llvm-lib: add a feature to merge library files.

[ruiu]

Summary

If an input file is actually an archive file, MSVC lib.exe doesn't add
that file to a resulting archive file. Instead, it will add its members
to a resulting archive. Therefore, by giving archive files to lib.exe,
you can merge them without extracting-and-rearchiving them.

This patch is to add the same functionality to llvm-lib, which is our
version of lib.exe.

[pcc]

llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp

181

Is this correct for thin archives? I believe that memory buffers for members of thin archives are owned by the Archive object.

Speaking of thin archives, we probably need to prevent this feature from being used with /llvmlibthin unless all input archives are thin.

llvm/lib/ToolDrivers/llvm-lib/LibDriver.cpp

 
 class LibOptTable : public opt::OptTable {
 public:
   LibOptTable() : OptTable(InfoTable, true) {}
 };
 
 }
 
-static std::string getOutputPath(opt::InputArgList *Args,
+static std::string getOutputPath(const opt::InputArgList &Args,
                                  const NewArchiveMember &FirstMember) {
-  if (auto *Arg = Args->getLastArg(OPT_out))
+  if (auto *Arg = Args.getLastArg(OPT_out))
     return Arg->getValue();
   SmallString<128> Val = StringRef(FirstMember.Buf->getBufferIdentifier());
   sys::path::replace_extension(Val, ".lib");
   return Val.str();
 }
 
-static std::vector<StringRef> getSearchPaths(opt::InputArgList *Args,
+static std::vector<StringRef> getSearchPaths(const opt::InputArgList &Args,
                                              StringSaver &Saver) {
   std::vector<StringRef> Ret;
   // Add current directory as first item of the search path.
   Ret.push_back("");
 
   // Add /libpath flags.
-  for (auto *Arg : Args->filtered(OPT_libpath))
+  for (auto *Arg : Args.filtered(OPT_libpath))
     Ret.push_back(Arg->getValue());
 
   // Add $LIB.
   Optional<std::string> EnvOpt = sys::Process::GetEnv("LIB");
   if (!EnvOpt.hasValue())
     return Ret;
   StringRef Env = Saver.save(*EnvOpt);
   while (!Env.empty()) {
for (StringRef Dir : Paths) {
     SmallString<128> Path = Dir;
     sys::path::append(Path, File);
     if (sys::fs::exists(Path))
       return Path.str().str();
   }
   return "";
 }
 
+// Open input files and return them as MemoryBuffers.
+static std::vector<std::unique_ptr<MemoryBuffer>>
+openFiles(const opt::InputArgList &Args, StringSaver &Saver) {
+  std::vector<StringRef> SearchPaths = getSearchPaths(Args, Saver);
+
+  std::vector<std::unique_ptr<MemoryBuffer>> Ret;
+
+  for (auto *Arg : Args.filtered(OPT_INPUT)) {
+    std::string Path = findInputFile(Arg->getValue(), SearchPaths);
+    if (Path.empty()) {
+      llvm::errs() << Arg->getValue() << ": no such file or directory\n";
+      return {};
+    }
+
+    ErrorOr<std::unique_ptr<MemoryBuffer>> MBOrErr =
+        MemoryBuffer::getFile(Path, -1, false);
+    if (!MBOrErr) {
+      llvm::errs() << "cannot open " << Arg->getValue() << ": "
+                   << MBOrErr.getError().message() << "\n";
+      return {};
+    }
+
+    file_magic Magic = identify_magic((*MBOrErr)->getBuffer());
+    if (Magic != file_magic::coff_object && Magic != file_magic::bitcode &&
+        Magic != file_magic::archive && Magic != file_magic::windows_resource) {
+      llvm::errs() << Arg->getValue()
+                   << ": not a COFF object, bitcode, archive or "
+                   << "resource file\n";
+      return {};
+    }
+
+    Ret.push_back(std::move(*MBOrErr));
+  }
+  return Ret;
+}
+
+// Create NewArchiveMembers for a given input file and add them to Members.
+// Returns true on success.
+static bool addMembers(std::vector<NewArchiveMember> &Members,
+                       MemoryBufferRef MB) {
+  // Regular path -- if a given file is not an archive, add it as a member.
+  if (identify_magic(MB.getBuffer()) != file_magic::archive) {
+    Members.push_back(NewArchiveMember(MB));
+    Members.back().IsNew = true;
+    return true;
+  }
+
+  // If a given file is an archive file, copy its members.
+  // This is Windows lib.exe-specific feature. Unix's "ar" doesn't do this.
+  // First, create an archive file instance.
+  Expected<std::unique_ptr<object::Archive>> FileOrErr =
+      object::Archive::create(MB);
+  if (!FileOrErr) {
+    handleAllErrors(FileOrErr.takeError(), [&](const ErrorInfoBase &EIB) {
+      llvm::errs() << "cannot open " << MB.getBufferIdentifier() << ": "
+                   << EIB.message() << "\n";
+    });
+    return false;
+  }
+  object::Archive *File = FileOrErr->get();
+
+  // Iterate over archive members to copy them.
+  Error Err = Error::success();
+  for (const ErrorOr<object::Archive::Child> &COrErr : File->children(Err)) {
+    if (!COrErr) {
+      llvm::errs() << MB.getBufferIdentifier()
+                   << ": could not get the child of the archive: "
+                   << COrErr.getError().message() << "\n";
+      return false;
+    }
+
+    Expected<MemoryBufferRef> MBOrErr = COrErr->getMemoryBufferRef();
+    if (!MBOrErr) {
+      handleAllErrors(FileOrErr.takeError(), [&](const ErrorInfoBase &EIB) {
+        llvm::errs() << MB.getBufferIdentifier()
+                     << ": could not get the buffer for a child of the archive"
+                     << EIB.message() << "\n";
+      });
+      return false;
+    }
+
+    Members.push_back(NewArchiveMember(MBOrErr.get()));
+    Members.back().IsNew = true;
+  }
+
+  if (Err) {
+    handleAllErrors(FileOrErr.takeError(), [&](const ErrorInfoBase &EIB) {
+      llvm::errs() << MB.getBufferIdentifier()
+                   << ": Archive::children failed: " << EIB.message() << "\n";
+    });
+    return false;
+  }
+  return true;
+}
+
 int llvm::libDriverMain(ArrayRef<const char *> ArgsArr) {
   BumpPtrAllocator Alloc;
   StringSaver Saver(Alloc);
 
