T.copy_ue4m3_scale_tile and T.ue4m3_scale_tile_source_coords were
NVFP4-specific helpers on the general T.* surface. Remove both and move the
abstraction down a level:
- The example now declares the packed scale source with its honest "tile rows"
shape ([n_mn_blocks * n_k_blocks * block_MN, block_K // 64] uint32): the
blockscaled_chunk_kmajor layout stores each (mn_block, k_block) tile
contiguously, so with this view every tile is a plain rectangular slice and
staging is a two-line T.Parallel loop with row-offset addressing only. The
host obtains the view zero-copy via
swizzle_blockscaled_chunk_kmajor_scale_words(...).reshape(-1, 4).
- tilelang.quantize.nvfp4 gains blockscaled_chunk_kmajor_tile_source_coords,
the hand-written offset formula for staging schedules that keep the 2-D
[MN, K/64] view (the maint benchmark's producer warp group uses it).
Compiler-internal staging was prototyped first (plain T.copy of the slice)
and rejected for now: the raw-pointer bulk-TMA path this lowers to on some
shapes never arrives on its mbarrier (deadlock, tracked upstream), and the
synchronous fallback stalls the producer warps (-8.5% at 2048^3). The example
comment documents this so the loop can become a plain T.copy once fixed.
Validation on RTX 5090: 123 tests pass; example outputs bitwise-identical to
the previous macro implementation on 5 shapes including M/N tail tiles
(257x384x512, 130x128x256, 128x136x256); example perf at parity
(100.1-100.4% over 2048^3/4096^3/8192^3/8192x8192x1536, interleaved A/B,
generated CUDA identical modulo a loop variable name); maint WS benchmark
kernel source byte-identical with --verify passing and perf unchanged
(641.9 / 1310.5 / 1149.5 TF at 2048^3 / 8192^3 / 8192x8192x1536).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
