s390x: Fix vec_xl/vec_xst type aliasing [PR114676]
The requirements of the vec_xl/vec_xst intrinsincs wrt aliasing of the
pointer argument are not really documented. As it turns out, users
are likely to get it wrong. With this patch we let the pointer
argument alias everything in order to make it more robust for users.
gcc/ChangeLog:
PR target/114676
* config/s390/s390-c.cc (s390_expand_overloaded_builtin): Use a
MEM_REF with an addend of type ptr_type_node.
gcc/testsuite/ChangeLog:
PR target/114676
* gcc.target/s390/zvector/pr114676.c: New test.