blob: 26a9030d4efb6427c3d349f7cb594e3f819bd14d [file] [log] [blame]
// 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 <atomic>
#include <map>
#include <memory>
#include <set>
#include <unordered_set>
#include <utility>
#include <vector>
#include "src/base/address-region.h"
#include "src/base/bit-field.h"
#include "src/base/macros.h"
#include "src/base/optional.h"
#include "src/builtins/builtins-definitions.h"
#include "src/handles/handles.h"
#include "src/trap-handler/trap-handler.h"
#include "src/utils/vector.h"
#include "src/wasm/compilation-environment.h"
#include "src/wasm/wasm-features.h"
#include "src/wasm/wasm-limits.h"
#include "src/wasm/wasm-module-sourcemap.h"
#include "src/wasm/wasm-tier.h"
namespace v8 {
namespace internal {
class Code;
class CodeDesc;
class Isolate;
namespace wasm {
class DebugInfo;
class NativeModule;
class WasmCodeManager;
struct WasmCompilationResult;
class WasmEngine;
class WasmImportWrapperCache;
struct WasmModule;
// Convenience macro listing all wasm runtime stubs. Note that the first few
// elements of the list coincide with {compiler::TrapId}, order matters.
V(WasmCompileLazy) \
V(WasmTriggerTierUp) \
V(WasmDebugBreak) \
V(WasmInt32ToHeapNumber) \
V(WasmTaggedNonSmiToInt32) \
V(WasmFloat32ToNumber) \
V(WasmFloat64ToNumber) \
V(WasmTaggedToFloat64) \
V(WasmAllocateJSArray) \
V(WasmAllocatePair) \
V(WasmAtomicNotify) \
V(WasmI32AtomicWait32) \
V(WasmI32AtomicWait64) \
V(WasmI64AtomicWait32) \
V(WasmI64AtomicWait64) \
V(WasmRefFunc) \
V(WasmMemoryGrow) \
V(WasmTableInit) \
V(WasmTableCopy) \
V(WasmTableGet) \
V(WasmTableSet) \
V(WasmStackGuard) \
V(WasmStackOverflow) \
V(WasmThrow) \
V(WasmRethrow) \
V(WasmTraceEnter) \
V(WasmTraceExit) \
V(WasmTraceMemory) \
V(ArgumentsAdaptorTrampoline) \
V(BigIntToI32Pair) \
V(BigIntToI64) \
V(DoubleToI) \
V(I32PairToBigInt) \
V(I64ToBigInt) \
V(RecordWrite) \
// Sorted, disjoint and non-overlapping memory regions. A region is of the
// form [start, end). So there's no [start, end), [end, other_end),
// because that should have been reduced to [start, other_end).
class V8_EXPORT_PRIVATE DisjointAllocationPool final {
explicit DisjointAllocationPool(base::AddressRegion region)
: regions_({region}) {}
// Merge the parameter region into this object. The assumption is that the
// passed parameter is not intersecting this object - for example, it was
// obtained from a previous Allocate. Returns the merged region.
base::AddressRegion Merge(base::AddressRegion);
// Allocate a contiguous region of size {size}. Return an empty pool on
// failure.
base::AddressRegion Allocate(size_t size);
// Allocate a contiguous region of size {size} within {region}. Return an
// empty pool on failure.
base::AddressRegion AllocateInRegion(size_t size, base::AddressRegion);
bool IsEmpty() const { return regions_.empty(); }
const auto& regions() const { return regions_; }
std::set<base::AddressRegion, base::AddressRegion::StartAddressLess> regions_;
class V8_EXPORT_PRIVATE WasmCode final {
enum Kind {
// Each runtime stub is identified by an id. This id is used to reference the
// stub via {RelocInfo::WASM_STUB_CALL} and gets resolved during relocation.
enum RuntimeStubId {
#define DEF_ENUM(Name) k##Name,
#define DEF_ENUM_TRAP(Name) kThrowWasm##Name,
#undef DEF_ENUM
Vector<byte> instructions() const {
return VectorOf(instructions_, static_cast<size_t>(instructions_size_));
Address instruction_start() const {
return reinterpret_cast<Address>(instructions_);
Vector<const byte> reloc_info() const {
return {protected_instructions_data().end(),
Vector<const byte> source_positions() const {
return {reloc_info().end(), static_cast<size_t>(source_positions_size_)};
// TODO(clemensb): Make this return int.
