This document describes when and how to add assembly code to routines in the Go-maintained packages.
In general, the rules are:
we prefer portable Go, not assembly. Code in assembly means (N packages * M architectures) to maintain, rather than just N packages.
assembly code needs benchmarks showing it's worth it
minimize use of assembly. We'd rather have a small amount of assembly for a 50% speedup rather than twice as much assembly for a 55% speedup.
make your assembly easy to review, and ideally auto-generated from a Go program so we can review the generator program. Comment it well.
test it well. The bar for new assembly code is high. It needs commensurate test coverage.
TODO: add more. This document is a work in progress.