An (explicit or implicit) operand may now be both a def and a use.
Also add a set of regs used by each instruction.
dump() no longer takes an optional argument, which doesn't work in gdb.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2821 91177308-0d34-0410-b5e6-96231b3b80d8