Path: utzoo!attcan!uunet!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!mips!gumby!lilian
From: lilian@mips.COM (Lilian Leung)
Newsgroups: comp.sys.mips
Subject: Re: f77 bug
Message-ID: <35353@mips.mips.COM>
Date: 1 Feb 90 21:47:41 GMT
References: <1990Feb1.170639.15889@sobmips.UUCP>
Sender: news@mips.COM
Reply-To: lilian@mips.COM (Lilian Leung)
Organization: MIPS Computer Systems, Sunnyvale, CA
Lines: 136

In article <1990Feb1.170639.15889@sobmips.UUCP> laporte@sobmips.UUCP (p.laporte) writes:
>We have found what we think is a bug in the fortran compiler (version 2.0)
>
>Here is a small program that demonstrate the problem. When we use the 
>optimiser we get incorrect results when doing a simple addition.
>
>Maybee someone at mips could tell me if they were aware of this bug and
>if there is a patch for it.
>
>Tks
>
>-----
>      implicit double precision(a-h, o-z)
>      
>      common ia,r(12),tb
>      data tb  / 0.02d0 /
>      r(4) = 4.0
>      r(5) = 1.0
>      r(6) = 2.0
>      r(7) = 3.0
>      write (*,10) r(4),r(5),r(6),r(7)
>      r1  = r(5)+r(6)
>      r2  = r(5)+r(7)
>      r3  = r(5)+r(6)+r(7)
>      write(*,20) r1, r2,r3
>      write(*,20) r(5)+r(6),r(5)+r(7),r(5)+r(6)+r(7)
>10    format ( " R(4)=",F8.5 "   R(5)=",F8.5  "   R(6)=",F8.5  
>     1    "   R(7)=",F8.5 //)
>20    format ( " R(5)+R(6)=", F8.5/ " R(5)+R(7)=",F8.5/ 
>     1    " R(5)+R(6)+R(7)=",F8.5 // )
>      stop
>      end      
>
>--------------------------------------------------
>          without any option
> R(4)= 4.00000   R(5)= 2.00000   R(6)= 0.00000   R(7)= 3.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
>--------------------------------------------------
>          with -O0 option
> R(4)= 4.00000   R(5)= 1.00000   R(6)= 2.00000   R(7)= 3.00000
>
>
> R(5)+R(6)= 3.00000
> R(5)+R(7)= 4.00000
> R(5)+R(6)+R(7)= 6.00000
>
>
> R(5)+R(6)= 3.00000
> R(5)+R(7)= 4.00000
> R(5)+R(6)+R(7)= 6.00000
>
>
>--------------------------------------------------
>          with -O1 option
> R(4)= 4.00000   R(5)= 2.00000   R(6)= 0.00000   R(7)= 3.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
>--------------------------------------------------
>          with -O2 option
> R(4)= 4.00000   R(5)= 2.00000   R(6)= 0.00000   R(7)= 3.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
>--------------------------------------------------
>          with -O3 option
> R(4)= 4.00000   R(5)= 2.00000   R(6)= 0.00000   R(7)= 3.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
> R(5)+R(6)= 4.00000
> R(5)+R(7)= 5.00000
> R(5)+R(6)+R(7)= 7.00000
>
>
>--------------------------------------------------
>          with -O0 and -g options
> R(4)= 4.00000   R(5)= 1.00000   R(6)= 2.00000   R(7)= 3.00000
>
>
> R(5)+R(6)= 3.00000
> R(5)+R(7)= 4.00000
> R(5)+R(6)+R(7)= 6.00000
>
>
> R(5)+R(6)= 3.00000
> R(5)+R(7)= 4.00000
> R(5)+R(6)+R(7)= 6.00000
>
>
>Pierre Laporte
>{attcan,mcgill-vision,telly}!sobeco!laporte



This is a verified bug under our version 2.0 FORTRAN compiler.  It has
been fixed in our 2.10 version.


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