[Bug c/33379] New: Bad code generation with O3

["tompa-l at prolan dot hu" <gcc-bugzilla at gcc dot gnu dot org>]

Hello ,

this code below compiles with different results.
with -O0 the result is 1.(expected res.)
from -O2 (and above) the result is 0.(BUG!)  

Thank You !


include<stdio.h>

#ifdef _BIG_ENDIAN
#define FP_SEG(fp) (*((unsigned short*)&(fp)))
#define FP_OFF(fp) (*((unsigned short*)&(fp)+1))
#else
#define FP_SEG(fp) (*((unsigned short*)&(fp)+1))
#define FP_OFF(fp) (*((unsigned short*)&(fp)))
#endif

#define BYTE unsigned char
#define _huge

unsigned short int zHugeOffset;


int main(){


        BYTE _huge *phb;

        unsigned short int selBit;


        FP_SEG(phb)=0; FP_OFF(phb)=0xffff; phb+=0x8000; selBit=FP_SEG(phb);


        zHugeOffset=selBit;

        printf("RESULT :%hd\n", zHugeOffset);


}


-- 
           Summary: Bad code generation with O3
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tompa-l at prolan dot hu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33379