Re: GCC viciously beaten by ICC in trig test!

[James Morrison <ja2morri@csclub.uwaterloo.ca>]

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