S/390: Support vector load/store alignment hints

S/390: Support vector load/store alignment hints

The IBM z14 POP adds an optional alignment operand to the vl, vst,
vlm, and vstm instruction (vector loads and stores). Vectors residing
on 8 or 16 byte boundaries might get loaded or stored faster on some
models given the instruction uses the proper hint operand.  A wrong
hint will hurt performance though.

The attached testcase align-1 currently fails due to:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88085

gcc/ChangeLog:

2018-11-21  Andreas Krebbel  <krebbel@linux.ibm.com>

	* configure.ac: Add check for Binutils to determine whether vector
	load/store alignments hints are being supported.
	* config.in: Regenerate.
	* configure: Regenerate.
	* config/s390/s390.c (print_operand): Support new output
	modifier A.
	* config/s390/s390.md ("movti"): Append alignment hint output
	using the new output modifier 'A'.
	* config/s390/vector.md ("mov<mode>", "*vec_tf_to_v1tf")
	("*vec_ti_to_v1ti"): Likewise.

gcc/testsuite/ChangeLog:

2018-11-21  Andreas Krebbel  <krebbel@linux.ibm.com>

	* gcc.target/s390/vector/align-1.c: New test.
	* gcc.target/s390/vector/align-2.c: New test.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@266336 138bc75d-0d04-0410-961f-82ee72b054a4