uint32_t index() const {
DCHECK_LE(0, index_);
return index_;
// Anonymous functions are functions that don't carry an index.
bool IsAnonymous() const { return index_ == kAnonymousFuncIndex; }
Kind kind() const { return KindField::decode(flags_); }
NativeModule* native_module() const { return native_module_; }
ExecutionTier tier() const { return ExecutionTierField::decode(flags_); }
Address constant_pool() const;
Address handler_table() const;
int handler_table_size() const;
Address code_comments() const;
int code_comments_size() const;
int constant_pool_offset() const { return constant_pool_offset_; }
int safepoint_table_offset() const { return safepoint_table_offset_; }
int handler_table_offset() const { return handler_table_offset_; }
int code_comments_offset() const { return code_comments_offset_; }
int unpadded_binary_size() const { return unpadded_binary_size_; }
int stack_slots() const { return stack_slots_; }
int tagged_parameter_slots() const { return tagged_parameter_slots_; }
bool is_liftoff() const { return tier() == ExecutionTier::kLiftoff; }
bool contains(Address pc) const {
return reinterpret_cast<Address>(instructions_) <= pc &&
pc < reinterpret_cast<Address>(instructions_ + instructions_size_);
// Only Liftoff code that was generated for debugging can be inspected
// (otherwise debug side table positions would not match up).
bool is_inspectable() const { return is_liftoff() && for_debugging(); }
Vector<const uint8_t> protected_instructions_data() const {
return {meta_data_.get(),
Vector<const trap_handler::ProtectedInstructionData> protected_instructions()
const {
return Vector<const trap_handler::ProtectedInstructionData>::cast(
void Validate() const;
void Print(const char* name = nullptr) const;
void MaybePrint(const char* name = nullptr) const;
void Disassemble(const char* name, std::ostream& os,
Address current_pc = kNullAddress) const;
static bool ShouldBeLogged(Isolate* isolate);
void LogCode(Isolate* isolate) const;
WasmCode(const WasmCode&) = delete;
WasmCode& operator=(const WasmCode&) = delete;
void IncRef() {
int old_val = ref_count_.fetch_add(1, std::memory_order_acq_rel);
DCHECK_LE(1, old_val);
DCHECK_GT(kMaxInt, old_val);
// Decrement the ref count. Returns whether this code becomes dead and needs
// to be freed.
int old_count = ref_count_.load(std::memory_order_acquire);
while (true) {
DCHECK_LE(1, old_count);
if (V8_UNLIKELY(old_count == 1)) return DecRefOnPotentiallyDeadCode();
if (ref_count_.compare_exchange_weak(old_count, old_count - 1,
std::memory_order_acq_rel)) {
return false;
// Decrement the ref count on code that is known to be dead, even though there
// might still be C++ references. Returns whether this drops the last
// reference and the code needs to be freed.
V8_WARN_UNUSED_RESULT bool DecRefOnDeadCode() {
return ref_count_.fetch_sub(1, std::memory_order_acq_rel) == 1;
// Decrement the ref count on a set of {WasmCode} objects, potentially
// belonging to different {NativeModule}s. Dead code will be deleted.
static void DecrementRefCount(Vector<WasmCode* const>);
// Returns the last source position before {offset}.
int GetSourcePositionBefore(int offset);
// Returns whether this code was generated for debugging. If this returns
// {kForDebugging}, but {tier()} is not {kLiftoff}, then Liftoff compilation
// bailed out.
