[Bug middle-end/49721] convert_memory_address_addr_space may generate invalid new insns

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49721

--- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-07-28 21:39:47 UTC ---
(In reply to comment #3)
> (In reply to comment #2)
> > The question is we have
> > 
> > (zero_extend:DI (plus:SI (FOO:SI) (const_int Y)))
> > 
> > Is is OK to transform it to
> > 
> > (plus:DI (zero_extend:DI (FOO:SI)) (const_int Y))
> 
> It is valid if addresses can never extend across singed SI_MAX and SI_MIN.

For POINTERS_EXTEND_UNSIGNED > 0, the valid address arrange is
0 to UINT_MAX.