target/6981: wrong code in 64-bit manipulation on x86

[mattias@virtutech.se]

>Number:         6981
>Category:       target
>Synopsis:       wrong code in 64-bit manipulation on x86
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Mon Jun 10 02:56:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Mattias Engdegård
>Release:        gcc version 3.1
>Organization:
>Environment:
redhat 6.2 host (x86)
>Description:
gcc 3.1 (x86 target) generates wrong code when the attached
file is compiled with -O2. The error is in the bar() function.
The attach file also serves as a testcase, returning 0 if
the bug is present, 1 otherwise.

(What makes the problem severe is that the wrong code is
generated silently and the exact circumstances unknown, so
we are going back to 3.0.4 meanwhile.)
>How-To-Repeat:
Compile the attached file with -O2, using plain gcc 3.1 for
x86, built from source with a default configuration.
>Fix:
Use a lower optimisation level than -O2
>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="sr1.c"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="sr1.c"

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