cuTile → Triton Conversion

Convert

@ct.kernel

kernels to

@triton.jit

. API mapping: references/api-mapping.md (cuTile → Triton).

In this skill’s Markdown, Triton launch syntax
kernel［grid］(…)
uses Unicode brackets so link checkers do not parse
[grid](…)
as a hyperlink; use normal ASCII brackets in real Triton code.

Instructions

Follow the phase-gated workflow in translations/workflow.md. Every conversion should go through analyze → convert → validate → test → benchmark, with explicit gates before moving on. Use the documents in Workflow Selection when the task matches a special case (errors, layout flags, perf).

Optimization strategy (perf-sensitive / attention) — If the op is attention, FMHA, sliding window, soft cap, or GQA (e.g. Gemma
```
gemma_attention
```
), read references/optimization-strategy.md before converting the inner loop, then apply §4 Gemma FMHA checklist. For other GEMM/BMM/attention-adjacent kernels, still skim §2–§3 of that file after TMA is done.
Select path — Existing TileGym op: standard mode in
```
translations/workflow.md
```
. If the cuTile source uses
```
transpose
```
/
```
transpose_v
```
, dual layouts, or MLA-style paths, read translations/advanced-patterns.md before writing Triton (two kernels +
```
META
```
grid, not one kernel +
```
tl.trans
```
).
Pre-flight — Run the Pre-flight Analysis grep commands on the cuTile source. Count
```
@ct.kernel
```
definitions; note TMA-relevant
```
ct.load
```
/
```
ct.store
```
,
```
ct.launch
```
,
```
Constant
```
, and layout flags.
Read mapping — Keep references/api-mapping.md open for cuTile → Triton API pairs. For runtime failures (illegal address, dtype, strides), use references/debugging.md.
Convert — Copy the Conversion Checklist into a todo list and execute in order. Structure and file placement: translations/file-structure.md. Mandatory: any 2D+ block-shaped tile load/store uses
```
tl.make_tensor_descriptor
```
(TMA), not raw
```
tl.load(ptr+offs, mask=…)
```
for full tiles—skipping this is the most common source of large regressions. Host side: Triton bracket launch <code>kernel［grid］(args)</code> with tuple or
```
lambda META: (…)
```
for autotune; no
```
ct.launch
```
.
Validate — Syntax-check the new Triton module; run the relevant TileGym pytest targets for the op:
```
pytest tests/ops/test_<op>.py -k "triton" -vs
```
. Fix failures before benchmarking.
Benchmark — Compare Triton vs cuTile on perf tests. If Triton is clearly slower, follow PERFORMANCE ANALYSIS (Phase c2t-5) in translations/workflow.md and references/optimizing-reference.md for GEMM/BMM/attention; use references/optimization-strategy.md as the ordered checklist. If you see 10–50× slowdowns, read CRITICAL PERFORMANCE PATTERNS in that same workflow file first.

Execution rules (MUST):

Create and track the conversion checklist (e.g. TodoWrite) before editing kernel code; complete steps in order—do not skip pre-flight or TMA decisions.
For attention / FMHA / Gemma / GQA / soft cap / sliding window: read references/optimization-strategy.md and apply §4 before treating the conversion as optimized.
Do not ship raw pointer+mask 2D+ tile loads where TMA applies; document any intentional exception.
If tests or benchmarks fail a gate, stop and fix before declaring the conversion done—do not stack unverified changes.

Workflow Selection

Existing TileGym op → Standard Mode: translations/workflow.md
Errors (
```
cudaErrorIllegalAddress
```
, shape mismatch, numerical mismatch) → references/debugging.md
Advanced patterns (TMA, dual layout flags
```
transpose
```
, autotune +
```
META
```
grid, Array.slice, ct.gather().item()) → translations/advanced-patterns.md (MLA-style two kernels, avoid 3–15× regression on
```
transpose=False
```
).
Performance (Triton kernel slower than cuTile, autotuning, profiling) → translations/workflow.md (section PERFORMANCE ANALYSIS (Phase c2t-5))
Optimization strategy hub (ordered checklist: advanced-patterns + optimizing-reference) → references/optimization-strategy.md — read first for attention/FMHA/Gemma; then drill into the two source docs as needed
Optimizing GEMM/BMM/attention (after TMA, or Triton 10–20% slower) → references/optimizing-reference.md — EVEN_K fast path, transpose via pointer arithmetic, grid layout, autotune breadth, epilogue subtile; use these patterns during conversion and before perf sign-off (summarized in optimization-strategy §2–§3)
Gemma attention / GQA FMHA conversion → references/optimization-strategy.md §4
Blackwell optimization (complex kernels with iterative algorithms, register pressure, loop unrolling) → references/optimizing-reference.md §9 — TMA descriptors,
```
loop_unroll_factor
```
, occupancy autotuning, TMEM-friendly block sizes, slab allocator, dual-path kernel design
⚠️ 10-50x REGRESSION (catastrophic slowdown after conversion) → translations/workflow.md — section CRITICAL PERFORMANCE PATTERNS (AVOID 10-50x REGRESSION)
⚠️ Good perf on
transpose=True
only, collapse on
transpose=False
(or opposite) → translations/advanced-patterns.md — §1 Dual layout flag; two
```
@triton.jit
```
kernels +
```
grid = lambda META: (... META["BLOCK_H"] ...)
```

