# State of symbolic shapes branch

**URL:** <https://dev-discuss.pytorch.org/t/state-of-symbolic-shapes-branch/777>\
**Category:** compiler\
**Created:** [September 19, 2022, 5:32pm UTC](https://dev-discuss.pytorch.org/t/state-of-symbolic-shapes-branch/777 "2022-09-19T17:32:53Z")\
**Posts on this page:** 1\
**Showing post:** 27

<div class="post-metadata">

**Author:** ![nunoplopes](https://avatars.discourse-cdn.com/v4/letter/n/ee59a6/32.png) [@nunoplopes](https://dev-discuss.pytorch.org/u/nunoplopes)\
**Post date:** [December 27, 2022, 9:52am UTC](https://dev-discuss.pytorch.org/t/state-of-symbolic-shapes-branch/777/27 "2022-12-27T09:52:38Z")

</div>

Regarding crashes:  
this one issues a warning:

```python
@torch.compile
def fn(a):
    b = a * a
    return b

# [WARNING] Unsupported: meta converter nyi with fake tensor propagation
print(fn(torch.tensor([1.0, 2.0], device="meta")))

```

Assert fails:

```auto
@torch.compile
def fn(a):
    b = a * a
    return b

with FakeTensorMode() as mode:
    print(fn(torch.empty([2,3])))

# File "_dynamo/variables/builder.py", line 611, in wrap_tensor
# assert type(value) in (torch.Tensor, torch.nn.Parameter)

```

Assert fails; could give a nice error message:

```python
# without allow_meta=True
with FakeTensorMode() as mode:
    print(fn(torch.empty([2,3], device="meta")))

# File "_subclasses/fake_tensor.py", line 587, in __init__
# assert device.type != "meta"

```

Another crash:

```python
torch._dynamo.config.dynamic_shapes = True
torch._functorch.config.use_dynamic_shapes = True

@torch.compile
def fn(a):
    b = a * a
    return b

print(fn(torch.tensor([1.0, 2.0])))

# File "sympy/core/cache.py", line 70, in wrapper
# retval = cfunc(*args, **kwargs)
# TypeError: unhashable type: 'SymInt'
# RuntimeError: Trying to extract a concrete int out of a symbolic int

```

All I was trying was to print some complicated symbolic shape expressions so I could understand the problem a bit better. But then I hit all these crashes, so I must be doing something very wrong…

---

_[View the full topic](https://dev-discuss.pytorch.org/t/state-of-symbolic-shapes-branch/777)._