// Copyright 2017 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 "src/wasm/wasm-code-manager.h"

#include <iomanip>

#include "src/assembler-inl.h"
#include "src/base/macros.h"
#include "src/base/platform/platform.h"
#include "src/codegen.h"
#include "src/disassembler.h"
#include "src/globals.h"
#include "src/macro-assembler-inl.h"
#include "src/macro-assembler.h"
#include "src/objects-inl.h"
#include "src/wasm/function-compiler.h"
#include "src/wasm/jump-table-assembler.h"
#include "src/wasm/wasm-module.h"
#include "src/wasm/wasm-objects-inl.h"
#include "src/wasm/wasm-objects.h"

#define TRACE_HEAP(...)                                   \
  do {                                                    \
    if (FLAG_wasm_trace_native_heap) PrintF(__VA_ARGS__); \
  } while (false)

namespace v8 {
namespace internal {
namespace wasm {

namespace {

// Binary predicate to perform lookups in {NativeModule::owned_code_} with a
// given address into a code object. Use with {std::upper_bound} for example.
struct WasmCodeUniquePtrComparator {
  bool operator()(Address pc, const std::unique_ptr<WasmCode>& code) const {
    DCHECK_NE(kNullAddress, pc);
    DCHECK_NOT_NULL(code);
    return pc < code->instruction_start();
  }
};

}  // namespace

void DisjointAllocationPool::Merge(AddressRange range) {
  auto dest_it = ranges_.begin();
  auto dest_end = ranges_.end();

  // Skip over dest ranges strictly before {range}.
  while (dest_it != dest_end && dest_it->end < range.start) ++dest_it;

  // After last dest range: insert and done.
  if (dest_it == dest_end) {
    ranges_.push_back(range);
    return;
  }

  // Adjacent (from below) to dest: merge and done.
  if (dest_it->start == range.end) {
    dest_it->start = range.start;
    return;
  }

  // Before dest: insert and done.
  if (dest_it->start > range.end) {
    ranges_.insert(dest_it, range);
    return;
  }

  // Src is adjacent from above. Merge and check whether the merged range is now
  // adjacent to the next range.
  DCHECK_EQ(dest_it->end, range.start);
  dest_it->end = range.end;
  auto next_dest = dest_it;
  ++next_dest;
  if (next_dest != dest_end && dest_it->end == next_dest->start) {
    dest_it->end = next_dest->end;
    ranges_.erase(next_dest);
  }
}

AddressRange DisjointAllocationPool::Allocate(size_t size) {
  for (auto it = ranges_.begin(), end = ranges_.end(); it != end; ++it) {
    size_t range_size = it->size();
    if (size > range_size) continue;
    AddressRange ret{it->start, it->start + size};
    if (size == range_size) {
      ranges_.erase(it);
    } else {
      it->start += size;
      DCHECK_LT(it->start, it->end);
    }
    return ret;
  }
  return {};
}

Address WasmCode::constant_pool() const {
  if (FLAG_enable_embedded_constant_pool) {
    if (constant_pool_offset_ < instructions().size()) {
      return instruction_start() + constant_pool_offset_;
    }
  }
  return kNullAddress;
}

size_t WasmCode::trap_handler_index() const {
  CHECK(HasTrapHandlerIndex());
  return static_cast<size_t>(trap_handler_index_);
}

void WasmCode::set_trap_handler_index(size_t value) {
  trap_handler_index_ = value;
}

void WasmCode::RegisterTrapHandlerData() {
  DCHECK(!HasTrapHandlerIndex());
  if (kind() != WasmCode::kFunction) return;

  Address base = instruction_start();

  size_t size = instructions().size();
  const int index =
      RegisterHandlerData(base, size, protected_instructions().size(),
                          protected_instructions().start());

  // TODO(eholk): if index is negative, fail.
  CHECK_LE(0, index);
  set_trap_handler_index(static_cast<size_t>(index));
}

bool WasmCode::HasTrapHandlerIndex() const { return trap_handler_index_ >= 0; }

bool WasmCode::ShouldBeLogged(Isolate* isolate) {
  return isolate->logger()->is_listening_to_code_events() ||
         isolate->is_profiling();
}

void WasmCode::LogCode(Isolate* isolate) const {
  DCHECK(ShouldBeLogged(isolate));
  if (IsAnonymous()) return;
  ModuleWireBytes wire_bytes(native_module()->wire_bytes());
  // TODO(herhut): Allow to log code without on-heap round-trip of the name.
  ModuleEnv* module_env = GetModuleEnv(native_module()->compilation_state());
  WireBytesRef name_ref =
      module_env->module->LookupFunctionName(wire_bytes, index());
  WasmName name_vec = wire_bytes.GetName(name_ref);
  MaybeHandle<String> maybe_name =
      isolate->factory()->NewStringFromUtf8(Vector<const char>::cast(name_vec));
  Handle<String> name;
  if (!maybe_name.ToHandle(&name)) {
    name = isolate->factory()->NewStringFromAsciiChecked("<name too long>");
  }
  int name_length;
  auto cname =
      name->ToCString(AllowNullsFlag::DISALLOW_NULLS,
                      RobustnessFlag::ROBUST_STRING_TRAVERSAL, &name_length);
  PROFILE(isolate,
          CodeCreateEvent(CodeEventListener::FUNCTION_TAG, this,
                          {cname.get(), static_cast<size_t>(name_length)}));
  if (!source_positions().is_empty()) {
    LOG_CODE_EVENT(isolate, CodeLinePosInfoRecordEvent(instruction_start(),
                                                       source_positions()));
  }
}

