[CK_TILE] Optimize static_ford and sequence compile-time infrastructure (#5938) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ## Problem Each `static_for<0, N, 1>` instantiates its lambda N times (one per `number<I>` type). When nested, intermediate lambdas capture the outer loop variable (a different type per iteration), creating unique closure types. For a 3-level nest with M=4, N=4, K=2, this produces 4 + 16 + 32 = 52 IR functions, of which 20 are intermediate closures that get inlined away but still cost frontend compile time. ck_tile's `static_ford` was supposed to eliminate these intermediates (as old CK's PR #5031 did successfully), but it used a **recursive** `static_ford_impl` that recreated the same closure pattern plus added `reorder_old_to_new`/`reorder_new_to_old` overhead. Additionally, the sequence utility layer (`sequence_sort`, `is_valid_sequence_map`) used recursive template metaprogramming that generated O(N log N) intermediate types for every permutation validation — called on every `reorder_new_to_old`/`reorder_old_to_new` invocation. ## Changes ### 1. Replace `sequence_sort` with constexpr insertion sort Replace recursive merge sort (`sequence_sort_impl` + `sorted_sequence_merge_impl`, O(N log N) intermediate type instantiations) with constexpr insertion sort using `static_array`. O(1) template depth, same `::type` and `::sorted2unsorted_map` API. ### 2. Replace `is_valid_sequence_map` with constexpr check Replace sort-based permutation validation (which instantiated the full `sequence_sort` chain) with a constexpr "seen array" loop. O(N) constexpr steps instead of O(N log N) template instantiations. ### 3. Replace recursive `static_ford` with flat-loop `index_decomposer` Replace `static_ford_impl` (recursive `static_for` nesting + `pop_front`/`push_back` + `reorder_old_to_new` per iteration) with flat `index_decomposer` using pre-computed strides. Add `decompose_reordered` alias that folds reordering into decomposition, and `inverse_perm` helper that avoids the `sequence_map_inverse` → `is_valid_sequence_map` → `sequence_sort` chain. ### 4. Eliminate internal lambda via `ford_applier` The flat-loop approach still used `static_for` with a lambda, creating M×N internal lambda instantiations per call site. Replace with `ford_applier` struct that calls `f(decompose<I>{})` directly via fold expression — zero intermediate closures: ```cpp // Before: 2×M×N function instantiations static_for<0, M*N, 1>{}([&](auto i) { f(decompose<i>{}); }); // After: M×N function instantiations (50% reduction) ford_applier<Decomposer, make_index_sequence<M*N>>{}(f); ``` Also unified identity and non-identity order paths into a single template with `constexpr if`. ### 5. Fix const-qualified sequence handling Fix `is_valid_sequence_map` to handle const-qualified sequence types via `remove_cvref_t` in callers (`tensor_adaptor.hpp`, `tile_distribution_encoding.hpp`). ## Results (this PR only, without flattening) ### Build Time (Wilcoxon signed-rank, 7 paired trials, gfx942, load ~5) | Target | Base (s) | Treat (s) | Delta | % | Wins | Significant? | |--------|----------|-----------|-------|---|------|-------------| | **flatmm** | 160.1 | 152.7 | **-7.4s** | **-4.6%** | 6/7 | **YES** (W+=1, p<0.05) | | universal_gemm | 228.4 | 224.7 | -3.7s | -1.6% | 6/7 | Trending (W+=4) | Per-trial diffs (flatmm): [-6, -20, -9, -8, -8, 4, -5] Per-trial diffs (universal_gemm): [-2, -6, 4, -3, -2, -11, -6] ### IR Function Counts (device trace, gfx942) | Target | Metric | Before | After | Delta | % | |--------|--------|--------|-------|-------|---| | **universal_gemm** | InstantiateFunction | 117,715 | 109,165 | **-8,550** | **-7.3%** | | **universal_gemm** | CodeGen Function | 47,912 | 45,044 | **-2,868** | **-6.0%** | | **flatmm** | InstantiateFunction | 100,939 | 95,127 | **-5,812** | **-5.8%** | | **flatmm** | CodeGen Function | 42,651 | 40,367 | **-2,284** | **-5.4%** | Note: The `ford_applier` (commit 3) has minimal additional effect in this PR since ck_tile code does not yet use `static_ford` extensively. Its impact compounds when the follow-up flattening PR #5939 converts 124 `static_for` nests to `static_ford`. Combined results with #5939: flatmm **-7.5%** wall time (p<0.01), CodeGen **-10.5%**. ### ASM Equivalence 7/7 PASS — 979,943 lines of device assembly verified identical (gfx942 + gfx1100). TUs: universal_gemm, flatmm_basic, fmha_bwd, reduce, bscale. ## Test plan - [x] `test_ck_tile_static_ford`: 13 behavioral tests (identity/non-identity orders, 1D-4D, unit dimensions, edge cases) - [x] `ck_tile_unit_sequence`: 88 tests (11 new for sorted2unsorted_map, is_valid_sequence_map edge cases, sequence_unique_sort map round-trip) - [x] ASM equivalence verified (980K lines) - [x] Wilcoxon timing verified (7 trials, flatmm p<0.05) - [ ] CI 🤖 Generated with [Claude Code](https://claude.com/claude-code)
CK Tile Testing Guide
This document describes the test organization and available test targets for CK Tile operations.