ForDebugging for_debugging() const {
return ForDebuggingField::decode(flags_);
enum FlushICache : bool { kFlushICache = true, kNoFlushICache = false };
friend class NativeModule;
WasmCode(NativeModule* native_module, int index, Vector<byte> instructions,
int stack_slots, int tagged_parameter_slots,
int safepoint_table_offset, int handler_table_offset,
int constant_pool_offset, int code_comments_offset,
int unpadded_binary_size,
Vector<const byte> protected_instructions_data,
Vector<const byte> reloc_info,
Vector<const byte> source_position_table, Kind kind,
ExecutionTier tier, ForDebugging for_debugging)
: native_module_(native_module),
flags_(KindField::encode(kind) | ExecutionTierField::encode(tier) |
{protected_instructions_data, reloc_info, source_position_table})),
unpadded_binary_size_(unpadded_binary_size) {
DCHECK_LE(safepoint_table_offset, unpadded_binary_size);
DCHECK_LE(handler_table_offset, unpadded_binary_size);
DCHECK_LE(code_comments_offset, unpadded_binary_size);
DCHECK_LE(constant_pool_offset, unpadded_binary_size);
std::unique_ptr<const byte[]> ConcatenateBytes(
std::initializer_list<Vector<const byte>>);
// Code objects that have been registered with the global trap handler within
// this process, will have a {trap_handler_index} associated with them.
int trap_handler_index() const {
return trap_handler_index_;
void set_trap_handler_index(int value) {
trap_handler_index_ = value;
bool has_trap_handler_index() const { return trap_handler_index_ >= 0; }
// Register protected instruction information with the trap handler. Sets
// trap_handler_index.
void RegisterTrapHandlerData();
// Slow path for {DecRef}: The code becomes potentially dead.
// Returns whether this code becomes dead and needs to be freed.
V8_NOINLINE bool DecRefOnPotentiallyDeadCode();
NativeModule* const native_module_ = nullptr;
byte* const instructions_;
const uint8_t flags_; // Bit field, see below.
// {meta_data_} contains several byte vectors concatenated into one:
// - protected instructions data of size {protected_instructions_size_}
// - relocation info of size {reloc_info_size_}
// - source positions of size {source_positions_size_}
// Note that the protected instructions come first to ensure alignment.
std::unique_ptr<const byte[]> meta_data_;
const int instructions_size_;
const int reloc_info_size_;
const int source_positions_size_;
const int protected_instructions_size_;
const int index_;
const int constant_pool_offset_;
const int stack_slots_;
// Number of tagged parameters passed to this function via the stack. This
// value is used by the stack walker (e.g. GC) to find references.
const int tagged_parameter_slots_;
// We care about safepoint data for wasm-to-js functions, since there may be
// stack/register tagged values for large number conversions.
const int safepoint_table_offset_;
const int handler_table_offset_;
const int code_comments_offset_;
const int unpadded_binary_size_;
int trap_handler_index_ = -1;
// Bits encoded in {flags_}:
using KindField = base::BitField8<Kind, 0, 3>;
using ExecutionTierField = KindField::Next<ExecutionTier, 2>;
using ForDebuggingField = ExecutionTierField::Next<ForDebugging, 2>;
// WasmCode is ref counted. Counters are held by:
// 1) The jump table / code table.
// 2) {WasmCodeRefScope}s.
// 3) The set of potentially dead code in the {WasmEngine}.
// If a decrement of (1) would drop the ref count to 0, that code becomes a
// candidate for garbage collection. At that point, we add a ref count for (3)
// *before* decrementing the counter to ensure the code stays alive as long as
// it's being used. Once the ref count drops to zero (i.e. after being removed
// from (3) and all (2)), the code object is deleted and the memory for the
// machine code is freed.
std::atomic<int> ref_count_{1};
// Check that {WasmCode} objects are sufficiently small. We create many of them,
// often for rather small functions.
// Increase the limit if needed, but first check if the size increase is
// justified.
STATIC_ASSERT(sizeof(WasmCode) <= 120);
WasmCode::Kind GetCodeKind(const WasmCompilationResult& result);
// Return a textual description of the kind.
const char* GetWasmCodeKindAsString(WasmCode::Kind);
// Manages the code reservations and allocations of a single {NativeModule}.
class WasmCodeAllocator {
// ARM64 only supports direct calls within a 128 MB range.
static constexpr size_t kMaxCodeSpaceSize = 128 * MB;
// Use 1024 MB limit for code spaces on other platforms. This is smaller than
// the total allowed code space (kMaxWasmCodeMemory) to avoid unnecessarily
// big reservations, and to ensure that distances within a code space fit
// within a 32-bit signed integer.
static constexpr size_t kMaxCodeSpaceSize = 1024 * MB;
// {OptionalLock} is passed between {WasmCodeAllocator} and {NativeModule} to
// indicate that the lock on the {WasmCodeAllocator} is already taken. It's
// optional to allow to also call methods without holding the lock.
class OptionalLock {
// External users can only instantiate a non-locked {OptionalLock}.