void WasmCode::Validate() const {
#ifdef DEBUG
  // We expect certain relocation info modes to never appear in {WasmCode}
  // objects or to be restricted to a small set of valid values. Hence the
  // iteration below does not use a mask, but visits all relocation data.
  for (RelocIterator it(instructions(), reloc_info(), constant_pool());
       !it.done(); it.next()) {
    RelocInfo::Mode mode = it.rinfo()->rmode();
    switch (mode) {
      case RelocInfo::WASM_CALL: {
        Address target = it.rinfo()->wasm_call_address();
        WasmCode* code = native_module_->Lookup(target);
        CHECK_NOT_NULL(code);
        CHECK_EQ(WasmCode::kJumpTable, code->kind());
        CHECK(code->contains(target));
        break;
      }
      case RelocInfo::WASM_STUB_CALL: {
        Address target = it.rinfo()->wasm_stub_call_address();
        WasmCode* code = native_module_->Lookup(target);
        CHECK_NOT_NULL(code);
        CHECK_EQ(WasmCode::kRuntimeStub, code->kind());
        CHECK_EQ(target, code->instruction_start());
        break;
      }
      case RelocInfo::INTERNAL_REFERENCE:
      case RelocInfo::INTERNAL_REFERENCE_ENCODED: {
        Address target = it.rinfo()->target_internal_reference();
        CHECK(contains(target));
        break;
      }
      case RelocInfo::JS_TO_WASM_CALL:
      case RelocInfo::EXTERNAL_REFERENCE:
      case RelocInfo::OFF_HEAP_TARGET:
      case RelocInfo::COMMENT:
      case RelocInfo::CONST_POOL:
      case RelocInfo::VENEER_POOL:
        // These are OK to appear.
        break;
      default:
        FATAL("Unexpected mode: %d", mode);
    }
  }
#endif
}

void WasmCode::Print(const char* name) const {
  StdoutStream os;
  os << "--- WebAssembly code ---\n";
  Disassemble(name, os);
  os << "--- End code ---\n";
}

void WasmCode::Disassemble(const char* name, std::ostream& os,
                           Address current_pc) const {
  if (name) os << "name: " << name << "\n";
  if (!IsAnonymous()) os << "index: " << index() << "\n";
  os << "kind: " << GetWasmCodeKindAsString(kind_) << "\n";
  os << "compiler: " << (is_liftoff() ? "Liftoff" : "TurboFan") << "\n";
  size_t body_size = instructions().size();
  os << "Body (size = " << body_size << ")\n";

#ifdef ENABLE_DISASSEMBLER
  size_t instruction_size = body_size;
  if (constant_pool_offset_ && constant_pool_offset_ < instruction_size) {
    instruction_size = constant_pool_offset_;
  }
  if (safepoint_table_offset_ && safepoint_table_offset_ < instruction_size) {
    instruction_size = safepoint_table_offset_;
  }
  DCHECK_LT(0, instruction_size);
  os << "Instructions (size = " << instruction_size << ")\n";
  Disassembler::Decode(nullptr, &os, instructions().start(),
                       instructions().start() + instruction_size,
                       CodeReference(this), current_pc);
  os << "\n";

  if (!protected_instructions_.is_empty()) {
    os << "Protected instructions:\n pc offset  land pad\n";
    for (auto& data : protected_instructions()) {
      os << std::setw(10) << std::hex << data.instr_offset << std::setw(10)
         << std::hex << data.landing_offset << "\n";
    }
    os << "\n";
  }

  if (!source_positions().is_empty()) {
    os << "Source positions:\n pc offset  position\n";
    for (SourcePositionTableIterator it(source_positions()); !it.done();
         it.Advance()) {
      os << std::setw(10) << std::hex << it.code_offset() << std::dec
         << std::setw(10) << it.source_position().ScriptOffset()
         << (it.is_statement() ? "  statement" : "") << "\n";
    }
    os << "\n";
  }

  os << "RelocInfo (size = " << reloc_info_.size() << ")\n";
  for (RelocIterator it(instructions(), reloc_info(), constant_pool());
       !it.done(); it.next()) {
    it.rinfo()->Print(nullptr, os);
  }
  os << "\n";
#endif  // ENABLE_DISASSEMBLER
}

const char* GetWasmCodeKindAsString(WasmCode::Kind kind) {
  switch (kind) {
    case WasmCode::kFunction:
      return "wasm function";
    case WasmCode::kWasmToJsWrapper:
      return "wasm-to-js";
    case WasmCode::kLazyStub:
      return "lazy-compile";
    case WasmCode::kRuntimeStub:
      return "runtime-stub";
    case WasmCode::kInterpreterEntry:
      return "interpreter entry";
    case WasmCode::kJumpTable:
      return "jump table";
  }
  return "unknown kind";
}

WasmCode::~WasmCode() {
  if (HasTrapHandlerIndex()) {
    CHECK_LT(trap_handler_index(),
             static_cast<size_t>(std::numeric_limits<int>::max()));
    trap_handler::ReleaseHandlerData(static_cast<int>(trap_handler_index()));
  }
}

