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Re: Cygnus Supported GCC vs. EGCS GCC
- To: frichard at bbn dot com
- Subject: Re: Cygnus Supported GCC vs. EGCS GCC
- From: jbuck at synopsys dot com (Joe Buck)
- Date: Tue, 14 Oct 97 9:47:37 PDT
- Cc: egcs at cygnus dot com, jvs at bbn dot com, asolomon at bbn dot com, kpowers at cygnus dot com
> I have the following question about the Cygnus Support version of GCC
> and the EGCS version on the Sun "Ultra 1 Model 170". I compiled and
> ran an optimized version of a program with the following (approximate)
> relative speed performances:
>
> COMPILER SPEED
> ===================================================================
> /opt/SUNWspro/bin/cc -fast: 1.0 (baseline)
> FSF-GCC 2.7.2 (-02): 1.4
> EGCS-GCC 971008 (-mcpu=ultrasparc -O2) 1.4
>
>
> So it appears that FSF-GCC 2.7.2 and EGCS-GCC 971008 are both about
> 40% slower than the Sun compiler when using optimzation.
No, it appears that gcc is about 40% slower than the Sun compiler on
this particular program. If the time is dominated by a single inner
loop, it's possible that a single missed optimization is the cause.
If scheduling is a problem, you might try seeing if the Haifa scheduler
does a better job.
> Does anyone know if I should I expect about the same 40% performance
> hit from the Cygnus Support version of GCC?
Unless you help solve the problem (do some profiling, help find the
cause), probably yes. (Of course with such a vague report the actual
answer is more like "Who knows?").