Go中的math.bits是否使用机器代码指令？

Question

The new golang package "math/bits" provides useful functions. The source code shows how the function result are computed.

Are these functions replaced by the corresponding processor OP codes when available?

Answer 1

Yes, as stated in Go 1.9 Release Notes: New bit manipulation package:

Go 1.9 includes a new package, math/bits, with optimized implementations for manipulating bits. On most architectures, functions in this package are additionally recognized by the compiler and treated as intrinsics for additional performance.

Some related / historical github issues:

math/bits: an integer bit twiddling library #18616

proposal: cmd/compile: intrinsicify user defined assembly functions #17373

Provide a builtin for population counting / hamming distance #10757