Extended Description

File: Transforms/InstSimplify/compare.ll

define i1 @​gep_same_base_constant_indices(i8* %a) {
; CHECK-NEXT: ret i1 true
;
%arrayidx1 = getelementptr inbounds i8, i8* %a, i64 1
%arrayidx2 = getelementptr inbounds i8, i8* %a, i64 10
%cmp = icmp slt i8* %arrayidx1, %arrayidx2
ret i1 %cmp
}

Folding such unsigned comparisons is correct, but not for signed as an object may cross the unsigned/signed line, e.g:
ptr = malloc(42) // 0x7fff..ff0
ptr + 42 // 0x8....