Re: GCC beaten by ICC in stupid trig test!

[Scott Robert Ladd <coyote at coyotegulch dot com>]

David Edelsohn wrote:
> 	What about the more general question of what type of customer uses
> ICC versus other compilers?  Are numericists using ICC?  Is GCC implicitly
> changing strategy with this proposal?

I know several types of customers (mine) who are using ICC in preference 
to GCC:

1) The developer of a real-time video codec, where Intel's C compiler 
produces code that is 15% faster than what is emitted from GCC.

2) A scientific institution writing C and Fortran 95 code for 
multiprocessor workstations, where they need/want OpenMP. Intel has 
OpenMP, GCC doesn't (we're working on it).

3) People who need a complete Fortran 95 (which Intel sells), but who 
don't want to spring for a commercial compiler. Note that Intel's 
Fortran 95 has some rough edges; if people can pay, they generally go 
for Absoft, PGI, or Lahey's products. I use Lahey myself.

Among people who *don't* use the Intel compiler are those who use other 
types of processors (including Opteron, since Intel turns off it's best 
optimizations on non-Intel processors). On my Opteron box, for example, 
gfortran is my only choice for a 64-bit hosted/64-bit generative Fortran 
95 compiler.

For Pentium 3 and 4, I find that Intel produces faster code on most 
numerical applications; I have seen little or not effect on accuracy. 
Again, this is why we need a *real* accuracy benchmark, so we can 
produce empirical data for understanding the trade-off between 
performance and accuracy.

--
Scott Robert Ladd
Coyote Gulch Productions (http://www.coyotegulch.com)
Software Invention for High-Performance Computing