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// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <math.h>
#include <stdint.h>
#include <stdlib.h>

#include <limits>

#include "src/base/bits.h"
#include "src/base/ieee754.h"
#include "src/base/safe_conversions.h"
#include "src/common/assert-scope.h"
#include "src/utils/memcopy.h"
#include "src/wasm/wasm-objects-inl.h"

#if defined(ADDRESS_SANITIZER) || defined(MEMORY_SANITIZER) || \
    defined(THREAD_SANITIZER) || defined(LEAK_SANITIZER) ||    \
    defined(UNDEFINED_SANITIZER)
#define V8_WITH_SANITIZER
#endif

#if defined(V8_OS_WIN) && defined(V8_WITH_SANITIZER)
// With ASAN on Windows we have to reset the thread-in-wasm flag. Exceptions
// caused by ASAN let the thread-in-wasm flag get out of sync. Even marking
// functions with DISABLE_ASAN is not sufficient when the compiler produces
// calls to memset. Therefore we add test-specific code for ASAN on
// Windows.
#define RESET_THREAD_IN_WASM_FLAG_FOR_ASAN_ON_WINDOWS
#include "src/trap-handler/trap-handler.h"
#endif

#include "src/base/memory.h"
#include "src/utils/utils.h"
#include "src/wasm/wasm-external-refs.h"

namespace v8::internal::wasm {

using base::ReadUnalignedValue;
using base::WriteUnalignedValue;

void f32_trunc_wrapper(Address data) {
  WriteUnalignedValue<float>(data, truncf(ReadUnalignedValue<float>(data)));
}

void f32_floor_wrapper(Address data) {
  WriteUnalignedValue<float>(data, floorf(ReadUnalignedValue<float>(data)));
}

void f32_ceil_wrapper(Address data) {
  WriteUnalignedValue<float>(data, ceilf(ReadUnalignedValue<float>(data)));
}

void f32_nearest_int_wrapper(Address data) {
  float input = ReadUnalignedValue<float>(data);
  float value = nearbyintf(input);
#if V8_OS_AIX
  value = FpOpWorkaround<float>(input, value);
#endif
  WriteUnalignedValue<float>(data, value);
}

void f64_trunc_wrapper(Address data) {
  WriteUnalignedValue<double>(data, trunc(ReadUnalignedValue<double>(data)));
}

void f64_floor_wrapper(Address data) {
  WriteUnalignedValue<double>(data, floor(ReadUnalignedValue<double>(data)));
}

void f64_ceil_wrapper(Address data) {
  WriteUnalignedValue<double>(data, ceil(ReadUnalignedValue<double>(data)));
}

void f64_nearest_int_wrapper(Address data) {
  double input = ReadUnalignedValue<double>(data);
  double value = nearbyint(input);
#if V8_OS_AIX
  value = FpOpWorkaround<double>(input, value);
#endif
  WriteUnalignedValue<double>(data, value);
}

void int64_to_float32_wrapper(Address data) {
  int64_t input = ReadUnalignedValue<int64_t>(data);
  WriteUnalignedValue<float>(data, static_cast<float>(input));
}

