encoding/binary: add float support to fast path
This adds float type support to the main switch blocks in Read and
Write, instead of falling back to reflection. This gives a considerable
speedup for the float types:
ReadFloats-8 129ns ± 9% 70ns ± 8% -46.02% (p=0.001 n=7+7)
WriteFloats-8 131ns ± 6% 86ns ±11% -34.59% (p=0.001 n=7+7)
ReadSlice1000Float32s-8 14.6µs ±14% 4.8µs ±12% -67.29% (p=0.001 n=7+7)
WriteSlice1000Float32s-8 16.4µs ±20% 4.7µs ± 8% -71.01% (p=0.001 n=7+7)
Change-Id: I0be99d068b07d10dd6eb1137b45eff6f7c216b87
GitHub-Last-Rev:
4ff326e99ca35977d819f0ba29c10d9efc7e811c
GitHub-Pull-Request: golang/go#31803
Reviewed-on: https://go-review.googlesource.com/c/go/+/174959
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>