[Bug optimization/13712] Executable runs 25% slower than when compiled with INTEL compiler

["william dot crocker at analog dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From william dot crocker at analog dot com  2004-01-29 16:27 -------
Subject: Re:  Executable runs 25% slower than when compiled with INTEL compiler

> 
> ------- Additional Comments From falk at debian dot org  2004-01-29 16:01 -------
> Thanks for the test case. I see it's using FP math heavily. Could you also
> try the options -ffast-math and -mfpmath=sse? AFAIK the Intel compiler does
> the equivalent of these switches by default so they are needed for a fair
> comparison.
>

Your email suggest that I sould put something (?) after the sse, but the 
online GCC doc does not show this.

I get this when compiling.

>/home/whc/lintel/gcc/usr_local/bin/g++ -O3 -c -Wno-deprecated -ffast-math -mfpmath=sse y.cc
cc1plus: warning: SSE instruction set disabled, using 387 arithmetics

I also tried -msse and -msse2, but got no better than 30 Seconds.

ANYWAY it runs and I get the following which now shows INTEL with only
a 22% advantage versus the previous 37%.

Bill

###### USING GCC ######

`/home/whc/lintel/gcc/usr_local/bin/g++ -v`
Reading specs from /home/whc/lintel/gcc/usr_local/lib/gcc-lib/i686-pc-linux-gnu/3.3.2/specs
Configured with: ./configure --prefix=/home/whc/lintel/gcc/usr_local --exec-prefix=/home/whc/lintel/gcc/usr_local
Thread model: posix
gcc version 3.3.2
/home/whc/lintel/gcc/usr_local/bin/g++ -O3 -c -Wno-deprecated -ffast-math -mfpmath=sse y.cc
cc1plus: warning: SSE instruction set disabled, using 387 arithmetics
ls -ls y.o
  46 -rw-r--r--    1 whc      cad         46676 Jan 29 11:05 y.o
/home/whc/lintel/gcc/usr_local/bin/g++ -O3 -o y y.o
/bin/csh -c "(setenv LD_LIBRARY_PATH /home/whc/lintel/gcc/usr_local/lib; time y)"
X422 = 469.196
30.669u 0.007s 0:31.04 98.7%	0+0k 0+0io 235pf+0w

###### USING ICC ######

/dcad/apps/intel/compiler70/ia32/bin/icc -V -c -O y.cc
Intel(R) C++ Compiler for 32-bit applications, Version 7.1   Build 20030307Z
Copyright (C) 1985-2003 Intel Corporation.  All rights reserved.

Edison Design Group C/C++ Front End, version 3.0 (Mar  8 2003 18:39:53)
Copyright 1988-2002 Edison Design Group, Inc.

ls -ls y.o
 144 -rw-r--r--    1 whc      cad        135824 Jan 29 11:06 y.o
/dcad/apps/intel/compiler70/ia32/bin/icc -o y y.o
/bin/csh -c "(setenv LD_LIBRARY_PATH /dcad/apps/intel/compiler70/ia32/lib; time y)"
X422 = 469.196
23.871u 0.011s 0:24.13 98.9%	0+0k 0+0io 178pf+0w









[whc@juno testcase]$ 


> 
> -- 
>            What    |Removed                     |Added
> ----------------------------------------------------------------------------
>   GCC build triplet|???                         |
>    GCC host triplet|DELL, Pentium4, Linux RedHat|
>                    |7.3                         |
>  GCC target triplet|???                         |i686-pc-linux-gnu
> 
> 
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13712
> 
> ------- You are receiving this mail because: -------
> You reported the bug, or are watching the reporter.
> 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13712