Re: Link-time optimzation

[Bernd Schmidt <bernds_cb1 at t-online dot de>]

Daniel Jacobowitz wrote:
> On Thu, Nov 17, 2005 at 03:42:29PM -0800, Ian Lance Taylor wrote:
>
> > I just tried a simple unoptimized compile.  -ftime-report said that
> > final took 5% of the time (obviously final does more than formatting),
> > and the assembler took 4% of the total user time, and system time took
> > 16% of wall clock time.  Cutting those numbers in half makes 1% seem
> > not implausible to me, maybe even low.
> >
> > I'm considering an unoptimized compile because that is where the
> > assembler makes the most difference--the compiler is faster and the
> > assembler output probably tends to be longer, and also an unoptimized
> > compile is when people care most about speed.  For an optimizing
> > compile, the assembler is obviously going to be less of a factor.
>
>
> Also, please keep in mind that generating and then assembling debug
> info takes a huge amount of I/O relative to code size.  I'd expect much
> more than 1% saving the write-out and write-in on -g.

So, maybe a simpler strategy could be to make minor modifications to gas 
and gcc so that the former is linked in and the latter can pass strings 
to it?  Maybe that could get us a performance improvement without the 
need for a massive overhaul of all backends, and the need to duplicate 
object code generation.


Bernd