[lld] Break cyclic dependency between lldDriver and lldMachO

[garious]

Summary

Moved getMemoryBuffer from DarwinLdDriver to MachOLinkingContext.

[ruiu]

LGTM. By the way when you upload a patch to Phabricator, please run diff with -u 100000 or something, so that entire file is included in a diff. That would help reviewers review code. Thanks!

include/lld/ReaderWriter/MachOLinkingContext.h

256

Please move this after private:.

[garious]

include/lld/ReaderWriter/MachOLinkingContext.h

256

No can do. Do you mean any method that it calls?

[ruiu]

include/lld/ReaderWriter/MachOLinkingContext.h

256

Ah right, we can't.

include/lld/Driver/Driver.h

   static bool parse(int argc, const char *argv[], MachOLinkingContext &info,
                     raw_ostream &diagnostics = llvm::errs());
 
-  // Reads a file from disk to memory. Returns only a needed chunk
-  // if a fat binary.
-  static ErrorOr<std::unique_ptr<MemoryBuffer>>
-  getMemoryBuffer(MachOLinkingContext &ctx, StringRef path);
-
 private:
   DarwinLdDriver() LLVM_DELETED_FUNCTION;
 };

include/lld/ReaderWriter/MachOLinkingContext.h

   /// Used to keep track of direct and indirect dylibs.
   void registerDylib(mach_o::MachODylibFile *dylib, bool upward) const;
 
+  // Reads a file from disk to memory. Returns only a needed chunk
+  // if a fat binary.
+  ErrorOr<std::unique_ptr<MemoryBuffer>> getMemoryBuffer(StringRef path);
+
   /// Used to find indirect dylibs. Instantiates a MachODylibFile if one
   /// has not already been made for the requested dylib.  Uses -L and -F
   /// search paths to allow indirect dylibs to be overridden.

lib/Driver/DarwinLdDriver.cpp

   if (ctx.logInputFiles())
     diag << path << "\n";
 
-  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr =
-    DarwinLdDriver::getMemoryBuffer(ctx, path);
+  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr = ctx.getMemoryBuffer(path);
   if (std::error_code ec = mbOrErr.getError())
     return makeErrorFile(path, ec);
   std::vector<std::unique_ptr<File>> files;

 
 namespace lld {
 
-ErrorOr<std::unique_ptr<MemoryBuffer>>
-DarwinLdDriver::getMemoryBuffer(MachOLinkingContext &ctx, StringRef path) {
-  ctx.addInputFileDependency(path);
-
-  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr =
-    MemoryBuffer::getFileOrSTDIN(path);
-  if (std::error_code ec = mbOrErr.getError())
-    return ec;
-  std::unique_ptr<MemoryBuffer> mb = std::move(mbOrErr.get());
-
-  // If buffer contains a fat file, find required arch in fat buffer
-  // and switch buffer to point to just that required slice.
-  uint32_t offset;
-  uint32_t size;
-  if (ctx.sliceFromFatFile(*mb, offset, size))
-    return MemoryBuffer::getFileSlice(path, size, offset);
-  return std::move(mb);
-}
-
 bool DarwinLdDriver::linkMachO(int argc, const char *argv[],
                                raw_ostream &diagnostics) {
   MachOLinkingContext ctx;

lib/ReaderWriter/MachO/MachOLinkingContext.cpp

   return *_writer;
 }
 
-MachODylibFile* MachOLinkingContext::loadIndirectDylib(StringRef path) {
+ErrorOr<std::unique_ptr<MemoryBuffer>>
+MachOLinkingContext::getMemoryBuffer(StringRef path) {
+  addInputFileDependency(path);
+
   ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr =
-    DarwinLdDriver::getMemoryBuffer(*this, path);
+    MemoryBuffer::getFileOrSTDIN(path);
+  if (std::error_code ec = mbOrErr.getError())
+    return ec;
+  std::unique_ptr<MemoryBuffer> mb = std::move(mbOrErr.get());
+
+  // If buffer contains a fat file, find required arch in fat buffer
+  // and switch buffer to point to just that required slice.
+  uint32_t offset;
+  uint32_t size;
+  if (sliceFromFatFile(*mb, offset, size))
+    return MemoryBuffer::getFileSlice(path, size, offset);
+  return std::move(mb);
+}
+
+MachODylibFile* MachOLinkingContext::loadIndirectDylib(StringRef path) {
+  ErrorOr<std::unique_ptr<MemoryBuffer>> mbOrErr = getMemoryBuffer(path);
   if (mbOrErr.getError())
     return nullptr;