Guard float token boundaries

[dduan]

Summary

• Guard float unpacking against truncated reserved float tokens and single-zero values before reading past token bounds.
• Add regression coverage for s = 0, sign-only, and truncated nan/inf prefixes.

Validation

• Not run in this split branch per instruction; this commit was already verified before PR splitting.

[github-actions]

�[33mWarning: running with the Swift runtime interposer on Linux to avoid the Swift 6.3 runtime hook crash. See https://github.com/ordo-one/benchmark/issues/349�[0m

Comparing results between 'main' and 'pull_request'

Host 'runnervm5mmn9' with 4 'x86_64' processors with 15 GB memory, running:
#18~24.04.1-Ubuntu SMP Thu May 28 16:39:11 UTC 2026

TOMLDecoderBenchmarks

Decode toml.io example metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	52	53	53	54	55	67	107	8022
pull_request	53	53	54	55	66	79	109	7730
Δ	1	0	1	1	11	12	2	-292
Improvement %	-2	0	-2	-2	-20	-18	-2	-292

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	765	765	765	765	765	765	765	8022
pull_request	765	765	765	765	765	765	765	7730
Δ	0	0	0	0	0	0	0	-292
Improvement %	0	0	0	0	0	0	0	-292

Parse toml.io example metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ns) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	4657	4719	4727	4759	4827	6191	24066	10000
pull_request	4647	4707	4727	4759	5151	9527	20641	10000
Δ	-10	-12	0	0	324	3336	-3425	0
Improvement %	0	0	0	0	-7	-54	14	0

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	31	31	31	31	31	31	31	10000
pull_request	31	31	31	31	31	31	31	10000
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

decode canada.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	241	242	242	244	249	249	249	5
pull_request	244	247	248	251	252	252	252	5
Δ	3	5	6	7	3	3	3	0
Improvement %	-1	-2	-2	-3	-1	-1	-1	0

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	1286	1286	1286	1286	1286	1286	1286	5
pull_request	1286	1286	1286	1286	1286	1286	1286	5
Δ	0	0	0	0	0	0	0	0
Improvement %	0	0	0	0	0	0	0	0

decode twitter.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	8370	9347	9388	9437	9478	9683	9938	106
pull_request	8389	9372	9437	9683	10068	10183	10228	104
Δ	19	25	49	246	590	500	290	-2
Improvement %	0	0	-1	-3	-6	-5	-3	-2

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	113	113	113	113	113	113	113	106
pull_request	113	113	113	113	113	113	113	104
Δ	0	0	0	0	0	0	0	-2
Improvement %	0	0	0	0	0	0	0	-2

parse GitHub events archive metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	119	120	120	121	155	155	155	8
pull_request	121	122	122	123	128	128	128	9
Δ	2	2	2	2	-27	-27	-27	1
Improvement %	-2	-2	-2	-2	17	17	17	1

Retains: results within specified thresholds, fold down for details.

Retains (K) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	394	394	394	394	394	394	394	8
pull_request	394	394	394	394	394	394	394	9
Δ	0	0	0	0	0	0	0	1
Improvement %	0	0	0	0	0	0	0	1

parse canada.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (ms) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	14	14	14	14	14	24	24	70
pull_request	14	14	15	15	15	24	24	68
Δ	0	0	1	1	1	0	0	-2
Improvement %	0	0	-7	-7	-7	0	0	-2

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	47	47	47	47	47	47	47	70
pull_request	47	47	47	47	47	47	47	68
Δ	0	0	0	0	0	0	0	-2
Improvement %	0	0	0	0	0	0	0	-2

parse twitter.toml metrics

Time (wall clock): results within specified thresholds, fold down for details.

Time (wall clock) (μs) *	p0	p25	p50	p75	p90	p99	p100	Samples
main	2145	2169	2177	2185	2204	2302	3550	446
pull_request	2179	2200	2214	2249	2302	2626	3598	435
Δ	34	31	37	64	98	324	48	-11
Improvement %	-2	-1	-2	-3	-4	-14	-1	-11

Retains: results within specified thresholds, fold down for details.

Retains *	p0	p25	p50	p75	p90	p99	p100	Samples
main	7736	7736	7736	7736	7736	7736	7736	446
pull_request	7736	7736	7736	7736	7736	7736	7736	435
Δ	0	0	0	0	0	0	0	-11
Improvement %	0	0	0	0	0	0	0	-11