In r257979, I added code to ensure that we wouldn't merge DebugLocEntries if the pieces they describe overlap. Unfortunately, I failed to cover the case, where there may have multiple active Expressions in the entry, in which case we need to make sure that no two values overlap before we can perform the merge.
This fixed PR26148.
Do we have to do n^2 comparisons? I vaguely remember the pieces being sorted by offset. Or was this only later?