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* [Bug c/28195] New: << (shift operator) does rotate operation
@ 2006-06-28 17:57 tetsuji dot rai at gmail dot com
2006-06-28 18:02 ` [Bug c/28195] " falk at debian dot org
2006-06-29 9:02 ` tetsuji dot rai at gmail dot com
0 siblings, 2 replies; 3+ messages in thread
From: tetsuji dot rai at gmail dot com @ 2006-06-28 17:57 UTC (permalink / raw)
To: gcc-bugs
When shift count is the same as the length of a variable (eg, l << 32 where
long int l;), this doesn't return 0, instead it returns a rotated value.
Below is assumed to return 0, but actually returns 2468.
---t2.c---(test case)
#include <stdio.h>
long long ll;
long l;
int
main(){
l = 1234;
ll = l << 33;
printf("%lld\n", ll);
return 0;
}
--------------------
--
Summary: << (shift operator) does rotate operation
Product: gcc
Version: 3.4.6
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tetsuji dot rai at gmail dot com
GCC build triplet: ia32 Gentoo Linux
GCC host triplet: ia32 Gentoo Linux
GCC target triplet: ia32 Gentoo Linux
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28195
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/28195] << (shift operator) does rotate operation
2006-06-28 17:57 [Bug c/28195] New: << (shift operator) does rotate operation tetsuji dot rai at gmail dot com
@ 2006-06-28 18:02 ` falk at debian dot org
2006-06-29 9:02 ` tetsuji dot rai at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: falk at debian dot org @ 2006-06-28 18:02 UTC (permalink / raw)
To: gcc-bugs
------- Comment #1 from falk at debian dot org 2006-06-28 17:57 -------
Shifting by an amount larger than the size of a type is undefined behavior,
so anything might happen. Gcc even warns about this.
--
falk at debian dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |RESOLVED
Resolution| |INVALID
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28195
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug c/28195] << (shift operator) does rotate operation
2006-06-28 17:57 [Bug c/28195] New: << (shift operator) does rotate operation tetsuji dot rai at gmail dot com
2006-06-28 18:02 ` [Bug c/28195] " falk at debian dot org
@ 2006-06-29 9:02 ` tetsuji dot rai at gmail dot com
1 sibling, 0 replies; 3+ messages in thread
From: tetsuji dot rai at gmail dot com @ 2006-06-29 9:02 UTC (permalink / raw)
To: gcc-bugs
------- Comment #2 from tetsuji dot rai at gmail dot com 2006-06-29 07:30 -------
sorry and thanks. my mistake.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28195
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2006-06-29 7:30 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2006-06-28 17:57 [Bug c/28195] New: << (shift operator) does rotate operation tetsuji dot rai at gmail dot com
2006-06-28 18:02 ` [Bug c/28195] " falk at debian dot org
2006-06-29 9:02 ` tetsuji dot rai at gmail dot com
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