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Re: [OT] GCC vs Intel C++ compiler benchmark
- From: Jan Hubicka <jh at suse dot cz>
- To: Claus Fischer <claus dot fischer at clausfischer dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Mon, 28 Jan 2002 13:45:54 +0100
- Subject: Re: [OT] GCC vs Intel C++ compiler benchmark
- References: <20020127124821.A25764@clausfischer.com>
>
> The rather biased article on http://www.open-mag.com/754088105111.htm
> compares Intel's C++ favourably to GCC, without disclosing many
> enlightening details.
>
> I'm not concerned with that but with the notable OS difference
> between Linux (SuSE 7.3) and Windows (XP Pro). IMHO a CPU bound
> benchmark should see less than 1 % influence from OS and C library.
> The graphics shows roughly 7% better performance on Windows for the
> same (Intel) compiler.
>
> Are there any ABI differences which would justify such a difference?
> Register use conventions? Other stuff that you could identify?
The common purposes I've hit are:
1) 64bit floating point control word settings in windows versus 90bit in Linux.
This can make measurable difference on Athlons and P3/P4.
2) register passing conventions - they helps just slightly for Intel's compiler
as it is using them anyway in local functions.
3) better optimized memcpy/memset in windows - this plays important role
for graphics...
>
> Unfortunately the benchmark gives no details about compiler options,
> so presumably the answer is `the benchmark is flawed' and `go ask
> them'. In this case don't bother to answer.
>
> Claus
>
> --
> Claus Fischer <claus.fischer@clausfischer.com>
> http://www.clausfischer.com/