I've been playing with running the testsuite with -gdwarf-5
-gsplit-dwarf and using the clang compiler. I did not find any tests
that showed the issues I was running into (but I did discover a small
bug in my patch, which my newer patch fixes).  With my fixed patch,
there are no testsuite differences.  I have created a new testsuite
test case, which does fail with current ToT and passes with my patch,
but that only works if you compile it with clang -- if you compile it
with GCC it passes in both cases (because GCC is not generating the
DW_FORM_rmglistx that my patch is handling/fixing).

I've updated the patch to include the requested format changes, remove
the pieces that are only used in an upcoming patch,  fix the small
issue I found while testing, and I've added the test to the testsuite.
To run the test and see the issue:

$  make check RUNTESTFLAGS="CC_FOR_TARGET=${CLANG_CC}
CXX_FOR_TARGET=${CLANG_CXX} dw5-rnglist-test.exp"

gdb/ChangeLog (updated)

2020-06-04  Caroline Tice  <cmtice@google.com>

        * dwarf2/read.c (struct dwop_section_names): Add rnglists_dwo.
        (dwop_section_names): Add .debug_rnglists.dwo, .zdebug_rnglists.dwo.
        (struct dwo_sections): Add rnglists field.
        (cu_debug_rnglist_section): New function (decl & definition).
        (dwarf2_locate_dwo_sections): Add code to read rnglists_dwo section.
        (dwarf2_rnglists_process): Add cases for DW_RLE_base_addressx,
        DW_RLE_startx_length, DW_RLE_startx_endx.  Also, update to only add
        the base address to DW_RLE_offset_pairs (not to all ranges).
        (dwarf2_get_pc_bounds): Check for DW_FORM_rnglistx when setting
        need_ranges_base.
        (dwarf2_record_block_ranges): Check for DW_FORM_rnglistx when setting
        need_ranges_base.
        (read_full_die_1): Add code to read DW_AT_rnglists_base and assign to
        cu->ranges_base.
        (partial_die_info::read): Check for DW_FORM_rnglistx when setting
        need_ranges_base.
        (read_rnglist_index): New function.
        (read_attribute_reprocess):  Add code for DW_FORM_rnglistx.
        (read_attribute_value): Mark DW_FORM_rnglistx with need_reprocess.

gdb/testsuite/ChangeLog:

2020-06-04  Caroline Tice  <cmtice@google.com>

        * gdb.dwarf2/dw5-rnglist-test.cc: New file.
        * gdb.dwarf2/dw5-rnglist-test.exp: New file.





On Wed, Jun 3, 2020 at 7:49 AM Tom Tromey <tom@tromey.com> wrote:
>
> Caroline> $ clang++ -gdwarf-5 -O0 -gsplit-dwarf pre-order.cpp
> Caroline> pre-order-common.cpp -o pre-order
>
> I wonder if the test suite can be run this way.
>
> Caroline> Oh.  Those get used in my next upcoming patch (where I update GDB to
> Caroline> handle DWARFv5 .dwp files).  I can either leave them in this patch, or
> Caroline> remove them from here and put them in the next one, whichever you
> Caroline> prefer.
>
> I think it's better for patches to be reasonably self-contained when
> possible.
>
> Also, there were other patches for DWARFv5 on the list in "recent" (this
> year) times.  I wonder if those are relevant / related.
>
> Tom