Pre-flight Analysis (Run BEFORE converting)

bash

# Count kernels (only main kernel gets @triton.jit, helpers stay plain def)
grep "@ct\.kernel" source.py | wc -l

# Check for patterns needing special handling
grep "ct\.transpose\|ct\.permute" source.py   # → use tl.trans/tl.permute
grep "ct\.astype" source.py                    # → use .to(dtype)
grep "ct\.load\|ct\.store" source.py          # → TMA for 2D+ (tl.make_tensor_descriptor), NOT raw tl.load(ptr+offs)
grep "ct\.launch" source.py                    # → bracket launch: kernel then [grid] then (args)
grep "ct\.Constant\|ct\.ConstInt" source.py    # → tl.constexpr
grep "ct\.cdiv" source.py                      # → triton.cdiv (host) or Python (a+b-1)//b
grep "ct\.bid\|ct\.num_blocks" source.py       # → tl.program_id/tl.num_programs
grep "1 << .*\.bit_length" source.py           # → triton.next_power_of_2 if needed
grep "transpose\|transpose_v" source.py       # → if hit, read translations/advanced-patterns.md (dual kernels + META grid)

Conversion Checklist

Copy this checklist and track progress:

Conversion Progress:
 [ ] Step 0 (attention / Gemma FMHA / GQA / soft cap / sliding window): Read [references/optimization-strategy.md](./references/optimization-strategy.md) and apply §4 checklist before inner-loop Triton
 [ ] Step 1: Pre-flight — run grep commands above, note special patterns and 2D+ loads (→ TMA)
 [ ] Step 2: Analyze source cuTile kernel (identify patterns, shapes, dtypes)
 [ ] Step 3: Create Triton file with correct structure (see translations/file-structure.md)
 [ ] Step 4: Convert kernel signature (tensor args → pointer args, Constant → constexpr)
 [ ] Step 4b: TMA (MANDATORY for 2D+ loads) — use tl.make_tensor_descriptor for every 2D+ tile load/store; do NOT ship raw tl.load(ptr+offs,mask) for block-shaped access (see workflow.md § TMA OPTIMIZATION)
 [ ] Step 5: Convert kernel body (apply gotchas table below + API mapping)
 [ ] Step 6: Convert host wrapper (grid tuple/lambda, bracket-style launch: kernel, grid, then arguments; no ct.launch); call triton.set_allocator(alloc_fn) if using TMA
 [ ] Step 7: Validate — run pytest or syntax check on Triton file
 [ ] Step 8: Test — run pytest, verify X passed 0 failed
 [ ] Step 9: If test fails → fix → re-validate → re-test (loop until green)
 [ ] Step 10: Benchmark — run perf test, compare vs cuTile (see workflow.md § PERFORMANCE ANALYSIS)
 [ ] Step 10b: If GEMM/BMM/attention and Triton &gt;20% slower → walk [references/optimization-strategy.md](./references/optimization-strategy.md) §2–§3 then [references/optimizing-reference.md](./references/optimizing-reference.md) (EVEN_K, transpose, grid, autotune, epilogue subtile), then re-benchmark
 [ ] Step 10c: If op has `transpose` / layout flag → read [translations/advanced-patterns.md](./translations/advanced-patterns.md); verify **separate kernels** per layout (not transpose-kernel + `tl.trans`); **autotuned** launches use `lambda META: (triton.cdiv(..., META["BLOCK_H"]), ...)` — no fixed `BLOCK_H`/`BLOCK_N` through `apply()` unless autotune is disabled

Post-conversion Verification (TMA is mandatory for 2D+ loads):
 [ ] TMA: All 2D+ tile loads use tl.make_tensor_descriptor(...).load([...]); no raw ptr+mask for block-shaped 2D+ access (else 5x-20x regression)
 [ ] Grid uses tuple or lambda (not 3-tuple required like cuTile)
 [ ] Triton autotune added if cuTile op used kernel_configs/autotune (see workflow § PERFORMANCE ANALYSIS)
 [ ] Host grid uses triton.cdiv where appropriate (not (a+b-1)//b only)
 [ ] Pointer/offset indexing: Triton uses element offsets (ptr + offs), not block index in tl.load (or use TMA descriptor)
 [ ] ct.astype(x, dtype) → x.to(dtype) in Triton
 [ ] ct.mma(a, b, acc=acc) → tl.dot(a, b, acc) (no keyword in Triton)
 [ ] Optional/None args: Triton allows None in kernel args if desired (cuTile required dummy+flag)
 [ ] Masking applied when BLOCK_SIZE > actual dimension (same as cuTile); with TMA, masks can often be removed for full tiles
 [ ] Reduction divisor uses actual_size, NOT BLOCK_SIZE
 [ ] fp32/tf32: Triton defaults allow_tf32=True; match cuTile behavior if you had explicit tf32 cast
 [ ] If any 2D+ load uses raw ptr+mask (exception only): document WHY TMA was not used
 [ ] tl.assume() alignment hints added for strides and pointers

Gotchas (Most Common Translation Errors) {#gotchas-most-common-translation-errors}

Comprehensive table of patterns that frequently break or regress when porting

@ct.kernel

@triton.jit

— mma accumulator, type cast, grid, TMA usage, dtype handling, layout flags, batched matmul, etc.

