Fix regression on MI300 caused by Async LDS optimization for MI350#156
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aryaman-gupta wants to merge 2 commits into
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Fix regression on MI300 caused by Async LDS optimization for MI350#156aryaman-gupta wants to merge 2 commits into
aryaman-gupta wants to merge 2 commits into
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cp_async_zfill_cg is async on Ampere+ and gfx950 but synchronous elsewhere. Inlining the sync fallback into the per-iteration row-load loop kills load pipelining (load->store dependency forces N waitcnts instead of one) and adds wave divergence on mixed-validity warps. Measured up to -19% BW on MI300 (gfx942) for weighted L=20/L=50. Wrap the row-store section in a #if matching the helper's dispatch: gfx950/Ampere keep the fused cp_async_zfill_cg loop; everything else gets the original two-loop pattern (load all -> masked store). Helper and gfx950 paths untouched. Co-Authored-By: Claude Opus 4 (1M context) <noreply@anthropic.com>
…ents about pipelining of memory ops
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