// SPDX-License-Identifier: Apache-2.0

// SPDX-FileCopyrightText: 2019-2024 Second State INC

#include "executor/executor.h"

#include <cstdint>

#include <utility>

namespace WasmEdge {

namespace Executor {

// Instantiate function instance. See "include/executor/executor.h".

Expect<void> Executor::instantiate(Runtime::Instance::ModuleInstance &ModInst,

                                   const AST::FunctionSection &FuncSec,

                                   const AST::CodeSection &CodeSec) {

  // Get the function type indices.

  auto TypeIdxs = FuncSec.getContent();

  auto CodeSegs = CodeSec.getContent();

  if (CodeSegs.size() == 0) {

    return {};

  }

  // The module will always choose the `for` loop in `else` case under

  // interpreter mode. Instead, if we do branch in the `for` loop which might

  // cause meaningless branch misses. Therefore we should check the first item

  // and dispatch it into different cases to reduce branch misses.

  if (CodeSegs[0].getSymbol() != false) {

    for (uint32_t I = 0; I < CodeSegs.size(); ++I) {

      auto Symbol = CodeSegs[I].getSymbol();

      ModInst.addFunc(

          TypeIdxs[I],

          (*ModInst.getType(TypeIdxs[I]))->getCompositeType().getFuncType(),

          std::move(Symbol));

    }

  } else {

    // Iterate through the code segments to instantiate function instances.

    for (uint32_t I = 0; I < CodeSegs.size(); ++I) {

      // Create and add the function instance into the module instance.

      ModInst.addFunc(

          TypeIdxs[I],

          (*ModInst.getType(TypeIdxs[I]))->getCompositeType().getFuncType(),

          CodeSegs[I].getLocals(), CodeSegs[I].getExpr().getInstrs());

    }

  }

  return {};

}

} // namespace Executor

} // namespace WasmEdge