[Bug tree-optimization/126085] If a in (-CST, 1-CST), then a + CST to a == (CST + 1)

[kaelfandrew at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126085

--- Comment #4 from Kael Franco <kaelfandrew at gmail dot com> ---
(In reply to Kael Franco from comment #3)
> This PR seems to be general version of above match pattern.
> 
> (type) ([CST,CST + 1]a == CST) -> (a - CST) ^ 1
> (type) ([CST,CST + 1]a != CST) -> a - CST

And:
(type) ([CST - 1,CST]a == CST) -> (a - (CST - 1))
(type) ([CST - 1,CST]a != CST) -> (a - (CST - 1)) ^ 1