From 0c74457f27ded6a67d539c5e5ee7064149ef423d Mon Sep 17 00:00:00 2001
From: Drew T <50529377+Druthulu@users.noreply.github.com>
Date: Thu, 3 Sep 2026 16:12:14 -0600
Subject: [PATCH] =?UTF-8?q?docs(cookbook):=20=C2=A7471=20=E2=80=94=20a=20l?=
 =?UTF-8?q?aunder's=20cost=20is=20an=20allocno,=20and=20$t0=20belongs=20to?=
 =?UTF-8?q?=20reload?=
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From the S76 func_80032A74 agent (422 ins, 408 -> 12).

Refines §153: the launder was necessary but created an allocno outranking the
value it was protecting; the cure was pinning the launder itself to $10 — and
NOT $8, which evicts reload's $t0 parameter reloads. So '§461: the launder is
the defect' has a third resolution beyond remove-it or move-it: pin it, and
choose the register with reload's own needs in mind.

New general fact: $t0 is unreachable from C because reload owns it — the
target's table bases are reload rematerialisations of a reg_equiv_constant
there. A residual of the form 'the target uses $t0 and I cannot' is a reload
artifact, not an unfound spelling.

Also pairs with §463/§469: a frame slot nothing reads is either an 8-byte
rounded spill or a §172 combine USE-orphan — both reproducible, neither
padding.
---
 docs/matching-cookbook.md | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/docs/matching-cookbook.md b/docs/matching-cookbook.md
index c6041fa0c..8bb993ae9 100644
--- a/docs/matching-cookbook.md
+++ b/docs/matching-cookbook.md
@@ -35461,3 +35461,27 @@ allocno class choice) but it drags the `*24` shift chain into `$s1`; plus operan
 `addu $s0,$s1,$s0`; plus the else-arm materialising `&D_800A46D2` into `$s1`. Law 1c verified: all 25
 symbols match the target's relocations, and the only difference is `D_800A46D2`'s **count** (4 vs 6),
 which is that residual rather than a wrong symbol.
+
+#### §471 — A LAUNDER'S REAL COST IS AN ALLOCNO, AND `$t0` IS RELOAD'S (`main:func_80032A74`, 408 → 12)
+
+**Source: the S76 agent.** Three facts, two of which refine entries already here.
+
+**1. §172's combine USE-orphan buys a never-referenced stack slot.** Promoting an `s16` memory local
+to `int` **twice** after a `CODE_LABEL` is the only way to produce the target's unused 8-byte slot at
+`0x48`. Pair this with §463/§469: when a frame has a slot nothing reads, it is either a spill (8-byte
+rounded) or an orphan of this kind — both are reproducible, neither is padding.
+
+**2. 🔴 REFINEMENT OF §153: THE LAUNDER'S REAL COST IS AN ALLOCNO THAT OUTRANKS THE VALUE YOU CARE
+ABOUT.** The §153 launder was necessary here, but it created an allocno outranking `vol` on priority.
+The cure was pinning the launder to **`$10`** — and specifically *not* `$8`, which evicts reload's
+`$t0` parameter reloads. So "the launder is the defect" (§461) has a third resolution beyond
+*remove it* or *move it*: **pin the launder itself, and pick the register with reload's own needs in
+mind.**
+
+**3. `$t0` IS UNREACHABLE FROM C BECAUSE RELOAD OWNS IT.** The target's `table` / `D_800A4C28` bases
+are reload **rematerialisations** of a `reg_equiv_constant` living in `$t0`. No C spelling or pin can
+put a value there, because reload claims it for its own reloads. When a residual is "the target uses
+`$t0` and I cannot", stop — that is a reload artifact, not a spelling you have not found yet.
+
+*(Also: merging `vol` and `m` into one variable puts the volume chain in `$a0`. Residual 12 is this
+`$t0` rematerialisation plus one `lh`/`lhu` row that is the orphan's only available site.)*