[Frontend][Relay][Parser] fix unparsable yolo formals (apache#6963)

* fix yolo formals

* fix lint

* move test to test_forward

python/tvm/relay/frontend/darknet.py

@@ -40,7 +40,7 @@ def _darknet_not_support(attr, op="relay"):
 
 def _get_params_prefix(opname, layer_num):
     """Makes the params prefix name from opname and layer number."""
-    return str(opname) + str(layer_num)
+    return str(opname).replace(".", "_") + str(layer_num)
 
 
 def _get_params_name(prefix, item):

tests/python/frontend/darknet/test_forward.py

@@ -46,6 +46,17 @@
 )
 
 
+def astext(program, unify_free_vars=False):
+    """check that program is parsable in text format"""
+    text = program.astext()
+    if isinstance(program, relay.Expr):
+        roundtrip_program = tvm.parser.parse_expr(text)
+    else:
+        roundtrip_program = tvm.parser.fromtext(text)
+
+    tvm.ir.assert_structural_equal(roundtrip_program, program, map_free_vars=True)
+
+
 def _read_memory_buffer(shape, data, dtype="float32"):
     length = 1
     for x in shape:
@@ -60,6 +71,10 @@ def _get_tvm_output(net, data, build_dtype="float32", states=None):
     """Compute TVM output"""
     dtype = "float32"
     mod, params = relay.frontend.from_darknet(net, data.shape, dtype)
+    # verify that from_darknet creates a valid, parsable relay program
+    mod = relay.transform.InferType()(mod)
+    astext(mod)
+
     target = "llvm"
     shape_dict = {"data": data.shape}
     lib = relay.build(mod, target, params=params)

tests/python/relay/test_ir_text_printer.py

@@ -21,6 +21,7 @@
 import numpy as np
 from tvm.relay import Expr
 from tvm.relay.analysis import free_vars
+import pytest
 
 DEBUG_PRINT = False
 
@@ -269,6 +270,4 @@ def test_span():
 
 
 if __name__ == "__main__":
-    import sys
-
-    pytext.argv(sys.argv)
+    pytest.main([__file__])