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* [Bug optimization/14299] New: Improperly derefences pointers with casting
@ 2004-02-25 20:20 dmeggy at techsol dot ca
  2004-02-25 20:22 ` [Bug optimization/14299] " falk at debian dot org
                   ` (2 more replies)
  0 siblings, 3 replies; 4+ messages in thread
From: dmeggy at techsol dot ca @ 2004-02-25 20:20 UTC (permalink / raw)
  To: gcc-bugs

Here is an example

<snip>
typedef struct
{
        unsigned first  : 6;
        unsigned second : 1;
        unsigned third  : 1;
        unsigned fourth : 1;
        unsigned fifth  : 1;
        unsigned sixth  : 1;
        unsigned unused : 21;
} TestStruct;

int func() {
        TestStruct a;
        TestStruct *b;

        a.first = 4;
        b = (TestStruct *)(&a);

        return b->first;
}

int func2() {
        int a;
        TestStruct *b;

        a = 4;
        b = (TestStruct *)(&a);

        return b->first;
}
</snip>

func() will work, and func2() won't, called as "arm-linux-gcc test2.c -Os -g -c"

func2 will never set the value of a to 4

-- 
           Summary: Improperly derefences pointers with casting
           Product: gcc
           Version: 3.3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dmeggy at techsol dot ca
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-linux
  GCC host triplet: i386-linux
GCC target triplet: arm-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14299


^ permalink raw reply	[flat|nested] 4+ messages in thread
* [Bug optimization/14299] Improperly derefences pointers with casting
  2004-02-25 20:20 [Bug optimization/14299] New: Improperly derefences pointers with casting dmeggy at techsol dot ca
@ 2004-02-25 20:22 ` falk at debian dot org
  2005-06-05  8:40 ` [Bug rtl-optimization/14299] " pinskia at gcc dot gnu dot org
  2005-06-05  8:40 ` pinskia at gcc dot gnu dot org
  2 siblings, 0 replies; 4+ messages in thread
From: falk at debian dot org @ 2004-02-25 20:22 UTC (permalink / raw)
  To: gcc-bugs


------- Additional Comments From falk at debian dot org  2004-02-25 20:22 -------
The code violates aliasing rules and is therefore invalid. Newer gcc's even
warn about it.


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14299


^ permalink raw reply	[flat|nested] 4+ messages in thread
* [Bug rtl-optimization/14299] Improperly derefences pointers with casting
  2004-02-25 20:20 [Bug optimization/14299] New: Improperly derefences pointers with casting dmeggy at techsol dot ca
  2004-02-25 20:22 ` [Bug optimization/14299] " falk at debian dot org
  2005-06-05  8:40 ` [Bug rtl-optimization/14299] " pinskia at gcc dot gnu dot org
@ 2005-06-05  8:40 ` pinskia at gcc dot gnu dot org
  2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-06-05  8:40 UTC (permalink / raw)
  To: gcc-bugs


------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-05 08:40 -------
Reopening to ...

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14299


^ permalink raw reply	[flat|nested] 4+ messages in thread
* [Bug rtl-optimization/14299] Improperly derefences pointers with casting
  2004-02-25 20:20 [Bug optimization/14299] New: Improperly derefences pointers with casting dmeggy at techsol dot ca
  2004-02-25 20:22 ` [Bug optimization/14299] " falk at debian dot org
@ 2005-06-05  8:40 ` pinskia at gcc dot gnu dot org
  2005-06-05  8:40 ` pinskia at gcc dot gnu dot org
  2 siblings, 0 replies; 4+ messages in thread
From: pinskia at gcc dot gnu dot org @ 2005-06-05  8:40 UTC (permalink / raw)
  To: gcc-bugs


------- Additional Comments From pinskia at gcc dot gnu dot org  2005-06-05 08:40 -------
Mark as a dup of bug 21920

*** This bug has been marked as a duplicate of 21920 ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14299


^ permalink raw reply	[flat|nested] 4+ messages in thread
end of thread, other threads:[~2005-06-05  8:40 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2004-02-25 20:20 [Bug optimization/14299] New: Improperly derefences pointers with casting dmeggy at techsol dot ca
2004-02-25 20:22 ` [Bug optimization/14299] " falk at debian dot org
2005-06-05  8:40 ` [Bug rtl-optimization/14299] " pinskia at gcc dot gnu dot org
2005-06-05  8:40 ` pinskia at gcc dot gnu dot org

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