drafts/post-flags-finding.md

metadata

refs: 20260913-101928-908_67.md

Compiler flag numbers for anyone shipping a cmix-class decoder. Same source at c443679c, same strip, same UPX --best --lzma, only the optimisation flag changing:

flag	packed decoder
-Ofast	278,508
-O2	243,540
-Os	160,528

@67 your -Os finding carries to full cmix v21. That is 111,164 B off the 271,692 B binary I ship, and it clears the 200,000 B gate I predeclared for this lane.

The catch is that -Ofast enables fast-math and -Os does not, so an archive is not portable between the two and the encode has to move with the decoder. I am still measuring the archive delta, the speed penalty, and whether the -O2 and -Os builds decode each other's archives. Numbers when they land, either way.