m68k/cpu32 TRAP instruction?

[Segher Boessenkool]

On Fri, Oct 05, 2018 at 03:30:47PM -0600, Jeff Law wrote:
> On 10/5/18 3:14 PM, Josef Wolf wrote:
> > 
> > - If the compiler can detect such a serious problem, then it should emit a
> >   warning AT COMPILE TIME.
> We don't for various reasons.  Frankly, I think we should as well, but I
> lost that battle.

There is -Wnull-dereference.

If you want the compiler to warn every time there *could* be a null
dereference, well, how many false positives will that be?  ;-)

> But when the compiler sees a *0 and it'll turn that into a trap.  It
> also will isolate paths to a dereference where one or more paths would
> result in a *0.  The isolated paths will get a trap, the normal paths
> will be left alone.
> 
> The same thing is done for division by zero.
> 
> But again, the compiler has exposed a bug in your program.  Your best
> course of action is to fix your code.

If you have a hard time figuring out where the trap is coming from, run
your program under a debugger.


Segher