whetstone benchmark intel C++ 12.0 versus gcc 4.5.1 on openSUSE 11.4 M5 64 Bit i7-950

whetstone benchmark intel C++ 12.0 versus gcc 4.5.1 on openSUSE 11.4 M5 64 Bit i7-950

Hi,

i have recompile the whetstone benchmark with icc 12.0 and with the gcc 4.5.1 all under openSUSE 11.4 M5 64 Bit
with an Intel i7-950 on ASUS Sabertooth X58 4.0 Ghz

the compile options for booth compilers the same:

-O3 -m64 -fast (or -ffast-math on gcc )

the result:

gcc 4.5.1 62500.0 MIPS ( or 61.0351 GFlops /sec )

icc 12.0 50000.0 MIPS (or 48.8281 GFlops /sec )

with other testprograms : the NIST scimark2

gcc 4.5.1 composite score: 1167.10
icc 12.0 composite score: 1663.45

why this difference ?, on whetstone the gcc are appr. 37 % faster than the icc 12.0
on scimark the icc appr 47 % faster than the gcc 4.5.1
i have nothing change on the sourcecode.

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