zp-runtime-div-hot — runtime-div-in-loop

ClaimCopy Anchor Link

i % runtime_pow2 vs i & (n-1) under Zig 0.17.0 -Ofast on this Linux machine shows a clear before/after wall-clock gap.

How measuredCopy Anchor Link

• Harness: packages/zperf/examples/bench/evidence_fill.zig (rule zp-runtime-div-hot cases)
• Build: zig build-exe -Ofast · optimize_mode=fast
• Timing: Io.Clock awake; warm=2; median of 9 rounds
• before: runtime_mod
• after: bitmask
• ops=2000000
• Raw: zp-runtime-div-hot.jsonl

Runtime (this evidence file)Copy Anchor Link

Lint mappingCopy Anchor Link

zperf-lint zp-runtime-div-hot / runtime-div-in-loop. Default severity in rules.zig is off (the CLI does not report the rule); see evidence-policy for keep/escalate. Evidence exists and agrees directionally.

VerdictCopy Anchor Link

Agree ~11.6× for power-of-two modulus.

LimitsCopy Anchor Link

Crypto/compiler_rt paths skipped; non-pow2 needs other rewrites.