From: molnarl AT cdata DOT tvnet DOT hu
Date: Mon, 9 Mar 1998 18:11:17 +0100 (MET)
To: DJGPP Workers List <djgpp-workers AT delorie DOT com>
Subject: bug in gcc 2.8.0 (and 2.7.2)
Message-ID: <Pine.GSO.3.96.980309180858.4081A-100000@dumballah.tvnet.hu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
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Hi!

I'm not sure whether it is a new bug. I've found it with the latest
test version of perl.

This program is a feature test for perl. Compile this with -O0 and it
prints 0, but with -O2 it prints 1. This bug also appears on linux
(2.7.2.3).

And another interesting thing: when you compile this with 2.8.0 and
-O2, gcc optimize out the whole test and the assembly is just an
exit(1)! Wow!

Laszlo

ps: the original code doesn't have any printf

---------8<-----------

#include <sys/types.h>
#include <signal.h>
void blech() { exit(7); }
void blech_in_list() { exit(4); }
unsigned long dummy_long(p) unsigned long p; { return p; }
unsigned int dummy_int(p) unsigned int p; { return p; }
unsigned short dummy_short(p) unsigned short p; { return p; }
main()
{
        double f = -123.;
        unsigned long along;
        unsigned int aint;
        unsigned short ashort;
        int result = 0;

        signal(SIGFPE, blech);
        along = (unsigned long)f;
        aint = (unsigned int)f;
        ashort = (unsigned short)f;
        if (along != (unsigned long)-123)
                result |= 1;
        if (aint != (unsigned int)-123)
                result |= 1;
        if (ashort != (unsigned short)-123)
                result |= 1;
        f = (double)0x40000000;
        f = f + f;
        along = 0;
        along = (unsigned long)f;
        if (along != 0x80000000)
                result |= 2;
        f -= 1.;
        along = 0;
        along = (unsigned long)f;
        if (along != 0x7fffffff)
                result |= 1;
        f += 2.;
        along = 0;
        along = (unsigned long)f;
        if (along != 0x80000001)
                result |= 2;
        if (result)
                printf ("%d",result),exit(result);
        signal(SIGFPE, blech_in_list);
        f = 123.;
        along = dummy_long((unsigned long)f);
        aint = dummy_int((unsigned int)f);
        ashort = dummy_short((unsigned short)f);
        if (along != (unsigned long)123)
                result |= 4;
        if (aint != (unsigned int)123)
                result |= 4;
        if (ashort != (unsigned short)123)
                result |= 4;
        printf ("%d",result);
        exit(result);

}