NativeModule::NativeModule(Isolate* isolate, const WasmFeatures& enabled,
                           bool can_request_more, VirtualMemory* code_space,
                           WasmCodeManager* code_manager,
                           std::shared_ptr<const WasmModule> module,
                           const ModuleEnv& env)
    : enabled_features_(enabled),
      module_(std::move(module)),
      compilation_state_(NewCompilationState(isolate, env)),
      free_code_space_({code_space->address(), code_space->end()}),
      wasm_code_manager_(code_manager),
      can_request_more_memory_(can_request_more),
      use_trap_handler_(env.use_trap_handler) {
  DCHECK_EQ(module_.get(), env.module);
  DCHECK_NOT_NULL(module_);
  VirtualMemory my_mem;
  owned_code_space_.push_back(my_mem);
  owned_code_space_.back().TakeControl(code_space);
  owned_code_.reserve(num_functions());

  uint32_t num_wasm_functions = module_->num_declared_functions;
  if (num_wasm_functions > 0) {
    code_table_.reset(new WasmCode*[num_wasm_functions]);
    memset(code_table_.get(), 0, num_wasm_functions * sizeof(WasmCode*));

    jump_table_ = CreateEmptyJumpTable(num_wasm_functions);
  }
}

void NativeModule::ReserveCodeTableForTesting(uint32_t max_functions) {
  DCHECK_LE(num_functions(), max_functions);
  WasmCode** new_table = new WasmCode*[max_functions];
  memset(new_table, 0, max_functions * sizeof(*new_table));
  memcpy(new_table, code_table_.get(),
         module_->num_declared_functions * sizeof(*new_table));
  code_table_.reset(new_table);

  // Re-allocate jump table.
  jump_table_ = CreateEmptyJumpTable(max_functions);
}

void NativeModule::LogWasmCodes(Isolate* isolate) {
  if (!WasmCode::ShouldBeLogged(isolate)) return;

  // TODO(titzer): we skip the logging of the import wrappers
  // here, but they should be included somehow.
  for (WasmCode* code : code_table()) {
    if (code != nullptr) code->LogCode(isolate);
  }
}

WasmCode* NativeModule::AddOwnedCode(
    Maybe<uint32_t> index, Vector<const byte> instructions,
    uint32_t stack_slots, size_t safepoint_table_offset,
    size_t handler_table_offset, size_t constant_pool_offset,
    OwnedVector<trap_handler::ProtectedInstructionData> protected_instructions,
    OwnedVector<const byte> reloc_info,
    OwnedVector<const byte> source_position_table, WasmCode::Kind kind,
    WasmCode::Tier tier) {
  WasmCode* code;
  {
    // Both allocation and insertion in owned_code_ happen in the same critical
    // section, thus ensuring owned_code_'s elements are rarely if ever moved.
    base::LockGuard<base::Mutex> lock(&allocation_mutex_);
    Address executable_buffer = AllocateForCode(instructions.size());
    if (executable_buffer == kNullAddress) {
      V8::FatalProcessOutOfMemory(nullptr, "NativeModule::AddOwnedCode");
      UNREACHABLE();
    }
    // Ownership will be transferred to {owned_code_} below.
    code = new WasmCode(
        this, index,
        {reinterpret_cast<byte*>(executable_buffer), instructions.size()},
        stack_slots, safepoint_table_offset, handler_table_offset,
        constant_pool_offset, std::move(protected_instructions),
        std::move(reloc_info), std::move(source_position_table), kind, tier);

    if (owned_code_.empty() ||
        code->instruction_start() > owned_code_.back()->instruction_start()) {
      // Common case.
      owned_code_.emplace_back(code);
    } else {
      // Slow but unlikely case.
      // TODO(mtrofin): We allocate in increasing address order, and
      // even if we end up with segmented memory, we may end up only with a few
      // large moves - if, for example, a new segment is below the current ones.
      auto insert_before = std::upper_bound(
          owned_code_.begin(), owned_code_.end(), code->instruction_start(),
          WasmCodeUniquePtrComparator{});
      owned_code_.emplace(insert_before, code);
    }
  }
  memcpy(reinterpret_cast<void*>(code->instruction_start()),
         instructions.start(), instructions.size());

  return code;
}

WasmCode* NativeModule::AddCodeCopy(Handle<Code> code, WasmCode::Kind kind,
                                    uint32_t index) {
  // TODO(wasm): Adding instance-specific wasm-to-js wrappers as owned code to
  // this NativeModule is a memory leak until the whole NativeModule dies.
  WasmCode* ret = AddAnonymousCode(code, kind);
  ret->index_ = Just(index);
  if (index >= module_->num_imported_functions) set_code(index, ret);
  return ret;
}

WasmCode* NativeModule::AddInterpreterEntry(Handle<Code> code, uint32_t index) {
  WasmCode* ret = AddAnonymousCode(code, WasmCode::kInterpreterEntry);
  ret->index_ = Just(index);
  base::LockGuard<base::Mutex> lock(&allocation_mutex_);
  PatchJumpTable(index, ret->instruction_start(), WasmCode::kFlushICache);
  set_code(index, ret);
  return ret;
}

