Re: [PATCH 2/2] Test case reproducing PR28030 bug

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2021-09-01 12:20 p.m., Kevin Buettner wrote:
> On Wed, 1 Sep 2021 09:35:09 -0400
> Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> wrote:
> 
>> Thanks for the test case.  The comments are very nice, it would be very
>> hard to understand without them.  They also communicate the intentions
>> well, that will be useful if someone needs to debug it in the future.
>>
>>>  gdb/testsuite/gdb.dwarf2/locexpr-dml-lib.c  |  48 +++
>>>  gdb/testsuite/gdb.dwarf2/locexpr-dml-main.c |  27 ++
>>>  gdb/testsuite/gdb.dwarf2/locexpr-dml.exp    | 360 ++++++++++++++++++++
>>>  gdb/testsuite/gdb.dwarf2/locexpr-dml.h      |  30 ++  
>>
>> What does "dml" stand for?
> 
> data member location, since the use of DW_AT_data_member_location was
> one (of several) key elements needed to reproduce the bug.
> 
> I'll make a note of the meaning of dml early in the file. If someone
> can think of a better name for this test case, I'll use that instead.

I would just spell it out (locexpr-data-member-location.exp).

>>> +# Compile the shared library: -DIS_SHAREDLIB prevents main() from
>>> +# being defined.  Note that debugging symbols will be present for
>>> +# this compilation.
>>> +if {[gdb_compile_shlib $libsrc $lib_so \
>>> +                       {additional_flags=-DIS_SHAREDLIB debug}] != ""} {
>>> +    untested "failed to compile shared library"
>>> +    return
>>> +}  
>>
>> I don't understand when $libsrc is compiled without -DIS_SHAREDLIB.
> 
> I call get_func_info in this test case.  It calls function_range. 
> which in turn calls gdb_compile.  It's compiled without -DIS_SHAREDLIB
> whenever get_func_info is called.
> 
> I'll find some place to mention this fact in one of the comments.

Ah, I see, thanks.  Hopefully compiling with and without the main
doesn't change the addresses of the functions you are getting info
for.

It would take a bit of cleanup before hand, but ideally the
function_range proc would be able to compile shared libraries, or work
on an already built binary.

Simon