MLBEDSW-5162 MLCE: Vela [3.1.0] falling to run with yolov4_int8.tflite

* fix indices for tflite mapping of EXP operator
* fix indices for tflite mapping of Transpose operator
* ensure read offset after slice is aligned to 16 bytes for NHCWB16 or force linear format
* add unit test to ensure mapping of indices is consistent across TFLite, TOSA and NNG

Signed-off-by: James Ward <james.ward@arm.com>
Change-Id: I17b6e44bc06853325d5eea62a558418ee1ebefe8

1 files changed, 10 insertions, 7 deletions

diff --git a/ethosu/vela/graph_optimiser_util.py b/ethosu/vela/graph_optimiser_util.py
index 73fbf6c7..3e15f126 100644
--- a/ethosu/vela/graph_optimiser_util.py
+++ b/ethosu/vela/graph_optimiser_util.py
@@ -49,15 +49,18 @@ def _avoid_nhcwb16_for_concat(tens):
 
 def _avoid_nhcwb16_for_split(tens):
     # If read offset is not a multiple of 16 in the C-dimension, NHCWB16 need to be avoided in the input
+
+    # Return True if NHCWB16 needs to be avoided
+    def offset_not_aligned(read_offset):
+        return read_offset is not None and (read_offset.depth % 16) != 0
+
     for cons_op in tens.consumer_list:
         if cons_op.ifm == tens:
-            read_offset = cons_op.read_offsets[0]
-        elif cons_op.type.is_binary_elementwise_op() and cons_op.ifm2 == tens:
-            read_offset = cons_op.read_offsets[1]
-        else:
-            assert False
-        if read_offset is not None and (read_offset[-1] % 16) != 0:
-            return True
+            if offset_not_aligned(cons_op.read_offsets[0]):
+                return True
+        if cons_op.ifm2 is not None and cons_op.ifm2 == tens:
+            if offset_not_aligned(cons_op.read_offsets[1]):
+                return True
     return False