// SPDX-License-Identifier: Apache-2.0

// SPDX-FileCopyrightText: Copyright The WasmEdge Authors

#include "executor/executor.h"

#include "common/spdlog.h"

#include "system/fault.h"

#include "system/stacktrace.h"

#include <cstdint>

#include <utility>

#include <vector>

namespace WasmEdge {

namespace Executor {

Executor::SavedThreadLocal::SavedThreadLocal(

    Executor &Ex, Runtime::StackManager &StackMgr,

    const Runtime::Instance::FunctionInstance &Func) noexcept {

  // Prepare the execution context.

  auto *ModInst =

      const_cast<Runtime::Instance::ModuleInstance *>(Func.getModule());

  SavedThis = This;

  This = &Ex;

  SavedExecutionContext = ExecutionContext;

  ExecutionContext.Memories = ModInst->MemoryPtrs.data();

  ExecutionContext.MemorySizes = ModInst->MemorySizePtrs.data();

  ExecutionContext.TableRefs = ModInst->TableRefPtrs.data();

  ExecutionContext.TableSizes = ModInst->TableSizePtrs.data();

  ExecutionContext.Globals = ModInst->GlobalPtrs.data();

  ExecutionContext.Tags =

      reinterpret_cast<void *const *>(ModInst->TagInsts.data());

  ExecutionContext.PendingExnTagAddr =

      reinterpret_cast<void *const *>(&PendingExn.TagInst);

  if (Ex.Stat) {

    ExecutionContext.InstrCount = &Ex.Stat->getInstrCountRef();

    ExecutionContext.CostTable = Ex.Stat->getCostTable().data();

    ExecutionContext.Gas = &Ex.Stat->getTotalCostRef();

    ExecutionContext.GasLimit = Ex.Stat->getCostLimit();

  }

  ExecutionContext.StopToken = &Ex.StopToken;

  ExecutionContext.ModuleInst = ModInst;

  SavedCurrentStack = CurrentStack;

  CurrentStack = &StackMgr;

}

Executor::SavedThreadLocal::~SavedThreadLocal() noexcept {

  CurrentStack = SavedCurrentStack;

  ExecutionContext = SavedExecutionContext;

  This = SavedThis;

}

Expect<AST::InstrView::iterator>

Executor::enterFunction(Runtime::StackManager &StackMgr,

                        const Runtime::Instance::FunctionInstance &Func,

                        const AST::InstrView::iterator RetIt, bool IsTailCall,

                        bool IsNativeEntry) {

  // RetIt: the return position when the entered function returns.

  // Check whether interruption occurred.

  if (unlikely(StopToken.exchange(0, std::memory_order_relaxed))) {

    spdlog::error(ErrCode::Value::Interrupted);

    return Unexpect(ErrCode::Value::Interrupted);

  }

  // Get the function type for the parameter and return counts.

  const auto &FuncType = Func.getFuncType();

  const uint32_t ArgsN = static_cast<uint32_t>(FuncType.getParamTypes().size());

  const uint32_t RetsN =

      static_cast<uint32_t>(FuncType.getReturnTypes().size());

  // For the exception handler, remove the inactive handlers caused by the

  // branches.

  const auto Instrs = Func.getInstrs();

  if (likely(RetIt) && RetIt != Instrs.begin()) {

    StackMgr.removeInactiveHandler(RetIt - 1);

  }

  if (Func.isHostFunction()) {

    // Host function case: Push args and call function.

    auto &HostFunc = Func.getHostFunc();

    // Finalize the host module on its first host-function invocation, after

    // which adding host instances to it is rejected.

    if (const auto *HostModInst = Func.getModule()) {

      HostModInst->finalizeInstantiation();

    }

    // Generate CallingFrame from current frame.

    // The module instance will be nullptr if current frame is a dummy frame.