void NativeModule::SetLazyBuiltin(Handle<Code> code) {
  uint32_t num_wasm_functions = module_->num_declared_functions;
  if (num_wasm_functions == 0) return;
  WasmCode* lazy_builtin = AddAnonymousCode(code, WasmCode::kLazyStub);
  // Fill the jump table with jumps to the lazy compile stub.
  Address lazy_compile_target = lazy_builtin->instruction_start();
  for (uint32_t i = 0; i < num_wasm_functions; ++i) {
    JumpTableAssembler::EmitLazyCompileJumpSlot(
        jump_table_->instruction_start(), i,
        i + module_->num_imported_functions, lazy_compile_target,
        WasmCode::kNoFlushICache);
  }
  Assembler::FlushICache(jump_table_->instructions().start(),
                         jump_table_->instructions().size());
}

void NativeModule::SetRuntimeStubs(Isolate* isolate) {
  DCHECK_NULL(runtime_stub_table_[0]);  // Only called once.
#define COPY_BUILTIN(Name)                                                     \
  runtime_stub_table_[WasmCode::k##Name] =                                     \
      AddAnonymousCode(isolate->builtins()->builtin_handle(Builtins::k##Name), \
                       WasmCode::kRuntimeStub);
#define COPY_BUILTIN_TRAP(Name) COPY_BUILTIN(ThrowWasm##Name)
  WASM_RUNTIME_STUB_LIST(COPY_BUILTIN, COPY_BUILTIN_TRAP);
#undef COPY_BUILTIN_TRAP
#undef COPY_BUILTIN
}

WasmCode* NativeModule::AddAnonymousCode(Handle<Code> code,
                                         WasmCode::Kind kind) {
  OwnedVector<byte> reloc_info =
      OwnedVector<byte>::New(code->relocation_size());
  memcpy(reloc_info.start(), code->relocation_start(), code->relocation_size());
  Handle<ByteArray> source_pos_table(code->SourcePositionTable(),
                                     code->GetIsolate());
  OwnedVector<byte> source_pos =
      OwnedVector<byte>::New(source_pos_table->length());
  source_pos_table->copy_out(0, source_pos.start(), source_pos_table->length());
  Vector<const byte> instructions(
      reinterpret_cast<byte*>(code->InstructionStart()),
      static_cast<size_t>(code->InstructionSize()));
  int stack_slots = code->has_safepoint_info() ? code->stack_slots() : 0;
  int safepoint_table_offset =
      code->has_safepoint_info() ? code->safepoint_table_offset() : 0;
  WasmCode* ret =
      AddOwnedCode(Nothing<uint32_t>(),           // index
                   instructions,                  // instructions
                   stack_slots,                   // stack_slots
                   safepoint_table_offset,        // safepoint_table_offset
                   code->handler_table_offset(),  // handler_table_offset
                   code->constant_pool_offset(),  // constant_pool_offset
                   {},                            // protected_instructions
                   std::move(reloc_info),         // reloc_info
                   std::move(source_pos),         // source positions
                   kind,                          // kind
                   WasmCode::kOther);             // tier

  // Apply the relocation delta by iterating over the RelocInfo.
  intptr_t delta = ret->instruction_start() - code->InstructionStart();
  int mode_mask = RelocInfo::kApplyMask |
                  RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL);
  RelocIterator orig_it(*code, mode_mask);
  for (RelocIterator it(ret->instructions(), ret->reloc_info(),
                        ret->constant_pool(), mode_mask);
       !it.done(); it.next(), orig_it.next()) {
    RelocInfo::Mode mode = it.rinfo()->rmode();
    if (RelocInfo::IsWasmStubCall(mode)) {
      uint32_t stub_call_tag = orig_it.rinfo()->wasm_call_tag();
      DCHECK_LT(stub_call_tag, WasmCode::kRuntimeStubCount);
      WasmCode* code =
          runtime_stub(static_cast<WasmCode::RuntimeStubId>(stub_call_tag));
      it.rinfo()->set_wasm_stub_call_address(code->instruction_start(),
                                             SKIP_ICACHE_FLUSH);
    } else {
      it.rinfo()->apply(delta);
    }
  }

  // Flush the i-cache here instead of in AddOwnedCode, to include the changes
  // made while iterating over the RelocInfo above.
  Assembler::FlushICache(ret->instructions().start(),
                         ret->instructions().size());
  if (FLAG_print_code || FLAG_print_wasm_code) ret->Print();
  ret->Validate();
  return ret;
}

WasmCode* NativeModule::AddCode(
    uint32_t index, const CodeDesc& desc, uint32_t stack_slots,
    size_t safepoint_table_offset, size_t handler_table_offset,
    OwnedVector<trap_handler::ProtectedInstructionData> protected_instructions,
    OwnedVector<const byte> source_pos_table, WasmCode::Tier tier) {
  OwnedVector<byte> reloc_info = OwnedVector<byte>::New(desc.reloc_size);
  memcpy(reloc_info.start(), desc.buffer + desc.buffer_size - desc.reloc_size,
         desc.reloc_size);
  WasmCode* ret = AddOwnedCode(
      Just(index), {desc.buffer, static_cast<size_t>(desc.instr_size)},
      stack_slots, safepoint_table_offset, handler_table_offset,
      desc.instr_size - desc.constant_pool_size,
      std::move(protected_instructions), std::move(reloc_info),
      std::move(source_pos_table), WasmCode::kFunction, tier);

