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Comment by kelnos | Hacker News Reader

And that's the thing, really. Sure, they're not free, but they're pretty cheap. In a project like OpenSSL, if C had bounds checking, it should be enabled, all the time. Sure, disable it for some random bit of custom high-perf software where you really need to eke out the last few percent of performance. But for 99% of everything else, leave the bounds checking turned on.

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> Sure, disable it for some random bit of custom high-perf software where you really need to eke out the last few percent of performance.

And that's the rub, isn't it? Getting that last bit of perf in the inner hot loop has traditionally often required people to write the entire thing in languages that are unsafe (ffi overhead often being enough that you can't just wrap up the hot loop and call the bit that needs to be performant from elsewhere).

I wonder how much good interop could get us.

I don't know, because if you're writing programs for things like IoT or embedded, then you're dealing with nothing but wimpy little low power processors where removing a bounds check gives you huge increases. Then, it makes no sense to have checks by default if you're going to get rid of them anyway.

if it’s a 4% gain. then it’s the same 4% game no matter if running on a big fast cpu or a 8bit micro controller. right?

It isn't because those microcontrollers are not that smart about branch prediction and instruction ordering so the penalty is often bigger. Same with reordering - might not matter that much on a big modern CPU but may matter way more on a device with a micro cache and very slow division for example.

I'll just point out that a wimpy low power processor that costs less than a buck has as much processing power as a 486. And the amount of processing tends to be on small amounts of data in short bursts.

Big problem as I see it is compiler writers using C++ with it's completely broken language and compilation model. Of course they think speed is the only important metric because C++ compilers compiling C++ compilers is very very slow. And they're dealing with trusted data 100% of the time and not the guys desperately trying to patch a zero day vulnerability at 2am.

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