func_02057410: the digit loop divides unsigned, and the reloc says so

[andrewboudreau]

A fakematch, found by pr_linkcheck and not by any byte gate.

What is wrong

func_02057410 is a printf-style formatter. At 0x02057b64 its digit loop calls a 64-bit divide helper, and we call the wrong one:

	word	destination	symbol
ROM	0xebfe8b9c	0x01ffa9dc	__aeabi_uldiv — unsigned
ours	0xebfe8bb2	0x01ffaa34	_ll_sdiv — signed

The bytes agreed regardless, because a relocated word is a wildcard to the byte comparison. So this has been sitting in the matched set with a call that resolves to the wrong function.

Why unsigned is right

The sign is consumed above the loop — the 0x80000000 test emits the minus prefix and negates v:

if ((((s64)zero << 32 | (u32)(v >> 32)) & 0x80000000) != 0) {
    prefixbuf[0] = minus;
    v = ~v + 1;            // from here v is a magnitude
    nprefix = one;
}

Every division below that point is on a magnitude, so the original divides unsigned. v stays s64 in our source, which selects the signed helper. Casting both operands to u64 at the two use sites selects the one the ROM uses.

Verified

gate	before	after
pr_linkcheck --files src/func_02057410.c	WRONG _ll_sdiv -> 0x01ffaa34	ok (verified, 1 slot)
rombuild.py -j16, full ROM	106/106 exact	106/106 exact, 10,813 reproducing, 0 mismatching, 87.88%
port_refcheck	—	393 checked, 0 stale

Byte-neutral: the change selects a different relocation target, and the relocated word was never part of the comparison.

How it surfaced

It blocks #1382, which touches none of this. pr_linkcheck expands a changed header through the reverse include graph, so that PR link-checks consumers it never names — including this file, whose blob is identical to main's. The verdict reproduces on a clean origin/main worktree, so it is main's defect, not that PR's.

🤖 Generated with Claude Code

https://claude.ai/code/session_015AXm5k53WFPjCYcDHRDX3x

[tangos-validator]

✅ PR validation — Passed

Committed merge introduces no reconstruction or attribution regression.

Full merge validation

Check	Result
Committed test merge	yes
Matched functions	11,178 / 11,347 (98.5%, +0)
Matched code bytes	2,078,800 / 2,211,124 (94.0%, +0)
Tracked source enrollment	10,785 functions, 1,936,196 bytes (87.57%, +0)
Perfect source moves	0 R100
Contributor credit	0 added, 0 changed, 0 lost
Relocation check	1 checked; 1 VERIFIED
Port reference check	393 checked; 0 stale
Module fidelity	106/106 exact; 100.000000% compared bytes
Code linked from verified source	10,813 functions, 1,943,084 bytes (87.88%)

Per-file link-check detail

All 1 changed file(s) compile to the ROM byte-for-byte with correct relocation targets.

File	Symbol	Result	Slots checked
src/func_02057410.c	func_02057410	✅ verified	1

_{The private worker commits a test merge, builds the stock ROM profile, compares every executable module, measures matched and source-built code, checks contributor lineage, and verifies affected relocations. The mod profile is opt-in and is not part of this merge gate.}