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Re: Unit at time compilation mode III
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Geert Bosch <bosch at gnat dot com>
- Cc: Richard dot Earnshaw at arm dot com, Jan Hubicka <jh at suse dot cz>, Fergus Henderson <fjh at cs dot mu dot oz dot au>, Richard Henderson <rth at redhat dot com>, Zack Weinberg <zack at codesourcery dot com>, gcc-patches at gcc dot gnu dot org
- Date: Thu, 13 Feb 2003 13:42:20 +0000
- Subject: Re: Unit at time compilation mode III
- Organization: ARM Ltd.
- Reply-to: Richard dot Earnshaw at arm dot com
>
> On Thursday, Feb 13, 2003, at 04:49 America/New_York, Richard Earnshaw
> wrote:
> > 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
>
> But what here is the unit? Mostly people refer to compilation unit
> as the smallest amount of code that can be compiled in a single
> compilation. In the usual C compilation environment this would
> result in one object file. The example you are giving is inter-unit
> optimization.
>
Precisely why I'm not keen on "unit-at-once" -- it's not clear what the
"unit" is.
> Basically we have
> - function-at-once intra-function optimization
> - unit-at-once inter-function, intra-unit optimization
> - all-at-once inter-unit optimization
>
Or
- function-at-once intra-function optimization
- file-at-once optimize over everything in the "file"
- all-at-once optimize over all files on the command line
R.