Add a new target independent COPY instruction and code to lower it.

The COPY instruction is intended to replace the target specific copy
instructions for virtual registers as well as the EXTRACT_SUBREG and
INSERT_SUBREG instructions in MachineFunctions. It won't we used in a selection
DAG.

COPY is lowered to native register copies by LowerSubregs.

llvm-svn: 107529
5 files changed
tree: 1ade653737281134fb2c5543c78507a8fe3fd0d7
  1. clang/
  2. compiler-rt/
  3. libcxx/
  4. lldb/
  5. llvm/