gqa(adr): ADR-0065 review fixes — KERNEL phase/repetition split, auto-bind conflict + MATH-TCM invariants, FIFO conservatism note, logical_bytes per-op summation

ADR-0065 review fixes: - D3 semantics clarified: position determines *phase* (pre-loop / head / in-accumulation / per-output-tile / post-loop), scope determines *repetition*. KERNEL = "once per CompositeCmd invocation", not "once per kernel launch" — removes ambiguity around softmax_merge's KERNEL scope at different positions before/after GEMM. - D4 MATH-TCM invariant: Phase 1 limits DMA auto-insertion to GEMM operands and head outputs; MATH operand with space="hbm" raises validation error at TLContext emit. Catches kernel misuse early; a MATH-with-HBM path is future work (explicit tl.load + MATH composite). - D6 #6 NEW: auto-bind conflict — explicit GEMM `a=` + prologue primary_out simultaneously → validation error (prevents "which value wins" ambiguity). - D6 #7 NEW: MATH operand TCM-only restatement. - Consequences/Negative: strict-FIFO conservatism note — safe but may under-expose composite-level overlap when handle-sharing composites could in principle run in parallel. - Test Requirements #10, #11: auto-bind conflict + MATH-HBM validation error tests. ADR-0064 Revision 2 clarification: - D2 counting rule: per-op summation, no deduplication. Same handle appearing in multiple OpSpecs or in rw_handles is counted independently — matches HW reality (each descriptor field is a distinct address slot, rw_handles is separate metadata block). Example walked through (mul_bcast with O in src_a + out + rw_handles). DDD-0065 follow-on: - §3.2: new test file test_tl_composite_validation.py covers auto-bind conflict, MATH-TCM, GEMM-count invariants. - §4.3: phase vs repetition split aligned with ADR-0065 D3. - §6 lowering pipeline: step 5 adds auto-bind conflict check; step 8 NEW — operand space validation; step 9 (size cap); step 10 (emit). - §8 strict-FIFO conservatism note: explains why next-tile #1 cross-tile pipelining still works under FIFO (no rw overlap), and where the conservatism would hurt (future handle-sharing recipes). - §10 verification: invariant-guard tests (auto-bind conflict, MATH TCM, per-op summation accuracy). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-06-10 16:29:39 -07:00
parent 95cecccd8e
commit a8d04750e6
5 changed files with 197 additions and 46 deletions
@@ -139,6 +139,17 @@ def _extra_bytes(v) -> int:
 (`DmaReadCmd`, `MathCmd` 등도 같은 룰 — dataclass 당 property 1 개,
 약 3 줄.)

+**카운팅 룰 — per-op 합산, dedup 없음.** `OpSpec` 안의 각 `TensorHandle`
+참조는 독립적으로 카운트 — 같은 핸들이 여러 OpSpec 에 등장하거나
+`rw_handles` 에도 있어도 마찬가지. `rw_handles` block 은 cross-composite
+해저드 추적 (ADR-0065 D6.3) 의 메타데이터로 `ops` 의 operand 참조와
+**별도** 카운트. 중복 제거 없음. HW 와 일치: descriptor 가 각 operand
+slot 을 독립 address field 로 인코딩하고 dispatcher 가 `rw_handles` 를
+별도 metadata block 으로 추적. 예: `OpSpec(kind="mul_bcast", operands=
+{"src_a": O, "src_b": corr}, out=O)` 는 핸들 `O` 를 *두 번* 카운트
+(`src_a` 한 번, `out` 한 번); 만약 `O` 가 둘러싼 CompositeCmd 의
+`rw_handles` 에도 있으면 세 번째 카운트.
+
 ### D3. Default — 일반 composite ≈ 43 ns 기준

 Anchor: **DMA-staged GEMM 경로용 단일-OpSpec composite** —
@@ -150,6 +150,19 @@ def _extra_bytes(v) -> int:
 (Identical rule for `DmaReadCmd`, `MathCmd`, etc. — one property per
 dataclass, ~3 lines each.)

