To: djgpp AT delorie DOT com
Subject: Program miscompiled by GCC
From: ilari DOT liusvaara AT purkki DOT mbnet DOT fi (Ilari Liusvaara)
Message-ID: <00CF54B.00640E1F47.uuout@purkki.mbnet.fi>
Date: Sun, 22 Jul 00 22:35:00 +0200
Organization: MBnet - MikroBitti
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Reply-To: djgpp AT delorie DOT com

I have a problem with GCC and most likely it is a bug:
 When I compile this program with -ansi, GCC 2.7.2.1 generates program that
 bombs and GCC 2.9.5.2 generates program that display resluts that do not
 make sense. The comments and messages are in finnish and I don't bother to
 translate them. I have marked the line that generates instructions that
 bomb the program when compiled with GCC 2.7.2.1 (at least SYMIFY tells
 that it is that line.) When I compile without -ansi, program works just
 fine. It seems thet misbehaving program generated by GCC 2.9.5.2 is
 compiled seriously wrong. As I investigated problem further, I got
 strong proof that the problem is indeed in the C compiler. Comparing
 assembler outputs revealed that there were two (2.9.5.1) or three (2.7.2.1)
 extra assembler commands in file generated by GCC with -ansi parameter.
 Removing them gives program that works. The miscompiled part is from
 function kysy(...). I have marked this problematic line too.

And by the way, I haven't subscribed to Djgpp mailing list.

Source code of troublematic program:

#include "stdio.h"
#include "stdlib.h"
#include "math.h"

#ifdef __GNUC__
    #ifdef __GNUG__
        extern "C"
        {                   /*M,,rittele 3 systeemifunktiota tyhjiksi*/
    #endif
        char ** __crt0_glob_function(char* _argument){return 0;}
        void   __crt0_load_environment_file(char* _app_name){;}
        void __crt0_setup_arguments(){;}
    #ifdef __GNUG__
        }
    #endif
#endif

#define Tnopeus_x (nopeus_x+tuuli)         /*Nopeus tuulen suhteen*/

long double kysy(const char* kysymys);

long double kysy(const char* kysymys)
{
    char buf[255];                  /*V,liaikaispuskuri*/
    printf("%s",kysymys); fflush(stdout);       /*Tulosta kysymys*/
    gets(buf);                                  /*ota vastaus*/
/***********************************************************************/
/**/return _atold(buf);              /*<--THIS LINE IS MISCOMPILED!!!! */
/***********************************************************************/


}


int main()
{
    long double massa,nopeus,kulma,vastus,tuuli,korkeus; /*Parametreja*/
    long double sij_x
ikan komponentit*/
    long double nopeus_x,nopeus_y;    /*Nopeuden komponentit*/
    long double aika
ika*/
    long double askel 001;       /*aika-askel numeerisessa ratkaisussa.*/
    long double vasen
semmaisin x-koordinatti.*/
    long double oikeaimmainen x-koordinatti.*/
    long double huippuinatti.*/
    long double kiihtyvyys˜0655;  /*painovoiman kiihtyvyys.*/

    massa    nopeus    kulma    vastus    tuuli    korkeus
    printf("Venaa hetki...\n");
    huippu.*/
    nopeus_x    nopeus_y    sij_y
    while(sij_y>
*/
    {                                   /*Alustetaan muuttujat*/
        long double voima_x
_y        long double neliovauhti        long double vauhti        long double f_magnitudi        aika+®l;                   /*P,ivitet,,n joitakin arvoja*/
/***********************************************************************/
/**/    sij_x+/***********************************************************************/
        sij_y+        if(vauhti!ttei vain vauhti ole 0*/
        {
            long double f_kerroin_x            long double f_kerroin_y            voima_x+þrroin_x*f_magnitudi;         /*Lasketaan lopullinen*/
            voima_y+þrroin_y*f_magnitudi;         /*Voima*/
        }
        nopeus_x+®l*voima_x/massa;             /*Lasketaan voiman vai-*/
        nopeus_y+®l*voima_y/massa;             /*kutus*/
        if(sij_x<vasen) vasen        if(sij_x>oikea) oikea        if(sij_y>huippu) huippu    }                                           /*Silmukka loppuu*/

    printf("Tulokset:\n");                        /*Tulostetaan tulos.*/
    printf("Lakikorkeus:%Gm\n",(double)huippu);
    printf("Kantama:%Gm\n",(double)sij_x);
    printf("Lentoaika:%Gs:\n",(double)aika);

printf("Iskunopeus:%Gm/s:\n",(double)sqrt(nopeus_x*nopeus_x+nopeus_y*nopeus_y))
;
    printf("Iskunopeus (x-komponentti):%Gm/s:\n",fabs((double)nopeus_x));
    printf("Iskunopeus (y-komponentti):%Gm/s:\n",fabs((double)nopeus_y));
    return 0;
}