[Bug tree-optimization/37867] inconsistent results on -O2 when reading bits from packed struct

[edwintorok at gmail dot com]

------- Comment #1 from edwintorok at gmail dot com  2008-10-18 13:39 -------
(In reply to comment #0)
> Running gcc-4.3 -O2 on PR1386.c I get different results than with -O1.
> 
> $ gcc-4.3 -O2 PR1386.c && ./a.out
> PR1386.c: In function ‘main’:
> PR1386.c:15: warning: large integer implicitly truncated to unsigned type
> PR1386.c:17: warning: large integer implicitly truncated to unsigned type
> bad bits: fffffffffffffff0

$ gcc-4.3 -O1 PR1386.c && ./a.out
PR1386.c: In function ‘main’:
PR1386.c:15: warning: large integer implicitly truncated to unsigned type
PR1386.c:17: warning: large integer implicitly truncated to unsigned type
bad bits: 0


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37867