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Date: Mon, 02 Jun 2003 17:44:00 -0000
From: "jourgun@club-internet.fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20030602174433.11066.jourgun@club-internet.fr>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug optimization/11066] New: error in the optimization of packed structures
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X-SW-Source: 2003-06/txt/msg00365.txt.bz2
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11066

           Summary: error in the optimization of packed structures
           Product: gcc
           Version: 3.2.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P2
         Component: optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jourgun@club-internet.fr
                CC: gcc-bugs@gcc.gnu.org

error in the optimization of packed structures, when using -O2 or -O3.
preprossesor file:

# 1 "test.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "c:/djgpp/lib/gcc-lib/djgpp/3.23/djgpp.ver" 1
# 1 "c:/djgpp/include/sys/version.h" 1 3
# 2 "c:/djgpp/lib/gcc-lib/djgpp/3.23/djgpp.ver" 2
# 2 "<command line>" 2
# 1 "test.c"
unsigned long long GateDescriptor(Offset,Segment,TypeDPL,ParamCount)
         unsigned long Offset;
         unsigned short Segment;
         unsigned char TypeDPL,ParamCount;
         {
             typedef struct {
                    unsigned short Offset0_15;
                    unsigned short Segment;
                    unsigned char ParamCount;
                    unsigned char TypeDPL;
                    unsigned short Offset16_31;
             }Tdescripteur __attribute__ ((packed));

             Tdescripteur Descripteur;

             Descripteur.Offset0_15=Offset;
             Descripteur.Offset16_31=Offset>>16;
             Descripteur.Segment=Segment;
             Descripteur.TypeDPL=TypeDPL;
             Descripteur.ParamCount=ParamCount;

             return *(unsigned long long*)&Descripteur;
         }

int main(void){
 printf("%llX",GateDescriptor(0x65B,0x08,0xEF,0));
 getchar();
}

Normaly, we would see :
EF000008065B
but we see:
EF000000065B

the complete command line is:
gcc test.c -o test.exe -O2

I am working on DJGPP on Windows XP.



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