bench: add variant-switch.mo (baseline)#6033
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…m dispatch Adds a benchmark that exercises variant-switch dispatch across several shapes, to serve as a baseline for dispatch-optimisation work. Actor methods: - go: top-level size tree + size fibCore, 10k iterations. - evalBench: fib(7) via direct AST eval, a compiled finally-tagless form, and the AST→FT transform itself — 100 iterations each. - weekdayBench: isWeekend vs isWeekendOr over a 7-arm Weekday variant, 10k iterations each — compares explicit-arm vs or-pattern forms. - getPerfData: reports rts_lifetime_instructions. Numbers on master (baseline): - size tree + fibCore (×10k): 137,590,321 instructions - eval fib(7) AST (×100): 24,509,348 - eval fib(7) FT (×100): 21,536,248 - AST→FT transform (×100): 1,189,148 - isWeekend (×10k × 7 arms): 10,010,321 - isWeekendOr (×10k × 7 arms): 11,050,321 This file lands intentionally on master so future dispatch work can show deltas against this reference point. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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variant-switch.mo benchmark (baseline)
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variant-switch.mo benchmark (baseline)variant-switch.mo (baseline)
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alexandru-uta
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Apr 20, 2026
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alexandru-uta
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thanks, nice benchmark.
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Summary
Adds
test/bench/variant-switch.mo— a small GHC-Core-like interpreter that exercises 9-arm variant-switch dispatch in several shapes. Serves as a reference point (baseline onmaster) for the dispatch-optimisation work on #5927 (maskedbr_table) and any follow-ups.Actor methods:
go— top-levelsize tree + size fibCore, ×10k.evalBench—fib(7)via direct AST eval, compiled finally-tagless form, and the AST→FT transform itself; ×100 each.weekdayBench—isWeekend(7 explicit arms) vsisWeekendOr(same dispatch viaor-patterns); ×10k over a 7-armWeekdayvariant.getPerfData— reportsrts_lifetime_instructions.Master baseline
size tree + fibCore(×10k)eval fib(7)AST (×100)eval fib(7)FT (×100)isWeekend(×10k × 7 arms)isWeekendOr(×10k × 7 arms)With #5927 applied, the explicit-arm dispatch numbers drop materially; or-patterns currently don't benefit (separate follow-up).
Test plan
make -C test/bench variant-switch.onlypasses onmaster.test/bench/ok/variant-switch.drun-run.ok.🤖 Generated with Claude Code