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Re: induct regression in gcc 4.3.1

From: Jack Howarth <howarth at bromo dot msbb dot uc dot edu>
To: fortran at gcc dot gnu dot org
Date: Sun, 22 Jun 2008 12:35:17 -0400
Subject: Re: induct regression in gcc 4.3.1
References: <20080621000141.GA25884@bromo.msbb.uc.edu> <485B71C7.1030909@sbcglobal.net> <20080621070035.GA28156@bromo.msbb.uc.edu> <93BA8017-6E17-4238-A848-F35F66EAD335@sandoe-acoustics.co.uk>

     While generating .s files for induct.f90, I discovered that
when I compile...

gfortran -fassociative-math -fno-signed-zeros -O3 induct.f90

or

gfortran -fassociative-math -fno-trapping-math -O3 induct.f90

I get the warning...

f951: warning: -fassociative-math disabled; other options take precedence

Only...

gfortran -fassociative-math -fno-signed-zeros -fno-trapping-math -O3 induct.f90

inhibits this message. This strongly suggests that the -fassociative-math 
(which is only active in concert with -fno-signed-zeros -fno-trapping-math)
is the cause of the performance regression in the code generated for
induct.f90 for gcc 4.3.1 on Macintel.
                     Jack

Follow-Ups:
- Re: induct regression in gcc 4.3.1
  - From: Tim Prince

References:
- induct regression in gcc 4.3.1
  - From: Jack Howarth
- Re: induct regression in gcc 4.3.1
  - From: Tim Prince
- Re: induct regression in gcc 4.3.1
  - From: Jack Howarth
- Re: induct regression in gcc 4.3.1
  - From: IainS

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