S/390: Use enabled attribute overrides to disable

 alternatives.

So far whenever we wanted to disable an alternative we have used mode
attributes emitting constraints matching an earlier alternative
assuming that due to this the later alternative will never be chosen.

With this patch the `enabled' attribute, which so far is only set from
`cpu_facility', is overridden to 0 to disable certain alternatives.
This comes handy when defining the substitutions later and while
adding it anyway I've used it for the existing cases as well.

gcc/ChangeLog:

2016-03-01  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/s390.md ("op_type", "atype", "length" attributes):
	Remove RRR type.  It doesn't really exist.
	("RRer", "f0", "v0", "vf", "vd", "op1", "Rf"): Remove mode
	attributes.
	("BFP", "DFP", "nDSF", "nDFDI"): Add mode attributes.
	("*cmp<mode>_ccs", "floatdi<mode>2", "add<mode>3")
	("*add<mode>3_cc", "*add<mode>3_cconly", "sub<mode>3")
	("*sub<mode>3_cc", "*sub<mode>3_cconly", "mul<mode>3")
	("fma<mode>4", "fms<mode>4", "div<mode>3", "*neg<mode>2")
	("*abs<mode>2", "*negabs<mode>2", "sqrt<mode>2"): Override
	`enabled' attribute.

From-SVN: r233842

gcc/ChangeLog

 2016-03-01  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>
 
+	* config/s390/s390.md ("op_type", "atype", "length" attributes):
+	Remove RRR type.  It doesn't really exist.
+	("RRer", "f0", "v0", "vf", "vd", "op1", "Rf"): Remove mode
+	attributes.
+	("BFP", "DFP", "nDSF", "nDFDI"): Add mode attributes.
+	("*cmp<mode>_ccs", "floatdi<mode>2", "add<mode>3")
+	("*add<mode>3_cc", "*add<mode>3_cconly", "sub<mode>3")
+	("*sub<mode>3_cc", "*sub<mode>3_cconly", "mul<mode>3")
+	("fma<mode>4", "fms<mode>4", "div<mode>3", "*neg<mode>2")
+	("*abs<mode>2", "*negabs<mode>2", "sqrt<mode>2"): Override
+	`enabled' attribute.
+
+2016-03-01  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>
+
 	* gensupport.c (process_substs_on_one_elem): Split loop to
 	complete mark_operands_used_in_match_dup on all expressions in the
 	vector first.