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byroot
commented
Jan 21, 2026
eregon
reviewed
Jan 21, 2026
The actual algorithm is largely unchanged, just allowed to use singlebyte checks for common encodings. It could certainly be optimized much further, as here again it often scans from the front of the string when we're interested in the back of it. But the algorithm as many Windows only corner cases so I'd rather ship a good improvement now and eventually come back to it later. Most of improvement here is from the reduced setup cost (avodi double null checks, avoid duping the argument, etc), and skipping the multi-byte checks. ``` compare-ruby: ruby 4.1.0dev (2026-01-19T03:51:30Z master 631bf19) +PRISM [arm64-darwin25] built-ruby: ruby 4.1.0dev (2026-01-21T08:21:05Z opt-basename 7eb1174) +PRISM [arm64-darwin25] ``` | |compare-ruby|built-ruby| |:----------|-----------:|---------:| |long | 3.412M| 18.158M| | | -| 5.32x| |long_name | 1.981M| 8.580M| | | -| 4.33x| |withext | 3.200M| 12.986M| | | -| 4.06x|
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The actual algorithm is largely unchanged, just allowed to use singlebyte checks for common encodings.
It could certainly be optimized much further, as here again it often scans from the front of the string when we're interested in the back of it. But the algorithm as many Windows only corner cases so I'd rather ship a good improvement now and eventually come back to it later.
Most of improvement here is from the reduced setup cost (avodi double null checks, avoid duping the argument, etc), and skipping the multi-byte checks.