    // For this case, use the module instance of this host function.

    const auto *ModInst = StackMgr.getModule();

    if (ModInst == nullptr) {

      ModInst = Func.getModule();

    }

    Runtime::CallingFrame CallFrame(this, ModInst);

    // Push frame.

    StackMgr.pushFrame(Func.getModule(), // Module instance

                       RetIt,            // Return PC

                       ArgsN,            // Only args, no locals in stack

                       RetsN,            // Returns num

                       IsTailCall,       // For tail-call

                       IsNativeEntry     // For native entry

    );

    // Do the statistics if the statistics turned on.

    if (Stat) {

      // Check host function cost.

      if (unlikely(!Stat->addCost(HostFunc.getCost()))) {

        spdlog::error(ErrCode::Value::CostLimitExceeded);

        return Unexpect(ErrCode::Value::CostLimitExceeded);

      }

      // Start recording time of running host function.

      Stat->stopRecordWasm();

      Stat->startRecordHost();

    }

    // Call pre-host-function

    HostFuncHelper.invokePreHostFunc();

    // Run host function.

    Span<ValVariant> Args = StackMgr.getTopSpan(ArgsN);

    for (uint32_t I = 0; I < ArgsN; I++) {

      // For the number type cases of the arguments, the unused bits should be

      // erased due to the security issue.

      cleanNumericVal(Args[I], FuncType.getParamTypes()[I]);

    }

    std::vector<ValVariant> Rets(RetsN);

    auto Ret = HostFunc.run(CallFrame, std::move(Args), Rets);

    // Call post-host-function

    HostFuncHelper.invokePostHostFunc();

    // Do the statistics if the statistics turned on.

    if (Stat) {

      // Stop recording time of running host function.

      Stat->stopRecordHost();

      Stat->startRecordWasm();

    }

    // Check the host function execution status.

    if (!Ret) {

      if (Ret.error() == ErrCode::Value::HostFuncError ||

          Ret.error().getCategory() != ErrCategory::WASM) {

        spdlog::error(Ret.error());

      }

      return Unexpect(Ret);

    }

    // Push returns back to the stack.

    for (auto &R : Rets) {

      StackMgr.push(std::move(R));

    }

    // For host function case, the continuation will be the continuation from

    // the popped frame.

    return StackMgr.popFrame();

  } else if (Func.isCompiledFunction()) {

    // Compiled function case: Execute the function and jump to the

    // continuation.

    // Push frame.

    StackMgr.pushFrame(Func.getModule(), // Module instance

                       RetIt,            // Return PC

                       ArgsN,            // Only args, no locals in stack

                       RetsN,            // Returns num

                       IsTailCall,       // For tail-call

                       IsNativeEntry     // For native entry

    );

    // Prepare arguments.

    Span<ValVariant> Args = StackMgr.getTopSpan(ArgsN);

    std::vector<ValVariant> Rets(RetsN);

    SavedThreadLocal Saved(*this, StackMgr, Func);

    ErrCode Err;

    try {

      // Get symbol and execute the function.

      Fault FaultHandler;

      uint32_t Code = PREPARE_FAULT(FaultHandler);

      if (Code != 0) {

        auto InnerStackTrace = FaultHandler.stacktrace();

        {

          std::array<void *, 256> Buffer;

          auto OuterStackTrace = stackTrace(Buffer);

          while (!OuterStackTrace.empty() && !InnerStackTrace.empty() &&

                 InnerStackTrace[InnerStackTrace.size() - 1] ==

                     OuterStackTrace[OuterStackTrace.size() - 1]) {

            InnerStackTrace = InnerStackTrace.first(InnerStackTrace.size() - 1);

            OuterStackTrace = OuterStackTrace.first(OuterStackTrace.size() - 1);

          }

        }

        StackTraceSize =

            compiledStackTrace(StackMgr, InnerStackTrace, StackTrace).size();

        Err = ErrCode(static_cast<ErrCategory>(Code >> 24), Code);

