diff: debug macros; one trivial size optimization

function                                             old     new   delta
diffreg                                             1781    1815     +34
isqrt                                                 64       -     -64
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(add/remove: 0/1 grow/shrink: 1/0 up/down: 34/-64)            Total: -30 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
1 file changed