This includes selecting which driver to emulate, option parsing, invocation
building, and running the link. This currently only supports a very basic
subset of ld for x86_64-linux.

lld -flavor ld obj.o -o obj

or symlink lld as (ld , link, ld64, core) to get the desired behavior without
-flavor.

llvm-svn: 169659

now Reader and Writer subclasses for each file format.  Each Reader and
Writer subclass defines an "options" class which controls how that Reader
or Writer operates.

llvm-svn: 157774

There are no tests for this yet because I still need to finish the
YAML -> COFF converter so we don't get binary files checked in.

llvm-svn: 156100

a hello world executable from atoms.  There is still much to be flushed out.
Added one test case, test/darwin/hello-world.objtxt, which exercises the
darwin platform.

Added -platform option to lld-core tool to dynamically select platform.

llvm-svn: 154242

Add first linker pass (StubsPass) which looks for calls to shared library
symbols and replaces them with calls to a StubAtom.  On ELF system, a "stub"
is a PLT entry.  Added a simple test case.

Pass a Platform object to YAML reader and writer for converting fixup kinds 
between names and values.

Change output of Resolver to be a File object instead of a vector of Atoms.
Thus, passes operate on a File instead of just Atoms.

Rework how to walk through a File's Atoms. Now iterator based instead of 
a method that visits each atom.  

llvm-svn: 152269

llvm-svn: 146844