Ask HN: Any project ideas for a newbie to x64 assembler?

When I was 14 or something, I learned x86 assembly by writing programs to other programs do things they weren't supposed to do, or things they could do under certain conditions; mainly patching other programs and finding inspiration in source code of a lot of viruses. There are a lot of things one could learn by disassembling.

Albeit not using gas, you may want to check out https://github.com/SnellerInc/sneller -- it has about ~250 primitives written in AVX-512. (Sneller founder)

SIMD-based image scaling. If you are good, a hand-tuned x64 assembler implementation can still beat what a C compiler emits.

Implement the latest flavor of YOLO (object recognition) using the latest parallelization CPU features.