[PATCH 1/5] Don't enable -gvariable-location-views by default for DWARF5.

Alexandre Oliva oliva@adacore.com
Tue Aug 25 04:05:12 GMT 2020

On Aug 24, 2020, Jakub Jelinek <jakub@redhat.com> wrote:

> On Mon, Aug 24, 2020 at 02:56:54PM +0200, Mark Wielaard wrote:
>> DWARF5 makes it possible to read loclists tables without consulting
>> the debuginfo tree by introducing a table header. Adding location views
>> breaks this (at least for binutils and elfutils). So don't enable
>> variable-location-views by default if DWARF5 or higher is selected.

> This should be discussed with Alex, CCed.
> I'd say elfutils/binutils should just show .debug_loclists independent of
> .debug_info if there are no loc views and use .debug_info otherwise.

I've suggested before that it made sense to me to start emitting
locviews when there were concrete plans to implement support for them in
debug info consumers.

Without such plans, it would make more sense to just disable them

Now, if there are any such plans, it is disabling them for the default
debug format that doesn't make much sense to me; it would seem to make
more sense to adopt and promote the proposed extension, implemented in
=incompat5 in GCC, but it would need some implementation work in
consumers to at least ignore the extension.

Red Hat has had me involved in these efforts for over a decade, but I'm
not aware of its plans any more, and I don't know of anyone else driving
the implementation of locviews in consumers, so, given the little I
know, this patch seems like a timid step in a reasonable direction:
outputting locviews is no use if there are no consumers for it, more so
when they actively disturb existing standard-compliant consumers.

Alexandre Oliva, happy hacker
Free Software Activist
GNU Toolchain Engineer

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