pytorch/torch/csrc/lazy/python
Bin Bao 6066e5929f [LT] Codegen ReuseNode for supported ops
Summary:
1. Update the codegen script to add a TrieCache lookup (ReuseNode)
before creating a new IR node. The following is an example generated
code,

```
    at::Tensor LazyNativeFunctions::add(const at::Tensor & self, const at::Tensor & other, const at::Scalar & alpha) {
        ...
        torch::lazy::NodePtr node = torch::lazy::ReuseNode<AddTensor>(lazy_self->GetIrValue(), lazy_other->GetIrValue(), node_alpha);
        if (!node) {
            auto out_meta = at::meta::add(self, other, alpha);
            std::vector<Shape> shapes{Shape(out_meta.scalar_type(), out_meta.sizes().vec())};
            TORCH_INTERNAL_ASSERT(shapes.size() == 1);
            if(symbolicShapeEnabled()){
                std::vector<jit::IValue> inputs = { self, other, alpha };
                char* schema_str = "aten::add.Tensor(Tensor self, Tensor other, *, Scalar alpha=1) -> Tensor";
                applySymbolicShapesOnLT(schema_str, inputs, shapes);
            }

            node = torch::lazy::MakeNode<AddTensor>(lazy_self->GetIrValue(), lazy_other->GetIrValue(), node_alpha, std::move(shapes));
            CacheNode(node);
        }
        ...
    }
```
2. TrieCache lookup depends on each IR node subclass to provide its own
comparison function. The following is an example generated code,

```
  bool CanBeReused(const torch::lazy::Value& self, const torch::lazy::Value& other, const torch::lazy::Value& alpha) const {
    size_t i = 0;
    return (operand(i++) == self &&
        operand(i++) == other &&
        operand(i++) == alpha);
  }
```

3. DeviceData is specially handled.

4. Non-codegen op changes are coming a separate PR.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/76738

Approved by: https://github.com/JackCaoG, https://github.com/wconstab
2022-05-13 19:13:58 +00:00
..
init.cpp [LT] Codegen ReuseNode for supported ops 2022-05-13 19:13:58 +00:00
init.h
python_util.cpp
python_util.h
README.md

Lazy Tensor Python Code

Lazy Tensor Core is part of libtorch, which can not depend on python.

Parts of lazy tensor core use python for 2 purposes A) py bindings let python programs call into lazy tensor c++ code B) lazy tensor core calls into python to use it (e.g. for grabbing stack traces)

(A) is trivial since the python bindings only depend on libtorch; (B) requires making libtorch_python register a function with libtorch if loaded, and having a default (no-op) function otherwise. Any functionality that strictly needs to depend on python should be part of the 'python' folder.