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FIX: Use Python range() in TMA warp for concrete per-iteration GMEM coords

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biondizzle
2026-05-22 18:26:31 +00:00
parent bb1d86f954
commit 3b46abdfc0
1 changed files with 8 additions and 13 deletions
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21
tests/fmha_v3_stage_c_example6.py
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@@ -207,25 +207,20 @@ class FmhaV3StageCMulti:
pipeline.pipeline_init_wait(cluster_shape_mn=cl_vmnk)
# ===== TMA LOAD warp =====
# GMEM tile coordinate: use a manual kv_coord counter.
# The induction variable from cutlass.range gets constant-folded by
# CuTeDSL's JIT — kt in tBgK[(None, kt)] bakes to 0 at runtime.
# Force the initial value to be an SSA value (not a constant literal)
# by computing zero as n_kv_tiles - n_kv_tiles. The JIT can't fold
# this because n_kv_tiles comes from cute.size() which returns an
# SSA Int32. Then kv_coord += 1 is properly tracked as iter_args
# on the underlying scf.for.
# GMEM tile coordinate: use Python range() so the JIT traces each
# iteration separately with concrete kt values. cutlass.range generates
# an scf.for where the induction variable gets constant-folded into
# the TMA descriptor (always 0 at runtime). Plain range() unrolls at
# trace time, giving each iteration a distinct static coordinate.
if warp_idx == self.tma_warp_id:
qp.reset(); qh = qp.acquire_and_advance()
cute.copy(tma_q, tAgQ[(None, Int32(0))], tAsQ[(None, qh.index)], tma_bar_ptr=qh.barrier)
qp.tail()
kvp.reset(); pk = kvp.try_acquire()
kv_coord = n_kv_tiles - n_kv_tiles # Force SSA zero (not constant-folded)
for kt in cutlass.range(0, n_kv_tiles, 1, unroll=1):
for kt in range(n_kv_tiles):
kvh = kvp.acquire_and_advance(pk)
cute.copy(tma_k, tBgK[(None, kv_coord)], tBsK[(None, kvh.index)], tma_bar_ptr=kvh.barrier)
cute.copy(tma_v, tVgV[(None, kv_coord)], tVsV[(None, kvh.index)], tma_bar_ptr=kvh.barrier)
kv_coord = kv_coord + Int32(1)
cute.copy(tma_k, tBgK[(None, Int32(kt))], tBsK[(None, kvh.index)], tma_bar_ptr=kvh.barrier)
cute.copy(tma_v, tVgV[(None, Int32(kt))], tVsV[(None, kvh.index)], tma_bar_ptr=kvh.barrier)
pk = cutlass.Boolean(1)
kvp.tail()