[ was: Re: [RFC] Allow parallel multifile with -p -e ]

On 3/26/21 5:47 PM, Jakub Jelinek wrote:
> On Fri, Mar 26, 2021 at 05:40:51PM +0100, Tom de Vries wrote:
>> The temporary multifile section contributions happen in random
>> order, so consequently the multifile layout will be different, and the
>> files referring to the multifile will be different.
> 
> What I meant is that each fork should use different temporary filenames
> for the multifiles, once all childs are done, merge them (depends on how
> exactly is the work distributed among the forks, if e.g. for 4 forks
> first fork gets first quarter of files, second second quarter etc., then
> just merge them in the order, otherwise more work would be needed to make
> the merging reproduceable.

I tried this approach for a bit, but this unfortunately doesn't work
verify easily.  The temp multifile contributions can contain
DW_FORM_ref_addr refs. If we concatenate different temp multifiles, we
invalidate those refs, and they need to be fixed up when reading them
in, which is cumbersome and errorprone.

So I've gone the more conservative way: serialize multifile contribution.

Any comments?

Thanks,
- Tom