pytorch/test/custom_operator/op.cpp
Brian Hirsh 4fcdbb824b Updating all call-sites of the legacy dispatcher registration API in fbcode to the new API. (#48178)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48178

I migrated all call sites that used the legacy dispatcher registration API (RegisterOperators()) to use the new API (TORCH_LIBRARY...). I found all call-sites by running `fbgs RegisterOperators()`. This includes several places, including other OSS code (nestedtensor, torchtext, torchvision). A few things to call out:

For simple ops that only had one registered kernel without a dispatch key, I replaced them with:
```
TORCH_LIBRARY_FRAGMENT(ns, m) {
   m.def("opName", fn_name);
}
```

For ops that registered to a specific dispatch key / had multiple kernels registered, I registered the common kernel (math/cpu) directly inside a `TORCH_LIBRARY_FRAGMENT` block, and registered any additional kernels from other files (e.g. cuda) in a separate `TORCH_LIBRARY_IMPL` block.

```
// cpu file
TORCH_LIBRARY_FRAGMENT(ns, m) {
  m.def("opName(schema_inputs) -> schema_outputs");
  m.impl("opName", torch::dispatch(c10::DispatchKey::CPU, TORCH_FN(cpu_kernel)));
}

// cuda file
TORCH_LIBRARY_IMPL(ns, CUDA, m) {
  m.impl("opName", torch::dispatch(c10::DispatchKey::CUDA, TORCH_FN(cuda_kernel)));
}
```
Special cases:

I found a few ops that used a (legacy) `CPUTensorId`/`CUDATensorId` dispatch key. Updated those to use CPU/CUDA- this seems safe because the keys are aliased to one another in `DispatchKey.h`

There were a handful of ops that registered a functor (function class) to the legacy API. As far as I could tell we don't allow this case in the new API, mainly because you can accomplish the same thing more cleanly with lambdas. Rather than delete the class I wrote a wrapper function on top of the class, which I passed to the new API.

There were a handful of ops that were registered only to a CUDA dispatch key. I put them inside a TORCH_LIBRARY_FRAGMENT block, and used a `def()` and `impl()` call like in case two above.

Test Plan: Imported from OSS

Reviewed By: ezyang

Differential Revision: D25056090

Pulled By: bdhirsh

fbshipit-source-id: 8f868b45f545e5da2f21924046e786850eba70d9
2020-12-02 11:19:31 -08:00

70 lines
2.1 KiB
C++

#include <torch/script.h>
#include "op.h"
#include <cstddef>
#include <string>
torch::List<torch::Tensor> custom_op(
torch::Tensor tensor,
double scalar,
int64_t repeat) {
torch::List<torch::Tensor> output;
output.reserve(repeat);
for (int64_t i = 0; i < repeat; ++i) {
output.push_back(tensor * scalar);
}
return output;
}
int64_t custom_op2(std::string s1, std::string s2) {
return s1.compare(s2);
}
struct CustomOpAutogradFunction : public torch::autograd::Function<CustomOpAutogradFunction> {
static torch::Tensor forward(
torch::autograd::AutogradContext* ctx,
torch::Tensor var1,
int64_t mul,
torch::Tensor var2,
c10::optional<torch::Tensor> var3) {
ctx->saved_data["mul"] = mul;
ctx->saved_data["var3_has_value"] = var3.has_value();
ctx->save_for_backward({var1, var2});
if (var3) {
return var1 + mul * var2 + var1 * var2 + var3.value();
}
return var1 + mul*var2 + var1*var2;
}
static torch::autograd::variable_list backward(torch::autograd::AutogradContext *ctx, torch::autograd::variable_list grad_output) {
int mul = ctx->saved_data["mul"].toInt();
bool var3_has_value = ctx->saved_data["var3_has_value"].toBool();
auto saved = ctx->get_saved_variables();
auto var1 = saved[0];
auto var2 = saved[1];
auto var3_grad = var3_has_value ? grad_output[0] : torch::Tensor();
torch::autograd::variable_list output = {
grad_output[0] + grad_output[0] * var2,
torch::Tensor(),
grad_output[0] * mul + grad_output[0] * var1,
var3_grad};
return output;
}
};
torch::Tensor custom_op_with_autograd(
torch::Tensor var1,
int64_t mul,
torch::Tensor var2,
c10::optional<torch::Tensor> var3) {
return CustomOpAutogradFunction::apply(var1, mul, var2, var3);
}
TORCH_LIBRARY_FRAGMENT(custom, m) {
m.def("op", custom_op);
m.def("op2", custom_op2);
m.def("op_with_defaults(Tensor tensor, float scalar = 1, int repeat = 1) -> Tensor[]", custom_op);
m.def("op_with_autograd(Tensor var1, int mul, Tensor var2, Tensor? var3=None) -> Tensor", custom_op_with_autograd);
}