+**Counting rule — per-op summation, no deduplication.** Each
+`TensorHandle` reference inside an `OpSpec` is counted independently,
+even when the same handle appears in multiple OpSpecs or in
+`rw_handles`. The `rw_handles` block is metadata for cross-composite
+hazard tracking (ADR-0065 D6.3) and is counted separately from
+operand references in `ops`. There is no deduplication. This matches
+HW reality: the descriptor encodes each operand slot as an independent
+address field, and the dispatcher tracks `rw_handles` as a distinct
+metadata block. Example: `OpSpec(kind="mul_bcast", operands={"src_a":
+O, "src_b": corr}, out=O)` counts handle `O` *twice* (once for
+`src_a`, once for `out`); if `O` is also in the enclosing
+CompositeCmd's `rw_handles`, it is counted a third time.
+
 ### D3. Defaults — anchored on a typical composite ≈ 43 ns

 Anchor: a **single-OpSpec composite for a DMA-staged GEMM path** —
@@ -94,19 +94,26 @@ named operand 로 PE_SCHEDULER 가 (positional 컨벤션 없이) 엔진 port 에

 ### D3. Position + scope 가 tile-loop 배치 결정

+**Semantics 분리.** *Position* 이 **phase** (tile-loop 수명주기 어디서
+실행되는지) 결정; *scope* 가 그 phase 안에서의 **repetition** 결정.
+`Scope.KERNEL` 의미는 "**`CompositeCmd` invocation 당 1 회**" — kernel
+launch 당 1 회 아님. 그 1 회 실행이 op 의 시퀀스 내 *position* 에서
+발생. 같은 KERNEL 값이 OpSpec 이 GEMM op 의 앞/위치/뒤에 있느냐에 따라
+*phase* 가 달라짐.
+
 PE_SCHEDULER 가 `cmd.ops` 에서 GEMM op 검색 (composite 당 ≤ 1, D6 참조).
 인덱스 `g`:

-| OpSpec position | scope | plan 내 배치 |
-|---|---|---|
-| `0 .. g-1` | KERNEL | pre-loop stages (tile loop 진입 전 1 회 실행) |
-| `g` | KERNEL | head GEMM (`extra["m"], extra["k"], extra["n"]` 로 tile loop drive) |
-| `g+1 .. ` | K_TILE | per K-tile epilogue (누산 loop 안) |
-| `g+1 .. ` | OUTPUT_TILE | per (m, n) tile epilogue (K 누산 후) |
-| `g+1 .. ` | KERNEL | post-loop stages (tile loop 종료 후 1 회) |
+| OpSpec position | scope | Phase | plan 내 배치 |
+|---|---|---|---|
+| `0 .. g-1` | KERNEL | pre-tile-loop | tile loop 진입 전 1 회 |
+| `g` | KERNEL | head GEMM | `extra["m"], extra["k"], extra["n"]` 로 tile loop drive |
+| `g+1 .. ` | K_TILE | in-accumulation | per K-tile epilogue (K 누산 loop 안) |
+| `g+1 .. ` | OUTPUT_TILE | per-output-tile | per (m, n) tile epilogue (K 누산 후) |
+| `g+1 .. ` | KERNEL | post-tile-loop | tile loop 종료 후 1 회 |

 GEMM op 가 없는 composite (예: MATH-only) 는 모든 op 를 KERNEL-scope
-직렬로 처리.
+직렬로 처리 — phase 가 "순서대로 single-shot" 으로 collapse.

 ### D4. PE_SCHEDULER 가 operand `space` 보고 DMA 자동 삽입

@@ -119,8 +126,13 @@ PE_SCHEDULER 가 GEMM 의 `operands` 와 `out` 검사. 각각:
 PE_SCHEDULER 가 핸들에서 추론**. `tl.ref(addr, shape)` → `space="hbm"`;
 `tl.zeros` / `tl.full` / `tl.load` 결과 → `space="tcm"`.

-비 GEMM op (prologue/epilogue 의 MATH chain) 은 TCM-resident operand
-(커널이 `tl.zeros` / `tl.full` 로 할당); DMA 삽입 없음.
+**비 GEMM op 은 TCM-only (Phase 1 한계, TLContext emit 시 강제).**
+모든 non-GEMM (MATH) OpSpec 의 모든 operand 는 **반드시**
+`space == "tcm"`. 커널이 `space == "hbm"` 핸들을 MATH operand 로 전달하면
+TLContext 가 emit 시 validation error. Phase 1 에서 DMA 자동 삽입을
+GEMM operand + head 출력 핸들로 제한; MATH-with-HBM 경로는 미래 확장
+(명시적 `tl.load` + MATH composite 분리, 또는 새 "DMA-as-prologue" recipe
+variant). 이 invariant 는 D6 #7 에 재기술.

