I think I found a bug in the optimizer...

[Mark Grosberg <myg at tempest dot din dot net>]

Hello all,

I have some code that I have had in a compiler I have been writing for
quite some time now. I think it is perfectly legal ANSI C.  It has been
compiling fine on older versions of GCC, but recently I tried compiling my
compiler on several machines with a newer GCC (and EGCS) compiler and I
ran into some problems.

Apparently, on gcc v2.95.2 (i386) and egcs v2.91.66 (PowerPC) when
compiling the file sys_unix.c of my compiler the GCC compiler seemed to
spin allocating memory. I noticed GCC using around 200MB and killed it. If I 
compile without any optimizations, the file compiles fine. 

So, I kept removing code from the file until I found the offending
routine. It is the following code:

-------------------------------------------------------------------------------

static struct utsname *get_unix_info(void)
{
  static BOOL              got_it = FALSE;
  static struct utsname    uinfo;

  if (got_it)
    return &uinfo;
  else
  {
    if (uname(&uinfo) >= 0)
      got_it = TRUE;
    else
      strcpy(uinfo.sysname,
        strcpy(uinfo.nodename,
        strcpy(uinfo.release,
        strcpy(uinfo.machine,  "*unknown*"))));

    return &uinfo;
  }
}

-------------------------------------------------------------------------------

Okay. It may seem silly how I nested the strcpy()'s like that, but
according to ANSI C, it should work fine (it's only an error case anyhow). 

However, the nested strcpy()'s seem to throw the GCC optimizer into an
endless loop.

I don't have the sources to any recent version of GCC (and my link is too
slow to download them in any appriciable amount of time), so I haven't
looked into the code for GCC yet, but I suspect it's a bug.

BTW: The compiler in question can be obtained from:

   http://www.conman.org/software/amc

If you wish to verify the results your self. In the mean time, I will be
changing the code so that it does not cause the compilations to fail. 

Thanks,
Mark G.