a <= abs(a) is always true

[k-arrows]

Alive2 Proof: https://alive2.llvm.org/ce/z/XD9--h
Original program: https://godbolt.org/z/aT8v6G8e9

[k-arrows]

Other missed optimizations on abs

1. abs(a) == a --> (a >= 0)
2. abs(a) == -a --> (a <= 0)

Alive2 Proof: https://alive2.llvm.org/ce/z/UaEEkb
Original program: https://godbolt.org/z/3897dn6fT

[pinskia]

I filed the GCC bug report for the full set of comparisons:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112626