feat: unify attention backend with multi-dim mask support

- Add attention() functional entry delegating to active backend
- GQA/MLA forward calls attention() instead of inline cache/SDPA
- CUDA kernels support 2D/3D/4D mask via mask_h_stride field
- CudaBackend.fwd_decode builds 2D padding mask for mixed seq_lens
- KVCache.max_len precomputed in bind_tasks to avoid GPU sync
- batch==1 decode short-circuits mask=None
- Split tests into conftest, test_backend, test_backend_equivalence, test_kernel_mask
- 440 tests pass, L20 decode 1.44-1.60x speedup vs torch native
This commit is contained in:
2026-07-30 20:38:34 +08:00
parent 97114b95a4
commit 3067a8e1a6
19 changed files with 438 additions and 81 deletions
+4 -4
View File
@@ -192,8 +192,8 @@ __device__ inline void mma_softmax_tile(
int kv0,
int maxc0, int maxc1,
int qrow0, int qrow1,
int mask_b_stride, int mask_q_stride,
int mask_batch,
int mask_b_stride, int mask_h_stride, int mask_q_stride,
int mask_batch, int mask_head,
const bool* __restrict__ mask,
float Sacc[Traits::NC8][4],
float Oacc[Traits::DN8][4],
@@ -204,8 +204,8 @@ __device__ inline void mma_softmax_tile(
int tid4 = lane & 3;
float rmax0 = -FLT_MAX, rmax1 = -FLT_MAX;
int mask_base0 = mask_batch * mask_b_stride + qrow0 * mask_q_stride;
int mask_base1 = mask_batch * mask_b_stride + qrow1 * mask_q_stride;
int mask_base0 = mask_batch * mask_b_stride + mask_head * mask_h_stride + qrow0 * mask_q_stride;
int mask_base1 = mask_batch * mask_b_stride + mask_head * mask_h_stride + qrow1 * mask_q_stride;
#pragma unroll
for (int n8 = 0; n8 < Traits::NC8; n8++) {
int cc = kv0 + n8 * 8 + 2 * tid4;