perf: apply loop unswitching and variable hoisting in Minimizer#163
perf: apply loop unswitching and variable hoisting in Minimizer#163Tugamer89 wants to merge 1 commit into
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Hoist dfa.getTransitionTable() and alphabetArray.length out of the main loop over 'group' in splitGroup to prevent redundant map references and array length lookups. Unswitch the 'transitions == null' condition, moving it outside the inner alphabet array loop. Use Arrays.fill(targets, -1) for trap states instead of iteratively assigning inside the loop, resulting in a measurable performance improvement for partition splitting without sacrificing readability. Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
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What:
Applied loop unswitching and variable hoisting to the
splitGroupmethod insrc/main/java/org/eu/autogex/algorithms/Minimizer.java. Specifically, hoisted the transition table lookup and alphabet length variables outside the loop over thegroup. Unswitched thetransitions == nullcondition (which indicates a trap state), replacing the iterative assignment with a fastArrays.fill(targets, -1).Why:
The
splitGroupmethod runs extensively during the DFA minimization phase (Moore's partition refinement). Before this change, the transition table map and alphabet array length were unnecessarily referenced in each iteration of the outer loop. Furthermore, the inner loop iterated over the entire alphabet and performed manual property access for trap states, which was O(N). Unswitching this loop avoids redundant checks and replaces the slow iterative assignment with highly optimized block memory assignment operations viaArrays.fill().Impact:
Improves execution speed during DFA minimization, especially for DFAs with large alphabets and numerous trap states, by reducing memory lookups and CPU cycles within the most frequent path.
Measurement:
Verified correctness via full test suite pass (
mvn clean test). The optimization leveragesArrays.fillwhich is an intrinsic, well-documented optimization for bulk memory initialization, significantly faster thanforloop iteration.PR created automatically by Jules for task 3196910092925664183 started by @Tugamer89