64-bit powerpc compare with constant problem

[David Edelsohn]

	You did not really address the question.  There are constants from
the program (either supplied by the programmer or generated by the
compiler to represent values in the program) and there are constants used
by the backend of the compiler.  GCC does not distinguish the two in all
cases.  GCC both knows the width of a word on the host while
simultaneously extending that host word to the width of the target when it
thinks that the host value can represent the target value.  I am not
commenting on whether the optimization is good or bad, but it is a
decision that makes the current problem rather cumbersome to solve.

David