On Monday, 11 May 2015 at 15:32:47 UTC, Benjamin Thaut wrote:
On Monday, 11 May 2015 at 14:57:46 UTC, Marco Leise wrote:
Is that what would happen?
Yes, that's exactly what would happen. You could go one step
further and not do it for all symbols, instead you make the
compiler emit a additional section with references to all
relevant data symbols. Then you only do the patching operation
on the data symbols and leave all other symbols as is. This
would greatly reduce the number of symbols that require
patching.
The exepcted data set size should be significantly smaller then
on linux. Because currently on linux D simply exports all
symbols. Which means that the linux loader does this patching
for all symbols. On windows only symbols with the "export"
protection level get exported. That means the set of symbols
this patching has to be done for is a lot smaller to begin
with. The additional optimization would reduce the number of
symbols to patch once again. So even if the custom
implementation is vastly inferior to what the linux loader does
(which I don't think it will be) it still should be fast enough
to not influence program startup time a lot.
Just as info, Windows is not alone.
There are a few other systems that follow the same process.
For example, Aix used to be Windows like and nowadays it has a
mix of ELF and Windows modes.
http://www.ibm.com/developerworks/aix/library/au-aix-symbol-visibility/
Symbian although dead, also used the Windows approach if I
remember correctly.
I expect other non-POSIX OSes not to follow the ELF way.
--
Paulo