void uint64_to_float32_wrapper(Address data) {
  uint64_t input = ReadUnalignedValue<uint64_t>(data);
#if defined(V8_OS_WIN)
  // On Windows, the FP stack registers calculate with less precision, which
  // leads to a uint64_t to float32 conversion which does not satisfy the
  // WebAssembly specification. Therefore we do a different approach here:
  //
  // / leading 0 \/  24 float data bits  \/  for rounding \/ trailing 0 \
  // 00000000000001XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX100000000000000
  //
  // Float32 can only represent 24 data bit (1 implicit 1 bit + 23 mantissa
  // bits). Starting from the most significant 1 bit, we can therefore extract
  // 24 bits and do the conversion only on them. The other bits can affect the
  // result only through rounding. Rounding works as follows:
  // * If the most significant rounding bit is not set, then round down.
  // * If the most significant rounding bit is set, and at least one of the
  //   other rounding bits is set, then round up.
  // * If the most significant rounding bit is set, but all other rounding bits
  //   are not set, then round to even.
  // We can aggregate 'all other rounding bits' in the second-most significant
  // rounding bit.
  // The resulting algorithm is therefore as follows:
  // * Check if the distance between the most significant bit (MSB) and the
  //   least significant bit (LSB) is greater than 25 bits. If the distance is
  //   less or equal to 25 bits, the uint64 to float32 conversion is anyways
  //   exact, and we just use the C++ conversion.
  // * Find the most significant bit (MSB).
  // * Starting from the MSB, extract 25 bits (24 data bits + the first rounding
  //   bit).
  // * The remaining rounding bits are guaranteed to contain at least one 1 bit,
  //   due to the check we did above.
  // * Store the 25 bits + 1 aggregated bit in an uint32_t.
  // * Convert this uint32_t to float. The conversion does the correct rounding
  //   now.
  // * Shift the result back to the original magnitude.
  uint32_t leading_zeros = base::bits::CountLeadingZeros(input);
  uint32_t trailing_zeros = base::bits::CountTrailingZeros(input);
  constexpr uint32_t num_extracted_bits = 25;
  // Check if there are any rounding bits we have to aggregate.
  if (leading_zeros + trailing_zeros + num_extracted_bits < 64) {
    // Shift to extract the data bits.
    uint32_t num_aggregation_bits = 64 - num_extracted_bits - leading_zeros;
    // We extract the bits we want to convert. Note that we convert one bit more
    // than necessary. This bit is a placeholder where we will store the
    // aggregation bit.
    int32_t extracted_bits =
        static_cast<int32_t>(input >> (num_aggregation_bits - 1));
    // Set the aggregation bit. We don't have to clear the slot first, because
    // the bit there is also part of the aggregation.
    extracted_bits |= 1;
    float result = static_cast<float>(extracted_bits);
    // We have to shift the result back. The shift amount is
    // (num_aggregation_bits - 1), which is the shift amount we did originally,
    // and (-2), which is for the two additional bits we kept originally for
    // rounding.
    int32_t shift_back = static_cast<int32_t>(num_aggregation_bits) - 1 - 2;
    // Calculate the multiplier to shift the extracted bits back to the original
    // magnitude. This multiplier is a power of two, so in the float32 bit
    // representation we just have to construct the correct exponent and put it
    // at the correct bit offset. The exponent consists of 8 bits, starting at
    // the second MSB (a.k.a '<< 23'). The encoded exponent itself is
    // ('actual exponent' - 127).
    int32_t multiplier_bits = ((shift_back - 127) & 0xff) << 23;
    result *= base::bit_cast<float>(multiplier_bits);
    WriteUnalignedValue<float>(data, result);
    return;
  }
#endif  // defined(V8_OS_WIN)
  WriteUnalignedValue<float>(data, static_cast<float>(input));
}

void int64_to_float64_wrapper(Address data) {
  int64_t input = ReadUnalignedValue<int64_t>(data);
  WriteUnalignedValue<double>(data, static_cast<double>(input));
}

void uint64_to_float64_wrapper(Address data) {
  uint64_t input = ReadUnalignedValue<uint64_t>(data);
  double result = static_cast<double>(input);

#if V8_CC_MSVC
  // With MSVC we use static_cast<double>(uint32_t) instead of
  // static_cast<double>(uint64_t) to achieve round-to-nearest-ties-even
  // semantics. The idea is to calculate
  // static_cast<double>(high_word) * 2^32 + static_cast<double>(low_word).
  uint32_t low_word = static_cast<uint32_t>(input & 0xFFFFFFFF);
  uint32_t high_word = static_cast<uint32_t>(input >> 32);

  double shift = static_cast<double>(1ull << 32);

  result = static_cast<double>(high_word);
  result *= shift;
  result += static_cast<double>(low_word);
#endif

