From 6ad89305b89ca3cce09bf66e5f893e8376c0eb60 Mon Sep 17 00:00:00 2001
From: Drew T <50529377+Druthulu@users.noreply.github.com>
Date: Mon, 31 Aug 2026 14:21:45 -0600
Subject: [PATCH] =?UTF-8?q?docs(cookbook):=20=C2=A7347/=C2=A7343=20addenda?=
=?UTF-8?q?=20=E2=80=94=20one=20variable=20per=20purpose=20(3rd=20instance?=
=?UTF-8?q?);=20sltiu=20proves=20an=20unsigned=20return?=
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---
docs/cookbook-index.md | 12 +++++++++---
docs/matching-cookbook.md | 25 +++++++++++++++++++++++++
2 files changed, 34 insertions(+), 3 deletions(-)
diff --git a/docs/cookbook-index.md b/docs/cookbook-index.md
index 3640006ec..263f6769c 100644
--- a/docs/cookbook-index.md
+++ b/docs/cookbook-index.md
@@ -2,7 +2,7 @@
> **Generated by `tools/cookbook_index.py` — do not hand-edit** (R33). Regenerate after adding a cookbook section.
>
-> `docs/matching-cookbook.md` is ~716 KB / 996 sections. Grepping it blind is how three P30 wave-1 agents each "discovered" an idiom that was already written down. **Start here, then read the section.** A section appears under every symptom it addresses.
+> `docs/matching-cookbook.md` is ~716 KB / 998 sections. Grepping it blind is how three P30 wave-1 agents each "discovered" an idiom that was already written down. **Start here, then read the section.** A section appears under every symptom it addresses.
**How to use:** name what you SEE in the diff (a stolen delay slot, an extra `la`, a swapped register pair, a `conflicting types` error), find that symptom below, read those sections first. If nothing fits, THEN grind — and add a section when you win.
@@ -555,7 +555,7 @@
- **§342** — A `void *` PARAMETER CAST TO ITS REAL TYPE IN A LOCAL IS **NOT** BYTE-NEUTRAL WHEN A LATER PARAMETER ALSO NEEDS A CALLEE-SAVED REGISTER (P31 S67; byte-proven ov_SC07_002/func_80181394, NEW LAW) L31257
- **§345** — A VOLATILE **STORE** EVICTS THE MEM FROM cse AND KEEPS `sh`; A VOLATILE **LOAD** BLOCKS combine AND DEGRADES `lh` INTO `lhu+sll+sra` (P31 S67; byte-proven ov_SC01_084/func_80181A7C) L31312
-### declarations, prototypes & K&R (106)
+### declarations, prototypes & K&R (107)
- **§3-T4** — Branch polarity: invert the source condition to flip gcc's chosen branch L90
- **§8c** — Splitting a TU means rebuilding its DECLARATION ENVIRONMENT, not moving text (Phase 26 session 6) L456
@@ -663,6 +663,7 @@
- **§342** — A `void *` PARAMETER CAST TO ITS REAL TYPE IN A LOCAL IS **NOT** BYTE-NEUTRAL WHEN A LATER PARAMETER ALSO NEEDS A CALLEE-SAVED REGISTER (P31 S67; byte-proven ov_SC07_002/func_80181394, NEW LAW) L31257
- **§343** — `decl_prior`'s FLEET MAJORITY CAN BE WRONG ABOUT THE TRUE SIGNATURE — READ THE RIVALS, NOT JUST THE WINNER (P31 S67; measured on func_8012BD14 / func_8012D624 / func_80143C74) L31274
- **§347** — LOOP REGISTER ASSIGNMENT IS A **DECLARATION-ORDER + LIVE-RANGE** DIAL: FIVE COMPOSABLE LEVERS, 178 -> 0 (P31 S67; byte-proven ov_SC06_029/func_8017EF34, 243 ins) L31342
+- **§343-addendum** — SECOND INSTANCE OF THE WRONG-MAJORITY DECL (same function) L31390
### jump tables & switches (51)
@@ -1234,7 +1235,7 @@
- **§342** — A `void *` PARAMETER CAST TO ITS REAL TYPE IN A LOCAL IS **NOT** BYTE-NEUTRAL WHEN A LATER PARAMETER ALSO NEEDS A CALLEE-SAVED REGISTER (P31 S67; byte-proven ov_SC07_002/func_80181394, NEW LAW) L31257
- **§343** — `decl_prior`'s FLEET MAJORITY CAN BE WRONG ABOUT THE TRUE SIGNATURE — READ THE RIVALS, NOT JUST THE WINNER (P31 S67; measured on func_8012BD14 / func_8012D624 / func_80143C74) L31274
-### (unbucketed — title matched no symptom vocabulary) (297)
+### (unbucketed — title matched no symptom vocabulary) (298)
- **§3-How** — to use this L30
- **§1** — Idiom catalog (asm pattern → C that produces it) L39
@@ -1533,6 +1534,7 @@
- **RETRIEVAL** — FAILURES this round L30765
- **§323b** — A SCRIPT THAT PARSES argv AT IMPORT CANNOT BE SHARED; EXTRACT THE PREDICATE, DO NOT COPY IT (P31 S67) L30935