      } else {

        auto &Wrapper = FuncType.getSymbol();

        Wrapper(&ExecutionContext, Func.getSymbol().get(), Args.data(),

                Rets.data());

      }

    } catch (const ErrCode &E) {

      Err = E;

    }

    if (unlikely(Err)) {

      if (Err != ErrCode::Value::Terminated) {

        spdlog::error(Err);

      }

      StackTraceSize +=

          interpreterStackTrace(

              StackMgr, Span<uint32_t>{StackTrace}.subspan(StackTraceSize))

              .size();

      return Unexpect(Err);

    }

    if (unlikely(PendingExn.TagInst != nullptr)) {

      // The exception escapes this frame: discard it, then hand off to the

      // native caller or continue the handler walk in the interpreter caller.

      const bool FromNative = StackMgr.isTopFrameNativeEntry();

      // Push the dummy results for popping the frame, then drop them because

      // the escaping exception produces no results.

      for (uint32_t I = 0; I < RetsN; ++I) {

        StackMgr.push(Rets[I]);

      }

      AST::InstrView::iterator ResumePC = StackMgr.popFrame();

      StackMgr.eraseValueStack(RetsN, 0);

      if (FromNative) {

        return Unexpect(ErrCode::Value::PendingException);

      }

      auto &TagInst = *PendingExn.TagInst;

      const auto *ExnInst = PendingExn.Inst;

      StackMgr.pushValVec(PendingExn.getPayload());

      PendingExn = {};

      EXPECTED_TRY(throwException(StackMgr, TagInst, ResumePC, ExnInst));

      return ResumePC + 1;

    }

    // Push returns back to the stack.

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

      StackMgr.push(Rets[I]);

    }

    // For compiled function case, the continuation will be the continuation

    // from the popped frame.

    return StackMgr.popFrame();

  } else {

    // WASM interpreter case: Jump to the start of the function body.

    // Push local variables into the stack.

    for (auto &Def : Func.getLocals()) {

      if (Def.second.isRefType() && !Def.second.isAbsHeapType()) {

        // For non-abstract heap types (concrete type indices), convert the

        // null ref to the abstract heap type so that ref.cast/ref.test won't

        // dereference a null pointer when checking the type.

        const auto &CompType = Func.getModule()

                                   ->unsafeGetType(Def.second.getTypeIndex())

                                   ->getCompositeType();

        auto BotTypeCode =

            CompType.isFunc() ? TypeCode::NullFuncRef : TypeCode::NullRef;

        RefVariant InitVal(ValType(TypeCode::RefNull, BotTypeCode));

        for (uint32_t I = 0; I < Def.first; I++) {

          StackMgr.push(InitVal);

        }

      } else {

        for (uint32_t I = 0; I < Def.first; I++) {

          StackMgr.push(ValueFromType(Def.second));

        }

      }

    }

    // Push frame.

    // The PC must -1 here because in the interpreter mode execution, the PC

    // will increase after the callee returns.

    StackMgr.pushFrame(Func.getModule(),           // Module instance

                       RetIt - 1,                  // Return PC

                       ArgsN + Func.getLocalNum(), // Arguments num + local num

                       RetsN,                      // Returns num

                       IsTailCall,                 // For tail-call

                       IsNativeEntry               // For native entry

    );

    // For the WASM interpreter case, the continuation will be the start of the

    // function body.

    return Instrs.begin();

  }

}

Expect<void>

Executor::branchToLabel(Runtime::StackManager &StackMgr,

                        const AST::Instruction::JumpDescriptor &JumpDesc,

                        AST::InstrView::iterator &PC) noexcept {

  // Check the stop token.

  if (unlikely(StopToken.exchange(0, std::memory_order_relaxed))) {

    spdlog::error(ErrCode::Value::Interrupted);

    return Unexpect(ErrCode::Value::Interrupted);

  }

  StackMgr.eraseValueStack(JumpDesc.StackEraseBegin, JumpDesc.StackEraseEnd);

  // PC needs -1 here because the PC will increase in the next iteration.