  WriteUnalignedValue<double>(data, result);
}

int32_t float32_to_int64_wrapper(Address data) {
  float input = ReadUnalignedValue<float>(data);
  if (base::IsValueInRangeForNumericType<int64_t>(input)) {
    WriteUnalignedValue<int64_t>(data, static_cast<int64_t>(input));
    return 1;
  }
  return 0;
}

int32_t float32_to_uint64_wrapper(Address data) {
  float input = ReadUnalignedValue<float>(data);
  if (base::IsValueInRangeForNumericType<uint64_t>(input)) {
    WriteUnalignedValue<uint64_t>(data, static_cast<uint64_t>(input));
    return 1;
  }
  return 0;
}

int32_t float64_to_int64_wrapper(Address data) {
  double input = ReadUnalignedValue<double>(data);
  if (base::IsValueInRangeForNumericType<int64_t>(input)) {
    WriteUnalignedValue<int64_t>(data, static_cast<int64_t>(input));
    return 1;
  }
  return 0;
}

int32_t float64_to_uint64_wrapper(Address data) {
  double input = ReadUnalignedValue<double>(data);
  if (base::IsValueInRangeForNumericType<uint64_t>(input)) {
    WriteUnalignedValue<uint64_t>(data, static_cast<uint64_t>(input));
    return 1;
  }
  return 0;
}

void float32_to_int64_sat_wrapper(Address data) {
  float input = ReadUnalignedValue<float>(data);
  if (base::IsValueInRangeForNumericType<int64_t>(input)) {
    WriteUnalignedValue<int64_t>(data, static_cast<int64_t>(input));
    return;
  }
  if (std::isnan(input)) {
    WriteUnalignedValue<int64_t>(data, 0);
    return;
  }
  if (input < 0.0) {
    WriteUnalignedValue<int64_t>(data, std::numeric_limits<int64_t>::min());
    return;
  }
  WriteUnalignedValue<int64_t>(data, std::numeric_limits<int64_t>::max());
}

void float32_to_uint64_sat_wrapper(Address data) {
  float input = ReadUnalignedValue<float>(data);
  if (base::IsValueInRangeForNumericType<uint64_t>(input)) {
    WriteUnalignedValue<uint64_t>(data, static_cast<uint64_t>(input));
    return;
  }
  if (input >= static_cast<float>(std::numeric_limits<uint64_t>::max())) {
    WriteUnalignedValue<uint64_t>(data, std::numeric_limits<uint64_t>::max());
    return;
  }
  WriteUnalignedValue<uint64_t>(data, 0);
}

void float64_to_int64_sat_wrapper(Address data) {
  double input = ReadUnalignedValue<double>(data);
  if (base::IsValueInRangeForNumericType<int64_t>(input)) {
    WriteUnalignedValue<int64_t>(data, static_cast<int64_t>(input));
    return;
  }
  if (std::isnan(input)) {
    WriteUnalignedValue<int64_t>(data, 0);
    return;
  }
  if (input < 0.0) {
    WriteUnalignedValue<int64_t>(data, std::numeric_limits<int64_t>::min());
    return;
  }
  WriteUnalignedValue<int64_t>(data, std::numeric_limits<int64_t>::max());
}

void float64_to_uint64_sat_wrapper(Address data) {
  double input = ReadUnalignedValue<double>(data);
  if (base::IsValueInRangeForNumericType<uint64_t>(input)) {
    WriteUnalignedValue<uint64_t>(data, static_cast<uint64_t>(input));
    return;
  }
  if (input >= static_cast<double>(std::numeric_limits<uint64_t>::max())) {
    WriteUnalignedValue<uint64_t>(data, std::numeric_limits<uint64_t>::max());
    return;
  }
  WriteUnalignedValue<uint64_t>(data, 0);
}

