Resolve import cycles.

lib/cretonne/meta/cretonne/ast.py

@@ -5,7 +5,7 @@ This module defines classes that can be used to create abstract syntax trees
 for patern matching an rewriting of cretonne instructions.
 """
 from __future__ import absolute_import
-from . import Instruction, BoundInstruction
+import cretonne
 
 try:
     from typing import Union, Tuple  # noqa
@@ -174,12 +174,12 @@ class Apply(Expr):
     """
 
     def __init__(self, inst, args):
-        # type: (Union[Instruction, BoundInstruction], Tuple[Expr, ...]) -> None  # noqa
+        # type: (Union[cretonne.Instruction, cretonne.BoundInstruction], Tuple[Expr, ...]) -> None  # noqa
-        if isinstance(inst, BoundInstruction):
+        if isinstance(inst, cretonne.BoundInstruction):
             self.inst = inst.inst
             self.typevars = inst.typevars
         else:
-            assert isinstance(inst, Instruction)
+            assert isinstance(inst, cretonne.Instruction)
             self.inst = inst
             self.typevars = ()
         self.args = args

lib/cretonne/meta/cretonne/typevar.py

@@ -6,7 +6,7 @@ polymorphic by using type variables.
 """
 from __future__ import absolute_import
 import math
-from . import OperandKind, value  # noqa
+import cretonne
 
 try:
     from typing import Tuple, Union # noqa
@@ -315,11 +315,11 @@ class TypeVar(object):
         return TypeVar(None, None, base=self, derived_func='DoubleWidth')
 
     def operand_kind(self):
-        # type: () -> OperandKind
+        # type: () -> cretonne.OperandKind
         # When a `TypeVar` object is used to describe the type of an `Operand`
         # in an instruction definition, the kind of that operand is an SSA
         # value.
-        return value  # type: ignore
+        return cretonne.value  # type: ignore
 
     def free_typevar(self):
         # type: () -> TypeVar