[Bug middle-end/5169] paradoxical subreg problem

["schlie at comcast dot net" <gcc-bugzilla at gcc dot gnu dot org>]

------- Additional Comments From schlie at comcast dot net  2005-02-20 06:44 -------
(In reply to comment #7)
With respect to: <http://gcc.gnu.org/ml/gcc/2002-01/msg01872.html>
and paradoxical subreg semantics on targets which support modes_tieable
(assuming that paradoxical subreg semantics applied to tied registers):

- It would seem that a paradoxical subreg need not have a memory operand
(as it would valid to be able to store a known lesser precision value in fewer
tied registers than the type that it logically represents may otherwise require)?

- nor does it seem to make sence in any circumstance to referance a wider
logical value than may be stored in a register or memory, without presuming
it's higher-order bits are of some known value (unless it's known that they're
logical value were to be effectivly replaced by the operation without regard to
it's initial value)?




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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=5169