alt Hacker NewsQuestion from someone trying to get better at Go: _before_ going all in with unsafe pointer operations, would it make sense to write a function harness & profile it with/without the -B flag to determine the actual impact of bounds check?
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Oh right so this is for the case where you say "I have given you an exactly known length of data to buzz round a million times, you don't needs to bounds check every time"?
Like, I have a hardcoded 1024-byte buffer, my loop is hardcoded so its index increases modulo 1024, it can never run off the end any more than you can overtake your own bike chain?
probably you do not need to do any of that.
better at Go to ship apps — none of that needed. actually opposite. the less complexity and low level details you hardcode yourself, the better. chances are, this low-level tech debt will bite you back when you have no time to deal with it. keep it simple.
better at Go to work with internals of Go/compilers/runtime — yes, but do you plan to ship one? or why it is needed at all? or do you work at Go core at Google?
Obviously. You also need to profile to make sure this is actually a hit spot, deploying unsafe to remove bounds checks which account for ~0% of runtime is a waste of effort.
And as the essay mentions there are also “hints” you can give the compiler to fold bounds checks which may be sufficient.