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Re: GCC viciously beaten by ICC in trig test!
- From: James Morrison <ja2morri at csclub dot uwaterloo dot ca>
- To: Roger Sayle <roger at eyesopen dot com>
- Cc: Scott Robert Ladd <coyote at coyotegulch dot com>, gcc at gcc dot gnu dot org
- Date: 15 Mar 2004 00:15:31 -0500
- Subject: Re: GCC viciously beaten by ICC in trig test!
- References: <Pine.LNX.4.44.0403141713460.12909-100000@www.eyesopen.com>
Roger Sayle <roger@eyesopen.com> writes:
> On Sun, 14 Mar 2004, Scott Robert Ladd wrote:
> > Consider the following program, compiled and run on a Pentium 4
> > (Northwood) system:
> >
> > #include <math.h>
>
> For a number of benchmarks, just this first line of source code above
> is enough to loose the race for GCC against Intel when compiling on Linux.
>
> Consider the following:
>
> #include <math.h>
>
> double doit(double a)
> {
> return sin(a) * sin(a);
> }
>
>
> Compiling with gcc -O2 -ffast-math on Linux generates x86 code that's
> significantly slower than Intel's compiler output. However, commenting
> out the "#include <math.h>" corrects the situation and GCC can then
> generate *exactly* the same sequence as icc.
You probably want to bring this up on libc-alpha to see if Ulrich will
remove the inline math functions then.
Jim