Refactor for Increased Safety without Performance Impacts #135
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This converts the core dragonbox algorithm for the float decimal writers to be completely safe. This ensures effectively all non-trivial uses of unsafe that could cause unsoundness are removed for 99% of users.
This causes ~0.5-1% regression in performance but this is well within an acceptable range for better safety guarantees. Most of the bounds checking is ellided by the compiler.
This in general for simple cases due to slight refactoring improves performance, however, it does have a noticeable (+2-7%) penalty in some corner cases which invoke the close-to-halfway rounding cases. That said, performance of this implementation of the Dragonbox algorithm without any unsafety always outperforms Ryu, which means it's still the fastest implementation out there even with slight regressions in corner cases.
This is a relatively trivial change and causes a small performance hit, but that change should be able to be mitigated with some minor refactoring.
One specific benchmark however has significant regressions, the random:big_ints/write_f32_lexical benchmark, while the f64 version does not. The benchmark is still considerably faster than ryu or fmt, however.
This does have some performance penalties but performance is still excellent, and so a few patches will need to be made so our compiler can elide more checks.
Performance enhancements will soon follow to restore any lost performance in some cases which impacted it up to 3%.
Alexhuszagh
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This introduces numerous different layers of security enhancements:
Closes #100.