[Bug c/43755] Bit shifting by a 8 byte variable isn't the same as bit shifting by an 8 or a 4 byte constant on 64bit platform.

2010-04-15 Thread jakub at gcc dot gnu dot org 


--- Comment #3 from jakub at gcc dot gnu dot org  2010-04-15 08:12 ---
The only bug here is in your program.
ISO C99, 6.5.7/3 says:
... "If the value of the right operand is negative or is
greater than or equal to the width of the promoted left operand, the behavior
is undefined."
and that's what happens here.  ~0 is 32-bit and shifting it by 32 is undefined
behavior.


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jakub at gcc dot gnu dot org changed:

   What|Removed |Added

 Status|UNCONFIRMED |RESOLVED
 Resolution||INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43755

[Bug c/43755] Bit shifting by a 8 byte variable isn't the same as bit shifting by an 8 or a 4 byte constant on 64bit platform.

2010-04-14 Thread mail dot alexhaase at gmail dot com 


--- Comment #2 from mail dot alexhaase at gmail dot com  2010-04-15 03:33 
---
I tested on 32bits and found slightly less confusing, though still confusing
results. Bug id #43756


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43755

[Bug c/43755] Bit shifting by a 8 byte variable isn't the same as bit shifting by an 8 or a 4 byte constant on 64bit platform.

2010-04-14 Thread mail dot alexhaase at gmail dot com 


--- Comment #1 from mail dot alexhaase at gmail dot com  2010-04-15 03:16 
---
Created an attachment (id=20384)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20384&action=view)
Bug demo


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43755