Evan Cheng ca9a936332 Change the definition of TargetRegisterInfo::getCrossCopyRegClass to be more
flexible.

If it returns a register class that's different from the input, then that's the
register class used for cross-register class copies.
If it returns a register class that's the same as the input, then no cross-
register class copies are needed (normal copies would do).
If it returns null, then it's not at all possible to copy registers of the
specified register class.

llvm-svn: 127368
2011-03-09 22:47:38 +00:00
..
2011-03-01 01:39:05 +00:00