compiler.embedding: use typedtree hash to iterate inference to fixpoint.

artiq/compiler/embedding.py

@@ -8,7 +8,7 @@ annotated as ``@kernel`` when they are referenced.
 import os, re, linecache, inspect, textwrap
 from collections import OrderedDict, defaultdict
 
-from pythonparser import ast, source, diagnostic, parse_buffer
+from pythonparser import ast, algorithm, source, diagnostic, parse_buffer
 
 from . import types, builtins, asttyped, prelude
 from .transforms import ASTTypedRewriter, Inferencer, IntMonomorphizer
@@ -101,6 +101,7 @@ class ASTSynthesizer:
 
                 constructor_type = types.TConstructor(instance_type)
                 constructor_type.attributes['__objectid__'] = builtins.TInt(types.TValue(32))
+                instance_type.constructor = constructor_type
 
                 self.type_map[typ] = instance_type, constructor_type
 
@@ -253,6 +254,24 @@ class StitchingInferencer(Inferencer):
 
         super().visit_AttributeT(node)
 
+class TypedtreeHasher(algorithm.Visitor):
+    def generic_visit(self, node):
+        def freeze(obj):
+            if isinstance(obj, ast.AST):
+                return self.visit(obj)
+            elif isinstance(obj, types.Type):
+                return hash(obj.find())
+            elif isinstance(obj, list):
+                return tuple(obj)
+            else:
+                assert obj is None or isinstance(obj, (bool, int, float, str))
+                return obj
+
+        fields = node._fields
+        if hasattr(node, '_types'):
+            fields = fields + node._types
+        return hash(tuple(freeze(getattr(node, field_name)) for field_name in fields))
+
 class Stitcher:
     def __init__(self, engine=None):
         if engine is None:
@@ -275,12 +294,17 @@ class Stitcher:
         inferencer = StitchingInferencer(engine=self.engine,
                                          value_map=self.value_map,
                                          quote=self._quote)
+        hasher = TypedtreeHasher()
 
         # Iterate inference to fixed point.
-        self.inference_finished = False
+        old_typedtree_hash = None
-        while not self.inference_finished:
+        while True:
-            self.inference_finished = True
             inferencer.visit(self.typedtree)
+            typedtree_hash = hasher.visit(self.typedtree)
+
+            if old_typedtree_hash == typedtree_hash:
+                break
+            old_typedtree_hash = typedtree_hash
 
         # After we have found all functions, synthesize a module to hold them.
         source_buffer = source.Buffer("", "<synthesized>")
@@ -488,7 +512,6 @@ class Stitcher:
                 # the final call.
                 function_node = self._quote_embedded_function(function)
                 self.typedtree.insert(0, function_node)
-                self.inference_finished = False
                 return function_node.name
             elif function.artiq_embedded.syscall is not None:
                 # Insert a storage-less global whose type instructs the compiler