Function exec_of 

pub fn exec_of(device: &Device, weight: Format, activation: Format) -> Exec

2026-09-30: How device executes a node of weight reading activation. NVFP4 weights under FP8 activations (W4A8 with group-16 E4M3 scales) have no single-instruction MMA on any device unless native_mma says so (fp4_fp8_nvfp4_scaled); they take the exact E4M3 path.