On Tue, 27 Jan 2009, James Dennett wrote:
> On Mon, Jan 26, 2009 at 11:52 PM, <zol...@bendor.com.au> wrote:
> > I was debugging a function and by inserting the debug statement crashed
> > the system. Some investigation revealed that gcc 4.3.2 arm-eabi (compiled
> > from sources) with -O2 under some circumstances assumes that if a pointer
> > is dereferenced, it can not be NULL therefore explicite tests against
> > NULL can be later eliminated.
>
> That's an optimization permitted by the language standard, but
> possibly unhelpful on your particular target. It is a case of a more
> general situation: the compiler can assume that code containing
> "undefined behavior" (such as a null-pointer dereference) is not
> executed, or equivalently that a condition that would lead to the
> execution of UB is always false.
>
> I don't know how much work it would be to disable this optimization in gcc.
> -- James
Try -fno-delete-null-pointer-checks.
--Kaveh
