The root cause was a classic fixed-size epsilon issue. The code that
checked if an fcurve was effectively flat, and thus shouldn't be
normalized, used a fixed-size epsilon that was reasonable for values
close-ish to zero, but didn't work well for values >= 1.0.
This patch addresses the issue by introducing a new function
`ulp_diff_ff()` that robustly computes the number of floating point
steps between two floats, and using that to ensure that a minimum
number of representable floats exist between the min/max values
of the curve. This approach scales appropriately up and down to
both huge and tiny values.
This patch also updates the existing `compare_ff_relative()` function
to use the new robust ulps code for the ulps-based part of its
comparison, resolving an issue documented in its unit tests where
it behaved poorly for values close to zero.
Pull Request: https://projects.blender.org/blender/blender/pulls/110796
d4d0daa934