Remove regions from types.

Unification-based inference for regions is useful with a language
that has let bindings (which would propagate the regions) and
functions polymorphic over regions. For reasons of simplicity,
ARTIQ has neither, and making unification-based inference work would
essentially mean adding region coercions between most AST nodes,
and having every source subexpression have its own region variable,
with the appropriate subtyping relationship.

It's simpler to just keep that state outside of typedtree.

artiq/compiler/module.py

@@ -15,6 +15,7 @@ class Module:
         inferencer = transforms.Inferencer(engine=engine)
         int_monomorphizer = transforms.IntMonomorphizer(engine=engine)
         monomorphism_validator = validators.MonomorphismValidator(engine=engine)
+        escape_validator = validators.EscapeValidator(engine=engine)
 
         parsetree, comments = parse_buffer(source_buffer, engine=engine)
         typedtree = asttyped_rewriter.visit(parsetree)
@@ -22,6 +23,7 @@ class Module:
         int_monomorphizer.visit(typedtree)
         inferencer.visit(typedtree)
         monomorphism_validator.visit(typedtree)
+        escape_validator.visit(typedtree)
 
         self.name = os.path.basename(source_buffer.name)
         self.globals = asttyped_rewriter.globals

artiq/compiler/types.py

@@ -82,8 +82,8 @@ class TMono(Type):
 
     attributes = {}
 
-    def __init__(self, name, params={}, region=None):
-        self.name, self.params, self.region = name, params, region
+    def __init__(self, name, params={}):
+        self.name, self.params = name, params
 
     def find(self):
         return self
@@ -125,7 +125,6 @@ class TTuple(Type):
     """
 
     attributes = {}
-    region = None
 
     def __init__(self, elts=[]):
         self.elts = elts
@@ -171,8 +170,8 @@ class TFunction(Type):
 
     attributes = {}
 
-    def __init__(self, args, optargs, ret, region=None):
-        self.args, self.optargs, self.ret, self.region = args, optargs, ret, region
+    def __init__(self, args, optargs, ret):
+        self.args, self.optargs, self.ret = args, optargs, ret
 
     def arity(self):
         return len(self.args) + len(self.optargs)
@@ -219,8 +218,6 @@ class TBuiltin(Type):
     type is treated specially according to its name.
     """
 
-    region = None
-
     def __init__(self, name):
         self.name = name
         self.attributes = {}

artiq/compiler/validators/escape.py

@@ -0,0 +1,10 @@
+"""
+:class:`EscapeValidator` verifies that no mutable data escapes
+the region of its allocation.
+"""
+
+from pythonparser import algorithm, diagnostic
+from .. import asttyped, types, builtins
+
+class EscapeValidator(algorithm.Visitor):
+    pass