src/writer/spirv/function.cc

// Copyright 2020 The Tint Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "src/writer/spirv/function.h"

namespace tint {
namespace writer {
namespace spirv {
namespace {

// Returns true if the given Op is a function terminator
bool OpIsFunctionTerminator(spv::Op op) {
  return op == spv::Op::OpReturn || op == spv::Op::OpReturnValue ||
         op == spv::Op::OpKill;
}

}  // namespace

Function::Function()
    : declaration_(Instruction{spv::Op::OpNop, {}}),
      label_op_(Operand::Int(0)) {}

Function::Function(const Instruction& declaration,
                   const Operand& label_op,
                   const InstructionList& params)
    : declaration_(declaration), label_op_(label_op), params_(params) {}

Function::Function(const Function& other) = default;

Function::~Function() = default;

void Function::iterate(std::function<void(const Instruction&)> cb) const {
  cb(declaration_);

  for (const auto& param : params_) {
    cb(param);
  }

  cb(Instruction{spv::Op::OpLabel, {label_op_}});

  for (const auto& var : vars_) {
    cb(var);
  }
  for (const auto& inst : instructions_) {
    cb(inst);
  }

  bool needs_terminator = false;
  if (instructions_.empty()) {
    needs_terminator = true;
  } else {
    const auto& last = instructions_.back();
    needs_terminator = !OpIsFunctionTerminator(last.opcode());
  }
  if (needs_terminator) {
    cb(Instruction{spv::Op::OpReturn, {}});
  }

  cb(Instruction{spv::Op::OpFunctionEnd, {}});
}

}  // namespace spirv
}  // namespace writer
}  // namespace tint