* Re: GCC viciously beaten by ICC in (poorly designed) trig test!
@ 2004-03-15 18:12 Nathanael Nerode
0 siblings, 0 replies; only message in thread
From: Nathanael Nerode @ 2004-03-15 18:12 UTC (permalink / raw)
To: coyote; +Cc: gcc
Scott Robert Ladd wrote:
>Using both GCC 3.3.3 and Intel C++ 8.0, I compiled the above with these command lines:
>
>
> gcc -o sincosg -lm -std=gnu99 -O3 -march=pentium4 \
> -mfpmath=387 -ffast-math -fomit-frame-pointer sincos.c
^^^^^^^^^^^^
> icc -o sincosi -lm -O3 -xN -tpp7 -ipo sincos.c
<snip>
>Examining the generated assembler source shows that Intel eliminates the
>function call to "doit()" entirely, replacing it with inline code that
>calls internal functions such as vmldSin2 and vmldCos2,
Did you try marking doit inline?
>while it's actual
>compilation of doit() uses the SSE2 sincos instruction, whereas GCC
>generates calls to the 387 instructions fsin and fcos.
Well, duh, given the command line options.
> -mfpmath=sse
Did this change the generated assembler to use the sse instructions?
It probably should have, and if it didn't, that's probably a bug.
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2004-03-15 18:12 GCC viciously beaten by ICC in (poorly designed) trig test! Nathanael Nerode
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