Revert "[llvm-ar] Use COFF archive format for COFF targets." (#82889)

Reverts #82642 for
lld/test/ELF/invalid/Output/data-encoding.test.tmp.a failures on
Windows.

Author: cjacek

llvm/include/llvm/Object/Archive.h

@@ -339,7 +339,6 @@ class Archive : public Binary {
   Kind kind() const { return (Kind)Format; }
   bool isThin() const { return IsThin; }
   static object::Archive::Kind getDefaultKindForHost();
-  static object::Archive::Kind getDefaultKindForTriple(Triple &T);
 
   child_iterator child_begin(Error &Err, bool SkipInternal = true) const;
   child_iterator child_end() const;

llvm/lib/Object/Archive.cpp

@@ -969,19 +969,12 @@ Archive::Archive(MemoryBufferRef Source, Error &Err)
   Err = Error::success();
 }
 
-object::Archive::Kind Archive::getDefaultKindForTriple(Triple &T) {
-  if (T.isOSDarwin())
-    return object::Archive::K_DARWIN;
-  if (T.isOSAIX())
-    return object::Archive::K_AIXBIG;
-  if (T.isOSWindows())
-    return object::Archive::K_COFF;
-  return object::Archive::K_GNU;
-}
-
 object::Archive::Kind Archive::getDefaultKindForHost() {
   Triple HostTriple(sys::getProcessTriple());
-  return getDefaultKindForTriple(HostTriple);
+  return HostTriple.isOSDarwin()
+             ? object::Archive::K_DARWIN
+             : (HostTriple.isOSAIX() ? object::Archive::K_AIXBIG
+                                     : object::Archive::K_GNU);
 }
 
 Archive::child_iterator Archive::child_begin(Error &Err,

llvm/lib/Object/ArchiveWriter.cpp

@@ -62,16 +62,12 @@ object::Archive::Kind NewArchiveMember::detectKindFromObject() const {
   Expected<std::unique_ptr<object::ObjectFile>> OptionalObject =
       object::ObjectFile::createObjectFile(MemBufferRef);
 
-  if (OptionalObject) {
-    if (isa<object::MachOObjectFile>(**OptionalObject))
-      return object::Archive::K_DARWIN;
-    if (isa<object::XCOFFObjectFile>(**OptionalObject))
-      return object::Archive::K_AIXBIG;
-    if (isa<object::COFFObjectFile>(**OptionalObject) ||
-        isa<object::COFFImportFile>(**OptionalObject))
-      return object::Archive::K_COFF;
-    return object::Archive::K_GNU;
-  }
+  if (OptionalObject)
+    return isa<object::MachOObjectFile>(**OptionalObject)
+               ? object::Archive::K_DARWIN
+               : (isa<object::XCOFFObjectFile>(**OptionalObject)
+                      ? object::Archive::K_AIXBIG
+                      : object::Archive::K_GNU);
 
   // Squelch the error in case we had a non-object file.
   consumeError(OptionalObject.takeError());
@@ -84,7 +80,10 @@ object::Archive::Kind NewArchiveMember::detectKindFromObject() const {
             MemBufferRef, file_magic::bitcode, &Context)) {
       auto &IRObject = cast<object::IRObjectFile>(**ObjOrErr);
       auto TargetTriple = Triple(IRObject.getTargetTriple());
-      return object::Archive::getDefaultKindForTriple(TargetTriple);
+      return TargetTriple.isOSDarwin()
+                 ? object::Archive::K_DARWIN
+                 : (TargetTriple.isOSAIX() ? object::Archive::K_AIXBIG
+                                           : object::Archive::K_GNU);
     } else {
       // Squelch the error in case this was not a SymbolicFile.
       consumeError(ObjOrErr.takeError());

llvm/test/tools/llvm-ar/coff-symtab.test

@@ -82,7 +82,6 @@ static void printArHelp(StringRef ToolName) {
     =darwin             -   darwin
     =bsd                -   bsd
     =bigarchive         -   big archive (AIX OS)
-    =coff               -   coff
   --plugin=<string>     - ignored for compatibility
   -h --help             - display this help and exit
   --output              - the directory to extract archive members to
@@ -194,7 +193,7 @@ static SmallVector<const char *, 256> PositionalArgs;
 static bool MRI;
 
 namespace {
-enum Format { Default, GNU, COFF, BSD, DARWIN, BIGARCHIVE, Unknown };
+enum Format { Default, GNU, BSD, DARWIN, BIGARCHIVE, Unknown };
 }
 
 static Format FormatType = Default;
@@ -1045,9 +1044,6 @@ static void performWriteOperation(ArchiveOperation Operation,
   case GNU:
     Kind = object::Archive::K_GNU;
     break;
-  case COFF:
-    Kind = object::Archive::K_COFF;
-    break;
   case BSD:
     if (Thin)
       fail("only the gnu format has a thin mode");
@@ -1380,7 +1376,6 @@ static int ar_main(int argc, char **argv) {
                        .Case("darwin", DARWIN)
                        .Case("bsd", BSD)
                        .Case("bigarchive", BIGARCHIVE)
-                       .Case("coff", COFF)
                        .Default(Unknown);
       if (FormatType == Unknown)
         fail(std::string("Invalid format ") + Match);