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Re: Unit at time compilation mode III

> On Wednesday, Feb 12, 2003, at 11:40 America/New_York, Richard Earnshaw 
> wrote:
> > It's true that unit-at-once could be interpreted to mean multiple 
> > files.
> > But if we enabled that, surely we'd want a separate flag for that to
> > distinguish it over doing whole files at once.  I can imagine people 
> > being
> > concerned about memory usage in the case where we allowed multiple 
> > files.
> Unit-at-once seems the right term. In particular, when Ada will use 
> this,
> a compilation may include many files for generics (=templates), 
> sub-units etc.
> Similarly, when you would use #include files in your C program, a single
> compilation would also compile multiple files.

Both of these are what I really think of as file-at-once.

unit-at-once (or inter-file) is more what I would expect to happen if the 
user specified

gcc -Oxxx -finter-file a.c b.c c.c d.c

etc.  The compiler can then do inter-file optimizations between all the .c 
files on the command line.  If we can see entire subtrees of the 
call-graph then we can do significantly more powerful optimizations, and 
particularly get a better idea of what aliasing or other memory updates 
may be involved.


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