  // Apply the relocation delta by iterating over the RelocInfo.
  intptr_t delta = ret->instructions().start() - desc.buffer;
  int mode_mask = RelocInfo::kApplyMask |
                  RelocInfo::ModeMask(RelocInfo::WASM_CALL) |
                  RelocInfo::ModeMask(RelocInfo::WASM_STUB_CALL);
  for (RelocIterator it(ret->instructions(), ret->reloc_info(),
                        ret->constant_pool(), mode_mask);
       !it.done(); it.next()) {
    RelocInfo::Mode mode = it.rinfo()->rmode();
    if (RelocInfo::IsWasmCall(mode)) {
      uint32_t call_tag = it.rinfo()->wasm_call_tag();
      Address target = GetCallTargetForFunction(call_tag);
      it.rinfo()->set_wasm_call_address(target, SKIP_ICACHE_FLUSH);
    } else if (RelocInfo::IsWasmStubCall(mode)) {
      uint32_t stub_call_tag = it.rinfo()->wasm_call_tag();
      DCHECK_LT(stub_call_tag, WasmCode::kRuntimeStubCount);
      WasmCode* code =
          runtime_stub(static_cast<WasmCode::RuntimeStubId>(stub_call_tag));
      it.rinfo()->set_wasm_stub_call_address(code->instruction_start(),
                                             SKIP_ICACHE_FLUSH);
    } else {
      it.rinfo()->apply(delta);
    }
  }

  // Flush the i-cache here instead of in AddOwnedCode, to include the changes
  // made while iterating over the RelocInfo above.
  Assembler::FlushICache(ret->instructions().start(),
                         ret->instructions().size());
  if (FLAG_print_code || FLAG_print_wasm_code) ret->Print();
  ret->Validate();
  return ret;
}

WasmCode* NativeModule::AddDeserializedCode(
    uint32_t index, Vector<const byte> instructions, uint32_t stack_slots,
    size_t safepoint_table_offset, size_t handler_table_offset,
    size_t constant_pool_offset,
    OwnedVector<trap_handler::ProtectedInstructionData> protected_instructions,
    OwnedVector<const byte> reloc_info,
    OwnedVector<const byte> source_position_table, WasmCode::Tier tier) {
  WasmCode* code = AddOwnedCode(
      Just(index), instructions, stack_slots, safepoint_table_offset,
      handler_table_offset, constant_pool_offset,
      std::move(protected_instructions), std::move(reloc_info),
      std::move(source_position_table), WasmCode::kFunction, tier);

  if (!code->protected_instructions_.is_empty()) {
    code->RegisterTrapHandlerData();
  }
  set_code(index, code);
  PatchJumpTable(index, code->instruction_start(), WasmCode::kFlushICache);
  // Note: we do not flush the i-cache here, since the code needs to be
  // relocated anyway. The caller is responsible for flushing the i-cache later.
  return code;
}

void NativeModule::PublishCode(WasmCode* code) {
  base::LockGuard<base::Mutex> lock(&allocation_mutex_);
  // Skip publishing code if there is an active redirection to the interpreter
  // for the given function index, in order to preserve the redirection.
  if (has_code(code->index()) &&
      this->code(code->index())->kind() == WasmCode::kInterpreterEntry) {
    return;
  }
  if (!code->protected_instructions_.is_empty()) {
    code->RegisterTrapHandlerData();
  }
  DCHECK(!code->IsAnonymous());
  set_code(code->index(), code);
  PatchJumpTable(code->index(), code->instruction_start(),
                 WasmCode::kFlushICache);
}

std::vector<WasmCode*> NativeModule::SnapshotCodeTable() const {
  base::LockGuard<base::Mutex> lock(&allocation_mutex_);
  std::vector<WasmCode*> result;
  result.reserve(code_table().size());
  for (WasmCode* code : code_table()) result.push_back(code);
  return result;
}

WasmCode* NativeModule::CreateEmptyJumpTable(uint32_t num_wasm_functions) {
  // Only call this if we really need a jump table.
  DCHECK_LT(0, num_wasm_functions);
  OwnedVector<byte> instructions = OwnedVector<byte>::New(
      JumpTableAssembler::SizeForNumberOfSlots(num_wasm_functions));
  memset(instructions.start(), 0, instructions.size());
  return AddOwnedCode(Nothing<uint32_t>(),       // index
                      instructions.as_vector(),  // instructions
                      0,                         // stack_slots
                      0,                         // safepoint_table_offset
                      0,                         // handler_table_offset
                      0,                         // constant_pool_offset
                      {},                        // protected_instructions
                      {},                        // reloc_info
                      {},                        // source_pos
                      WasmCode::kJumpTable,      // kind
                      WasmCode::kOther);         // tier
}

void NativeModule::PatchJumpTable(uint32_t func_index, Address target,
                                  WasmCode::FlushICache flush_icache) {
  DCHECK_LE(module_->num_imported_functions, func_index);
  uint32_t slot_idx = func_index - module_->num_imported_functions;
  JumpTableAssembler::PatchJumpTableSlot(jump_table_->instruction_start(),
                                         slot_idx, target, flush_icache);
}

Address NativeModule::AllocateForCode(size_t size) {
  // This happens under a lock assumed by the caller.
  size = RoundUp(size, kCodeAlignment);
  AddressRange mem = free_code_space_.Allocate(size);
  if (mem.is_empty()) {
    if (!can_request_more_memory_) return kNullAddress;

