possible gcse failure: not able to eliminate redundant loads

[Robert Dewar]

> At the expense of getting nice crashes at points where NULL is
> dereferenced, which often makes it easy to find bugs?  Oh, and there's

umm ... optimization is about favoring fast execution of code over 
debuggability, so yes, exactly that is the trade off. Note that there
is absolutely NOTHING to stop a compiler from generating code that
diagnoses dereferences of null pointers in fully optimized code if
that's what you want (it is for example required in Ada!)