Re: [Nmh-workers] strcasecmp.c and gcc -O2

[Josh Bressers]

> 
> strcasecomp(a,b) segfaults if a=NULL and compiled with -O2 and gcc >= 4.1.1.
> 
> The code in question is:
> 
> 
> int
> mh_strcasecmp (const char *s1, const char *s2) 
> {
>     const unsigned char *us1, *us2;
> 
>     us1 = (const unsigned char *) s1,
>     us2 = (const unsigned char *) s2;
> 
>     if (!us1)
>         us1 = "";
>     if (!us2)
>         us2 = "";
>  
>     while (tolower(*us1) == tolower(*us2++)) 
>         if (*us1++ == '\0')
>             return (0);
>     return (tolower(*us1) - tolower(*--us2));
> }
> 
> 
> It seems the compiler (using -O2) totally optimizes away the two if clauses. 
> Looking at the assembler:
> 

I don't see this behavior with gcc 4.1.2 on Fedora 7.  It's quite possible
you're seeing a gcc bug.  I'd suggest writing a minimalistic freestanding
testcase.  If that testcase still exhibits this behavior, submit a bug
report to the gcc folks.

-- 
    JB