The basic idea behind this PR is that we want to continue using the guarding implementations of contiguity tests, if all of the elements are backend (aka, have hints). If they don't have hints, we'll have to do something slower (use the non-short circuiting, non guarding implementations of contiguity), but most of the time you aren't dealing with unbacked SymInts.
So this PR has three parts.
1. We expose `has_hint` on `SymNode`. This allows us to query whether or not a SymInt is backed or not from C++. Fairly self explanatory. Will require LTC/XLA updates; but for backends that don't support unbacked SymInts you can just always return true.
2. We update `compute_non_overlapping_and_dense` to test if the inputs are hinted. If they are all hinted, we use the conventional C++ implementation. Otherwise we call into Python. The Python case is not heavily tested right now because I haven't gotten all of the pieces for unbacked SymInts working yet. Coming soon.
3. We add stubs for all of the other contiguity tests. The intention is to apply the same treatment to them as well, but this is not wired up yet for safety reasons.
Signed-off-by: Edward Z. Yang <ezyang@meta.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94431
Approved by: https://github.com/voznesenskym
I saw some missed optimization opportunities in C10 using std::move and thought I would submit a PR to fix them. There are particularly a lot of them dealing with the symbolic operators which are used in quite a few places including in loops.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88512
Approved by: https://github.com/ezyang
This refactor was prompted by challenges handling mixed int/float
operations in C++. A previous version of this patch
added overloads for each permutation of int/float and was unwieldy
https://github.com/pytorch/pytorch/pull/87722/ This PR takes a different
approach.
The general outline of the patch is to combine the C++ types SymIntNode
and SymFloatNode into a single type, SymNode. This is type erased; we
no longer know statically at C++ if we have an int/float and have to test
it with the is_int()/is_float() virtual methods. This has a number of
knock on effects.
- We no longer have C++ classes to bind to Python. Instead, we take an
entirely new approach to our Python API, where we have a SymInt/SymFloat
class defined entirely in Python, which hold a SymNode (which corresponds
to the C++ SymNode). However, SymNode is not pybind11-bound; instead,
it lives as-is in Python, and is wrapped into C++ SymNode using PythonSymNode
when it goes into C++. This implies a userland rename.
In principle, it is also possible for the canonical implementation of SymNode
to be written in C++, and then bound to Python with pybind11 (we have
this code, although it is commented out.) However, I did not implement
this as we currently have no C++ implementations of SymNode.
Because we do return SymInt/SymFloat from C++ bindings, the C++ binding
code needs to know how to find these classes. Currently, this is done
just by manually importing torch and getting the attributes.
- Because SymInt/SymFloat are easy Python wrappers, __sym_dispatch__ now
takes SymInt/SymFloat, rather than SymNode, bringing it in line with how
__torch_dispatch__ works.
Some miscellaneous improvements:
- SymInt now has a constructor that takes SymNode. Note that this
constructor is ambiguous if you pass in a subclass of SymNode,
so an explicit downcast is necessary. This means toSymFloat/toSymInt
are no more. This is a mild optimization as it means rvalue reference
works automatically.
- We uniformly use the caster for c10::SymInt/SymFloat, rather than
going the long way via the SymIntNode/SymFloatNode.
- Removed some unnecessary toSymInt/toSymFloat calls in normalize_*
functions, pretty sure this doesn't do anything.
- guard_int is now a free function, since to guard on an int you cannot
assume the method exists. A function can handle both int and SymInt
inputs.
- We clean up the magic method definition code for SymInt/SymFloat/SymNode.
ONLY the user classes (SymInt/SymFloat) get magic methods; SymNode gets
plain methods; this is to help avoid confusion between the two types.
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
cc @jansel @mlazos @soumith @voznesenskym @yanboliang @penguinwu @anijain2305
Pull Request resolved: https://github.com/pytorch/pytorch/pull/87817
Approved by: https://github.com/albanD, https://github.com/anjali411
This is by no means comprehensive, but adds initial support for SymInt as a Scalar.
Things that don't work yet but need to:
- for some reason `torch.add(tensor, sym_int)` got matched to the `add.Tensor(Tensor self, Tensor other, *, Scalar alpha=1) -> Tensor` schema
- `x + sym_int` failed bc we tried to turn `x` into a sym int:
```
"__radd__",
[](c10::SymIntNode a, py::object b) -> c10::SymIntNode {
auto snb = toSymIntNode(a, b);
return a->add(snb);
})
```
- Many more things I'm sure
Pull Request resolved: https://github.com/pytorch/pytorch/pull/84958
Approved by: https://github.com/ezyang
