lld-link: Remove /msvclto option

[thakis]

Summary

This was useful for LTO bringup in lld-link while lld couldn't write PDBs. Now that it can, this should no longer be needed. Hopefully the flag is obscure enough and recent enough, that nobody uses it – but if somebody should use it, they should be able to just stop passing it and things should continue to work.

[hans]

lgtm

[thakis]

r338615, thanks!

lld/COFF/Driver.h

private:
   // There are four different entry point functions for them,
   // {w,}{WinMain,main}CRTStartup, respectively. The linker needs to
   // choose the right one depending on which "main" function is defined.
   // This function looks up the symbol table and resolve corresponding
   // entry point name.
   StringRef findDefaultEntry();
   WindowsSubsystem inferSubsystem();
 
-  void invokeMSVC(llvm::opt::InputArgList &Args);
-
   void addBuffer(std::unique_ptr<MemoryBuffer> MB, bool WholeArchive);
   void addArchiveBuffer(MemoryBufferRef MBRef, StringRef SymName,
                         StringRef ParentName);
 
   void enqueuePath(StringRef Path, bool WholeArchive);
 
   void enqueueTask(std::function<void()> Task);
   bool run();

lld/COFF/Driver.cpp

for (COFFShortExport E1 : M.Exports) {
     E2.Noname = E1.Noname;
     E2.Data = E1.Data;
     E2.Private = E1.Private;
     E2.Constant = E1.Constant;
     Config->Exports.push_back(E2);
   }
 }
 
-// A helper function for filterBitcodeFiles.
-static bool needsRebuilding(MemoryBufferRef MB) {
-  // The MSVC linker doesn't support thin archives, so if it's a thin
-  // archive, we always need to rebuild it.
-  std::unique_ptr<Archive> File =
-      CHECK(Archive::create(MB), "Failed to read " + MB.getBufferIdentifier());
-  if (File->isThin())
-    return true;
-
-  // Returns true if the archive contains at least one bitcode file.
-  for (MemoryBufferRef Member : getArchiveMembers(File.get()))
-    if (identify_magic(Member.getBuffer()) == file_magic::bitcode)
-      return true;
-  return false;
-}
-
-// Opens a given path as an archive file and removes bitcode files
-// from them if exists. This function is to appease the MSVC linker as
-// their linker doesn't like archive files containing non-native
-// object files.
-//
-// If a given archive doesn't contain bitcode files, the archive path
-// is returned as-is. Otherwise, a new temporary file is created and
-// its path is returned.
-static Optional<std::string>
-filterBitcodeFiles(StringRef Path, std::vector<std::string> &TemporaryFiles) {
-  std::unique_ptr<MemoryBuffer> MB = CHECK(
-      MemoryBuffer::getFile(Path, -1, false, true), "could not open " + Path);
-  MemoryBufferRef MBRef = MB->getMemBufferRef();
-  file_magic Magic = identify_magic(MBRef.getBuffer());
-
-  if (Magic == file_magic::bitcode)
-    return None;
-  if (Magic != file_magic::archive)
-    return Path.str();
-  if (!needsRebuilding(MBRef))
-    return Path.str();
-
-  std::unique_ptr<Archive> File =
-      CHECK(Archive::create(MBRef),
-            MBRef.getBufferIdentifier() + ": failed to parse archive");
-
-  std::vector<NewArchiveMember> New;
-  for (MemoryBufferRef Member : getArchiveMembers(File.get()))
-    if (identify_magic(Member.getBuffer()) != file_magic::bitcode)
-      New.emplace_back(Member);
-
-  if (New.empty())
-    return None;
-
-  log("Creating a temporary archive for " + Path + " to remove bitcode files");
-
-  SmallString<128> S;
-  if (std::error_code EC = sys::fs::createTemporaryFile(
-          "lld-" + sys::path::stem(Path), ".lib", S))
-    fatal("cannot create a temporary file: " + EC.message());
-  std::string Temp = S.str();
-  TemporaryFiles.push_back(Temp);
-
-  Error E =
-      llvm::writeArchive(Temp, New, /*WriteSymtab=*/true, Archive::Kind::K_GNU,
-                         /*Deterministics=*/true,
-                         /*Thin=*/false);
-  handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
-    error("failed to create a new archive " + S.str() + ": " + EI.message());
-  });
-  return Temp;
-}
-
-// Create response file contents and invoke the MSVC linker.
-void LinkerDriver::invokeMSVC(opt::InputArgList &Args) {
-  std::string Rsp = "/nologo\n";
-  std::vector<std::string> Temps;
-
-  // Write out archive members that we used in symbol resolution and pass these
-  // to MSVC before any archives, so that MSVC uses the same objects to satisfy
-  // references.
-  for (ObjFile *Obj : ObjFile::Instances) {
-    if (Obj->ParentName.empty())
-      continue;
-    SmallString<128> S;
-    int Fd;
-    if (auto EC = sys::fs::createTemporaryFile(
-            "lld-" + sys::path::filename(Obj->ParentName), ".obj", Fd, S))
-      fatal("cannot create a temporary file: " + EC.message());
-    raw_fd_ostream OS(Fd, /*shouldClose*/ true);
-    OS << Obj->MB.getBuffer();
-    Temps.push_back(S.str());
-    Rsp += quote(S) + "\n";
-  }
-
-  for (auto *Arg : Args) {
-    switch (Arg->getOption().getID()) {
-    case OPT_linkrepro:
-    case OPT_lldmap:
-    case OPT_lldmap_file:
-    case OPT_lldsavetemps:
-    case OPT_msvclto:
-      // LLD-specific options are stripped.
-      break;
-    case OPT_opt:
-      if (!StringRef(Arg->getValue()).startswith("lld"))
-        Rsp += toString(*Arg) + " ";
-      break;
-    case OPT_INPUT: {
-      if (Optional<StringRef> Path = doFindFile(Arg->getValue())) {
-        if (Optional<std::string> S = filterBitcodeFiles(*Path, Temps))
-          Rsp += quote(*S) + "\n";
-        continue;
-      }
-      Rsp += quote(Arg->getValue()) + "\n";
-      break;
-    }
-    default:
-      Rsp += toString(*Arg) + "\n";
-    }
-  }
-
-  std::vector<StringRef> ObjFiles = Symtab->compileBitcodeFiles();
-  runMSVCLinker(Rsp, ObjFiles);
-
-  for (StringRef Path : Temps)
-    sys::fs::remove(Path);
-}
-
 void LinkerDriver::enqueueTask(std::function<void()> Task) {
   TaskQueue.push_back(std::move(Task));
 }
 
 bool LinkerDriver::run() {
   ScopedTimer T(InputFileTimer);
 
   bool DidWork = !TaskQueue.empty();
do {
     // Windows specific -- if __load_config_used can be resolved, resolve it.
     if (Symtab->findUnderscore("_load_config_used"))
       addUndefined(mangle("_load_config_used"));
   } while (run());
 
   if (errorCount())
     return;
 
-  // If /msvclto is given, we use the MSVC linker to link LTO output files.
-  // This is useful because MSVC link.exe can generate complete PDBs.
-  if (Args.hasArg(OPT_msvclto)) {
-    invokeMSVC(Args);
-    return;
-  }
-
   // Do LTO by compiling bitcode input files to a set of native COFF files then
   // link those files.
   Symtab->addCombinedLTOObjects();
   run();
 
   // Make sure we have resolved all symbols.
   Symtab->reportRemainingUndefines();
   if (errorCount())

lld/COFF/DriverUtils.cpp

MemoryBufferRef convertResToCOFF(ArrayRef<MemoryBufferRef> MBs) {
   if (!E)
     fatal("failed to write .res to COFF: " + toString(E.takeError()));
 
   MemoryBufferRef MBRef = **E;
   make<std::unique_ptr<MemoryBuffer>>(std::move(*E)); // take ownership
   return MBRef;
 }
 
-// Run MSVC link.exe for given in-memory object files.
-// Command line options are copied from those given to LLD.
-// This is for the /msvclto option.
-void runMSVCLinker(std::string Rsp, ArrayRef<StringRef> Objects) {
-  // Write the in-memory object files to disk.
-  std::vector<TemporaryFile> Temps;
-  for (StringRef S : Objects) {
-    Temps.emplace_back("lto", "obj", S);
-    Rsp += quote(Temps.back().Path) + "\n";
-  }
-
-  log("link.exe " + Rsp);
-
-  // Run MSVC link.exe.
-  Temps.emplace_back("lto", "rsp", Rsp);
-  Executor E("link.exe");
-  E.add(Twine("@" + Temps.back().Path));
-  E.run();
-}
-
 // Create OptTable
 
 // Create prefix string literals used in Options.td
 #define PREFIX(NAME, VALUE) const char *const NAME[] = VALUE;
 #include "Options.inc"
 #undef PREFIX
 
