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by xxs 885 days ago
>With that said, convincing a compiler to elide bounds checks (especially Java's JIT compiler) is a hugely frustrating (and for some algorithms futile) task.

Adding explicit checks does work to a certain degree but it can change with the compiler, and it requires to keep checking the generated assembly - not fun (no unsafe, either but still)
1 comments
iscoelho 885 days ago
These explicit checks are basically what I mean by "convincing the compiler" (and sometimes, it isn't quite convinced!) - Yeah. Not fun at all.

Especially in Java, because "the assembly" can change as the JIT evolves. What is optimized today may not be tomorrow.

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xxs 885 days ago
Some 12-13y back (time does fly) Cliff Click (hotspot architect) had a series of blogs on optimizations, incl. the lattice checks (i.e. within bounds). Was quite insightful. It was called: "Too Much Theory" [0]

>What is optimized today may not be tomorrow.

Exactly. (Also most developers will have exceptionally hard time maintaining such code)

[0]: https://web.archive.org/web/20120328222841/http://cliffc.org...

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