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Subject: Re: intel C compiler (Which VC++ compiler options give fast chess engines? )

Author: Dann Corbit

Date: 10:37:04 03/15/01

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On March 15, 2001 at 09:26:08, martin fierz wrote:

>hi,
>
>i got the intel C compiler from www.intel.com (41MB download, free, but limited
>to 30 days of testing). After running the installation program you can use the
>intel compiler instead of the microsoft compiler with one click in the visual C
>IDE. it seems to have more optimization options than the microsoft compiler.
>
>i used it to compile my checkers program, but it made about the same kN/s with
>the same compile options. i also tried to use some advanced options (profile
>guided optimization), then i got about 5% more kN/s but the program crashed very
>often :-(
>
>does anyone else here have some experience with the intel compiler? are these
>numbers realistic? is my 5% result the best you can get, or is it too little?
>i'm running on a AMD Athlon K7 - does it matter that this is a
>non-intel-processor? or are the optimizations the compiler makes for intel
>processors also beneficial for AMD processors?

I absolutely love the Intel compiler.  On average, it does better than any other
compiler I own on the PC platform.  It won't always be faster than Microsoft
(which is a very good compiler) but most of the time it is.  On very rare
occastions, the MS compiler will emit a faster binary.  Generally speaking, I
get a speedup between 5% and 50% compared to Microsoft, and much larger compared
to Borland or GCC when using the Intel compiler.

The most helpful options are /Qip and /Qipo (you can use both at the same time).
 Also, try /Qgen_profx and do a very long profile (overnight).  Use the
generated file for both profile guided optimization and simply as a link order
file.  Quite often, the link order file will also speed up a Microsoft build.
If your integer to floating point conversions could be rounded instead of
truncated, then try /Qrcd as this sometimes gives a speedup and sometimes
produces more desirable results than simple truncation.

Try /W5 also, as this will produce a large number of very valuable diagnostics.

If your program is crashing, I suspect a programming error.  Turn the warnings
up to the highest level, and it may help to find something.



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