S/390: Use UNSPEC_GET_TP for thread pointer loads

S/390: Use UNSPEC_GET_TP for thread pointer loads

gcc/ChangeLog:

2019-10-24  Ilya Leoshkevich  <iii@linux.ibm.com>

	* config/s390/s390.c (s390_get_thread_pointer): Use
	gen_get_thread_pointer.
	(s390_expand_split_stack_prologue): Likewise.
	* config/s390/s390.md (UNSPEC_GET_TP): New UNSPEC.
	(*get_tp_31): New 31-bit splitter for UNSPEC_GET_TP.
	(*get_tp_64): New 64-bit splitter for UNSPEC_GET_TP.
	(get_thread_pointer<mode>): Use UNSPEC_GET_TP, use
	parameterized name.

gcc/testsuite/ChangeLog:

2019-10-24  Ilya Leoshkevich  <iii@linux.ibm.com>

	* gcc.target/s390/load-thread-pointer-once-2.c: New test.

From-SVN: r277368