- **§330** — THE NEIGHBOUR-SHAPE LEVER IS THE CHEAPEST FIRST MOVE, AND IT IS UNDER-USED (P31 S67; four independent instances in one 20-function wave) L31042
+- **§347-addendum** — A THIRD INSTANCE, AND THE SHARPEST STATEMENT OF THE RULE (md_MAIN_025/func_800CB300, 243 ins) L31372
## All sections, in order
@@ -2533,6 +2535,8 @@
- **§345** — A VOLATILE **STORE** EVICTS THE MEM FROM cse AND KEEPS `sh`; A VOLATILE **LOAD** BLOCKS combine AND DEGRADES `lh` INTO `lhu+sll+sra` (P31 S67; byte-proven ov_SC01_084/func_80181A7C) L31312
- **§346** — `c ? X : -X` TAKES expand_expr's COND_EXPR **SINGLETON** PATH (copy, then negate IN PLACE) — AN if/else STATEMENT GIVES THE TWO-ARM FORM (P31 S67; byte-proven ov_SC03_102/func_80180C38, closed the last instruction) L31322
- **§347** — LOOP REGISTER ASSIGNMENT IS A **DECLARATION-ORDER + LIVE-RANGE** DIAL: FIVE COMPOSABLE LEVERS, 178 -> 0 (P31 S67; byte-proven ov_SC06_029/func_8017EF34, 243 ins) L31342
+- **§347-addendum** — A THIRD INSTANCE, AND THE SHARPEST STATEMENT OF THE RULE (md_MAIN_025/func_800CB300, 243 ins) L31372
+- **§343-addendum** — SECOND INSTANCE OF THE WRONG-MAJORITY DECL (same function) L31390
---
@@ -3541,3 +3545,5 @@ Notes routinely quote that as a section id. This table resolves it. Grep bait: `
| L31312 | §345 | A VOLATILE **STORE** EVICTS THE MEM FROM cse AND KEEPS `sh`; A VOLATILE **LOAD** BLOCKS co |
| L31322 | §346 | `c ? X : -X` TAKES expand_expr's COND_EXPR **SINGLETON** PATH (copy, then negate IN PLACE) |
| L31342 | §347 | LOOP REGISTER ASSIGNMENT IS A **DECLARATION-ORDER + LIVE-RANGE** DIAL: FIVE COMPOSABLE LEV |
+| L31372 | §347-addendum | A THIRD INSTANCE, AND THE SHARPEST STATEMENT OF THE RULE (md_MAIN_025/func_800CB300, 243 i |
+| L31390 | §343-addendum | SECOND INSTANCE OF THE WRONG-MAJORITY DECL (same function) |
diff --git a/docs/matching-cookbook.md b/docs/matching-cookbook.md
index b54a2f9a9..9033b68eb 100644
--- a/docs/matching-cookbook.md
+++ b/docs/matching-cookbook.md
@@ -31368,3 +31368,28 @@ Companion from that function, worth its own note: **`sp20[1] -= 0x20; sp20[1] -=
SEPARATE statements on an `s32` temp.** Any single expression lets gcc associate `0x20` into the giv,
and `loop.c` strength-reduces `0x20 + 4*i` into one register, while a bare `4*i` giv sits below the
worth-while threshold.
+
+### §347-addendum — A THIRD INSTANCE, AND THE SHARPEST STATEMENT OF THE RULE (md_MAIN_025/func_800CB300, 243 ins)
+
+**Reusing generic `v0` / `v1` locals across UNRELATED blocks makes them GLOBAL pseudos, and
+global-alloc pins a global pseudo to one hard register FOR THE WHOLE FUNCTION.** Splitting them into
+per-use locals (`hv` / `bit` / `flags` / `st`) fixed **three separate register residuals at once**
+(idx 89-92 and 197-214) *and* was what flipped the chained-assignment block from near-8 to MATCH.
+
+That is now three independent byte-proven instances of the same law in one session
+(§347 lever 4, `ov_SC03_105/func_80182DCC`'s three `range` locals, and this):
+**a Ghidra-style reused scratch variable is a register bug waiting to happen. One variable per
+purpose, always** — it costs nothing when it does not matter and fixes whole blocks when it does.
+
+Also from this function, an ablation record worth keeping: §205's chained assignment
+`*(u16*)(s0+0x18) = *(u16*)(s0+0x1A) = hv;` is the ONLY spelling that both creates the surviving
+`addu $v1,$v0,$zero` copy AND leaves sched1 free to hoist `sll/sra/slti` above the two `sh`.
+**Six ablations refuted:** explicit copy, re-set-source per §220-4, boolean temp, `hv = (s16)hv`
+pre-sign-extend, `+=`, and the plain two-statement form (which is exactly the copy short, 242 ins).
+
+### §343-addendum — SECOND INSTANCE OF THE WRONG-MAJORITY DECL (same function)
+
+The switch bound is `sltiu`, so `func_801633A8` must return **u32** — while the card's `decl_prior`
+fleet row says `s32`. Same shape as §343: the corpus majority is a propagated spelling, and the
+INSTRUCTION decides. An unsigned compare on the return value is direct evidence of an unsigned
+return type.