[Bugfix][TVMScript] Handle LetStmt for var1 = var2 expressions

python/tvm/script/parser/core/parser.py

@@ -186,8 +186,8 @@ def exist(self, value: Any) -> bool:
         res : bool
             The existence of the value.
         """
-        for v in self.name2value.values():
-            if v is value:
+        for value_stack in self.name2value.values():
+            if value in value_stack:
                 return True
         return False
 

tests/python/unittest/test_tvmscript_syntax_sugar.py

@@ -399,5 +399,30 @@ def implicit(A: T.Buffer(1, "int32")):
     assert_structural_equal(implicit, explicit)
 
 
+def test_preserve_trivial_let_binding():
+    @T.prim_func
+    def explicit(i: T.int32):
+        j = T.int32()
+        T.LetStmt(i, var=j)
+        T.evaluate(j)
+
+    @T.prim_func
+    def implicit(i: T.int32):
+        j = i
+        T.evaluate(j)
+
+    assert_structural_equal(implicit, explicit)
+
+
+def test_preserve_parameter_name():
+    @T.prim_func
+    def func(i: T.int32):
+        j = i
+        T.evaluate(j)
+
+    param_name = func.params[0].name
+    assert param_name == "i"
+
+
 if __name__ == "__main__":
     tvm.testing.main()