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by colejohnson66
1584 days ago
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My guess would be a pipelining issue where `INTO` isn't treated as a `Jcc`, but as an `INT` (mainly because it is an interrupt). Agner Fog's instruction tables[0] show (for the Pentium 4) `Jcc` takes one uOP with a throughput of 2-4. `INTO`, OTOH, when not taken uses four uOPs with a throughput of 18! Zen 3 is much better with a throughput of 2, but that's still worse than `JO raiseINTO`. [0]: https://www.agner.org/optimize/instruction_tables.pdf |
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