elementwise.md

Elementwise Kernel Performance Checklist

These are empirically-backed heuristics, not hard requirements. A violation is not necessarily wrong — but should be deliberate and documented. Flag unchecked items as "needs justification", not "needs fix". See elementwise-evidence.md for reasoning and data.

Strategy (§1)

• Unary-like kernel → register_copy
• Binary broadcast → explicit_parallel
• Binary same-shape → auto-selects register_copy

Vectorization (§2)

• register_copy path uses T.alloc_fragment + T.copy
• Bool inputs packed as uint8 in Op layer

Config (§3)

• explicit_parallel npt: fp16/bf16=4, fp32=4, fp8=16
• register_copy npt: fp16/bf16=8, fp32=4, fp8=16
• autotune_configs defined for all template kernels (Unary, Binary, FusedGated): threads∈{128,256,512} × npt∈{2,4,8}; fp8: npt∈{16,32}
• All kernel classes (template and custom) cache _compiled_fn in init_config()
• Serialization-fallback autotune() override for template kernels with closure-based op_func

Code Quality (§4–§6)

• op_func uses TileLang intrinsics over manual comparison chains
• Results written in-place to input register fragment