Overview
CK Tile tests are organized with multiple levels of granularity to support different development workflows:
- Global test labels - Run tests across all operations
- Operation-specific umbrella targets - Run all tests for a specific operation
- Individual test executables - Run specific tests
Global Test Labels
These targets run tests across all CK operations (not just CK Tile):
ninja smoke
Run fast smoke tests (tests that complete within ~30 seconds on gfx90a).
ninja smoke
ninja regression
Run slower, more comprehensive regression tests.
ninja regression
ninja check
Run ALL available tests in the entire codebase.
ninja check
Operation-Specific Umbrella Targets
These targets allow you to run all tests for a specific CK Tile operation. This is useful when making changes to a particular operation and wanting to validate all related tests without running the entire test suite.
GEMM Operations
ck_tile_gemm_tests
Run all basic GEMM pipeline tests (memory, compute variants, persistent, etc.)
ninja ck_tile_gemm_tests
Test executables included:
test_ck_tile_gemm_pipeline_memtest_ck_tile_gemm_pipeline_compv3test_ck_tile_gemm_pipeline_compv4test_ck_tile_gemm_pipeline_persistenttest_ck_tile_gemm_pipeline_compv6test_ck_tile_gemm_pipeline_comp_async(gfx95 only)test_ck_tile_gemm_pipeline_*_wmmavariants (gfx11/gfx12 only)
ck_tile_gemm_block_scale_tests
Run all GEMM tests with block-scale quantization (AQuant, BQuant, ABQuant, etc.)
ninja ck_tile_gemm_block_scale_tests
Test executables included: 29 test executables covering:
- AQuant tests (memory pipelines, base layouts, prefill, preshuffle, transpose)
- ABQuant tests (base, padding, preshuffle)
- BQuant tests (1D/2D variants, transpose)
- BQuant with PreshuffleB (decode/prefill, 1D/2D)
- BQuant with PreshuffleQuant (decode/prefill, 1D/2D)
- RowColQuant and TensorQuant tests
ck_tile_gemm_streamk_tests
Run all GEMM StreamK tests (tile partitioner, reduction, smoke, extended)
ninja ck_tile_gemm_streamk_tests
Test executables included:
test_ck_tile_streamk_tile_partitionertest_ck_tile_streamk_reductiontest_ck_tile_streamk_smoketest_ck_tile_streamk_extended
ck_tile_grouped_gemm_quant_tests
Run all grouped GEMM quantization tests
ninja ck_tile_grouped_gemm_quant_tests
Test executables included:
test_ck_tile_grouped_gemm_quant_rowcoltest_ck_tile_grouped_gemm_quant_tensortest_ck_tile_grouped_gemm_quant_aquanttest_ck_tile_grouped_gemm_quant_bquanttest_ck_tile_grouped_gemm_quant_bquant_preshuffleb
Other Operations
ck_tile_fmha_tests
Run all FMHA (Flash Multi-Head Attention) tests
ninja ck_tile_fmha_tests
Test executables included: Forward and backward tests for fp16, bf16, fp8bf16, fp32
ck_tile_reduce_tests
Run all reduce operation tests
ninja ck_tile_reduce_tests
Test executables included:
test_ck_tile_reduce2dtest_ck_tile_multi_reduce2d_threadwisetest_ck_tile_multi_reduce2d_multiblock
Individual Test Executables
You can also build and run individual test executables:
Build a specific test
ninja test_ck_tile_gemm_pipeline_mem
Run a specific test directly
./build/bin/test_ck_tile_gemm_pipeline_mem
Run a specific test through ctest
ctest -R test_ck_tile_gemm_pipeline_mem --output-on-failure