  PC += (JumpDesc.PCOffset - 1);

  // A branch leaves the innermost blocks without running their `end`, so the

  // handlers it strands are the top of the handler stack right now. Drop them

  // here: once a later try_table is pushed on top they are indistinguishable

  // from active handlers, and their stale VPos would invert the erase range in

  // popTopHandler. PC + 1 is the instruction being branched to.

  StackMgr.removeInactiveHandler(PC + 1);

  return {};

}

Expect<void> Executor::throwException(

    Runtime::StackManager &StackMgr, Runtime::Instance::TagInstance &TagInst,

    AST::InstrView::iterator &PC,

    const Runtime::Instance::ExceptionInstance *ExnInst) noexcept {

  StackMgr.removeInactiveHandler(PC);

  auto AssocValSize = TagInst.getTagType().getAssocValSize();

  while (true) {

    // Pop the top handler.

    auto Handler = StackMgr.popTopHandler(AssocValSize);

    if (!Handler.has_value()) {

      break;

    }

    // Checking through the catch clause.

    for (const auto &C : Handler->CatchClause) {

      if (!C.IsAll && getTagInstByIdx(StackMgr, C.TagIndex) != &TagInst) {

        // Specific-tag clauses require tag-address equivalence; skip the

        // ones that do not match.

        continue;

      }

      if (C.IsRef) {

        // Allocate the exception instance lazily on the first catch_ref;

        // reuse the one passed in by throw_ref to preserve exnref identity.

        const Runtime::Instance::ExceptionInstance *Inst = ExnInst;

        if (Inst == nullptr) {

          auto Payload = StackMgr.getTopSpan(AssocValSize);

          std::vector<ValVariant> Vec(Payload.begin(), Payload.end());

          auto *ModInst = const_cast<Runtime::Instance::ModuleInstance *>(

              StackMgr.getModule());

          Inst = ModInst->newException(&TagInst, std::move(Vec));

        }

        if (C.IsAll) {

          StackMgr.eraseValueStack(AssocValSize, 0);

        }

        StackMgr.push(

            RefVariant(ValType(TypeCode::Ref, TypeCode::ExnRef), Inst));

      } else if (C.IsAll) {

        StackMgr.eraseValueStack(AssocValSize, 0);

      }

      // When an exception is caught, move the PC to the try block and branch to

      // the label.

      PC = Handler->Try;

      return branchToLabel(StackMgr, C.Jump, PC);

    }

  }

  if (StackMgr.isTopFrameNativeEntry()) {

    // Stopped at a frame entered from the native code: record the exception

    // as pending and restore the stack; the native caller continues it.

    PendingExn.TagInst = &TagInst;

    PendingExn.Inst = ExnInst;

    PendingExn.setPayload(StackMgr.getTopSpan(AssocValSize));

    // Push the dummy results for popping the frame, then drop them because

    // the escaping exception produces no results.

    const uint32_t Arity = StackMgr.getFramesSpan().back().Arity;

    for (uint32_t I = 0; I < Arity; ++I) {

      StackMgr.push(ValVariant());

    }

    StackMgr.popFrame();

    StackMgr.eraseValueStack(Arity, 0);

    return Unexpect(ErrCode::Value::PendingException);

  }

  spdlog::error(ErrCode::Value::UncaughtException);

  return Unexpect(ErrCode::Value::UncaughtException);

}

Expect<void>

Executor::checkOffsetOverflow(const Runtime::Instance::MemoryInstance &MemInst,

                              const AST::Instruction &Instr, const uint64_t Val,

                              const uint64_t Size) const noexcept {

  // This function simply checks that the calculated offset fits in 64 bits.

  uint64_t StartOffset;

#if defined(_MSC_VER) && !defined(__clang__) // MSVC

  if (std::numeric_limits<uint64_t>::max() - Instr.getMemoryOffset() < Val) {

    StartOffset = Instr.getMemoryOffset() + Val;

#else

  if (unlikely(

          __builtin_add_overflow(Instr.getMemoryOffset(), Val, &StartOffset))) {

#endif

    spdlog::error(ErrCode::Value::MemoryOutOfBounds);

    spdlog::error(

        ErrInfo::InfoBoundary(StartOffset, Size, MemInst.getSize(), true));

    spdlog::error(

        ErrInfo::InfoInstruction(Instr.getOpCode(), Instr.getOffset()));

    return Unexpect(ErrCode::Value::MemoryOutOfBounds);

  }

  return {};

}

const AST::SubType *Executor::getDefTypeByIdx(Runtime::StackManager &StackMgr,

                                              const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetType(Idx);

}

const WasmEdge::AST::CompositeType &

Executor::getCompositeTypeByIdx(Runtime::StackManager &StackMgr,

                                const uint32_t Idx) const noexcept {

  auto *DefType = getDefTypeByIdx(StackMgr, Idx);

  assuming(DefType);

  const auto &CompType = DefType->getCompositeType();

  assuming(!CompType.isFunc());

  return CompType;

}

const ValType &

Executor::getStructStorageTypeByIdx(Runtime::StackManager &StackMgr,

                                    const uint32_t Idx,

                                    const uint32_t Off) const noexcept {

  const auto &CompType = getCompositeTypeByIdx(StackMgr, Idx);

  assuming(static_cast<uint32_t>(CompType.getFieldTypes().size()) > Off);

  return CompType.getFieldTypes()[Off].getStorageType();

}

const ValType &

Executor::getArrayStorageTypeByIdx(Runtime::StackManager &StackMgr,

                                   const uint32_t Idx) const noexcept {

  const auto &CompType = getCompositeTypeByIdx(StackMgr, Idx);

  assuming(static_cast<uint32_t>(CompType.getFieldTypes().size()) == 1);

  return CompType.getFieldTypes()[0].getStorageType();

}

Runtime::Instance::FunctionInstance *

Executor::getFuncInstByIdx(Runtime::StackManager &StackMgr,

                           const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetFunction(Idx);

}

Runtime::Instance::TableInstance *

Executor::getTabInstByIdx(Runtime::StackManager &StackMgr,

                          const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetTable(Idx);

}

Runtime::Instance::MemoryInstance *

Executor::getMemInstByIdx(Runtime::StackManager &StackMgr,

                          const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetMemory(Idx);

}

Runtime::Instance::TagInstance *

Executor::getTagInstByIdx(Runtime::StackManager &StackMgr,

                          const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetTag(Idx);

}

Runtime::Instance::GlobalInstance *

Executor::getGlobInstByIdx(Runtime::StackManager &StackMgr,

                           const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetGlobal(Idx);

}

Runtime::Instance::ElementInstance *

Executor::getElemInstByIdx(Runtime::StackManager &StackMgr,

                           const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetElem(Idx);

}

Runtime::Instance::DataInstance *

Executor::getDataInstByIdx(Runtime::StackManager &StackMgr,

                           const uint32_t Idx) const {

  const auto *ModInst = StackMgr.getModule();

  // When the top frame is a dummy frame, the instance cannot be found.

  if (unlikely(ModInst == nullptr)) {

    return nullptr;

  }

  return ModInst->unsafeGetData(Idx);

