swjng opened a new pull request, #19511:
URL: https://github.com/apache/tvm/pull/19511
## Motivation
PyTorch's `torch.flip(x, dims=[...])` reverses every listed axis. The
Relax converter `_flip` (`base_fx_graph_translator.py`) instead coerces
the list to a single integer:
```python
if isinstance(dims, list | tuple) and len(dims) > 0:
dims = dims[0]
```
Only the first axis is forwarded to `relax.op.flip`, which is itself
single-axis. The remaining axes are silently dropped.
Minimal repro (vs PyTorch eager) on a `(3, 4)` input with
`dims=[-1, -2]`:
```
ref: [11, 10, 9, 8, 7, 6, 5, 4, ...] # both axes flipped
tvm: [ 3, 2, 1, 0, 7, 6, 5, 4, ...] # only last axis flipped
```
max_abs_diff = 8.0. Both the `torch.export` and legacy fx paths share
this converter, so both are affected.
## Fix
Iterate over `dims` in the converter and emit one `relax.op.flip` per
axis (flips along distinct axes commute, so the order is irrelevant).
A scalar `dims` is wrapped to a single-element list; non-int /
non-sequence arguments still raise `TypeError`.
`relax.op.flip` itself is unchanged: it is used elsewhere as a
single-axis op, and widening its signature would expand the scope of
this fix beyond the PyTorch frontend.
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