RISC perspective -- register variables

[Graham Ross]

Rick Thomas is right about no aliases for a register variable.

I consider this a much more important result than the "fast"
idea.  The elimination of aliases is the only way to achieve
code hoisting, one of the nicest optimizations there is.  I
think the V6-V7 improvement of allowing more than 3 register
variables (how many of us remember that one?) was one of the
more insightful changes to C.  It showed a much keener awareness
of language concepts and a small but welcome departure from
implementation details.