Wrong RTL instruction deleted

[Florian Weimer]

* Robert Dewar:

> Right, the above code would be invalid. At least that's my
> understanding. It would be interesting to try the identical
> code in Ada. There for *sure* I know that the first example
> would be valid and the second example invalid :-)

I think the original C++ code is a well-formed program.  It does
however result in unspecified behavior.

(Keep in mind that C++ as specified doesn't share C's aliasing rules.)