Optimize refcounting for cdef assignments (like it was)

Cython/Compiler/ExprNodes.py

@@ -809,6 +809,7 @@ class NameNode(AtomicExprNode):
     #  interned_cname  string
     
     is_name = 1
+    skip_assignment_decref = False
 
     def create_analysed_rvalue(pos, env, entry):
         node = NameNode(pos)
@@ -1030,7 +1031,7 @@ class NameNode(AtomicExprNode):
                 rhs.generate_disposal_code(code)
                 
         else:
-            if self.type.is_pyobject:
+            if self.type.is_pyobject and not self.skip_assignment_decref:
                 #print "NameNode.generate_assignment_code: to", self.name ###
                 #print "...from", rhs ###
                 #print "...LHS type", self.type, "ctype", self.ctype() ###

Cython/Compiler/Main.py

@@ -359,7 +359,7 @@ def create_default_pipeline(context, options, result):
     from ParseTreeTransforms import WithTransform, NormalizeTree, PostParse
     from ParseTreeTransforms import AnalyseDeclarationsTransform, AnalyseExpressionsTransform
     from ParseTreeTransforms import CreateClosureClasses, MarkClosureVisitor, DecoratorTransform
-    from Optimize import FlattenInListTransform, SwitchTransform
+    from Optimize import FlattenInListTransform, SwitchTransform, OptimizeRefcounting
     from Buffer import BufferTransform
     from ModuleNode import check_c_classes
     
@@ -375,6 +375,7 @@ def create_default_pipeline(context, options, result):
         AnalyseExpressionsTransform(context),
         BufferTransform(context),
         SwitchTransform(),
+        OptimizeRefcounting(context),
 #        CreateClosureClasses(context),
         create_generate_code(context, options, result)
     ]

Cython/Compiler/Nodes.py

@@ -2231,8 +2231,10 @@ class SingleAssignmentNode(AssignmentNode):
     #
     #  lhs      ExprNode      Left hand side
     #  rhs      ExprNode      Right hand side
+    #  first    bool          Is this guaranteed the first assignment to lhs?
     
     child_attrs = ["lhs", "rhs"]
+    first = False
 
     def analyse_declarations(self, env):
         self.lhs.analyse_target_declaration(env)

Cython/Compiler/Optimize.py

@@ -134,3 +134,16 @@ class FlattenInListTransform(Visitor.VisitorTransform):
     def visit_Node(self, node):
         self.visitchildren(node)
         return node
+
+
+class OptimizeRefcounting(Visitor.CythonTransform):
+    def visit_SingleAssignmentNode(self, node):
+        if node.first:
+            lhs = node.lhs
+            if isinstance(lhs, ExprNodes.NameNode) and lhs.entry.type.is_pyobject:
+                # Have variable initialized to 0 rather than None
+                lhs.entry.init_to_none = False
+                lhs.entry.init = 0
+                # Set a flag in NameNode to skip the decref
+                lhs.skip_assignment_decref = True
+        return node

Cython/Compiler/ParseTreeTransforms.py

@@ -138,7 +138,7 @@ class PostParse(CythonTransform):
                         raise PostParseError(decl.pos, ERR_CDEF_INCLASS)
                     stats.append(SingleAssignmentNode(node.pos,
                         lhs=NameNode(node.pos, name=decl.name),
-                        rhs=decl.default))
+                        rhs=decl.default, first=True))
                     decl.default = None
         return stats