int32_t int64_div_wrapper(Address data) {
  int64_t dividend = ReadUnalignedValue<int64_t>(data);
  int64_t divisor = ReadUnalignedValue<int64_t>(data + sizeof(dividend));
  if (divisor == 0) {
    return 0;
  }
  if (divisor == -1 && dividend == std::numeric_limits<int64_t>::min()) {
    return -1;
  }
  WriteUnalignedValue<int64_t>(data, dividend / divisor);
  return 1;
}

int32_t int64_mod_wrapper(Address data) {
  int64_t dividend = ReadUnalignedValue<int64_t>(data);
  int64_t divisor = ReadUnalignedValue<int64_t>(data + sizeof(dividend));
  if (divisor == 0) {
    return 0;
  }
  if (divisor == -1 && dividend == std::numeric_limits<int64_t>::min()) {
    WriteUnalignedValue<int64_t>(data, 0);
    return 1;
  }
  WriteUnalignedValue<int64_t>(data, dividend % divisor);
  return 1;
}

int32_t uint64_div_wrapper(Address data) {
  uint64_t dividend = ReadUnalignedValue<uint64_t>(data);
  uint64_t divisor = ReadUnalignedValue<uint64_t>(data + sizeof(dividend));
  if (divisor == 0) {
    return 0;
  }
  WriteUnalignedValue<uint64_t>(data, dividend / divisor);
  return 1;
}

int32_t uint64_mod_wrapper(Address data) {
  uint64_t dividend = ReadUnalignedValue<uint64_t>(data);
  uint64_t divisor = ReadUnalignedValue<uint64_t>(data + sizeof(dividend));
  if (divisor == 0) {
    return 0;
  }
  WriteUnalignedValue<uint64_t>(data, dividend % divisor);
  return 1;
}

uint32_t word32_ctz_wrapper(Address data) {
  return base::bits::CountTrailingZeros(ReadUnalignedValue<uint32_t>(data));
}

uint32_t word64_ctz_wrapper(Address data) {
  return base::bits::CountTrailingZeros(ReadUnalignedValue<uint64_t>(data));
}

uint32_t word32_popcnt_wrapper(Address data) {
  return base::bits::CountPopulation(ReadUnalignedValue<uint32_t>(data));
}

uint32_t word64_popcnt_wrapper(Address data) {
  return base::bits::CountPopulation(ReadUnalignedValue<uint64_t>(data));
}

uint32_t word32_rol_wrapper(Address data) {
  uint32_t input = ReadUnalignedValue<uint32_t>(data);
  uint32_t shift = ReadUnalignedValue<uint32_t>(data + sizeof(input)) & 31;
  return (input << shift) | (input >> ((32 - shift) & 31));
}

uint32_t word32_ror_wrapper(Address data) {
  uint32_t input = ReadUnalignedValue<uint32_t>(data);
  uint32_t shift = ReadUnalignedValue<uint32_t>(data + sizeof(input)) & 31;
  return (input >> shift) | (input << ((32 - shift) & 31));
}

void word64_rol_wrapper(Address data) {
  uint64_t input = ReadUnalignedValue<uint64_t>(data);
  uint64_t shift = ReadUnalignedValue<uint64_t>(data + sizeof(input)) & 63;
  uint64_t result = (input << shift) | (input >> ((64 - shift) & 63));
  WriteUnalignedValue<uint64_t>(data, result);
}

void word64_ror_wrapper(Address data) {
  uint64_t input = ReadUnalignedValue<uint64_t>(data);
  uint64_t shift = ReadUnalignedValue<uint64_t>(data + sizeof(input)) & 63;
  uint64_t result = (input >> shift) | (input << ((64 - shift) & 63));
  WriteUnalignedValue<uint64_t>(data, result);
}