 ### D5. RECIPE_DESCRIPTORS — TLContext 내부, `pe_commands.py` 가 아님

@@ -189,6 +201,14 @@ op="gemm", ...)` 에서:
   로 lowering.
 5. **PE_SCHEDULER recipe-free.** PE_SCHEDULER 는 RECIPE_DESCRIPTORS import
   안 함, "softmax_merge" 의 존재 모름, recipe 별 코드 분기 없음.
+6. **암묵 operand 대체 없음 (auto-bind 충돌).** prologue recipe 가
+   `primary_out` 선언하고 head op 의 auto-bind 대상 operand (예: GEMM
+   `a`) 도 *커널이 명시적* 으로 제공하면, TLContext 가 emit 시 validation
+   error. 커널은 recipe 가 바인딩하게 두거나 (operand 생략) **혹은**
+   명시적으로 지정 (prologue 생략, 또는 `primary_out` 없는 recipe 사용)
+   해야 함. "어느 값이 이기느냐" 의 모호함 방지.
+7. **MATH operand TCM-only.** D4 의 재기술: 모든 비 GEMM OpSpec 의 모든
+   operand 는 `space == "tcm"`. Phase 1 에서 TLContext emit 시 강제.

 ### D7. Boundary 요약 (compiler vs scheduler vs engine)

@@ -268,6 +288,13 @@ scratch 에서 읽는 형태 — 순환 tile-loop 의존성. **기각 (incorrect
  auto-bind. ~80–120 LOC.
 - PE_SCHEDULER 의 `_generate_plan` 에 position-기반 스캔 + DMA 자동 삽입
  + strict-FIFO RW tracker. ~60–100 LOC.
+- **strict-FIFO RW 해저드 추적이 안전하지만 보수적.** 두 composite 가
+  `rw_handle` 을 공유할 때 신규는 모든 이전 겹치는 composite 가 *완전히
+  완료* 될 때까지 대기 — 원칙적으로 overlap 가능한 경우에도
+  (예: 다음-tile #1 = Q·Kᵀ 가 m/l/O 안 만지므로 현재-tile 의 #2 와
+  overlap 가능하지만, 같은 핸들을 만지는 후속 path 도 FIFO 로 직렬화).
+  더 똑똑한 scheduler 대비 **composite-level overlap 을 과소 노출**.
+  RW-aware reorder (A4) 가 연기된 개선.

 ## Open review items

@@ -311,9 +338,17 @@ scratch 에서 읽는 형태 — 순환 tile-loop 의존성. **기각 (incorrect
 8. **GEMM-count invariant.** GEMM OpSpec 두 개 가진 composite 가
   TLContext emit 시 validation error.
 9. **Composite 크기 cap 안에 (ADR-0064 D7).** Decode opt2 의 `#2`
-   composite (10 ops, ~310 logical bytes) 가 default
-   `MAX_COMPOSITE_LOGICAL_BYTES=1024` 안에 편안히 — segmentation 없음.
-   recipe lowering 테스트가 `cmd.logical_bytes < 1024` 단언.
+   composite (10 ops, ~322 logical bytes — operand 핸들의 per-op 합산)
+   가 default `MAX_COMPOSITE_LOGICAL_BYTES=1024` 안에 편안히 —
+   segmentation 없음. recipe lowering 테스트가 `cmd.logical_bytes
+   < 1024` 단언.
+10. **Auto-bind 충돌.** `tl.composite(op="gemm", a=A_handle,
+    prologue=[{"op": "softmax_merge", ...}], ...)` 처럼 softmax_merge 가
+    `primary_out` 선언하는데 `a` 도 명시되면 emit 시 validation error
+    (D6.6).
+11. **MATH operand TCM invariant.** `tl.composite(op="math",
+    a=tl.ref(addr, shape), ...)` (HBM-resident 핸들을 MATH operand 로
+    전달) 가 emit 시 validation error (D6.7).

 ## Dependencies

@@ -103,19 +103,27 @@ takes `operands["a"]`, `operands["b"]`) without positional convention.

