[Bug debug/103241] Odd 0 length entries in location lists

["aoliva at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103241

--- Comment #14 from Alexandre Oliva <aoliva at gcc dot gnu.org> ---
Hi, Will, Jakub, Martin,

There's nothing particularly unusual about apparently empty ranges, especially
when views are enabled, since the very point of location views is to enable
multiple states to be distinguished at the same PC.

It is a little odd that an additional location entry gets emitted for prot at
function entry.  I suppose inspection of gimple dumps will show some SSA
assignment apparently setting some prot version, and that we end up outputting
a new entry for it.  The difference between the two locations, one without and
the other with DW_OP_piece, suggests that some internal state change was
perceived between one view and the other; it might be something about
(do-nothing) promotions between the argument bindings for the prototype and the
body.

We might be able to get rid of the restatement of the binding with some more
effort.