[Bug rtl-optimization/99930] Failure to optimize floating point -abs(x) in nontrivial code at -O2/3

[segher at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99930

--- Comment #10 from Segher Boessenkool <segher at gcc dot gnu.org> ---
That is a USE of a constant, which is a no-op always.  Here we have a USE
of a register, which is not.  We actually have *two* uses of pseudos, and
combine cannot know what that means for the target (all PARALLELs are split
up in combine).