MLBEDSW-7196 Add LSTM support

Added int8 and int16 UNIDIRECTIONAL_SEQUENCE_LSTM support.
The implementation does not include support for:
* CIFG
* Peephole
* Projection
* Normalisation

This change also:
* Removed unused Op.BlockLSTM operation type.
* Removed the only one consumer limitation on putting the SplitSliceRead
  on the tensor consumer(s), if all consumers fullfills the requirements
* Added Op.VariableTensorWrite as a Operation.memory_function to make
  sure writes to variable tensors:
  * Always use linear mode
  * Are not moved to fast scratch
  * Are not fused with other elementwise operation tensor ranges

Change-Id: Ief831738924ac3d1f2ba6d41f10bd6dc969911f3
Signed-off-by: Fredrik Svedberg <fredrik.svedberg@arm.com>

1 files changed, 34 insertions, 0 deletions

diff --git a/ethosu/vela/test/test_tflite_model_semantic.py b/ethosu/vela/test/test_tflite_model_semantic.py
index fd23d042..d4c92553 100644
--- a/ethosu/vela/test/test_tflite_model_semantic.py
+++ b/ethosu/vela/test/test_tflite_model_semantic.py
@@ -576,3 +576,37 @@ def test_matching_in_out_quant():
     dim = create_const_tensor("expand_dims_dim", [], DataType.uint8, 0)
     op = testutil.create_op(Op.ExpandDims, [ifm, dim], ofm, set_ifm_ofm_shapes=False)
     assert not semantic_checker.is_operator_semantic_valid(op)
+
+
+def test_lstm_semantics():
+    # Test valid configurations
+    op = testutil.create_lstm_op(3, 12, 24, 20, DataType.int8)
+    assert semantic_checker.is_operator_semantic_valid(op)
+    assert semantic_checker.is_operator_semantic_valid(testutil.create_lstm_op(3, 12, 24, 20, DataType.int16))
+    # Test invalid datatype
+    assert not semantic_checker.is_operator_semantic_valid(testutil.create_lstm_op(3, 12, 24, 20, DataType.uint8))
+    # Test invalid shape
+    ifm_shape = op.ifm.shape
+    ofm_shape = op.ofm.shape
+    op.ifm.shape = [12, 24]
+    assert not semantic_checker.is_operator_semantic_valid(op)
+    op.ifm.shape = ifm_shape
+    op.ofm.shape = [12, 20]
+    assert not semantic_checker.is_operator_semantic_valid(op)
+    op.ofm.shape = ofm_shape
+    # Test invalid number of intermediates
+    intermediate = op.intermediates.pop()
+    assert not semantic_checker.is_operator_semantic_valid(op)
+    op.intermediates.append(intermediate)
+    op.intermediates.append(intermediate)
+    assert not semantic_checker.is_operator_semantic_valid(op)
+    op.intermediates.pop()
+    # Test invalid number of inputs
+    input = op.inputs.pop()
+    assert not semantic_checker.is_operator_semantic_valid(op)
+    op.inputs.append(input)
+    op.inputs.append(input)
+    assert not semantic_checker.is_operator_semantic_valid(op)
+    op.inputs.pop()
+    # Test restored valid configuration
+    assert semantic_checker.is_operator_semantic_valid(op)