| The reasoning is here:
https://github.com/golang/go/issues/40255 Copy of part of it: 1) While 387 support isn’t a huge maintenance burden, it does take time away from performance and feature work and represents a fair amount of latent complexity. 2) 387 support has been a regular source of bugs (#36400, #27516, #22429, #17357, #13923, #12970, #4798, just to name a few). 3) 387 bugs often go undetected for a long time because we don’t have builders that support only 387 (so unsupported instructions can slip in unnoticed). 4) Raising the minimum requirement to SSE2 would allow us to also assume many other useful architectural features, such as proper memory fences and 128 bit registers, which would simplify the compiler and runtime and allow for much more efficient implementations of core functions like memmove on 386. 5) We’re exploring switching to a register-based calling convention in Go 1.16, which promises significant performance improvements, but retaining 387 support will definitely complicate this and slow our progress. The 5) didnt make it into go1.16 but will be focused on again for go1.17. |