 ### D3. Position + scope determines tile-loop placement

+**Semantics split.** *Position* determines the **phase** (where in the
+tile-loop lifecycle the op fires); *scope* determines the **repetition**
+within that phase. `Scope.KERNEL` means "**once per `CompositeCmd`
+invocation**", not "once per kernel launch" — its single firing happens
+at the op's position in the sequence. The same KERNEL value carries
+different *phases* depending on whether the OpSpec sits before, at, or
+after the GEMM op.
+
 PE_SCHEDULER scans `cmd.ops` for the GEMM op (≤1 per CompositeCmd, see
 D6). Calling its index `g`:

-| OpSpec position | scope | Placement in plan |
-|---|---|---|
-| `0 .. g-1` | KERNEL | pre-loop stages (run once before tile loop) |
-| `g` | KERNEL | head GEMM (drives tile loop with `extra["m"], extra["k"], extra["n"]`) |
-| `g+1 .. ` | K_TILE | per K-tile epilogue (inside accumulation loop) |
-| `g+1 .. ` | OUTPUT_TILE | per (m, n) tile epilogue (after K accumulation) |
-| `g+1 .. ` | KERNEL | post-loop stages (run once after tile loop) |
+| OpSpec position | scope | Phase | Placement in plan |
+|---|---|---|---|
+| `0 .. g-1` | KERNEL | pre-tile-loop | run once before tile loop |
+| `g` | KERNEL | head GEMM | drives tile loop with `extra["m"], extra["k"], extra["n"]` |
+| `g+1 .. ` | K_TILE | in-accumulation | per K-tile epilogue (inside K accumulation loop) |
+| `g+1 .. ` | OUTPUT_TILE | per-output-tile | per (m, n) tile epilogue (after K accumulation) |
+| `g+1 .. ` | KERNEL | post-tile-loop | run once after tile loop |

 A composite with no GEMM op (e.g., MATH-only composite) treats all ops
-as KERNEL-scope sequential.
+as KERNEL-scope sequential — phase collapses to "single-shot in order".

 ### D4. PE_SCHEDULER auto-inserts DMAs from operand `space`

@@ -130,9 +138,15 @@ DMA cmds for composite operands; PE_SCHEDULER infers them from
 handles**. `tl.ref(addr, shape)` returns a handle with `space="hbm"`;
 `tl.zeros` / `tl.full` / `tl.load` outputs return `space="tcm"`.

-Non-GEMM ops (MATH chain in prologue / epilogue) have TCM-resident
-operands (kernel allocates via `tl.zeros` / `tl.full`); no DMA inserted
-for them.
+**Non-GEMM ops are TCM-only (Phase 1 limit, enforced at TLContext emit).**
+Every operand of every non-GEMM (MATH) OpSpec **must** have
+`space == "tcm"`. If a kernel passes a handle with `space == "hbm"` as a
+MATH operand, TLContext raises a validation error at emit time. This
+keeps DMA auto-insertion bounded to GEMM operands and head output
+handles in Phase 1; a MATH-with-HBM path would require a future
+extension (split into explicit `tl.load` + MATH composite, or a new
+"DMA-as-prologue" recipe variant). This invariant is also restated in
+D6 #7.

 ### D5. RECIPE_DESCRIPTORS — TLContext-internal, NOT in `pe_commands.py`

@@ -211,6 +225,16 @@ sees only the flat ops list.
 5. **PE_SCHEDULER recipe-free.** PE_SCHEDULER does not import
   RECIPE_DESCRIPTORS, does not know that "softmax_merge" exists, and
   has no recipe-specific code branches.
+6. **No implicit operand replacement (auto-bind conflict).** If a
+   prologue recipe declares a `primary_out` AND the head op's auto-bind
+   target operand (e.g., GEMM `a`) is *also* provided by the kernel
+   explicitly, TLContext raises a validation error at emit time. The
+   kernel must either let the recipe bind (omit the operand) **or**
+   specify it explicitly (omit the prologue, or use a recipe without
+   `primary_out`). This prevents the ambiguity of "which value wins".
+7. **MATH operands TCM-only.** Restatement of D4: every operand of a
+   non-GEMM OpSpec must have `space == "tcm"`. Phase 1 enforced at
+   TLContext emit.

