Hi, Archie! Long time...
On Jul 18, 2004, Archie Cobbs <archie@xxxxxxxxxxxx> wrote:
> r2 = (void *)0; /* or (void *)1, etc. */
> if (*r1 != *r2)
> return 1;
> return 1;
> However, in my application I'm relying on the side effects of
> dereferencing a null pointer (ie., SEGV signal), so that causes
> bugs for me.
> I understand that according to the C standard dereferencing a null
> pointer results in "undefined" behavior, so gcc is not behaving
> incorrectly.
> However, is there some way to get the desired semantics?
If you insert an `asm ("" : "+X" (r2));' statement after the
assignment to r2, such that the compiler will no longer have any idea
that r2 is NULL, and won't optimize away the dereference.
--
Alexandre Oliva http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}