void float64_pow_wrapper(Address data) {
  double x = ReadUnalignedValue<double>(data);
  double y = ReadUnalignedValue<double>(data + sizeof(x));
  WriteUnalignedValue<double>(data, base::ieee754::pow(x, y));
}

template <typename T, T (*float_round_op)(T)>
void simd_float_round_wrapper(Address data) {
  constexpr int n = kSimd128Size / sizeof(T);
  for (int i = 0; i < n; i++) {
    T input = ReadUnalignedValue<T>(data + (i * sizeof(T)));
    T value = float_round_op(input);
#if V8_OS_AIX
    value = FpOpWorkaround<T>(input, value);
#endif
    WriteUnalignedValue<T>(data + (i * sizeof(T)), value);
  }
}

void f64x2_ceil_wrapper(Address data) {
  simd_float_round_wrapper<double, &ceil>(data);
}

void f64x2_floor_wrapper(Address data) {
  simd_float_round_wrapper<double, &floor>(data);
}

void f64x2_trunc_wrapper(Address data) {
  simd_float_round_wrapper<double, &trunc>(data);
}

void f64x2_nearest_int_wrapper(Address data) {
  simd_float_round_wrapper<double, &nearbyint>(data);
}

void f32x4_ceil_wrapper(Address data) {
  simd_float_round_wrapper<float, &ceilf>(data);
}

void f32x4_floor_wrapper(Address data) {
  simd_float_round_wrapper<float, &floorf>(data);
}

void f32x4_trunc_wrapper(Address data) {
  simd_float_round_wrapper<float, &truncf>(data);
}

void f32x4_nearest_int_wrapper(Address data) {
  simd_float_round_wrapper<float, &nearbyintf>(data);
}

namespace {
class V8_NODISCARD ThreadNotInWasmScope {
// Asan on Windows triggers exceptions to allocate shadow memory lazily. When
// this function is called from WebAssembly, these exceptions would be handled
// by the trap handler before they get handled by Asan, and thereby confuse the
// thread-in-wasm flag. Therefore we disable ASAN for this function.
// Alternatively we could reset the thread-in-wasm flag before calling this
// function. However, as this is only a problem with Asan on Windows, we did not
// consider it worth the overhead.
#if defined(RESET_THREAD_IN_WASM_FLAG_FOR_ASAN_ON_WINDOWS)

 public:
  ThreadNotInWasmScope() : thread_was_in_wasm_(trap_handler::IsThreadInWasm()) {
    if (thread_was_in_wasm_) {
      trap_handler::ClearThreadInWasm();
    }
  }

  ~ThreadNotInWasmScope() {
    if (thread_was_in_wasm_) {
      trap_handler::SetThreadInWasm();
    }
  }

 private:
  bool thread_was_in_wasm_;
#else

 public:
  ThreadNotInWasmScope() {
    // This is needed to avoid compilation errors (unused variable).
    USE(this);
  }
#endif
};

inline uint8_t* EffectiveAddress(Tagged<WasmInstanceObject> instance,
                                 uint32_t mem_index, uintptr_t index) {
  return instance->memory_base(mem_index) + index;
}

template <typename V>
V ReadAndIncrementOffset(Address data, size_t* offset) {
  V result = ReadUnalignedValue<V>(data + *offset);
  *offset += sizeof(V);
  return result;
}

constexpr int32_t kSuccess = 1;
constexpr int32_t kOutOfBounds = 0;
}  // namespace

int32_t memory_init_wrapper(Address data) {
  ThreadNotInWasmScope thread_not_in_wasm_scope;
  DisallowGarbageCollection no_gc;
  size_t offset = 0;
  Tagged<WasmInstanceObject> instance = WasmInstanceObject::cast(
      ReadAndIncrementOffset<Tagged<Object>>(data, &offset));
  uint32_t mem_index = ReadAndIncrementOffset<uint32_t>(data, &offset);
  uintptr_t dst = ReadAndIncrementOffset<uintptr_t>(data, &offset);
  uint32_t src = ReadAndIncrementOffset<uint32_t>(data, &offset);
  uint32_t seg_index = ReadAndIncrementOffset<uint32_t>(data, &offset);
  uint32_t size = ReadAndIncrementOffset<uint32_t>(data, &offset);

