add TI_PRINT_PREPROCESSED

fix TI_PRINT_PROCESSED

python/taichi/lang/__init__.py

@@ -76,6 +76,11 @@ def init(default_fp=None, default_ip=None, print_preprocessed=None, debug=None,
     elif dfl_ip is not None:
       raise ValueError(f'Unrecognized TI_DEFAULT_IP: {dfl_ip}, should be 32 or 64')
 
+  if print_preprocessed is None: # won't override
+    print_preprocessed = os.environ.get("TI_PRINT_PREPROCESSED")
+    if print_preprocessed is not None:
+      print_preprocessed = bool(int(print_preprocessed))
+
   if default_fp is not None:
     ti.get_runtime().set_default_fp(default_fp)
   if default_ip is not None:

python/taichi/lang/transformer.py

@@ -216,8 +216,11 @@ def visit_block(self, list_stmt):
     for i, l in enumerate(list_stmt):
       list_stmt[i] = self.visit(l)
 
+  def visit_Return(self, node):
+    print('visited return!')
+
   def visit_If(self, node):
-    self.generic_visit(node, ['body', 'orelse'])
+    self.generic_visit(node)
 
     is_static_if = isinstance(node.test, ast.Call) and isinstance(
         node.test.func, ast.Attribute)