Hi all,

I request you all to please review the patch. Below are the details.

Problem Description:
GDB produces internal error while processing DW_FORM_loclistx / DW_FORM_rnglistx,
$ make check RUNTESTFLAGS="CXX_FOR_TARGET=/path/to/clang++ " TEST=gdb.dwarf2/dw5-rnglist-test.exp
Below is the snippet from gdb.log file.
---------
(gdb) file /dir/gdb/testsuite/outputs/gdb.dwarf2/dw5-rnglist-test/dw5-rnglist-test
Reading symbols from /dir/gdb/testsuite/outputs/gdb.dwarf2/dw5-rnglist-test/dw5-rnglist-test...
gdb/dwarf2/attribute.h:232: internal-error: void attribute::set_unsigned_reprocess(ULONGEST): Assertion `form_requires_reprocessing ()' failed.
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) ERROR: Couldn't load dw5-rnglist-test into GDB (GDB internal error).
Resyncing due to internal error.
---------
This is due to incomplete handling of DW_FORM_loclistx / DW_FORM_rnglistx,
which is available with -gdwarf-5 option for clang compiler.
Resolution:
Forms DW_FORM_loclistx / DW_FORM_rnglistx need two phases of processing.
The required modifications in various routines are added to fix the issue.

gdb/ChangeLog:

2021-01-21  Alok Kumar Sharma  <AlokKumar.Sharma@amd.com>

        * dwarf2/attribute.c (form_is_unsigned): Handle DW_FORM_loclistx.
        (form_requires_reprocessing): Handle DW_FORM_loclistx and
        DW_FORM_rnglistx.
        * dwarf2/attribute.h (set_address): Handle DW_FORM_loclistx and
        DW_FORM_rnglistx.
        * dwarf2/read.c (read_attribute_reprocess): Replaced as_unsigned with
        as_unsigned_reprocess for DW_FORM_loclistx and DW_FORM_rnglistx.

Regards,
Alok