    Address hint = owned_code_space_.empty() ? kNullAddress
                                             : owned_code_space_.back().end();
    VirtualMemory empty_mem;
    owned_code_space_.push_back(empty_mem);
    VirtualMemory& new_mem = owned_code_space_.back();
    wasm_code_manager_->TryAllocate(size, &new_mem,
                                    reinterpret_cast<void*>(hint));
    if (!new_mem.IsReserved()) return kNullAddress;
    wasm_code_manager_->AssignRanges(new_mem.address(), new_mem.end(), this);

    free_code_space_.Merge({new_mem.address(), new_mem.end()});
    mem = free_code_space_.Allocate(size);
    if (mem.is_empty()) return kNullAddress;
  }
  Address commit_start = RoundUp(mem.start, AllocatePageSize());
  Address commit_end = RoundUp(mem.end, AllocatePageSize());
  // {commit_start} will be either mem.start or the start of the next page.
  // {commit_end} will be the start of the page after the one in which
  // the allocation ends.
  // We start from an aligned start, and we know we allocated vmem in
  // page multiples.
  // We just need to commit what's not committed. The page in which we
  // start is already committed (or we start at the beginning of a page).
  // The end needs to be committed all through the end of the page.
  if (commit_start < commit_end) {
#if V8_OS_WIN
    // On Windows, we cannot commit a range that straddles different
    // reservations of virtual memory. Because we bump-allocate, and because, if
    // we need more memory, we append that memory at the end of the
    // owned_code_space_ list, we traverse that list in reverse order to find
    // the reservation(s) that guide how to chunk the region to commit.
    for (auto it = owned_code_space_.crbegin(),
              rend = owned_code_space_.crend();
         it != rend && commit_start < commit_end; ++it) {
      if (commit_end > it->end() || it->address() >= commit_end) continue;
      Address start = std::max(commit_start, it->address());
      size_t commit_size = static_cast<size_t>(commit_end - start);
      DCHECK(IsAligned(commit_size, AllocatePageSize()));
      if (!wasm_code_manager_->Commit(start, commit_size)) {
        return kNullAddress;
      }
      committed_code_space_.fetch_add(commit_size);
      commit_end = start;
    }
#else
    size_t commit_size = static_cast<size_t>(commit_end - commit_start);
    DCHECK(IsAligned(commit_size, AllocatePageSize()));
    if (!wasm_code_manager_->Commit(commit_start, commit_size)) {
      return kNullAddress;
    }
    committed_code_space_.fetch_add(commit_size);
#endif
  }
  DCHECK(IsAligned(mem.start, kCodeAlignment));
  allocated_code_space_.Merge(std::move(mem));
  TRACE_HEAP("Code alloc for %p: %" PRIuPTR ",+%zu\n", this, mem.start, size);
  return mem.start;
}

WasmCode* NativeModule::Lookup(Address pc) const {
  base::LockGuard<base::Mutex> lock(&allocation_mutex_);
  if (owned_code_.empty()) return nullptr;
  auto iter = std::upper_bound(owned_code_.begin(), owned_code_.end(), pc,
                               WasmCodeUniquePtrComparator());
  if (iter == owned_code_.begin()) return nullptr;
  --iter;
  WasmCode* candidate = iter->get();
  DCHECK_NOT_NULL(candidate);
  return candidate->contains(pc) ? candidate : nullptr;
}

Address NativeModule::GetCallTargetForFunction(uint32_t func_index) const {
  // TODO(clemensh): Measure performance win of returning instruction start
  // directly if we have turbofan code. Downside: Redirecting functions (e.g.
  // for debugging) gets much harder.

  // Return the jump table slot for that function index.
  DCHECK_NOT_NULL(jump_table_);
  uint32_t slot_idx = func_index - module_->num_imported_functions;
  uint32_t slot_offset = JumpTableAssembler::SlotIndexToOffset(slot_idx);
  DCHECK_LT(slot_offset, jump_table_->instructions().size());
  return jump_table_->instruction_start() + slot_offset;
}

uint32_t NativeModule::GetFunctionIndexFromJumpTableSlot(
    Address slot_address) const {
  DCHECK(is_jump_table_slot(slot_address));
  uint32_t slot_offset =
      static_cast<uint32_t>(slot_address - jump_table_->instruction_start());
  uint32_t slot_idx = JumpTableAssembler::SlotOffsetToIndex(slot_offset);
  DCHECK_LT(slot_idx, module_->num_declared_functions);
  return module_->num_imported_functions + slot_idx;
}

void NativeModule::DisableTrapHandler() {
  // Switch {use_trap_handler_} from true to false.
  DCHECK(use_trap_handler_);
  use_trap_handler_ = false;

  // Clear the code table (just to increase the chances to hit an error if we
  // forget to re-add all code).
  uint32_t num_wasm_functions = module_->num_declared_functions;
  memset(code_table_.get(), 0, num_wasm_functions * sizeof(WasmCode*));

  // TODO(clemensh): Actually free the owned code, such that the memory can be
  // recycled.
}

NativeModule::~NativeModule() {
  TRACE_HEAP("Deleting native module: %p\n", reinterpret_cast<void*>(this));
  compilation_state_.reset();  // Cancels tasks, needs to be done first.
  wasm_code_manager_->FreeNativeModule(this);
}

