ValueTracking attempts to match compare+select patterns to FP min/max operations, but it was created before the newer IEEE-754-2019 minimum/maximum ops were defined. Ie, matchSelectPattern() does not account for the -0.0/+0.0 behavior that is specified in the newer standard.
FMINIMUM/FMAXIMUM nodes were created to map to the newer standard:
/// FMINIMUM/FMAXIMUM - NaN-propagating minimum/maximum that also treat -0.0 /// as less than 0.0. While FMINNUM_IEEE/FMAXNUM_IEEE follow IEEE 754-2008 /// semantics, FMINIMUM/FMAXIMUM follow IEEE 754-2018 draft semantics.
We could adjust ValueTracking to deal with signed zero, but it seems like a moot point given the divergent NaN behavior discussed in D143056, so just delete this possibility to avoid bugs when converting IR to SDAG.