  uint64_t mem_size = instance->memory_size(mem_index);
  if (!base::IsInBounds<uint64_t>(dst, size, mem_size)) return kOutOfBounds;

  uint32_t seg_size = instance->data_segment_sizes()->get(seg_index);
  if (!base::IsInBounds<uint32_t>(src, size, seg_size)) return kOutOfBounds;

  uint8_t* seg_start = reinterpret_cast<uint8_t*>(
      instance->data_segment_starts()->get(seg_index));
  std::memcpy(EffectiveAddress(instance, mem_index, dst), seg_start + src,
              size);
  return kSuccess;
}

int32_t memory_copy_wrapper(Address data) {
  ThreadNotInWasmScope thread_not_in_wasm_scope;
  DisallowGarbageCollection no_gc;
  size_t offset = 0;
  Tagged<WasmInstanceObject> instance = WasmInstanceObject::cast(
      ReadAndIncrementOffset<Tagged<Object>>(data, &offset));
  uint32_t dst_mem_index = ReadAndIncrementOffset<uint32_t>(data, &offset);
  uint32_t src_mem_index = ReadAndIncrementOffset<uint32_t>(data, &offset);
  uintptr_t dst = ReadAndIncrementOffset<uintptr_t>(data, &offset);
  uintptr_t src = ReadAndIncrementOffset<uintptr_t>(data, &offset);
  uintptr_t size = ReadAndIncrementOffset<uintptr_t>(data, &offset);

  uint64_t dst_mem_size = instance->memory_size(dst_mem_index);
  uint64_t src_mem_size = instance->memory_size(src_mem_index);
  if (!base::IsInBounds<uint64_t>(dst, size, dst_mem_size)) return kOutOfBounds;
  if (!base::IsInBounds<uint64_t>(src, size, src_mem_size)) return kOutOfBounds;

  // Use std::memmove, because the ranges can overlap.
  std::memmove(EffectiveAddress(instance, dst_mem_index, dst),
               EffectiveAddress(instance, src_mem_index, src), size);
  return kSuccess;
}

int32_t memory_fill_wrapper(Address data) {
  ThreadNotInWasmScope thread_not_in_wasm_scope;
  DisallowGarbageCollection no_gc;

  size_t offset = 0;
  Tagged<WasmInstanceObject> instance = WasmInstanceObject::cast(
      ReadAndIncrementOffset<Tagged<Object>>(data, &offset));
  uint32_t mem_index = ReadAndIncrementOffset<uint32_t>(data, &offset);
  uintptr_t dst = ReadAndIncrementOffset<uintptr_t>(data, &offset);
  uint8_t value =
      static_cast<uint8_t>(ReadAndIncrementOffset<uint32_t>(data, &offset));
  uintptr_t size = ReadAndIncrementOffset<uintptr_t>(data, &offset);

  uint64_t mem_size = instance->memory_size(mem_index);
  if (!base::IsInBounds<uint64_t>(dst, size, mem_size)) return kOutOfBounds;

  std::memset(EffectiveAddress(instance, mem_index, dst), value, size);
  return kSuccess;
}

namespace {
inline void* ArrayElementAddress(Address array, uint32_t index,
                                 int element_size_bytes) {
  return reinterpret_cast<void*>(array + WasmArray::kHeaderSize -
                                 kHeapObjectTag + index * element_size_bytes);
}
inline void* ArrayElementAddress(Tagged<WasmArray> array, uint32_t index,
                                 int element_size_bytes) {
  return ArrayElementAddress(array.ptr(), index, element_size_bytes);
}
}  // namespace

