function.cpp

#include <torch/csrc/jit/mobile/function.h>

#include <caffe2/serialize/inline_container.h>
#include <torch/csrc/jit/mobile/interpreter.h>
#include <torch/csrc/jit/runtime/instruction.h>
#include <torch/csrc/jit/runtime/operator.h>

namespace torch {
namespace jit {

char const* toString(OpCode op);
namespace mobile {
Function::Function(c10::QualifiedName name)
    : name_(std::move(name)), code_(std::make_shared<Code>()) {}

const c10::QualifiedName& Function::qualname() const {
  return name_;
}

const std::string& Function::name() const {
  return name_.name();
}

void Function::append_instruction(OpCode op, int X, int N, int64_t dbg_handle) {
  TORCH_CHECK(
      isOpSupportedInMobile(op),
      toString(op),
      " is not supported in mobile module.");
  code_->instructions_with_handles_.emplace_back(
      Instruction(op, X, N), dbg_handle);
}

bool Function::append_operator(
    const std::string& name,
    const std::string& overload_name,
    const c10::optional<int>& num_specified_args,
    int64_t model_version, /* TODO: T90339189 deprecate all v3 when v3 models
                              are removed */
    OperatorCacheType& operator_cache) {
  // TODO: The c10::OperatorName class contains 2 std::string members, one
  // for the operator name, and one for the overload name. Creating a new
  // object of type c10::OperatorName creates these 2 strings, which cause
  // a heap memory allocation for each element element in code->opnames_.
  // This can be a significant perf. overhead for models that have a very
  // large list of operators.

  // Keep the original opname in code_
  code_->op_names_.emplace_back(name, overload_name);
  const auto& opname = code_->op_names_.back();

  const auto& opname_c10 = opname;
  std::function<void(Stack&)> fn;

  auto it = operator_cache.find(opname);
  if (it != operator_cache.end()) {
    // Operator (with fully qualified name) was found in the cache.
    if (it->second.has_same_arg_num(num_specified_args)) {
      // And it has the same number (or unspecified number) or arguments.
      code_->operators_.emplace_back(it->second.fn);
      return true;
    }
    // Operator found, but different argument list or specified/unspecified.
    // Fall back to creating one from scratch.
  }

  auto jit_op = findOperatorFor(opname);
  const std::vector<c10::Argument>* pArgs = nullptr;
  if (jit_op) {
    fn = [jit_op](Stack& stack) { jit_op->getOperation()(stack); };
    pArgs = &jit_op->schema().arguments();
  } else {
    auto op = c10::Dispatcher::singleton().findSchema(opname_c10);
    if (op.has_value()) {
      fn = [op](Stack& stack) { op->callBoxed(&stack); };
      if (op->hasSchema()) {
        pArgs = &op->schema().arguments();
      } else {
        TORCH_CHECK(false, "arguments are missing for operator ", opname);
      }
    } else {
      return false;
    }
  }

  TORCH_INTERNAL_ASSERT_DEBUG_ONLY(pArgs);
  const auto& args = *pArgs;
  if (model_version == 0x3LL &&
      opname == c10::OperatorName("aten::_convolution", "")) {
    // Since byte-code versions 0x4L, convolution has an additional
    // default-value argument (allow_tf32=True, see
    // https://github.com/pytorch/pytorch/pull/40737). This wrapper handles
    // backward compatibility with models of byte-code version <= 0x3L, where
    // this bool argument does not yet exist.
    fn = [fn](Stack& stack) {
      stack.push_back(true);
      fn(stack);
    };
  } else {
    // num_specified_args >= 0 indicates number of arguments are available
    // from model. We can use it to handle backward compatibility.
    if (num_specified_args &&
        num_specified_args.value() < static_cast<int64_t>(args.size())) {
      fn = [fn, num_specified_args, args](Stack& stack) {
        std::vector<IValue> out_args;
        // The following logic pops and temporarily stores all out arguments
        // from the stack (which can be 0 or more, and always appended to the
        // schema), in order to push the necessary default values. Finally, the
        // out arguments are pushed back into the stack.
        for (size_t i = args.size() - 1; i > 0 && args.at(i).is_out(); i--) {
          out_args.push_back(stack.back());
          stack.pop_back();
        }
        size_t start_index = num_specified_args.value() - out_args.size();
        TORCH_CHECK(
            start_index >= 0,
            "The number of output arguments is: ",
            out_args.size(),
            ", which is more then the number of specified arguments: ",
            num_specified_args.value());
        for (size_t i = start_index; i < (args.size() - out_args.size()); ++i) {
          TORCH_CHECK(
              args[i].default_value().has_value(),
              "Error happened at preparing for default values for the argument. The ",
              i,
              "th argument ",
              args[i].name(),
              " does not have a specified value or default value. ");

          stack.push_back(args[i].default_value());
        }
        stack.insert(stack.end(), out_args.rbegin(), out_args.rend());
        fn(stack);
      };
    }
  }
  code_->operators_.emplace_back(fn);
  if (it == operator_cache.end()) {
    // We came here because the operator name wasn't found in the cache,
    // not because there was a schema mismatch. Do add into the cache.
    operator_cache.insert(std::make_pair(
        opname, OperatorFunctionWithSchema{fn, num_specified_args}));
  }
  return true;
}

void Function::append_constant(const c10::IValue& constant) {
  code_->constants_.push_back(constant);
}

void Function::append_type(const at::TypePtr& type) {
  code_->types_.push_back(type);
}

void Function::set_register_size(size_t size) {
  code_->register_size_ = size;
}

int64_t Function::get_debug_handle(size_t pc) const {
  TORCH_CHECK(code_, "Valid code must exist.");
  TORCH_CHECK(
      pc < code_->instructions_with_handles_.size(),
      "Module debug info index out of boundary.");
  return code_->instructions_with_handles_[pc].debug_handle;
}

void Function::setSchema(c10::FunctionSchema schema) {
  schema_ = std::move(schema);
}

const at::optional<c10::FunctionSchema>& Function::getSchema() const {
  return schema_;
}

bool Function::run(Stack& stack) const {
  const auto& schema = getSchema();
  if (schema) { // if we have a schema then resolve optional args if any
    schema->checkAndNormalizeInputs(
        stack, std::unordered_map<std::string, IValue>{} /*kwargs*/);
  }
  InterpreterState interp_state(code_);
  return interp_state.run(stack);
}

c10::IValue Function::operator()(Stack& stack) const {
  run(stack);
  return stack.front();
}

const std::shared_ptr<Code> Function::get_code() const {
  return code_;
}

int64_t Function::getExceptionDebugHandle() const {
  size_t pc = getInterpretersExceptionPC();
  // we dont do bounds check given that pc is obtained
  // via internal method of getInterpretersExceptionPC
  // which returns the PC of where the interpreter is.
  // Although .at will do bounds check anyway.
  return code_->instructions_with_handles_.at(pc).debug_handle;
}

} // namespace mobile
} // namespace jit
} // namespace torch