[PATCH] [lld][ELF] Add linker script ENTRY command

[Rui Ueyama]

  It seems that TargetInfo and its subclasses are not copyable even after separating LinkerInput. The classes have many fields that are not copyable, such as memory allocators, file readers and writers. I think such fields are implementation details and not part of the API because they are used only in Core Linking. But they make TargetInfo hard to copy.

  We may want to split TargetInfo into two classes.

   - New TargetInfo class is a public API and is constructed and modified by Driver.This class has default copy constructor.
   - A new class have other fields that are not exposed to Driver. It holds a copy of TargetInfo, list of input files, memory allocators, readers, writers, etc. This is not copyable.

  What do you think?

http://llvm-reviews.chandlerc.com/D833

BRANCH
  linker-script-entry

ARCANIST PROJECT
  lld