 // Create table mapping all options defined in Options.td

lld/COFF/Options.td

 
 // LLD extensions
 def debug_ghash : F<"debug:ghash">;
 def debug_dwarf : F<"debug:dwarf">;
 def debug_symtab : F<"debug:symtab">;
 def export_all_symbols : F<"export-all-symbols">;
 def kill_at : F<"kill-at">;
 def lldmingw : F<"lldmingw">;
-def msvclto : F<"msvclto">;
 def output_def : Joined<["/", "-"], "output-def:">;
 def pdb_source_path : P<"pdbsourcepath",
                         "Base path used to make relative source file path absolute in PDB">;
 def rsp_quoting : Joined<["--"], "rsp-quoting=">,
   HelpText<"Quoting style for response files, 'windows' (default) or 'posix'">;
 def dash_dash_version : Flag<["--"], "version">,
   HelpText<"Print version information">;
 

lld/test/COFF/msvclto-archive.ll

-; REQUIRES: x86
-;; Make sure we re-create archive files to strip bitcode files.
-
-;; Do not create empty archives because the MSVC linker
-;; doesn't support them.
-; RUN: llvm-as -o %t.obj %s
-; RUN: rm -f %t-main1.a
-; RUN: llvm-ar cru %t-main1.a %t.obj
-; RUN: mkdir -p %t.dir
-; RUN: llvm-mc -triple=x86_64-pc-windows-msvc -filetype=obj -o %t.dir/bitcode.obj %p/Inputs/msvclto.s
-; RUN: lld-link %t-main1.a %t.dir/bitcode.obj /msvclto /out:%t.exe /opt:lldlto=1 /opt:icf \
-; RUN:   /entry:main /verbose 2> %t.log || true
-; RUN: FileCheck -check-prefix=BC %s < %t.log
-; BC-NOT: Creating a temporary archive for
-
-; RUN: rm -f %t-main2.a
-; RUN: llvm-ar cru %t-main2.a %t.dir/bitcode.obj
-; RUN: lld-link %t.obj %t-main2.a /msvclto /out:%t.exe /opt:lldlto=1 /opt:icf \
-; RUN:   /entry:main /verbose 2> %t.log || true
-; RUN: FileCheck -check-prefix=OBJ %s < %t.log
-; OBJ-NOT: Creating a temporary archive
-
-;; Make sure that we always rebuild thin archives because
-;; the MSVC linker doesn't support thin archives.
-; RUN: rm -f %t-main3.a
-; RUN: llvm-ar cruT %t-main3.a %t.dir/bitcode.obj
-; RUN: lld-link %t.obj %t-main3.a /msvclto /out:%t.exe /opt:lldlto=1 /opt:icf \
-; RUN:   /entry:main /verbose 2> %t.log || true
-; RUN: FileCheck -check-prefix=THIN %s < %t.log
-; THIN: Creating a temporary archive
-
-target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-windows-msvc"
-
-declare void @foo()
-
-define i32 @main() {
-  call void @foo()
-  ret i32 0
-}

lld/test/COFF/msvclto-order.ll

-; REQUIRES: x86
-; RUN: opt -thinlto-bc %s -o %t.obj
-; RUN: llc -filetype=obj %S/Inputs/msvclto-order-a.ll -o %T/msvclto-order-a.obj
-; RUN: llvm-ar crs %T/msvclto-order-a.lib %T/msvclto-order-a.obj
-; RUN: llc -filetype=obj %S/Inputs/msvclto-order-b.ll -o %T/msvclto-order-b.obj
-; RUN: llvm-ar crs %T/msvclto-order-b.lib %T/msvclto-order-b.obj
-; RUN: lld-link /verbose /msvclto /out:%t.exe /entry:main %t.obj \
-; RUN:     %T/msvclto-order-a.lib %T/msvclto-order-b.lib 2> %t.log || true
-; RUN: FileCheck %s < %t.log
-
-; CHECK: : link.exe
-; CHECK-NOT: .lib{{$}}
-; CHECK: lld-msvclto-order-a{{.*}}.obj
-; CHECK-NOT: lld-msvclto-order-b{{.*}}.obj
-; CHECK: .lib{{$}}
-
-target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-windows-msvc"
-
-declare void @foo()
-
-define i32 @main() {
-  call void @foo()
-  ret i32 0
-}

lld/test/COFF/msvclto.ll

-; REQUIRES: x86
-; RUN: llvm-as -o %t.obj %s
-; RUN: mkdir -p %t.dir
-; RUN: llvm-mc -triple=x86_64-pc-windows-msvc -filetype=obj -o %t.dir/bitcode.obj %p/Inputs/msvclto.s
-; RUN: lld-link %t.obj %t.dir/bitcode.obj /msvclto /out:%t.exe /opt:lldlto=1 /opt:icf \
-; RUN:   /entry:main /verbose 2> %t.log || true
-; RUN: FileCheck %s < %t.log
-
-; CHECK: /opt:icf /entry:main
-; CHECK: /verbose
-
-target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-windows-msvc"
-
-declare void @foo()
-
-define i32 @main() {
-  call void @foo()
-  ret i32 0
-}