Douglas Katzman wrote:
> With single-bit fixnum tags, move-to-word/integer can be done in 4 or 5
> instructions (including the initial move) versus 7 instructions.
> fixnump/signed-byte-64 can be done without use of a constant, sometimes
> just 1 instruction, plus the conditional jump or move.
> Also fixnump/unsigned-byte-64 could emit 'mov rdx,rdx' or similar
> because it used (inst mov tmp value) where it meant (move tmp value).
Committed in 6794373 (More efficient integer=>word conversion and
fixnump tests on x86-64)