Re: pdumping "into" the executable

[Daniel Colascione <dancol@dancol.org>]

On 12/31/1969 04:00 PM, Paul Eggert wrote:
> On 02/26/2018 01:18 PM, dancol@dancol.org wrote:
>>> Or, just turn the dump to a C file, then compile it
>>> and do a second link.  Aside from (maybe hypothetical) C compiler
>>> limits, that would be very portable.
>> But not redumpable.
> 
> Why couldn't it be redumpable? All that the user should need is a C 
> compiler. That's not unreasonable.

I thought we had this argument back when we were talking about modules. 
I think it's unacceptable to require a C compiler and the presence of 
Emacs unlinked objects for the proper operation of an end-user feature.

>> Besides, the problem with a second link is that it might change the
>> relative positions of symbols within Emac
> 
> How could that be a problem? Symbols known to C code are known by their 
> fixed offsets and the second link wouldn't change these offsets, and 
> symbols not known to C code need to be reallocated anyway during loading.

The linker is what determines into-translation-unit offsets, not the 
compiler. The offsets are patched in at link time. There's no particular 
requirement to perform the link the same way every time.