[mac/lld] Add support for the LC_LINKER_OPTION load command in o files

clang puts `-framework CoreFoundation` in this load command for files
that use @available / __builtin_available. Without support for this,
binaries that don't explicitly link to CoreFoundation fail to link.

Differential Revision: https://reviews.llvm.org/D92624

lld/MachO/Driver.cpp

@@ -332,6 +332,59 @@ static InputFile *addFile(StringRef path, bool forceLoadArchive) {
   return newFile;
 }
 
+static void addLibrary(StringRef name, bool isWeak) {
+  if (Optional<std::string> path = findLibrary(name)) {
+    auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path, false));
+    if (isWeak && dylibFile)
+      dylibFile->forceWeakImport = true;
+    return;
+  }
+  error("library not found for -l" + name);
+}
+
+static void addFramework(StringRef name, bool isWeak) {
+  if (Optional<std::string> path = findFramework(name)) {
+    auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path, false));
+    if (isWeak && dylibFile)
+      dylibFile->forceWeakImport = true;
+    return;
+  }
+  error("framework not found for -framework " + name);
+}
+
+// Parses LC_LINKER_OPTION contents, which can add additional command line flags.
+void macho::parseLCLinkerOption(InputFile* f, unsigned argc, StringRef data) {
+  SmallVector<const char *, 4> argv;
+  size_t offset = 0;
+  for (unsigned i = 0; i < argc && offset < data.size(); ++i) {
+    argv.push_back(data.data() + offset);
+    offset += strlen(data.data() + offset) + 1;
+  }
+  if (argv.size() != argc || offset > data.size())
+    fatal(toString(f) + ": invalid LC_LINKER_OPTION");
+
+  MachOOptTable table;
+  unsigned missingIndex, missingCount;
+  opt::InputArgList args = table.ParseArgs(argv, missingIndex, missingCount);
+  if (missingCount)
+    fatal(Twine(args.getArgString(missingIndex)) + ": missing argument");
+  for (auto *arg : args.filtered(OPT_UNKNOWN))
+    error("unknown argument: " + arg->getAsString(args));
+
+  for (auto *arg : args) {
+    switch (arg->getOption().getID()) {
+    case OPT_l:
+      addLibrary(arg->getValue(), false);
+      break;
+    case OPT_framework:
+      addFramework(arg->getValue(), false);
+      break;
+    default:
+      error(arg->getSpelling() + " is not allowed in LC_LINKER_OPTION");
+    }
+  }
+}
+
 static void addFileList(StringRef path) {
   Optional<MemoryBufferRef> buffer = readFile(path);
   if (!buffer)
@@ -707,29 +760,13 @@ bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
       addFile(arg->getValue(), true);
       break;
     case OPT_l:
-    case OPT_weak_l: {
-      StringRef name = arg->getValue();
-      if (Optional<std::string> path = findLibrary(name)) {
-        auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path, false));
-        if (opt.getID() == OPT_weak_l && dylibFile)
-          dylibFile->forceWeakImport = true;
-        break;
-      }
-      error("library not found for -l" + name);
+    case OPT_weak_l:
+      addLibrary(arg->getValue(), opt.getID() == OPT_weak_l);
       break;
-    }
     case OPT_framework:
-    case OPT_weak_framework: {
-      StringRef name = arg->getValue();
-      if (Optional<std::string> path = findFramework(name)) {
-        auto *dylibFile = dyn_cast_or_null<DylibFile>(addFile(*path, false));
-        if (opt.getID() == OPT_weak_framework && dylibFile)
-          dylibFile->forceWeakImport = true;
-        break;
-      }
-      error("framework not found for -framework " + name);
+    case OPT_weak_framework:
+      addFramework(arg->getValue(), opt.getID() == OPT_weak_framework);
       break;
-    }
     case OPT_platform_version:
       handlePlatformVersion(arg);
       break;

lld/MachO/Driver.h

@@ -36,6 +36,8 @@ enum {
 #undef OPTION
 };
 
+void parseLCLinkerOption(InputFile*, unsigned argc, StringRef data);
+
 std::string createResponseFile(const llvm::opt::InputArgList &args);
 
 // Check for both libfoo.dylib and libfoo.tbd (in that order).

lld/MachO/InputFiles.cpp

@@ -383,6 +383,13 @@ ObjFile::ObjFile(MemoryBufferRef mb, uint32_t modTime, StringRef archiveName)
   auto *buf = reinterpret_cast<const uint8_t *>(mb.getBufferStart());
   auto *hdr = reinterpret_cast<const mach_header_64 *>(mb.getBufferStart());
 
+  if (const load_command *cmd = findCommand(hdr, LC_LINKER_OPTION)) {
+    auto *c = reinterpret_cast<const linker_option_command *>(cmd);
+    StringRef data{reinterpret_cast<const char *>(c + 1),
+                   c->cmdsize - sizeof(linker_option_command)};
+    parseLCLinkerOption(this, c->count, data);
+  }
+
   if (const load_command *cmd = findCommand(hdr, LC_SEGMENT_64)) {
     auto *c = reinterpret_cast<const segment_command_64 *>(cmd);
     sectionHeaders = ArrayRef<section_64>{

lld/test/MachO/lc-linker-option.ll

@@ -0,0 +1,55 @@
+# REQUIRES: x86
+# RUN: rm -rf %t
+# RUN: split-file %s %t
+
+# RUN: llvm-as %t/framework.ll -o %t/framework.o
+# RUN: %lld %t/framework.o -o %t/frame
+# RUN: llvm-objdump --macho --all-headers %t/frame | FileCheck --check-prefix=FRAME %s
+# FRAME:          cmd LC_LOAD_DYLIB
+# FRAME-NEXT: cmdsize
+# FRAME-NEXT:    name /System/Library/Frameworks/CoreFoundation.framework/CoreFoundation
+
+# RUN: llvm-as %t/l.ll -o %t/l.o
+# RUN: %lld %t/l.o -o %t/l
+# RUN: llvm-objdump --macho --all-headers %t/l | FileCheck --check-prefix=LIB %s
+# LIB:          cmd LC_LOAD_DYLIB
+# LIB-NEXT: cmdsize
+# LIB-NEXT:    name /usr/lib/libSystem.B.dylib
+
+# RUN: llvm-as %t/invalid.ll -o %t/invalid.o
+# RUN: not %lld %t/invalid.o -o /dev/null 2>&1 | FileCheck --check-prefix=INVALID %s
+# INVALID: error: -why_load is not allowed in LC_LINKER_OPTION
+
+#--- framework.ll
+target triple = "x86_64-apple-macosx10.15.0"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+!0 = !{!"-framework", !"CoreFoundation"}
+!llvm.linker.options = !{!0}
+
+define void @main() {
+  ret void
+}
+
+#--- l.ll
+target triple = "x86_64-apple-macosx10.15.0"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+!0 = !{!"-lSystem"}
+!llvm.linker.options = !{!0}
+
+define void @main() {
+  ret void
+}
+
+#--- invalid.ll
+
+target triple = "x86_64-apple-macosx10.15.0"
+target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+
+!0 = !{!"-why_load"}
+!llvm.linker.options = !{!0}
+
+define void @main() {
+  ret void
+}