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Mail Archives: djgpp/1994/03/30/03:29:15

To: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: DJGPP Speed
Date: Wed, 30 Mar 94 09:28:32 +0200
From: eliz AT is DOT elta DOT co DOT il

> preprocessed and assembler files tend to be MICH bigger than the C source
> ......  Reading and writing by cc1 CAN be a big impact.
> ......  I imagine most of the bottleneck is still in the I/O.

Whatever the size of the intermediate files (whoever is interested just how
large they are, can look in the TMPDIR with any kind of UNDELETE utility to
find out), the actual time spent in CPP and AS is still about 15% of the 
elapsed time, according to my observations.  Evidently, the I/O is *not* so
big a bottleneck.

> ... are you using 32bit or 16bit version of gcc.exe?

I used both.  The results barely changed.  Again, that disk cache must be doing
a heck of a good job.

> *shrug*  If you don't like the speed... get the source and tweak it...

I didn't say I didn't like the speed.  I'm familiar with the speed from working
on Sparc.  Do you *really* think I got into all this trouble of downloading
multi-MByte zip files just because I want a compiler faster than BCC???  Still,
I thought it would be interesting for you out there to know that a (fairly
average) 486 with no fancy disk drive/controller can deliver something close
to a Sparc2.

> ..... speed of the generated code is secondary.

Now, *that* is definitely *not* true.  GCC is famous for its superb
optimizations; e.g., on a Sparc I saw code generated by it outperform native
compilers by as much as 20% for the same program source.  Don't see why the
same should not be true for 386/486 variant.

> ... then you're probably spending too much time in the compiler and
> less time designing and verifying code.

Don't debugging and verifying mean constant recompilation?  DJ says that it
takes him less than 30 minutes to compile GCC, which is less than pizza delivery
time.  Of course, we in this remote region of ours have different schedules for
pizza delivery, but slashing that down to, say, 10 minutes makes *a lot* of
difference when developing a new version.

Bottom line: I think we should be aware of the speed of our tools.  Based on my
measurements, it seems DJ GCC does very well: I won't expect it to perform
better than the variant which runs on a Sparc.

		Eli Zaretskii.

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