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180 points xnacly | 1 comments | 14 Jul 25 14:42 UTC | HN request time: 0.209s | source

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userbinator ◴[15 Jul 25 04:40 UTC] No.44567872[source]▶

Replacing the switch with an array index and a jump.

Compilers will compile switches to a branch tree, two-level jump table, or single-level jump table depending on density and optimisation options. If manually using a jump table is faster, you either have a terrible compiler or just haven't explored its optimisation settings enough.

replies(1): >>44568068 #

1. teo_zero ◴[15 Jul 25 05:25 UTC] No.44568068[source]▶

>>44567872 #

But the compiler will always add the jump back to the top of the loop, so it's two jumps per cycle. Manual dispatch is one jump per cycle.

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