Xref: news2.mv.net comp.os.msdos.djgpp:2663
From: jan AT stack DOT urc DOT tue DOT nl (Jan Oonk)
Newsgroups: comp.os.msdos.djgpp
Subject: Compile bug?
Date: 12 Apr 1996 16:03:09 +0200
Organization: MCGV Stack, Eindhoven University of Technology, the Netherlands.
Lines: 68
Message-ID: <4klnqt$pes@toad.stack.urc.tue.nl>
NNTP-Posting-Host: toad.stack.urc.tue.nl
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Hi!

Here's a short testprogram to show a compile bug(???) or my mistake :)

#include<stdio.h>

struct TInfo{
  int v0;
  int v1;
};

void Proc(TInfo *p)
{ putchar(p->v1);
}

inline void Proc2(TInfo *p)
{ asm volatile
    ("movl %0,%%eax \n"
     "movl 4(%%eax),%%eax \n"
     "pushl %%eax \n"
     "call  _putchar \n" : : "g" (p)
                           : "eax");
}

inline void Proc3(int v1)
{ asm volatile
    ("movl %0,%%eax \n"
     "pushl %%eax \n"
     "call  _putchar \n" : : "g" (v1)
                           : "eax");
}

int main(void)
{
  TInfo Info;
  TInfo *PInfo;
  PInfo=&Info;

  PInfo->v1=1;            //Works with -O0 and -O2
  Proc(PInfo);
  PInfo->v1=2;
  Proc(PInfo);

//Following line is "removed"/optimized out by DJGPP with -O2 compileoption
  PInfo->v1=1;            //Only works in -O0 !! ???? and NOT in -O2
  Proc2(PInfo);
  PInfo->v1=2;
  Proc2(PInfo);

  PInfo->v1=1;            //Works with -O0 and -O2
  Proc3(PInfo->v1);
  PInfo->v1=2;
  Proc3(PInfo->v1);

  return 0;
}

I debugged it and it the PInfo->v1=1 is removed(optimized out) by the
compiler...!


Can anyone please help me to point out (no doubt) my mistake!

Thanks in advance,
   A not so experienced C/C++/DJGPP programmer :)
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