optimization/4875: Optimiser produces incorrect code for i386 platforms

optimization/4875: Optimiser produces incorrect code for i386 platforms

[ahelm]

>Number:         4875
>Category:       optimization
>Synopsis:       Optimiser produces incorrect code for i386 platforms
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 14 04:26:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Anton Helm
>Release:        gcc v3.0.2
>Organization:
>Environment:
gcc v3.0.2
Exactly the same behaviour using DJGPP
and Linux version.
>Description:
When running the attached program compiled with
any optimisation level greater than 0 the results
are incorrect. Hexadecimal output of the variable s
suggests that an incorrect sign extension is performed.
I.e. the 32 high bits of s are set to 1 when assigning a
positive long or long long literal to a long long variable.

The behaviour has been verified with gcc 3.0.2 on 
PC/WinNT with DJGPP and on Linux.
Both show the incorrect results.
I don't have any detailed information on the two
Linux systems used to verify the problem because I didn't
run the tests there myself. I only know that one was a 
SUSE and the other a Redhat distribution.

gcc v3.0.2 on Solaris v2.6 doesn't show this error.
>How-To-Repeat:
gcc -Wall o.c
gcc -Wall -O2 o.c

Run both executables and compare output.
>Fix:
Do not use any optimisation :-(
>Release-Note:
>Audit-Trail:
>Unformatted:
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Re: optimization/4875: Optimiser produces incorrect code for i386 platforms

[rth]

The following reply was made to PR optimization/4875; it has been noted by GNATS.

From: rth@gcc.gnu.org
To: ahelm@gmx.net, gcc-bugs@gcc.gnu.org, gcc-gnats@gcc.gnu.org,
  gcc-prs@gcc.gnu.org, rth@gcc.gnu.org
Cc:  
Subject: Re: optimization/4875: Optimiser produces incorrect code for i386 platforms
Date: 27 Nov 2001 09:07:32 -0000

 Synopsis: Optimiser produces incorrect code for i386 platforms
 
 State-Changed-From-To: analyzed->closed
 State-Changed-By: rth
 State-Changed-When: Tue Nov 27 01:07:31 2001
 State-Changed-Why:
     http://gcc.gnu.org/ml/gcc-patches/2001-11/msg01813.html
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&pr=4875&database=gcc

Re: optimization/4875: Optimiser produces incorrect code for i386 platforms

[rth]

Synopsis: Optimiser produces incorrect code for i386 platforms

State-Changed-From-To: analyzed->closed
State-Changed-By: rth
State-Changed-When: Tue Nov 27 01:07:31 2001
State-Changed-Why:
    http://gcc.gnu.org/ml/gcc-patches/2001-11/msg01813.html

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&pr=4875&database=gcc

Re: optimization/4875: Optimiser produces incorrect code for i386 platforms

[rth]

The following reply was made to PR optimization/4875; it has been noted by GNATS.

From: rth@gcc.gnu.org
To: ahelm@gmx.net, gcc-bugs@gcc.gnu.org, gcc-gnats@gcc.gnu.org,
  gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, rth@gcc.gnu.org
Cc:  
Subject: Re: optimization/4875: Optimiser produces incorrect code for i386 platforms
Date: 27 Nov 2001 01:57:25 -0000

 Synopsis: Optimiser produces incorrect code for i386 platforms
 
 Responsible-Changed-From-To: unassigned->rth
 Responsible-Changed-By: rth
 Responsible-Changed-When: Mon Nov 26 17:57:24 2001
 Responsible-Changed-Why:
     Mine.
 State-Changed-From-To: open->analyzed
 State-Changed-By: rth
 State-Changed-When: Mon Nov 26 17:57:24 2001
 State-Changed-Why:
     Test case committed as gcc.c-torture/execute/20011126-1.c;
     fix forthcoming.
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&pr=4875&database=gcc

Re: optimization/4875: Optimiser produces incorrect code for i386 platforms

[rth]

Synopsis: Optimiser produces incorrect code for i386 platforms

Responsible-Changed-From-To: unassigned->rth
Responsible-Changed-By: rth
Responsible-Changed-When: Mon Nov 26 17:57:24 2001
Responsible-Changed-Why:
    Mine.
State-Changed-From-To: open->analyzed
State-Changed-By: rth
State-Changed-When: Mon Nov 26 17:57:24 2001
State-Changed-Why:
    Test case committed as gcc.c-torture/execute/20011126-1.c;
    fix forthcoming.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&pr=4875&database=gcc