Re: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

Re: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

[giovannibajo]

Synopsis: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

State-Changed-From-To: open->feedback
State-Changed-By: bajo
State-Changed-When: Wed May 14 10:26:29 2003
State-Changed-Why:
    See Dara's question.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8474

Re: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

[ehrhardt]

Synopsis: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

State-Changed-From-To: feedback->open
State-Changed-By: cae
State-Changed-When: Wed May 21 09:28:53 2003
State-Changed-Why:
    Feedback received.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8474

RE: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

[Dara Hazeghi]

The following reply was made to PR optimization/8474; it has been noted by GNATS.

From: Dara Hazeghi <dhazeghi@yahoo.com>
To: Dave <davejf@starband.net>
Cc: gcc-gnats@gcc.gnu.org
Subject: RE: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine
Date: Mon, 19 May 2003 17:38:50 -0700 (PDT)

 --- Dave <davejf@starband.net> wrote:
 > New results are attached - sorry for the delay (been
 > busy lately).
 
 No problem. It doesn't look like the problem is
 solved, so I guess we'll leave the PR open, and hope
 somebody notices it...
 
 Thanks for your feedback,
 
 Dara
 
 > 
 > These were run on Red Hat 9 (I installed that rather
 > than Mandrake v9.1)
 > rather than the original RH 8 system.
 > 
 > Doesn't seem to be any improvement for P4 or with
 > gcc 3.4.
 > 
 > - Dave
 > 
 > On Wed, 2003-05-14 at 19:43, Dara Hazeghi wrote:
 > > Doh, I forgot to statically link the 3.4 ones (new
 > > version of libstdc++). Just a sec...
 > > 
 > > Here, I statically linked them (the 3.4 ones) this
 > > time.
 > > 
 > > Dara
 > > 
 > whetstone took: 1.05 secs for 952 MFLOPS (w/  math
 > lib)
 > whetstone took: 0.39 secs for 2564 MFLOPS (w/o math
 > lib)
 > 
 > whet33p4
 > whetstone took: 1.04 secs for 962 MFLOPS (w/  math
 > lib)
 > whetstone took: 0.40 secs for 2500 MFLOPS (w/o math
 > lib)
 > 
 > whet34p3
 > whetstone took: 1.05 secs for 952 MFLOPS (w/  math
 > lib)
 > whetstone took: 0.40 secs for 2500 MFLOPS (w/o math
 > lib)
 > 
 > whet34p4
 > whetstone took: 1.06 secs for 943 MFLOPS (w/  math
 > lib)
 > whetstone took: 0.39 secs for 2564 MFLOPS (w/o math
 > lib)
 > 
 > 
 
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Re: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine

[Dara Hazeghi]

The following reply was made to PR optimization/8474; it has been noted by GNATS.

From: Dara Hazeghi <dhazeghi@yahoo.com>
To: gcc-gnats@gcc.gnu.org, davejf@starband.net
Cc:  
Subject: Re: optimization/8474: -mcpu=i686 produces much faster code than -mcpu=pentium4 on a P4 machine
Date: Tue, 13 May 2003 11:41:24 -0700

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit- 
 trail&database=gcc&pr=8474
 
 Hello,
 
 would it be possible for you to check whether this is still the case  
 with gcc 3.3 prerelease? IIRC, Jan Hubricka and others have done a fair  
 bit of work to ensure that P-IV optimized code is as good as or better  
 than i686 code. Alternatively, if you can't build 3.3, can I send you  
 P-IV optimized binaries of your testcase, and see if the problem is  
 still there? Thanks,
 
 Dara