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A leap year check in three instructions

(hueffner.de)
420 points gnabgib | 3 comments | 15 May 25 21:57 UTC | HN request time: 0.66s | source
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qingcharles ◴[15 May 25 22:22 UTC] No.43999955[source]▶
I love these incomprehensible magic number optimizations. Every time I see one I wonder how many optimizations like this we missed back in the old days when we were writing all our inner loops in assembly?

Does anyone have a collection of these things?

replies(4): >>43999992 #>>44000134 #>>44000173 #>>44000633 #
1. tylerhou ◴[15 May 25 22:48 UTC] No.44000134[source]▶
You should look at supercompilation.
replies(1): >>44002008 #
2. mshockwave ◴[16 May 25 05:08 UTC] No.44002008[source]▶
sometimes also known as superoptimization, which many of them also use SMT solvers like Z3 mentioned in the article
replies(1): >>44002057 #
3. tylerhou ◴[16 May 25 05:19 UTC] No.44002057[source]▶
Yes, sorry, superoptimization is the correct term.