[TF FE] Use Convert instead of ConvertLike for Slice stop#36209
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The TF/TFLite Slice translator builds the absolute `stop` as
Select(Less(size, 0), ConvertLike(ShapeOf(data), size), Add(start, size)).
v8::Slice resolves `stop` through value-bounds propagation
(evaluate_both_bounds), not constant folding. ConvertLike implements only
constant_fold, not evaluate_lower/upper, so the bound walk breaks at
ConvertLike before reaching Select, and the Slice output is left dynamic even
when the data shape and start/size are fully static. This trips downstream
consumers that require a static shape.
Build the negative-size branch with v0::Convert (to size's element type)
instead of v1::ConvertLike. Convert is value-identical here but already
implements bound evaluation, so bounds propagate through the whole cascade:
Select resolves its statically-false condition and Slice infers a static
output during validate_and_infer_types(), with no folding pass. This also
makes the size = -1 ("to end") case static whenever the data shape is static.
Add a TF frontend regression test (slice_static_shape.pbtxt) that converts a
static-input Slice without MOC and asserts the Slice output stays static.
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category: TF FE
mvafin
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Jun 3, 2026
| // resolve `stop` and keep the output static when the data shape is static. | ||
| Output<Node> stop_neg = make_shared<v3::ShapeOf>(input); | ||
| stop_neg = make_shared<v1::ConvertLike>(stop_neg, size); | ||
| stop_neg = make_shared<v0::Convert>(stop_neg, size.get_element_type()); |
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That is not good, because size is input to operation, it can be dynamic and can have dynamic type, that is why ConvertLike was used here
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Details:
The TF/TFLite Slice translator builds the absolute
stopasSelect(Less(size, 0), ConvertLike(ShapeOf(data), size), Add(start, size)).v8::Slice resolves
stopthrough value-bound propagation (evaluate_both_bounds),not constant folding. ConvertLike implements only
constant_fold, notevaluate_lower/evaluate_upper, so the bound walk breaks at ConvertLike beforereaching Select. As a result the Slice output stays dynamic even when the data
shape and start/size are static. This later trips consumers that need a static
shape (e.g. read_model fed into NPUW: "to_shape was called on a dynamic shape").
Build the negative-size branch with
v0::Convert(to size's element type)instead of
v1::ConvertLike. Convert is value-identical here but alreadyimplements bound evaluation, so bounds propagate through the cascade: Select
resolves its statically-false condition and Slice infers a static output during
validate_and_infer_types(), with no folding pass. This also makes thesize = -1case static when the data shape is static.Add a TF frontend test that converts a static-input Slice without MOC and checks
the Slice output stays static.
Tickets: