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#include <c10/util/irange.h>
#include <torch/csrc/autograd/cpp_hook.h>
#include <torch/csrc/autograd/custom_function.h>
#include <torch/csrc/autograd/variable.h>
#include <utility>
namespace {
using torch::autograd::Variable;
void check_single_result(
const at::TensorBase& value,
const at::TensorBase& result,
const std::string& hook_name) {
if (!value.defined()) {
throw std::runtime_error(
"can't replace a empty gradient with a non-empty value");
}
torch::autograd::check_variable_result(value, result, hook_name);
}
} // namespace
namespace torch::autograd {
CppFunctionTensorPreHook::CppFunctionTensorPreHook(
std::shared_ptr<hooks_list> hooks,
size_t value_idx)
: hooks_(std::move(hooks)), value_idx_(value_idx) {}
variable_list CppFunctionTensorPreHook::operator()(
const variable_list& values) {
auto value = values[value_idx_];
for (const auto i : c10::irange(hooks_->size())) {
auto& hook = (*hooks_)[i];
if (!hook) {
// hook was removed
continue;
}
auto res = hook(value);
if (!res.defined()) {
// Don't change gradient
continue;
}
check_single_result(value, res, std::to_string(i));
value = std::move(res);
}
variable_list results(values);
results[value_idx_] = value;
return results;
}
CppFunctionSingleTensorPreHook::CppFunctionSingleTensorPreHook(
std::function<at::TensorBase(const at::TensorBase&)> hook,
size_t value_idx)
: hook_(std::move(hook)), value_idx_(value_idx) {}
variable_list CppFunctionSingleTensorPreHook::operator()(
const variable_list& values) {
const auto& value = values[value_idx_];
auto res = hook_(value);
TORCH_INTERNAL_ASSERT(
!res.defined(),
"CppFunctionSingleTensorPreHook currently only supports hooks that don't return");
variable_list results(values);
return results;
}
} // namespace torch::autograd
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