}

TypeCode Executor::toBottomType(Runtime::StackManager &StackMgr,

                                const ValType &Type) const {

  if (Type.isRefType()) {

    if (Type.isAbsHeapType()) {

      switch (Type.getHeapTypeCode()) {

      case TypeCode::NullFuncRef:

      case TypeCode::FuncRef:

        return TypeCode::NullFuncRef;

      case TypeCode::NullExternRef:

      case TypeCode::ExternRef:

        return TypeCode::NullExternRef;

      case TypeCode::NullRef:

      case TypeCode::AnyRef:

      case TypeCode::EqRef:

      case TypeCode::I31Ref:

      case TypeCode::StructRef:

      case TypeCode::ArrayRef:

        return TypeCode::NullRef;

      case TypeCode::NullExnRef:

      case TypeCode::ExnRef:

        return TypeCode::NullExnRef;

      default:

        assumingUnreachable();

      }

    } else {

      const auto &CompType = StackMgr.getModule()

                                 ->unsafeGetType(Type.getTypeIndex())

                                 ->getCompositeType();

      if (CompType.isFunc()) {

        return TypeCode::NullFuncRef;

      } else {

        return TypeCode::NullRef;

      }

    }

  } else {

    return Type.getCode();

  }

}

void Executor::cleanNumericVal(ValVariant &Val,

                               const ValType &Type) const noexcept {

  if (Type.isNumType()) {

    switch (Type.getCode()) {

    case TypeCode::I32: {

      uint32_t V = Val.get<uint32_t>();

      Val.emplace<uint128_t>(static_cast<uint128_t>(0U));

      Val.emplace<uint32_t>(V);

      break;

    }

    case TypeCode::F32: {

      float V = Val.get<float>();

      Val.emplace<uint128_t>(static_cast<uint128_t>(0U));

      Val.emplace<float>(V);

      break;

    }

    case TypeCode::I64: {

      uint64_t V = Val.get<uint64_t>();

      Val.emplace<uint128_t>(static_cast<uint128_t>(0U));

      Val.emplace<uint64_t>(V);

      break;

    }

    case TypeCode::F64: {

      double V = Val.get<double>();

      Val.emplace<uint128_t>(static_cast<uint128_t>(0U));

      Val.emplace<double>(V);

      break;

    }

    default:

      break;

    }

  }

}

ValVariant Executor::packVal(const ValType &Type,

                             const ValVariant &Val) const noexcept {

  if (Type.isPackType()) {

    switch (Type.getCode()) {

    case TypeCode::I8:

      if constexpr (Endian::native == Endian::little) {

        return ValVariant(Val.get<uint32_t>() & 0xFFU);

      } else {

        return ValVariant(Val.get<uint32_t>() << 24);

      }

    case TypeCode::I16:

      if constexpr (Endian::native == Endian::little) {

        return ValVariant(Val.get<uint32_t>() & 0xFFFFU);

      } else {

        return ValVariant(Val.get<uint32_t>() << 16);

      }

    default:

      assumingUnreachable();

    }

  }

  return Val;

}

std::vector<ValVariant>

Executor::packVals(const ValType &Type,

                   std::vector<ValVariant> &&Vals) const noexcept {

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

    Vals[I] = packVal(Type, Vals[I]);

  }

  return std::move(Vals);

}

ValVariant Executor::unpackVal(const ValType &Type, const ValVariant &Val,

                               bool IsSigned) const noexcept {

  if (Type.isPackType()) {

    uint32_t Num = Val.get<uint32_t>();

    switch (Type.getCode()) {

    case TypeCode::I8:

      if constexpr (Endian::native == Endian::big) {

        Num >>= 24;

      }

      if (IsSigned) {

        return static_cast<uint32_t>(static_cast<int8_t>(Num));

      } else {

        return static_cast<uint32_t>(static_cast<uint8_t>(Num));

      }

    case TypeCode::I16:

      if constexpr (Endian::native == Endian::big) {

        Num >>= 16;

      }

      if (IsSigned) {

        return static_cast<uint32_t>(static_cast<int16_t>(Num));

      } else {

        return static_cast<uint32_t>(static_cast<uint16_t>(Num));

      }

    default:

      assumingUnreachable();

    }

  }

  return Val;

}

} // namespace Executor

} // namespace WasmEdge