WasmCodeManager::WasmCodeManager(size_t max_committed) {
  DCHECK_LE(max_committed, kMaxWasmCodeMemory);
  remaining_uncommitted_code_space_.store(max_committed);
}

bool WasmCodeManager::Commit(Address start, size_t size) {
  DCHECK(IsAligned(start, AllocatePageSize()));
  DCHECK(IsAligned(size, AllocatePageSize()));
  // Reserve the size. Use CAS loop to avoid underflow on
  // {remaining_uncommitted_}. Temporary underflow would allow concurrent
  // threads to over-commit.
  while (true) {
    size_t old_value = remaining_uncommitted_code_space_.load();
    if (old_value < size) return false;
    if (remaining_uncommitted_code_space_.compare_exchange_weak(
            old_value, old_value - size)) {
      break;
    }
  }
  PageAllocator::Permission permission = FLAG_wasm_write_protect_code_memory
                                             ? PageAllocator::kReadWrite
                                             : PageAllocator::kReadWriteExecute;

  bool ret = SetPermissions(start, size, permission);
  TRACE_HEAP("Setting rw permissions for %p:%p\n",
             reinterpret_cast<void*>(start),
             reinterpret_cast<void*>(start + size));

  if (!ret) {
    // Highly unlikely.
    remaining_uncommitted_code_space_.fetch_add(size);
    return false;
  }
  return ret;
}

void WasmCodeManager::AssignRanges(Address start, Address end,
                                   NativeModule* native_module) {
  lookup_map_.insert(std::make_pair(start, std::make_pair(end, native_module)));
}

void WasmCodeManager::TryAllocate(size_t size, VirtualMemory* ret, void* hint) {
  DCHECK_GT(size, 0);
  size = RoundUp(size, AllocatePageSize());
  if (hint == nullptr) hint = GetRandomMmapAddr();

  if (!AlignedAllocVirtualMemory(size, static_cast<size_t>(AllocatePageSize()),
                                 hint, ret)) {
    DCHECK(!ret->IsReserved());
  }
  TRACE_HEAP("VMem alloc: %p:%p (%zu)\n",
             reinterpret_cast<void*>(ret->address()),
             reinterpret_cast<void*>(ret->end()), ret->size());
}

void WasmCodeManager::SampleModuleSizes(Isolate* isolate) const {
  base::LockGuard<base::Mutex> lock(&native_modules_mutex_);
  for (NativeModule* native_module : native_modules_) {
    int code_size =
        static_cast<int>(native_module->committed_code_space_.load() / MB);
    isolate->counters()->wasm_module_code_size_mb()->AddSample(code_size);
  }
}

namespace {

void ModuleSamplingCallback(v8::Isolate* v8_isolate, v8::GCType type,
                            v8::GCCallbackFlags flags, void* data) {
  Isolate* isolate = reinterpret_cast<Isolate*>(v8_isolate);
  isolate->wasm_engine()->code_manager()->SampleModuleSizes(isolate);
}

}  // namespace

// static
void WasmCodeManager::InstallSamplingGCCallback(Isolate* isolate) {
  isolate->heap()->AddGCEpilogueCallback(ModuleSamplingCallback,
                                         v8::kGCTypeMarkSweepCompact, nullptr);
}

// static
size_t WasmCodeManager::EstimateNativeModuleSize(const WasmModule* module) {
  constexpr size_t kCodeSizeMultiplier = 4;
  constexpr size_t kImportSize = 32 * kPointerSize;

  uint32_t num_wasm_functions = module->num_declared_functions;

  size_t estimate =
      AllocatePageSize() /* TODO(titzer): 1 page spot bonus */ +
      sizeof(NativeModule) +
      (sizeof(WasmCode*) * num_wasm_functions /* code table size */) +
      (sizeof(WasmCode) * num_wasm_functions /* code object size */) +
      (kImportSize * module->num_imported_functions /* import size */) +
      (JumpTableAssembler::SizeForNumberOfSlots(num_wasm_functions));

  for (auto& function : module->functions) {
    estimate += kCodeSizeMultiplier * function.code.length();
  }

  return estimate;
}

bool WasmCodeManager::ShouldForceCriticalMemoryPressureNotification() {
  base::LockGuard<base::Mutex> lock(&native_modules_mutex_);
  // TODO(titzer): we force a critical memory pressure notification
  // when the code space is almost exhausted, but only upon the next module
  // creation. This is only for one isolate, and it should really do this for
  // all isolates, at the point of commit.
  constexpr size_t kCriticalThreshold = 32 * 1024 * 1024;
  return native_modules_.size() > 1 &&
         remaining_uncommitted_code_space_.load() < kCriticalThreshold;
}

std::unique_ptr<NativeModule> WasmCodeManager::NewNativeModule(
    Isolate* isolate, const WasmFeatures& enabled, size_t memory_estimate,
    bool can_request_more, std::shared_ptr<const WasmModule> module,
    const ModuleEnv& env) {
  if (ShouldForceCriticalMemoryPressureNotification()) {
    (reinterpret_cast<v8::Isolate*>(isolate))
        ->MemoryPressureNotification(MemoryPressureLevel::kCritical);
  }

  VirtualMemory mem;
  // If the code must be contiguous, reserve enough address space up front.
  size_t vmem_size = kRequiresCodeRange ? kMaxWasmCodeMemory : memory_estimate;
  TryAllocate(vmem_size, &mem);
  if (mem.IsReserved()) {
    Address start = mem.address();
    size_t size = mem.size();
    Address end = mem.end();
    std::unique_ptr<NativeModule> ret(
        new NativeModule(isolate, enabled, can_request_more, &mem, this,
                         std::move(module), env));
    TRACE_HEAP("New NativeModule %p: Mem: %" PRIuPTR ",+%zu\n", this, start,
               size);
    base::LockGuard<base::Mutex> lock(&native_modules_mutex_);
    AssignRanges(start, end, ret.get());
    native_modules_.emplace(ret.get());
    return ret;
  }

