zp-invariant-float-div — invariant-float-div

ClaimCopy Anchor Link

float / loop-invariant vs multiply by reciprocal 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-invariant-float-div cases)
• Build: zig build-exe -Ofast · optimize_mode=fast
• Timing: Io.Clock awake; warm=2; median of 9 rounds
• before: float_div_loop
• after: mul_reciprocal
• ops=2000000
• Raw: zp-invariant-float-div.jsonl

Runtime (this evidence file)Copy Anchor Link

Lint mappingCopy Anchor Link

zperf-lint zp-invariant-float-div / invariant-float-div. Default severity in rules.zig is hint; see evidence-policy for keep/escalate. Evidence exists and agrees directionally.

VerdictCopy Anchor Link

Agree ~2.00× without fast-math (ReleaseFast does not enable it).

LimitsCopy Anchor Link

Rounding differs slightly; validate numerics.