Add constraint summaries to RecipeConstraints.

Most instructions don't have any fixed register constraints. Add boolean
summaries that can be used to check if it is worthwhile to scan the
constraint lists when looking for a fixed register constraint.

Also add a tied_ops summary bool which indicates that the instruction
has tied operand constraints.

lib/cretonne/meta/gen_encoding.py

@@ -474,6 +474,15 @@ def emit_recipe_constraints(isa, fmt):
             with fmt.indented('RecipeConstraints {', '},'):
                 emit_operand_constraints(r, r.ins, 'ins', tied_i2o, fmt)
                 emit_operand_constraints(r, r.outs, 'outs', tied_o2i, fmt)
+                fmt.format(
+                        'fixed_ins: {},',
+                        str(any(isinstance(c, Register)
+                            for c in r.ins)).lower())
+                fmt.format(
+                        'fixed_outs: {},',
+                        str(any(isinstance(c, Register)
+                            for c in r.outs)).lower())
+                fmt.format('tied_ops: {},', str(bool(tied_i2o)).lower())
 
 
 def emit_operand_constraints(