[Bug c/46517] New: Wrong result on left shift operator without optimization

[Bug c/46517] New: Wrong result on left shift operator without optimization

[lepinat at free dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46517

           Summary: Wrong result on left shift operator without
                    optimization
           Product: gcc
           Version: 4.4.4
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: lepinat@free.fr


The next samples compiled without opimisation give not the same result
in both case if it's use has constante the result is good
(the test is on intel platfom)

#> gcc -o shift  shift.c
result:
constant val=0
variable val=1

#> gcc -O2 -o shift  shift.c
result:
constant val=0
variable val=0


On the first case is not a shift but it's rotate

you can verify by changing the constant:
example SHIFT = 34 the the result is 

constant val=0
variable val=4


---->8---->8---->8---->8---->8
#include <stdio.h>


#define SHIFT    (4*8)



int main(int argc, char* argv[])

{

    int val = SHIFT;



    printf("constant val=%x\n", (1<<SHIFT));



    printf("variable val=%x\n", (1<<val));

    return 0;

}



---->8---->8---->8---->8---->8

[Bug c/46517] Wrong result on left shift operator without optimization

[schwab@linux-m68k.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46517

Andreas Schwab <schwab@linux-m68k.org> changed:

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

--- Comment #1 from Andreas Schwab <schwab@linux-m68k.org> 2010-11-17 09:45:15 UTC ---
.

*** This bug has been marked as a duplicate of bug 46460 ***