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Refactor `binary_search_by` to use conditional moves Refactor the if/else checking on `cmp::Ordering` variants to a "branchless" reassignment of left and right. This change results in fewer branches and instructions. https://rust.godbolt.org/z/698eYffTx --- I saw consistent benchmark improvements locally. Performance of worst case seems about the same, maybe slightly faster for the L3 test. Current ``` slice::binary_search_l1 43.00ns/iter +/- 3.00ns slice::binary_search_l1_with_dups 25.00ns/iter +/- 0.00ns slice::binary_search_l1_worst_case 10.00ns/iter +/- 0.00ns slice::binary_search_l2 64.00ns/iter +/- 1.00ns slice::binary_search_l2_with_dups 42.00ns/iter +/- 0.00ns slice::binary_search_l2_worst_case 16.00ns/iter +/- 0.00ns slice::binary_search_l3 132.00ns/iter +/- 2.00ns slice::binary_search_l3_with_dups 108.00ns/iter +/- 2.00ns slice::binary_search_l3_worst_case 33.00ns/iter +/- 3.00ns ``` This PR ``` slice::binary_search_l1 21.00ns/iter +/- 0.00ns slice::binary_search_l1_with_dups 14.00ns/iter +/- 0.00ns slice::binary_search_l1_worst_case 9.00ns/iter +/- 0.00ns slice::binary_search_l2 34.00ns/iter +/- 0.00ns slice::binary_search_l2_with_dups 23.00ns/iter +/- 0.00ns slice::binary_search_l2_worst_case 16.00ns/iter +/- 0.00ns slice::binary_search_l3 92.00ns/iter +/- 3.00ns slice::binary_search_l3_with_dups 63.00ns/iter +/- 1.00ns slice::binary_search_l3_worst_case 29.00ns/iter +/- 0.00ns ``` |
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| alloc | ||
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| core | ||
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| panic_unwind | ||
| portable-simd | ||
| proc_macro | ||
| profiler_builtins | ||
| rtstartup | ||
| rustc-std-workspace-alloc | ||
| rustc-std-workspace-core | ||
| rustc-std-workspace-std | ||
| std | ||
| stdarch@f4528dd6e8 | ||
| sysroot | ||
| test | ||
| unwind | ||