Add string conversions for predicates and encodings.

This is just used for printing better comments in generated code.

meta/cretonne/__init__.py

@@ -1003,6 +1003,9 @@ class EncRecipe(object):
         if instp:
             assert instp.predicate_context() == format
 
+    def __str__(self):
+        return self.name
+
 
 class Encoding(object):
     """
@@ -1034,6 +1037,9 @@ class Encoding(object):
         self.instp = And.combine(recipe.instp, instp)
         self.isap = And.combine(recipe.isap, instp)
 
+    def __str__(self):
+        return '[{}/{:02x}]'.format(self.recipe, self.encbits)
+
     def ctrl_typevar(self):
         """
         Get the controlling type variable for this encoding or `None`.

meta/cretonne/predicates.py

@@ -65,6 +65,14 @@ class Predicate(object):
                 (p.predicate_context() for p in parts))
         assert self.context, "Incompatible predicate parts"
 
+    def __str__(self):
+        s = '{}({})'.format(
+                type(self).__name__,
+                ' ,'.join(map(str, self.parts)))
+        if self.name:
+            s = '{}={}'.format(self.name, s)
+        return s
+
     def predicate_context(self):
         return self.context
 
@@ -164,6 +172,10 @@ class FieldPredicate(object):
         self.function = function
         self.args = args
 
+    def __str__(self):
+        args = (self.field.name,) + tuple(map(str, self.args))
+        return '{}({})'.format(self.function, ', '.join(args))
+
     def predicate_context(self):
         """
         This predicate can be evaluated in the context of an instruction

meta/gen_encoding.py

@@ -203,6 +203,8 @@ def gen_isa(cpumodes, fmt):
         for level2 in level1:
             for enclist in level2:
                 fmt.comment(enclist.name())
+                for enc in enclist.encodings:
+                    fmt.comment('{} when {}'.format(enc, enc.instp))
 
 
 def generate(isas, out_dir):