Lawrence Gold wrote:
> 
> On Fri, Sep 28, 2001 at 04:13:11PM +0000, Adam D. Moss wrote:
> >
> > When I get a working build I'll submit a patch for
> > appropriate makefile.unix options to Lawrence (if he
> > doesn't mind :)).
> 
> Please do.  I'm very interested in giving this compiler a try.

I spent a couple of days on this and met with success but
results were rather mixed!

Assorted notes:

* icc doesn't support the same inline asm syntax as gcc, so
we lose the inline assembly (m68k asm core is okay though).

* icc doesn't seem to like having its objects ranlib'd (at
least for the more aggressive optimisations).

* 'static __inline__' is bad in icc, so I reverted to
'static'.  Haven't tried simply 'static inline' yet.

* I just couldn't get a successful link with icc's -wp_ipo
option.  That's a shame because that's where icc's code really
starts to out-run gcc's.  -ipo is working, but isn't giving the
same sorts of wins.

* Letting icc use MMX doesn't seem to give any sort of a win.

* I'm not using an intel processor, which icc seems somewhat
geared towards.  However, I *do* see performance wins with icc
in most apps except for xmame!

Performance notes:

* Some games (irobot, cps2 games) get a 6-15% frame-rate boost.

* Some games (eprom, paperboy, smashtv) get a 5-25% frame-rate drop.

* irobot's performance in DGA1 is much poorer, despite its performance
in an X window being improved.  Odd.  Seems specific to irobot.

On the whole I'd say that more games get a drop than a boost.
Why would this be?  One reason would be the lack of inline assembly
and __inline__.  Another would be that one of icc's most interesting
optimizations (-wp_ipo) just doesn't work with xmame.  Finally,
[x]mame has simply been written very much with djpp/gcc's particular
optimization foibles in mind.

I'll submit makefile.unix patches to Lawrence anyway, so people
can experiment for themselves!

--Adam

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