Thanks for the pointer to #4299. Unfortunately, custom asm isn't going to be nearly as fast as what we're doing, but I left a comment to that affect. As for ad

Thanks for the pointer to #4299. Unfortunately, custom asm isn't going to be nearly as fast as what we're doing, but I left a comment to that affect. As for adding options to Go TLS, it is worth filing an issue for sure. Go 1 compatibility guarantee (and resulting standard library interface freeze) definitely restricts options here, but yeah I'll look into it.