Remove permanent output scanning code that eats quite a bit of processing time.

Cython/Compiler/Code.py

@@ -119,8 +119,6 @@ modifier_output_mapper = {
     'inline': 'CYTHON_INLINE'
 }.get
 
-is_self_assignment = re.compile(r" *(\w+) = (\1);\s*$").match
-
 
 class IncludeCode(object):
     """
@@ -1880,8 +1878,6 @@ class CCodeWriter(object):
         self.put(code)
 
     def put(self, code):
-        if is_self_assignment(code):
-            return
         fix_indent = False
         if "{" in code:
             dl = code.count("{")

Cython/Compiler/ExprNodes.py

@@ -2307,7 +2307,7 @@ class NameNode(AtomicExprNode):
 
                         if is_pythran_expr(self.type):
                             code.putln('new (&%s) decltype(%s){%s};' % (self.result(), self.result(), result))
-                        else:
+                        elif result != self.result():
                             code.putln('%s = %s;' % (self.result(), result))
                 if debug_disposal_code:
                     print("NameNode.generate_assignment_code:")
@@ -7729,7 +7729,7 @@ class SequenceNode(ExprNode):
             code.put_decref(target_list, py_object_type)
             code.putln('%s = %s; %s = NULL;' % (target_list, sublist_temp, sublist_temp))
             code.putln('#else')
-            code.putln('%s = %s;' % (sublist_temp, sublist_temp)) # avoid warning about unused variable
+            code.putln('(void)%s;' % sublist_temp)  # avoid warning about unused variable
             code.funcstate.release_temp(sublist_temp)
             code.putln('#endif')
 

Cython/Compiler/Nodes.py

@@ -2046,6 +2046,7 @@ class FuncDefNode(StatNode, BlockNode):
             if err_val is None and default_retval:
                 err_val = default_retval
             if err_val is not None:
+                if err_val != Naming.retval_cname:
                     code.putln("%s = %s;" % (Naming.retval_cname, err_val))
             elif not self.return_type.is_void:
                 code.putln("__Pyx_pretend_to_initialize(&%s);" % Naming.retval_cname)