S/390: Define vectorization_cost hook

S/390: Define vectorization_cost hook

Define the vectorization_cost hook.  The only change right now
compared to the default implementation is the reduced costs for
unaligned loads/stores.  This is supposed to prevent unnecessary loop
peeling performed to reach better alignments.

Further tuning of this hook is required.

-Andreas-

gcc/ChangeLog:

2016-12-02  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc/config/s390/s390.c (s390_builtin_vectorization_cost): New
	function.
	(TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST): Define target
	macro.

gcc/testsuite/ChangeLog:

2016-12-02  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.target/s390/vector/vec-nopeel-1.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@243158 138bc75d-0d04-0410-961f-82ee72b054a4