From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeffrey A Law <law@hurl.cygnus.com>
To: Toon Moene <toon@moene.indiv.nluug.nl>
Cc: craig@jcb-sc.com, shancock@home.com, egcs-bugs@cygnus.com
Subject: Re: optimization bug in g77 
Date: Sun, 28 Feb 1999 23:30:00 -0000
Message-id: <13398.918948431@hurl.cygnus.com>
References: <36B8C2A7.7304B9B@moene.indiv.nluug.nl>
X-SW-Source: 1999-02n/msg00415.html
List-Id: <gcc-bugs.sourceware.org>

I just tried this one with the current sources and I get the same results
with -O0, -O1, -O2, -O2 -funroll-loops on my i686 linux box.  It may be
the case that this was being mis-compiled due to the two strength reduction
bugs Joern fixed yesterday.


  In message < 36B8C2A7.7304B9B@moene.indiv.nluug.nl >you write:
  > craig@jcb-sc.com wrote:
  > 
  > > Could you be more specific about just what the bug is?  We aren't
  > > normally able to try to debug other peoples' programs, assuming that
  > > the bug will turn out to be in the compiler.  (We do it on occasion,
  > > though.)
  > 
  > I've downsized the code a bit :-)
  > 
  >       program wrbug
  >       common/buf3d/id3d(10,1)
  >       do j=1,10
  >         id3d(j,1) = j
  >       enddo
  >       call wr3d
  >       end
  >       subroutine wr3d
  >       integer ip(10)
  >       integer irec(5,1)                                               
  >       common/buf3d/id3d(10,1)
  >       common/temp2/i1,i2,i3,i4,i5,i6,i7,i8,i9,i10
  >       equivalence (i1,ip)
  >       n = 1
  > c     do 100 n=1,1
  >          do 10 j=1,10
  >             ip(j)=id3d(j,n)
  >    10    continue
  >          irec(1,n)=or(i1,lshift(i2,16))
  >          irec(2,n)=or(i3,lshift(i4,16))
  >          irec(3,n)=or(i5,lshift(i6,16))
  >          irec(4,n)=or(i7,lshift(i8,16))
  >          irec(5,n)=or(i9,lshift(i10,16))
  > c 100 continue
  >       print*,irec
  >       return
  >       end
  > 
  > This code works when compiled with option -O using:
  > 
  > [toon@moene g77-bugs]$ g77 -v
  > g77 version egcs-2.91.59 19981124 (egcs-1.1.1 pre-release #3) (from
  > FSF-g77 version 0.5.24-19980804)
  > Driving: g77 -v -c -xf77-version /dev/null -xnone
  > Reading specs from
  > /usr/local/lib/gcc-lib/i686-pc-linux-gnu/egcs-2.91.59/specs
  > gcc version egcs-2.91.59 19981124 (egcs-1.1.1 pre-release #3)
  > 
  > If you remove the two comment `c`s and thereby enable the outer loop,
  > the final print statement will print 5 zero's, which definitely is not
  > TRTTD.
  > 
  > However,
  > 
  > [toon@moene g77-bugs]$ /usr/snp/bin/g77 -v
  > g77 version egcs-2.93.04 19990203 (gcc2 ss-980929 experimental) (from
  > FSF-g77 version 0.5.24-19980804)
  > Driving: /usr/snp/bin/g77 -v -c -xf77-version /dev/null -xnone
  > Reading specs from
  > /usr/snp/lib/gcc-lib/i686-pc-linux-gnu/egcs-2.93.04/specs
  > gcc version egcs-2.93.04 19990203 (gcc2 ss-980929 experimental)
  > 
  > gives the correct answers.
  > 
  > HTH,
  > 
  > -- 
  > Toon Moene (toon@moene.indiv.nluug.nl)
  > Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
  > Phone: +31 346 214290; Fax: +31 346 214286
g77 Support: fortran@gnu.org; egcs: egcs-bugs@cygnus.com