[InstCombine] canonicalize "(C2 - Y) > C" as (Y + ~C2) < ~C
The test diffs show that we have better analysis/folds for 'add'
(although we should at least have the simplifications
independently, so we don't have the one-use restriction).
This is related to solving regressions that would appear in
transforms related to D111410, and that is part of a series
of enhancements that may eventually helpi solve PR34047.
https://alive2.llvm.org/ce/z/3tB9KG
define i1 @src(i8 %x, i8 %C, i8 %C2) {
%sub = sub nuw i8 %C2, %x
%r = icmp slt i8 %sub, %C
ret i1 %r
}
define i1 @tgt(i8 %x, i8 %C, i8 %C2) {
%Cnot = xor i8 %C, -1
%C2not = xor i8 %C2, -1
%add = add nuw i8 %x, %C2not
%r = icmp sgt i8 %add, %Cnot
ret i1 %r
}