void array_copy_wrapper(Address raw_instance, Address raw_dst_array,
                        uint32_t dst_index, Address raw_src_array,
                        uint32_t src_index, uint32_t length) {
  DCHECK_GT(length, 0);
  ThreadNotInWasmScope thread_not_in_wasm_scope;
  DisallowGarbageCollection no_gc;
  Tagged<WasmArray> dst_array = WasmArray::cast(Tagged<Object>(raw_dst_array));
  Tagged<WasmArray> src_array = WasmArray::cast(Tagged<Object>(raw_src_array));

  bool overlapping_ranges =
      dst_array.ptr() == src_array.ptr() &&
      (dst_index < src_index ? dst_index + length > src_index
                             : src_index + length > dst_index);
  wasm::ValueType element_type = src_array->type()->element_type();
  if (element_type.is_reference()) {
    Tagged<WasmInstanceObject> instance =
        WasmInstanceObject::cast(Tagged<Object>(raw_instance));
    Isolate* isolate = instance->GetIsolate();
    ObjectSlot dst_slot = dst_array->ElementSlot(dst_index);
    ObjectSlot src_slot = src_array->ElementSlot(src_index);
    if (overlapping_ranges) {
      isolate->heap()->MoveRange(dst_array, dst_slot, src_slot, length,
                                 UPDATE_WRITE_BARRIER);
    } else {
      isolate->heap()->CopyRange(dst_array, dst_slot, src_slot, length,
                                 UPDATE_WRITE_BARRIER);
    }
  } else {
    int element_size_bytes = element_type.value_kind_size();
    void* dst = ArrayElementAddress(dst_array, dst_index, element_size_bytes);
    void* src = ArrayElementAddress(src_array, src_index, element_size_bytes);
    size_t copy_size = length * element_size_bytes;
    if (overlapping_ranges) {
      MemMove(dst, src, copy_size);
    } else {
      MemCopy(dst, src, copy_size);
    }
  }
}

void array_fill_wrapper(Address raw_array, uint32_t index, uint32_t length,
                        uint32_t emit_write_barrier, uint32_t raw_type,
                        Address initial_value_addr) {
  ThreadNotInWasmScope thread_not_in_wasm_scope;
  DisallowGarbageCollection no_gc;
  ValueType type = ValueType::FromRawBitField(raw_type);
  int8_t* initial_element_address = reinterpret_cast<int8_t*>(
      ArrayElementAddress(raw_array, index, type.value_kind_size()));
  int64_t initial_value = *reinterpret_cast<int64_t*>(initial_value_addr);
  const int bytes_to_set = length * type.value_kind_size();

  // If the initial value is zero, we memset the array.
  if (type.is_numeric() && initial_value == 0) {
    std::memset(initial_element_address, 0, bytes_to_set);
    return;
  }

  // We implement the general case by setting the first 8 bytes manually, then
  // filling the rest by exponentially growing {memcpy}s.

  DCHECK_GE(static_cast<size_t>(bytes_to_set), sizeof(int64_t));

  switch (type.kind()) {
    case kI64:
    case kF64: {
      *reinterpret_cast<int64_t*>(initial_element_address) = initial_value;
      break;
    }
    case kI32:
    case kF32: {
      int32_t* base = reinterpret_cast<int32_t*>(initial_element_address);
      base[0] = base[1] = static_cast<int32_t>(initial_value);
      break;
    }
    case kI16: {
      int16_t* base = reinterpret_cast<int16_t*>(initial_element_address);
      base[0] = base[1] = base[2] = base[3] =
          static_cast<int16_t>(initial_value);
      break;
    }
    case kI8: {
      int8_t* base = reinterpret_cast<int8_t*>(initial_element_address);
      for (size_t i = 0; i < sizeof(int64_t); i++) {
        base[i] = static_cast<int8_t>(initial_value);
      }
      break;
    }
    case kRefNull:
    case kRef:
      if constexpr (kTaggedSize == 4) {
        int32_t* base = reinterpret_cast<int32_t*>(initial_element_address);
        base[0] = base[1] = static_cast<int32_t>(initial_value);
      } else {
        *reinterpret_cast<int64_t*>(initial_element_address) = initial_value;
      }
      break;
    case kS128:
    case kRtt:
    case kVoid:
    case kBottom:
      UNREACHABLE();
  }

