this, FirstRegularData, FirstRegularStartOfFile), Err);
 
-  const char *Loc = Data.getBufferStart() + getFirstChildOffset();
+  const char *Loc = Data.getBufferStart() + strlen(Magic);
   Child C(this, Loc, &Err);
   if (Err)
     return child_end();
@@ -1137,39 +997,6 @@ Expected<Optional<Archive::Child>> Archive::findSym(StringRef name) const {
 }
 
 // Returns true if archive file contains no member file.
-bool Archive::isEmpty() const {
-  return Data.getBufferSize() == getArchiveMagicLen();
-}
+bool Archive::isEmpty() const { return Data.getBufferSize() == 8; }
 
 bool Archive::hasSymbolTable() const { return !SymbolTable.empty(); }
-
-BigArchive::BigArchive(MemoryBufferRef Source, Error &Err)
-    : Archive(Source, Err) {
-  ErrorAsOutParameter ErrAsOutParam(&Err);
-  StringRef Buffer = Data.getBuffer();
-  ArFixLenHdr = reinterpret_cast<const FixLenHdr *>(Buffer.data());
-
-  StringRef RawOffset = getFieldRawString(ArFixLenHdr->FirstChildOffset);
-  if (RawOffset.getAsInteger(10, FirstChildOffset))
-    // TODO: Out-of-line.
-    Err = malformedError("malformed AIX big archive: first member offset \"" +
-                         RawOffset + "\" is not a number");
-
-  RawOffset = getFieldRawString(ArFixLenHdr->LastChildOffset);
-  if (RawOffset.getAsInteger(10, LastChildOffset))
-    // TODO: Out-of-line.
-    Err = malformedError("malformed AIX big archive: last member offset \"" +
-                         RawOffset + "\" is not a number");
-
-  child_iterator I = child_begin(Err, false);
-  if (Err)
-    return;
-  child_iterator E = child_end();
-  if (I == E) {
-    Err = Error::success();
-    return;
-  }
-  setFirstRegular(*I);
-  Err = Error::success();
-  return;
-}