[Bug c/69504] XMM register variable ICE with vector extensions

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69504

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think at some point the FEs created array-refs here.  I think I suggested
that elsewhere during last stage1 but nobody implemented that ... (now it's
already again quite late).

Thus for vector[i] create

  ARRAY_REF<VIEW_CONVERT <array-type-for-vector-type> (vector), i>

avoiding the need to take the address of vector.

Thus instead of

  bool non_lvalue
    = convert_vector_to_pointer_for_subscript (loc, &array, index);

convert the vector to an array type via a VIEW_CONVERT.  That should work
for both r and lvalues.  Of course it may trigger interesting new paths
should this survive until RTL expansion ;)

The other option is in convert_vector_to_pointer_for_subscript, force
the !lvalue_p path for DECL_HARD_REGISTER *vecp.