  int bytes_already_set = sizeof(int64_t);

  while (bytes_already_set * 2 <= bytes_to_set) {
    std::memcpy(initial_element_address + bytes_already_set,
                initial_element_address, bytes_already_set);
    bytes_already_set *= 2;
  }

  if (bytes_already_set < bytes_to_set) {
    std::memcpy(initial_element_address + bytes_already_set,
                initial_element_address, bytes_to_set - bytes_already_set);
  }

  if (emit_write_barrier) {
    DCHECK(type.is_reference());
    Tagged<WasmArray> array = WasmArray::cast(Tagged<Object>(raw_array));
    Isolate* isolate = array->GetIsolate();
    ObjectSlot start(reinterpret_cast<Address>(initial_element_address));
    ObjectSlot end(
        reinterpret_cast<Address>(initial_element_address + bytes_to_set));
    isolate->heap()->WriteBarrierForRange(array, start, end);
  }
}

double flat_string_to_f64(Address string_address) {
  Tagged<String> s = String::cast(Tagged<Object>(string_address));
  return FlatStringToDouble(s, ALLOW_TRAILING_JUNK,
                            std::numeric_limits<double>::quiet_NaN());
}

void sync_stack_limit(Isolate* isolate) {
  CHECK(v8_flags.experimental_wasm_stack_switching);
  DisallowGarbageCollection no_gc;

  isolate->SyncStackLimit();
}

intptr_t switch_to_the_central_stack(Isolate* isolate, uintptr_t current_sp) {
  CHECK(v8_flags.experimental_wasm_stack_switching);

  ThreadLocalTop* thread_local_top = isolate->thread_local_top();
  StackGuard* stack_guard = isolate->stack_guard();

  CHECK_EQ(thread_local_top->secondary_stack_sp_, 0);
  CHECK_EQ(thread_local_top->secondary_stack_limit_, 0);

  auto secondary_stack_limit = stack_guard->real_jslimit();

  stack_guard->SetStackLimitForStackSwitching(
      thread_local_top->central_stack_limit_);

  thread_local_top->secondary_stack_limit_ = secondary_stack_limit;
  thread_local_top->secondary_stack_sp_ = current_sp;
  thread_local_top->is_on_central_stack_flag_ = true;

  auto counter = isolate->wasm_switch_to_the_central_stack_counter();
  isolate->set_wasm_switch_to_the_central_stack_counter(counter + 1);

  return thread_local_top->central_stack_sp_;
}

void switch_from_the_central_stack(Isolate* isolate) {
  CHECK(v8_flags.experimental_wasm_stack_switching);

  ThreadLocalTop* thread_local_top = isolate->thread_local_top();
  CHECK_NE(thread_local_top->secondary_stack_sp_, 0);
  CHECK_NE(thread_local_top->secondary_stack_limit_, 0);

  auto secondary_stack_limit = thread_local_top->secondary_stack_limit_;
  thread_local_top->secondary_stack_limit_ = 0;
  thread_local_top->secondary_stack_sp_ = 0;
  thread_local_top->is_on_central_stack_flag_ = false;

  StackGuard* stack_guard = isolate->stack_guard();
  stack_guard->SetStackLimitForStackSwitching(secondary_stack_limit);
}

}  // namespace v8::internal::wasm

#undef V8_WITH_SANITIZER
#undef RESET_THREAD_IN_WASM_FLAG_FOR_ASAN_ON_WINDOWS

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