S/390: Use wfc for scalar vector compares

S/390: Use wfc for scalar vector compares

The z13 vector support used the vector style comparison instructions
also for the scalar compares in vector registers.  However, it is much
more convenient to just use the compare scalar instruction for that
purpose.  The advantage is that this instruction generates a CC result
as our compares usually do.  So this results in quite some code to be
removed from the backend.

Regression tested on s390x.

gcc/ChangeLog:

2017-03-24  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/2964.md: Remove the single element vector compare
	instructions which are no longer used.
	* config/s390/s390.c (s390_select_ccmode): Remove handling of
	vector CCmodes.
	(s390_canonicalize_comparison): Remove handling of DFmode
	compares.
	(s390_expand_vec_compare_scalar): Remove function.
	(s390_emit_compare): Don't call s390_expand_vec_compare_scalar.
	* config/s390/s390.md ("*vec_cmp<insn_cmp>df_cconly"): Remove
	pattern.
	("*cmp<mode>_ccs"): Add wfcdb instruction.

gcc/testsuite/ChangeLog:

2017-03-24  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.target/s390/vector/vec-scalar-cmp-1.c: Adjust for the
	comparison instructions used from now on.

From-SVN: r246450