[Test] start adding a test for ext lookups

tests/fpgadataflow/test_fpgadataflow_lookup.py

@@ -36,6 +36,7 @@ from torch import nn
 from finn.core.datatype import DataType
 from finn.core.modelwrapper import ModelWrapper
 from finn.core.onnx_exec import execute_onnx
+from finn.custom_op.registry import getCustomOp
 from finn.transformation.fpgadataflow.compile_cppsim import CompileCppSim
 from finn.transformation.fpgadataflow.convert_to_hls_layers import InferLookupLayer
 from finn.transformation.fpgadataflow.hlssynth_ip import HLSSynthIP
@@ -130,3 +131,42 @@ def test_fpgadataflow_lookup(edt, embedding_cfg, exec_mode):
         model = model.transform(PrepareRTLSim())
     ret_sim = execute_onnx(model, {iname: itensor})
     assert (exp_out == ret_sim[oname]).all()
+
+
+@pytest.mark.vivado
+@pytest.mark.slow
+def test_fpgadataflow_lookup_external():
+    edt = DataType["INT8"]
+    embedding_cfg = (200000, DataType["UINT32"], 300)
+    ishape = (1, 600)
+    num_embeddings, idt, embedding_dim = embedding_cfg
+    eshape = (num_embeddings, embedding_dim)
+    exp_oshape = tuple(list(ishape) + [embedding_dim])
+    embeddings = gen_finn_dt_tensor(edt, eshape)
+    model = make_lookup_model(embeddings, ishape, idt, edt)
+    assert len(model.graph.node) == 1
+    assert model.graph.node[0].op_type == "Gather"
+    iname = model.graph.input[0].name
+    ename = model.graph.node[0].input[0]
+    oname = model.graph.output[0].name
+    assert model.get_tensor_datatype(iname) == idt
+    assert model.get_tensor_datatype(ename) == edt
+    assert model.get_tensor_datatype(oname) == edt
+    assert tuple(model.get_tensor_shape(ename)) == eshape
+    assert tuple(model.get_tensor_shape(oname)) == exp_oshape
+    assert (model.get_initializer(ename) == embeddings).all()
+    # itensor = gen_finn_dt_tensor(idt, ishape).astype(np.int64)
+    # itensor = np.clip(itensor, 0, num_embeddings - 1)
+    # ret = execute_onnx(model, {iname: itensor})
+    # exp_out = np.take(embeddings, itensor, axis=0)
+    # assert (exp_out == ret[oname]).all()
+    # call transformation to convert to HLS and verify conversion
+    model = model.transform(InferLookupLayer())
+    assert model.graph.node[0].op_type == "Lookup"
+    assert model.graph.node[0].input[0] == iname
+    assert model.graph.node[0].input[1] == ename
+    assert model.graph.node[0].output[0] == oname
+    getCustomOp(model.graph.node[0]).set_nodeattr("mem_mode", "external")
+    model = model.transform(GiveUniqueNodeNames())
+    model = model.transform(PrepareIP("xczu3eg-sbva484-1-e", 10))
+    model = model.transform(HLSSynthIP())