On 9/3/25 1:27 PM, Sam James wrote:
Back in GCC 8, with r8-5241-g8697bf9f46f361 (-gstatement-frontiers),
r8-6658-g58006663903200, r8-6657-gbd2b9f1e2d67ec (-gvariable-location-views),
some advanced GNU extensions to DWARF were introduced and enabled by default
with the aim of improving debugging optimized code.
Unfortunately, as of yet, consumer support has't materialised in neither
GDB nor LLDB and there's no sign of any progress on those fronts. On the
GCC side, there's a large number of -fcompare-debug issues involving
-gstatement-frontiers, and some others involving -gvariable-location-views,
and there's nobody working on those at present.
And cases where statement frontiers and/or location views cause compile
time to explode.
Alexandre Oliva was the architct of the work and has recommended they
be turned off by default for the foreseeable future. Implement that.
And I believe I green-lit the effort from the Red Hat side at the time
with the expectation that the GDB effort would follow shortly after we
had the GCC bits ready. That didn't materialize for "reasons".
gcc/ChangeLog:
PR debug/99654
PR debug/104277
PR middle-end/103836
PR debug/121045
* common.opt (gvariable-location-views): Default to 0, not 1.
(gvariable-location-views=incompat5): Default to 0, not 2.
* opts.cc (finish_options): Don't default-enable
opts->x_debug_nonbind_markers_p for DWARF.
* toplev.cc (process_options): Don't default-enable
debug_variable_location_views.
gcc/testsuite/ChangeLog:
* g++.dg/debug/dwarf2/deallocator.C: Adjust test.
* gcc.dg/debug/dwarf2/inline2.c: Pass -gstatement-frontiers
-gvariable-location-views.
* gcc.dg/debug/dwarf2/inline6.c: Ditto.
---
Bootstrapped and tested on x86_64-pc-linux-gnu. OK?
I'm generally supportive. But given the nature of the change I'd like
to hear from Jakub & Richi before acking.
jeff
