Bug#179712: gcc-3.2 -O2 miscompilation (i386)

[Marko Kreen <marko@l-t.ee>]

Package: gcc-3.2
Version: 1:3.2.2-0pre8
Severity: normal


gcc-3.2 -O2 miscompiles following program:

---------------------------------------------
extern int write(int fd, void *buf, int len);
extern int toupper(int c);

void strupr (char *s)
{
        while (*s)
                *s++ = toupper(*s);
}

int main(int argc, char *argv[])
{
        char s[] = "foo";
        strupr(s);
        write(1, s, 3);
        write(1, "\n", 1);
        return 0;
}

---------------------------------------------
$ gcc-3.2 -Wall -O2 -o test test.c 
test.c: In function `strupr':
test.c:7: warning: operation on `s' may be undefined
$ ./test
OO
$
---------------------------------------------

gcc-2.95 compiles it correctly, also gcc-3.2 when optimizing 
less than -O2.  When the "toupper(*s)" is replaced with "*s & 0x5f"
gcc-3.2 -O2 also works and without warning.

found the error when tried to compile glheretic.

-- System Information:
Debian Release: testing/unstable
Architecture: i386
Kernel: Linux snoopy 2.4.20 #1 SMP Mon Jan 13 17:12:00 EET 2003 i686
Locale: LANG=C, LC_CTYPE=C

Versions of packages gcc-3.2 depends on:
ii  binutils                  2.13.90.0.16-1 The GNU assembler, linker and bina
ii  cpp-3.2                   1:3.2.2-0pre8  The GNU C preprocessor
ii  gcc-3.2-base              1:3.2.2-0pre8  The GNU Compiler Collection (base 
ii  libc6                     2.3.1-10       GNU C Library: Shared libraries an
ii  libgcc1                   1:3.2.2-0pre8  GCC support library

-- no debconf information