EN/NN compared the source against an uninitialized temp, usually the
previous lane's all-ones mask (a NaN), so every lane came out as NaN. NI
used a less-than compare, which is false for a NaN. TR set the bit and
then replaced it with a garbage bit from the temp. Found by
cpu/vfpu/specials.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>