[PATCH] gdb: add build mode to reverse order of _initialize function calls

[Simon Marchi]

On 2021-05-17 3:26 p.m., Andrew Burgess wrote:
> * Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> [2021-05-17 14:00:03 -0400]:
> 
>> We should not assume any order in which the _initialize functions get
>> called.  However, since their order comes from the order of source files
>> baked into the Makefile, it's possible for such dependencies to creep in
>> and for us not to notice.
>>
>> I think that a good way to test for such dependencies is to reverse the
>> order of the calls.  Add an option in the Makefile to do this.  It can
>> be used as:
>>
>>   $ make REVERSE_INIT_FILES=1
>>
>> before init.c gets generated (if you want to re-generate init.c, either
>> do a "make clean" or remove stamp-init).
> 
> Instead of making this a build option, did you consider modifying
> initialize_all_files to something like this totally untested code:
> 
>   void
>   initialize_all_files (bool reverse_p)
>   {
>     std::vector<void (*) (void)> func = {
>       _initialize_arc_linux_tdep,
>       _initialize_arc_tdep,
>       _initialize_arm_fbsd_tdep,
>       _initialize_arm_linux_tdep,
>       _initialize_arm_netbsd_tdep,
>       _initialize_armobsd_tdep,
>       ... etc ...
>    };
> 
>    if (reverse_p)
>      std::reverse(func.begin(), func.end());
> 
>    for (auto f : func)
>      f ();
>   }
> 
> then all you'd need is to add a new command line flag which controls
> reverse_p.
> 
> The benefit as I see it is that (a) we can add a test that is run in
> every run of the testsuite that starts GDB with this new command line
> flag, and does a few basic tests, and (b) we can easily pass the new
> command line flag to the testsuite from the command line, and so run
> _all_ tests with the reverse init order.
> 
> Just a thought.

That sounds much better indeed!

I'll give it a shot eventually.

Simon