 ### D7. Boundary summary (compiler vs scheduler vs engine)

@@ -297,6 +321,15 @@ input from #1's epilogue scratch — circular tile-loop dependency.
  primary_out auto-bind. ~80–120 LOC.
 - PE_SCHEDULER's `_generate_plan` gets a position-based scan + DMA
  auto-insertion + strict-FIFO RW tracker. ~60–100 LOC.
+- **Strict-FIFO RW hazard tracking is safe but conservative.** When
+  two composites share any `rw_handle`, the new one waits for *all*
+  prior overlapping composites to fully complete — even when their
+  compute could in principle overlap (e.g., next-tile #1 = Q·Kᵀ does
+  not touch m/l/O and could overlap with this-tile's #2, but FIFO
+  still serializes any path that touches the same handles down the
+  line). This **may under-expose composite-level overlap** relative to
+  a smarter scheduler. RW-aware reorder (A4) is the deferred
+  improvement.

 ## Open review items

@@ -344,9 +377,17 @@ input from #1's epilogue scratch — circular tile-loop dependency.
 8. **GEMM-count invariant.** A composite with two GEMM OpSpecs raises a
   validation error at TLContext emit.
 9. **Within composite size cap (ADR-0064 D7).** Decode opt2's `#2`
-   composite (10 ops, ~310 logical bytes) fits comfortably under the
-   default `MAX_COMPOSITE_LOGICAL_BYTES=1024` — no segmentation. The
-   recipe lowering test asserts `cmd.logical_bytes < 1024`.
+   composite (10 ops, ~322 logical bytes — per-op summation of operand
+   handles) fits comfortably under the default
+   `MAX_COMPOSITE_LOGICAL_BYTES=1024` — no segmentation. The recipe
+   lowering test asserts `cmd.logical_bytes < 1024`.
+10. **Auto-bind conflict.** `tl.composite(op="gemm", a=A_handle,
+    prologue=[{"op": "softmax_merge", ...}], ...)` where softmax_merge
+    declares `primary_out` raises a validation error at emit time
+    (D6.6).
+11. **MATH operand TCM invariant.** `tl.composite(op="math",
+    a=tl.ref(addr, shape), ...)` (passing an HBM-resident handle as a
+    MATH operand) raises a validation error at emit time (D6.7).

 ## Dependencies

@@ -92,7 +92,8 @@ without importing `tl_recipes`.
 | `tests/test_tl_recipe_softmax_merge.py` | recipe lowering — given inputs, asserts CompositeCmd has 10 ops in expected order + `rw_handles == (m, l, O)` |
 | `tests/test_pe_scheduler_strict_fifo.py` | two consecutive composites sharing rw_handles complete in dispatch order; no stage interleave |
 | `tests/test_pe_scheduler_auto_dma.py` | `space=hbm` operand → DMA_READ stage; `space=tcm` → none; `out.space=hbm` → DMA_WRITE |
-| `tests/test_pe_cost_model.py` | ADR-0064 Rev2 — typical 1-GEMM composite at 45 ns; topology override path; `PeCpuOverheadCmd` bypass |
+| `tests/test_pe_cost_model.py` | ADR-0064 Rev2 — typical 1-GEMM composite at ~43 ns; topology override path; `PeCpuOverheadCmd` bypass; per-op summation rule (ADR-0064 D2) |
+| `tests/test_tl_composite_validation.py` | auto-bind conflict (D6.6); MATH operand TCM-only (D6.7); GEMM-count > 1 (D6.1) |
 | `tests/attention/test_gqa_decode_opt2.py` | opt2 numeric parity with opt3; K-before-V DMA invariant; per-tile dispatch ratio measurement |

 ---
@@ -147,15 +148,26 @@ Backward compat: existing `operands: tuple[Any, ...]` use sites
 h}` / `operands={"src": h}` per a small lookup in
 `pe_commands.EPILOGUE_OPS`.

