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A leap year check in three instructions

(hueffner.de)
420 points gnabgib | 1 comments | 15 May 25 21:57 UTC | HN request time: 0.272s | source
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drewg123 ◴[15 May 25 22:47 UTC] No.44000124[source]▶
I tend to be of the opinion that for modern general purpose CPUs in this era, such micro-optimizations are totally unnecessary because modern CPUs are so fast that instructions are almost free.

But do you know what's not free? Memory accesses[1]. So when I'm optimizing things, I focus on making things more cache friendly.

[1] http://gec.di.uminho.pt/discip/minf/ac0102/1000gap_proc-mem_...

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drewg123 ◴[15 May 25 22:57 UTC] No.44000191[source]▶
To temper this slightly, these sorts of optimizations are useful on embedded CPUs for device firmware, IOT, etc. I've worked on smart NIC CPUs where cycles were so precious we'd do all kinds of crazy unreadable things.
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sitzkrieg ◴[15 May 25 23:05 UTC] No.44000245[source]▶
on the flip side of the topic, trying to do any datetime handling on the edge of embedded compute is going to be wrong 100% of the time anyway
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1. RaoulP ◴[15 May 25 23:41 UTC] No.44000441[source]▶
Would you mind elaborating?