See: references/gotchas.md — read this BEFORE writing the Triton kernel.

Performance Gotchas (10-50x Regression Risk) {#performance-gotchas-10-50x-regression-risk}

⚠️ These cause CATASTROPHIC slowdowns. Check BEFORE benchmarking.

Patterns and their impact: TMA vs raw ptr+mask (5-20×), autotune vs fixed tile sizes (2-3×),

broadcast_to + tl.dot

(10-50×),

extract_slice

chains (2-5×), and more.

See: references/performance-gotchas.md — full regression-risk table.

Full details: translations/workflow.md — section CRITICAL PERFORMANCE PATTERNS (AVOID 10-50x REGRESSION).

Full API mapping: references/api-mapping.md.

Triton math dtype (erf/erfc/exp/log/sqrt) and the "don't substitute erf with tanh" pattern: references/debugging.md — section Triton Math Function Dtype Requirements (CRITICAL).

Optimization strategy (hub)

File: references/optimization-strategy.md

Summarizes translations/advanced-patterns.md (layout flags, dual kernels, autotune+

META

, batched launch, Blackwell pointers) and references/optimizing-reference.md (post-TMA micro-opts, §9) into §1–§3 plus a mandatory §4 Gemma FMHA checklist.

Rule: For attention / FMHA / Gemma-style conversions, open optimization-strategy in the same session as workflow — do not rely on TMA alone for perf sign-off.

Reference Documents {#reference-documents}

Read from cuTile → Triton perspective. Core files live in this skill under ``.

Category	Document	Content
Strategy	optimization-strategy.md	Ordered hub: advanced-patterns + optimizing-reference; §4 Gemma FMHA mandatory checklist
Workflows	translations/workflow.md	Standard c2t conversion (phases + checklist)
	translations/file-structure.md	Where to place Triton files when converting from cuTile
	translations/advanced-patterns.md	Dual layout flags (transpose), autotune + `META` grid, MLA-style two kernels
API	api-mapping.md	cuTile → Triton mapping
	optimizing-reference.md	GEMM/BMM/attention optimizations (EVEN_K, transpose, grid, autotune, epilogue subtile)
Gotchas	gotchas.md	Common cuTile→Triton translation errors (mma, dtype, grid, TMA, layout flags)
	performance-gotchas.md	10-50× regression-risk table (TMA vs ptr+mask, broadcast_to, extract_slice chains, autotune)
Testing & errors	references/debugging.md	Triton runtime errors (cudaErrorIllegalAddress, pointer type, stride overflow)

Worked Examples

Use cutile_kernel.py as source and triton_kernel.py as target:

Example	Directory	Complexity
Vector Add	examples/01_vector_add/	Basic
Softmax	examples/02_softmax/	Intermediate
LayerNorm	examples/03_layernorm/	Intermediate
MatMul	examples/04_matmul/	Advanced
Attention	examples/05_attention/	Advanced

Read

cutile_kernel.py

first, then

triton_kernel.py

, to see the inverse mapping.

⚠️ MANDATORY COMPLETION CHECKLIST (DO NOT SKIP)

A conversion is NOT COMPLETE until ALL items are checked. Copy and complete:

MANDATORY COMPLETION GATES:
 [ ] 1. CORRECTNESS: pytest passes with 0 failures
     Command: python -m pytest {test_path} -k "test_op and triton" -vs --tb=short
     Gate: "X passed, 0 failed"

 [ ] 2. TMA OPTIMIZATION: All 2D+ tile loads use tl.make_tensor_descriptor
     Verify: grep -n "tl.load.*mask" triton_file.py | wc -l  # Should be 0 for 2D+ ops
     Skip = 5-20x performance regression

 [ ] 3. PERFORMANCE TEST: Triton within 20% of cuTile baseline
     Command: python -m pytest {test_path} -k "test_perf" --print-record -v
     OR: Run benchmark script: cd tests/benchmark && python bench_{op}.py
     Gate: Triton TFLOPS >= 0.8 * CuTile TFLOPS

 [ ] 4. PERFORMANCE COMPARISON RECORDED:
     Document results:
     | Config | Triton (TFLOPS) | CuTile (TFLOPS) | Ratio |
     |--------|-----------------|-----------------|-------|
     | [fill] | [fill]          | [fill]          | [fill]|

CONVERSION COMPLETE: All 4 gates passed? → YES / NO

Why this matters:

Gate 1 catches functional bugs
Gate 2 prevents catastrophic 5-20x regressions (most common mistake)
Gate 3 validates that optimization was effective
Gate 4 creates accountability record

If any gate fails: Fix and re-verify before declaring complete.

converting-cutile-to-triton

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