It's possible to have a constant expression who's size is quite big (e.g.,

i128). In that case, we may not be able to print out the MCExpr as an
expression. For instance, we could have an MCExpr like this:

    0xBEEF0000BEEF0000 | (0xBEEF0000BEEF0000 << 64)

The MCExpr printer handles sizes up to 64-bits, but this expression would
require 128-bits. In this situation, try to evaluate the constant expression and
emit that as the value into 64-bit chunks.
<rdar://problem/11070338>

llvm-svn: 153081