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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>
namespace {
using torch::autograd::Variable;
void check_single_result(
const at::TensorBase& value,
const at::TensorBase& result,
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 {
namespace autograd {
// NOLINTNEXTLINE(modernize-pass-by-value)
CppFunctionPreHook::CppFunctionPreHook(
const std::shared_ptr<hooks_list>& hooks,
int value_idx)
: hooks_(hooks), value_idx_(value_idx) {}
variable_list CppFunctionPreHook::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, c10::to_string(i));
value = std::move(res);
}
variable_list results(values);
results[value_idx_] = value;
return results;
}
} // namespace autograd
} // namespace torch
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