-### 4.3 `Scope` semantics (position-based for KERNEL)
+### 4.3 `Scope` semantics — phase vs repetition (ADR-0065 D3)

 `Scope` keeps its three values (`KERNEL`, `K_TILE`, `OUTPUT_TILE`).
-What changes: `KERNEL` no longer means "once anywhere"; it now means
-"execute at this op's position in the sequence — once". Combined with
-position relative to the GEMM op:
- KERNEL ops *before* GEMM → pre-tile-loop (single shot)
- KERNEL ops *after* GEMM → post-tile-loop (single shot)
- K_TILE / OUTPUT_TILE ops *after* GEMM → inside tile loop as before
+What changes is the **semantics split**:
+- **Position** determines the *phase* (where in the tile-loop lifecycle
+  the op fires — pre-loop / in-loop / post-loop).
+- **Scope** determines the *repetition* within the phase
+  (KERNEL = once per `CompositeCmd` invocation; K_TILE = per K-tile
+  iteration; OUTPUT_TILE = per output tile).
+
+`KERNEL` does *not* mean "once per kernel launch" or "once anywhere".
+It means "once per `CompositeCmd` invocation, at this op's position".
+A composite with multiple KERNEL-scope ops (e.g., softmax_merge's 8
+prologue ops) executes each exactly once, in sequence order, before
+the GEMM tile loop begins.
+
+Concretely:
+- KERNEL ops *before* GEMM → pre-tile-loop (single shot, in order)
+- KERNEL ops *after* GEMM → post-tile-loop (single shot, in order)
+- K_TILE / OUTPUT_TILE ops *after* GEMM → inside tile loop as today

 ---

@@ -258,9 +270,14 @@ Lowering steps in `TLContext.composite()`:
   - Build `OpSpec(kind=op_kind, scope=Scope.KERNEL, operands={...},
     extra={...}, out=...)`.
   - `out` is the handle for `dst` slot; `operands` is `{src*: handle}`.
-5. **Auto-bind head GEMM.** GEMM OpSpec built from `op="gemm"`,
-   `operands={"a": P_handle, "b": V_handle}`, `out=<output handle>`,
-   `extra={"m": G, "k": TILE, "n": d}`.
+5. **Auto-bind head GEMM (with conflict check, ADR-0065 D6.6).** GEMM
+   OpSpec built from `op="gemm"`, `operands={"a": P_handle, "b":
+   V_handle}`, `out=<output handle>`, `extra={"m": G, "k": TILE, "n":
+   d}`. **Validation:** if the kernel passed `a=<some handle>`
+   explicitly AND there is a prologue recipe with `primary_out` that
+   would auto-bind into `a`, raise a validation error (auto-bind
+   conflict). The kernel must omit `a` (let recipe bind) or omit the
+   prologue / use a `primary_out=None` recipe (no auto-bind).
 6. **Build epilogue OpSpecs.** Each `epilogue=[{...}]` entry maps to
   `OpSpec(kind=..., scope=Scope.OUTPUT_TILE, operands={...}, ...)`.
   The `add` epilogue specifically gets `operands={"other": O_handle}`
@@ -268,12 +285,23 @@ Lowering steps in `TLContext.composite()`:
 7. **Compute `rw_handles`.** Collect all handles tagged RW in prologue
   recipes + the head GEMM's `out` (if accumulating) + any RW epilogue
   targets. For softmax_merge: `rw_handles = (m, l, O)`.
-8. **Check composite size cap (ADR-0064 D7).** Compute
-   `cmd.logical_bytes`; if > `MAX_COMPOSITE_LOGICAL_BYTES` (default
-   1024), segment deterministically by op index. softmax_merge's 10-op
-   composite (~310 bytes) is well under the cap → single segment, no
-   split for decode opt2.
-9. **Emit `CompositeCmd`.** `ops = (8 MATH + 1 GEMM + 1 MATH(add))`,
+8. **Operand space validation (ADR-0065 D6.7).** For each generated
+   OpSpec in the about-to-emit `ops`:
+   - If `kind == "gemm"`: operands may be HBM (auto-DMA) or TCM. Output
+     handle may be HBM (auto-DMA_WRITE) or TCM.
+   - If `kind != "gemm"` (MATH): **every** `operands.values()` handle
+     must have `space == "tcm"`. HBM operand → validation error.
+   This catches kernel misuse (passing `tl.ref(...)` into MATH ops)
+   early. softmax_merge's 8 MATH ops only ever reference TCM-resident
+   handles (kernel-allocated `m, l, O` + scratch `m_loc, m_new, corr,
+   P, l_loc`) — invariant naturally holds.
+9. **Check composite size cap (ADR-0064 D7).** Compute
+   `cmd.logical_bytes` using the per-op summation rule (ADR-0064 D2);
+   if > `MAX_COMPOSITE_LOGICAL_BYTES` (default 1024), segment
+   deterministically by op index. softmax_merge's 10-op composite
+   (~322 bytes per-op-summed) is well under the cap → single segment,
+   no split for decode opt2.
+10. **Emit `CompositeCmd`.** `ops = (8 MATH + 1 GEMM + 1 MATH(add))`,
    `rw_handles = (m, l, O)`, `completion = new`.

