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c/6346: sign extension missing after cast down and up on long long bitfield
- From: Servatius dot Brandt at fujitsu-siemens dot com
- To: gcc-gnats at gcc dot gnu dot org
- Cc: Joachim dot Canisius at fujitsu-siemens dot com, Erwin dot Unruh at fujitsu-siemens dot com, Heinrich dot Brand at fujitsu-siemens dot com
- Date: 18 Apr 2002 08:47:20 -0000
- Subject: c/6346: sign extension missing after cast down and up on long long bitfield
- Reply-to: Servatius dot Brandt at fujitsu-siemens dot com
>Number: 6346
>Category: c
>Synopsis: sign extension missing after cast down and up on long long bitfield
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Thu Apr 18 01:56:01 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Servatius.Brandt@fujitsu-siemens.com
>Release: gcc-3.0.4
>Organization:
>Environment:
sparc-sun-solaris2.8
>Description:
After converting the result of the |= operation on an
unsigned long long bitfield down to a signed char or short,
the conversion up to long long or unsigned long long forgets
the sign extension.
The problem is the same with and without optimization.
>How-To-Repeat:
gcc bug15.c && ./a.out
Output is 256, 256, 65536, 65536, -1, -1, -1, -1.
Correct output would be "-1" eigth times.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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