  V8::FatalProcessOutOfMemory(isolate, "WasmCodeManager::NewNativeModule");
  return nullptr;
}

bool NativeModule::SetExecutable(bool executable) {
  if (is_executable_ == executable) return true;
  TRACE_HEAP("Setting module %p as executable: %d.\n", this, executable);

  if (FLAG_wasm_write_protect_code_memory) {
    PageAllocator::Permission permission =
        executable ? PageAllocator::kReadExecute : PageAllocator::kReadWrite;
#if V8_OS_WIN
    // On windows, we need to switch permissions per separate virtual memory
    // reservation. This is really just a problem when the NativeModule is
    // growable (meaning can_request_more_memory_). That's 32-bit in production,
    // or unittests.
    // For now, in that case, we commit at reserved memory granularity.
    // Technically, that may be a waste, because we may reserve more than we
    // use. On 32-bit though, the scarce resource is the address space -
    // committed or not.
    if (can_request_more_memory_) {
      for (auto& vmem : owned_code_space_) {
        if (!SetPermissions(vmem.address(), vmem.size(), permission)) {
          return false;
        }
        TRACE_HEAP("Set %p:%p to executable:%d\n", vmem.address(), vmem.end(),
                   executable);
      }
      is_executable_ = executable;
      return true;
    }
#endif
    for (auto& range : allocated_code_space_.ranges()) {
      // allocated_code_space_ is fine-grained, so we need to
      // page-align it.
      size_t range_size = RoundUp(range.size(), AllocatePageSize());
      if (!SetPermissions(range.start, range_size, permission)) {
        return false;
      }
      TRACE_HEAP("Set %p:%p to executable:%d\n",
                 reinterpret_cast<void*>(range.start),
                 reinterpret_cast<void*>(range.end), executable);
    }
  }
  is_executable_ = executable;
  return true;
}

void WasmCodeManager::FreeNativeModule(NativeModule* native_module) {
  base::LockGuard<base::Mutex> lock(&native_modules_mutex_);
  DCHECK_EQ(1, native_modules_.count(native_module));
  native_modules_.erase(native_module);
  TRACE_HEAP("Freeing NativeModule %p\n", this);
  for (auto& vmem : native_module->owned_code_space_) {
    lookup_map_.erase(vmem.address());
    Free(&vmem);
    DCHECK(!vmem.IsReserved());
  }
  native_module->owned_code_space_.clear();

  size_t code_size = native_module->committed_code_space_.load();
  DCHECK(IsAligned(code_size, AllocatePageSize()));
  remaining_uncommitted_code_space_.fetch_add(code_size);
}

// TODO(wasm): We can make this more efficient if needed. For
// example, we can preface the first instruction with a pointer to
// the WasmCode. In the meantime, we have a separate API so we can
// easily identify those places where we know we have the first
// instruction PC.
WasmCode* WasmCodeManager::GetCodeFromStartAddress(Address pc) const {
  WasmCode* code = LookupCode(pc);
  // This method can only be called for valid instruction start addresses.
  DCHECK_NOT_NULL(code);
  DCHECK_EQ(pc, code->instruction_start());
  return code;
}

NativeModule* WasmCodeManager::LookupNativeModule(Address pc) const {
  base::LockGuard<base::Mutex> lock(&native_modules_mutex_);
  if (lookup_map_.empty()) return nullptr;

  auto iter = lookup_map_.upper_bound(pc);
  if (iter == lookup_map_.begin()) return nullptr;
  --iter;
  Address range_start = iter->first;
  Address range_end = iter->second.first;
  NativeModule* candidate = iter->second.second;

  DCHECK_NOT_NULL(candidate);
  return range_start <= pc && pc < range_end ? candidate : nullptr;
}

WasmCode* WasmCodeManager::LookupCode(Address pc) const {
  NativeModule* candidate = LookupNativeModule(pc);
  return candidate ? candidate->Lookup(pc) : nullptr;
}

void WasmCodeManager::Free(VirtualMemory* mem) {
  DCHECK(mem->IsReserved());
  void* start = reinterpret_cast<void*>(mem->address());
  void* end = reinterpret_cast<void*>(mem->end());
  size_t size = mem->size();
  mem->Free();
  TRACE_HEAP("VMem Release: %p:%p (%zu)\n", start, end, size);
}

size_t WasmCodeManager::remaining_uncommitted_code_space() const {
  return remaining_uncommitted_code_space_.load();
}

// TODO(v8:7424): Code protection scopes are not yet supported with shared code
// enabled and need to be revisited to work with --wasm-shared-code as well.
NativeModuleModificationScope::NativeModuleModificationScope(
    NativeModule* native_module)
    : native_module_(native_module) {
  if (FLAG_wasm_write_protect_code_memory && native_module_ &&
      (native_module_->modification_scope_depth_++) == 0) {
    bool success = native_module_->SetExecutable(false);
    CHECK(success);
  }
}

NativeModuleModificationScope::~NativeModuleModificationScope() {
  if (FLAG_wasm_write_protect_code_memory && native_module_ &&
      (native_module_->modification_scope_depth_--) == 1) {
    bool success = native_module_->SetExecutable(true);
    CHECK(success);
  }
}

}  // namespace wasm
}  // namespace internal
}  // namespace v8
#undef TRACE_HEAP