 **Legacy lowering.** Pre-existing
@@ -384,6 +412,17 @@ overlap is partial, the new composite waits for all prior overlapping
 composites to *fully* drain — simple, easy to reason about, easy to
 test. (RW-aware reorder deferred per ADR-0065 A4.)

+**Conservatism trade-off (ADR-0065 Consequences/Negative).** This rule
+is safe but may under-expose overlap. Concretely for decode opt2:
+next-tile's #1 (Q·Kᵀ) does not touch `(m, l, O)` and *could* in
+principle run while this-tile's #2 is still computing on those handles.
+Under strict FIFO, next-tile's #1 still gets dispatched (no rw overlap
+with prior in-flight) — so #1 cross-tile pipelining is preserved.
+However, if a future bench composed multiple #2-like recipes that share
+handles, FIFO would serialize them even when their compute could
+overlap. Acceptable for Phase 1; revisit when a real workload shows
+the gap.
+
 ---

 ## 9. Phased implementation plan (test-first per CLAUDE.md)
@@ -392,7 +431,7 @@ Each phase is an independent Phase-1 → Phase-2 cycle per CLAUDE.md Part 1.

 | Phase | Deliverable | Gate |
 |---|---|---|
-| **P0 (= ADR-0064 Rev2)** | `logical_bytes` property + dispatch formula + topology override; one-time goldens regeneration | typical composite ≈ 45 ns; dispatch ratio test infrastructure in place |
+| **P0 (= ADR-0064 Rev2)** | `logical_bytes` property + dispatch formula + topology override + size cap; one-time goldens regeneration | typical 1-OpSpec composite ≈ 43 ns; dispatch ratio test infrastructure in place |
 | **P1** | `CompositeCmd` flat-ops dataclass refactor + `OpSpec.operands: dict` + legacy `tl.composite` lowering preserved | every existing bench's op_log byte-equal pre/post |
 | **P2** | `tl_recipes.py` + `RECIPE_DESCRIPTORS["softmax_merge"]` + TLContext lowering for `prologue=[...]` | recipe lowering test (10 ops, rw_handles, addresses) passes |
 | **P3** | PE_SCHEDULER `_generate_plan` flat-ops + `PipelinePlan.prologue_stages` + DMA auto-insertion + `_feed_loop` extension | all existing bench Stage sequences unchanged; new MATH chain visible in op_log for opt2 mock |
@@ -453,6 +492,18 @@ Mirrors ADR-0065 §Test Requirements; grounded in SPEC R2/R5, ADR-0023/
 - **Sensitivity sweep.** Repeat with `R ∈ {0.25, 0.0625, 0.03125}`
  cycles/byte; assert opt2 < opt3 in all three. (ADR-0064 Test #9.)

+**Invariant guards (P2):**
+- Auto-bind conflict: `tl.composite(op="gemm", a=A_handle,
+  prologue=[{"op": "softmax_merge", "s": Sj, "m": m, "l": l, "O": O}],
+  ...)` → `pytest.raises(ValidationError, match="auto-bind conflict")`.
+- MATH operand TCM-only: `tl.composite(op="math", a=tl.ref(addr,
+  shape), ...)` → `pytest.raises(ValidationError, match="MATH operand
+  must be TCM")`.
+- Per-op logical_bytes summation: a synthetic composite with the same
+  handle `O` in 3 OpSpecs + in `rw_handles` reports
+  `logical_bytes` higher than a deduplicated equivalent by exactly
+  `3 × 8` (operand references) + `8` (rw_handles entry) = 32 bytes.
+
 **Determinism (all phases):**
 - Identical inputs → identical op_log + latency (SPEC §0.1).