[llvm-ar][Archive] Use getDefaultTargetTriple instead of host triple for the fallback archive format. (#82888)

Author: cjacek

clang/tools/clang-offload-packager/ClangOffloadPackager.cpp

@@ -197,7 +197,7 @@ static Error unbundleImages() {
 
       if (Error E = writeArchive(
               Args["file"], Members, SymtabWritingMode::NormalSymtab,
-              Archive::getDefaultKindForHost(), true, false, nullptr))
+              Archive::getDefaultKind(), true, false, nullptr))
         return E;
     } else if (Args.count("file")) {
       if (Extracted.size() > 1)

llvm/docs/CommandGuide/llvm-ar.rst

@@ -262,8 +262,9 @@ Other
 .. option:: --format=<type>
 
  This option allows for default, gnu, darwin or bsd ``<type>`` to be selected.
- When creating an ``archive``, ``<type>`` will default to that of the host
- machine.
+ When creating an ``archive`` with the default ``<type>``, :program:``llvm-ar``
+ will attempt to infer it from the input files and fallback to the default
+ toolchain target if unable to do so.
 
 .. option:: -h, --help
 

llvm/docs/ReleaseNotes.rst

@@ -143,6 +143,10 @@ Changes to the LLVM tools
   files using reference types and GC are also supported (but also only for
   functions, globals, and data, and only for listing symbols and names).
 
+* llvm-ar now utilizes LLVM_DEFAULT_TARGET_TRIPLE to determine the archive format
+  if it's not specified with the ``--format`` argument and cannot be inferred from
+  input files.
+
 Changes to LLDB
 ---------------------------------
 

llvm/include/llvm/Object/Archive.h

@@ -338,7 +338,7 @@ class Archive : public Binary {
 
   Kind kind() const { return (Kind)Format; }
   bool isThin() const { return IsThin; }
-  static object::Archive::Kind getDefaultKindForHost();
+  static object::Archive::Kind getDefaultKind();
 
   child_iterator child_begin(Error &Err, bool SkipInternal = true) const;
   child_iterator child_end() const;

llvm/lib/Object/Archive.cpp

@@ -969,8 +969,8 @@ Archive::Archive(MemoryBufferRef Source, Error &Err)
   Err = Error::success();
 }
 
-object::Archive::Kind Archive::getDefaultKindForHost() {
-  Triple HostTriple(sys::getProcessTriple());
+object::Archive::Kind Archive::getDefaultKind() {
+  Triple HostTriple(sys::getDefaultTargetTriple());
   return HostTriple.isOSDarwin()
              ? object::Archive::K_DARWIN
              : (HostTriple.isOSAIX() ? object::Archive::K_AIXBIG

llvm/lib/Object/ArchiveWriter.cpp

@@ -90,7 +90,7 @@ object::Archive::Kind NewArchiveMember::detectKindFromObject() const {
     }
   }
 
-  return object::Archive::getDefaultKindForHost();
+  return object::Archive::getDefaultKind();
 }
 
 Expected<NewArchiveMember>

llvm/tools/llvm-ar/llvm-ar.cpp

@@ -670,7 +670,7 @@ Expected<std::unique_ptr<Binary>> getAsBinary(const Archive::Child &C,
 }
 
 template <class A> static bool isValidInBitMode(const A &Member) {
-  if (object::Archive::getDefaultKindForHost() != object::Archive::K_AIXBIG)
+  if (object::Archive::getDefaultKind() != object::Archive::K_AIXBIG)
     return true;
   LLVMContext Context;
   Expected<std::unique_ptr<Binary>> BinOrErr = getAsBinary(Member, &Context);
@@ -1036,10 +1036,10 @@ static void performWriteOperation(ArchiveOperation Operation,
       }
     } else if (NewMembersP)
       Kind = !NewMembersP->empty() ? NewMembersP->front().detectKindFromObject()
-                                   : object::Archive::getDefaultKindForHost();
+                                   : object::Archive::getDefaultKind();
     else
       Kind = !NewMembers.empty() ? NewMembers.front().detectKindFromObject()
-                                 : object::Archive::getDefaultKindForHost();
+                                 : object::Archive::getDefaultKind();
     break;
   case GNU:
     Kind = object::Archive::K_GNU;
@@ -1331,7 +1331,7 @@ static int ar_main(int argc, char **argv) {
 
   // Get BitMode from enviorment variable "OBJECT_MODE" for AIX OS, if
   // specified.
-  if (object::Archive::getDefaultKindForHost() == object::Archive::K_AIXBIG) {
+  if (object::Archive::getDefaultKind() == object::Archive::K_AIXBIG) {
     BitMode = getBitMode(getenv("OBJECT_MODE"));
     if (BitMode == BitModeTy::Unknown)
       BitMode = BitModeTy::Bit32;
@@ -1392,8 +1392,7 @@ static int ar_main(int argc, char **argv) {
       continue;
 
     if (strncmp(*ArgIt, "-X", 2) == 0) {
-      if (object::Archive::getDefaultKindForHost() ==
-          object::Archive::K_AIXBIG) {
+      if (object::Archive::getDefaultKind() == object::Archive::K_AIXBIG) {
         Match = *(*ArgIt + 2) != '\0' ? *ArgIt + 2 : *(++ArgIt);
         BitMode = getBitMode(Match);
         if (BitMode == BitModeTy::Unknown)
@@ -1432,8 +1431,7 @@ static int ranlib_main(int argc, char **argv) {
           cl::PrintVersionMessage();
           return 0;
         } else if (arg.front() == 'X') {
-          if (object::Archive::getDefaultKindForHost() ==
-              object::Archive::K_AIXBIG) {
+          if (object::Archive::getDefaultKind() == object::Archive::K_AIXBIG) {
             HasAIXXOption = true;
             arg.consume_front("X");
             const char *Xarg = arg.data();
@@ -1464,7 +1462,7 @@ static int ranlib_main(int argc, char **argv) {
     }
   }
 
-  if (object::Archive::getDefaultKindForHost() == object::Archive::K_AIXBIG) {
+  if (object::Archive::getDefaultKind() == object::Archive::K_AIXBIG) {
     // If not specify -X option, get BitMode from enviorment variable
     // "OBJECT_MODE" for AIX OS if specify.
     if (!HasAIXXOption) {