   // Parse command line arguments.
   SmallVector<const char *, 20> NewArgs(ArgsArr.begin(), ArgsArr.end());
   cl::ExpandResponseFiles(Saver, cl::TokenizeWindowsCommandLine, NewArgs);
   ArgsArr = NewArgs;
int llvm::libDriverMain(ArrayRef<const char *> ArgsArr) {
   }
   for (auto *Arg : Args.filtered(OPT_UNKNOWN))
     llvm::errs() << "ignoring unknown argument: " << Arg->getSpelling() << "\n";
 
   // If no input files, silently do nothing to match lib.exe.
   if (!Args.hasArgNoClaim(OPT_INPUT))
     return 0;
 
-  std::vector<StringRef> SearchPaths = getSearchPaths(&Args, Saver);
-
-  // Create a NewArchiveMember for each input file.
-  std::vector<NewArchiveMember> Members;
-  for (auto *Arg : Args.filtered(OPT_INPUT)) {
-    std::string Path = findInputFile(Arg->getValue(), SearchPaths);
-    if (Path.empty()) {
-      llvm::errs() << Arg->getValue() << ": no such file or directory\n";
-      return 1;
-    }
-
-    Expected<NewArchiveMember> MOrErr =
-        NewArchiveMember::getFile(Saver.save(Path), /*Deterministic=*/true);
-    if (!MOrErr) {
-      handleAllErrors(MOrErr.takeError(), [&](const ErrorInfoBase &EIB) {
-        llvm::errs() << Arg->getValue() << ": " << EIB.message() << "\n";
-      });
-      return 1;
-    }
+  // Create NewArchiveMembers from input files.
+  std::vector<std::unique_ptr<MemoryBuffer>> Files = openFiles(Args, Saver);
+  if (Files.empty())
 
-    file_magic Magic = identify_magic(MOrErr->Buf->getBuffer());
-    if (Magic != file_magic::coff_object && Magic != file_magic::bitcode &&
-        Magic != file_magic::windows_resource) {
-      llvm::errs() << Arg->getValue()
-                   << ": not a COFF object, bitcode or resource file\n";
+  std::vector<NewArchiveMember> Members;
+  for (std::unique_ptr<MemoryBuffer> &MB : Files)
+    if (!addMembers(Members, MB->getMemBufferRef()))
       return 1;
-    }
-    Members.emplace_back(std::move(*MOrErr));
-  }
 
   // Create an archive file.
-  std::string OutputPath = getOutputPath(&Args, Members[0]);
+  std::string OutputPath = getOutputPath(Args, Members[0]);
   std::error_code EC =
       writeArchive(OutputPath, Members,
                    /*WriteSymtab=*/true, object::Archive::K_GNU,
                    /*Deterministic*/ true, Args.hasArg(OPT_llvmlibthin));
 
   if (EC) {
     llvm::errs() << OutputPath << ": " << EC.message() << "\n";
     return 1;
   }
-
   return 0;
 }

llvm/test/LibDriver/invalid.test

 RUN: not llvm-lib %S/Inputs/cl-gl.obj 2>&1 | FileCheck %s
-CHECK: not a COFF object, bitcode or resource file
+CHECK: not a COFF object, bitcode, archive or resource file

llvm/test/LibDriver/merge.test

+If a given file is an archive file, MSVC lib.exe adds its members to a resulting
+archive instead of adding the input archive file itself to a resulting archive.
+
+Clean up a working directory.
+RUN: rm -rf %t
+RUN: mkdir -p %t/foo
+RUN: cd %t
+
+Make foo/a.obj, foo/b.obj, and b.lib.
+RUN: llvm-mc -triple=x86_64-pc-windows-msvc -filetype=obj -o foo/a.obj %S/Inputs/a.s
+RUN: llvm-mc -triple=x86_64-pc-windows-msvc -filetype=obj -o foo/b.obj %S/Inputs/b.s
+RUN: llvm-lib -out:b.lib foo/b.obj
+
+RUN: llvm-lib -out:foo.lib foo/a.obj b.lib
+RUN: llvm-ar t foo.lib | FileCheck %s
+
+CHECK: foo/a.obj
+CHECK: foo/b.obj