bound

Documentation

Overview

Package bound is a simple benchmark of the x86 BOUND instruction. Spoiler alert. It's slow.

Results

On my MacBook Pro (Intel Core i5-3210M @ 2.50 GHz), using BOUND is 9x slower than using CMP after you subtract out the cost of the benchmark loop:

g% 386 go test -bench . -benchtime 10s
testing: warning: no tests to run
PASS
BenchmarkNop	1000000000	         0.33 ns/op
BenchmarkBound	1000000000	         3.35 ns/op
BenchmarkCmp	1000000000	         0.66 ns/op
BenchmarkCmpReg	1000000000	         0.67 ns/op
ok  	rsc.io/tmp/bound	9.147s
g%

Maybe someone familiar with the CPU architecture of the Core i5 can explain to me why I have a 2.50 GHz clock speed but instruction retirement seems to be running at 3 GHz.