OptionalLock() = default;
bool is_locked() const { return allocator_ != nullptr; }
friend class WasmCodeAllocator;
// {Lock} is called from the {WasmCodeAllocator} if no locked {OptionalLock}
// is passed.
void Lock(WasmCodeAllocator*);
WasmCodeAllocator* allocator_ = nullptr;
WasmCodeAllocator(WasmCodeManager*, VirtualMemory code_space,
std::shared_ptr<Counters> async_counters);
// Call before use, after the {NativeModule} is set up completely.
void Init(NativeModule*);
size_t committed_code_space() const {
return committed_code_space_.load(std::memory_order_acquire);
size_t generated_code_size() const {
return generated_code_size_.load(std::memory_order_acquire);
size_t freed_code_size() const {
return freed_code_size_.load(std::memory_order_acquire);
// Allocate code space. Returns a valid buffer or fails with OOM (crash).
Vector<byte> AllocateForCode(NativeModule*, size_t size);
// Allocate code space within a specific region. Returns a valid buffer or
// fails with OOM (crash).
Vector<byte> AllocateForCodeInRegion(NativeModule*, size_t size,
const WasmCodeAllocator::OptionalLock&);
// Sets permissions of all owned code space to executable, or read-write (if
// {executable} is false). Returns true on success.
V8_EXPORT_PRIVATE bool SetExecutable(bool executable);
// Free memory pages of all given code objects. Used for wasm code GC.
void FreeCode(Vector<WasmCode* const>);
// Retrieve the number of separately reserved code spaces.
size_t GetNumCodeSpaces() const;
// Sentinel value to be used for {AllocateForCodeInRegion} for specifying no
// restriction on the region to allocate in.
static constexpr base::AddressRegion kUnrestrictedRegion{
kNullAddress, std::numeric_limits<size_t>::max()};
// The engine-wide wasm code manager.
WasmCodeManager* const code_manager_;
mutable base::Mutex mutex_;
// Protected by {mutex_}:
// Code space that was reserved and is available for allocations (subset of
// {owned_code_space_}).
DisjointAllocationPool free_code_space_;
// Code space that was allocated for code (subset of {owned_code_space_}).
DisjointAllocationPool allocated_code_space_;
// Code space that was allocated before but is dead now. Full pages within
// this region are discarded. It's still a subset of {owned_code_space_}.
DisjointAllocationPool freed_code_space_;
std::vector<VirtualMemory> owned_code_space_;
// End of fields protected by {mutex_}.
std::atomic<size_t> committed_code_space_{0};
std::atomic<size_t> generated_code_size_{0};
std::atomic<size_t> freed_code_size_{0};
bool is_executable_ = false;
std::shared_ptr<Counters> async_counters_;
class V8_EXPORT_PRIVATE NativeModule final {
static constexpr bool kNeedsFarJumpsBetweenCodeSpaces = true;
static constexpr bool kNeedsFarJumpsBetweenCodeSpaces = false;
NativeModule(const NativeModule&) = delete;
NativeModule& operator=(const NativeModule&) = delete;
// {AddCode} is thread safe w.r.t. other calls to {AddCode} or methods adding
// code below, i.e. it can be called concurrently from background threads.
// The returned code still needs to be published via {PublishCode}.
std::unique_ptr<WasmCode> AddCode(int index, const CodeDesc& desc,
int stack_slots, int tagged_parameter_slots,
Vector<const byte> protected_instructions,
Vector<const byte> source_position_table,
WasmCode::Kind kind, ExecutionTier tier,
ForDebugging for_debugging);
// {PublishCode} makes the code available to the system by entering it into
// the code table and patching the jump table. It returns a raw pointer to the
// given {WasmCode} object. Ownership is transferred to the {NativeModule}.
WasmCode* PublishCode(std::unique_ptr<WasmCode>);
std::vector<WasmCode*> PublishCode(Vector<std::unique_ptr<WasmCode>>);
WasmCode* AddDeserializedCode(
int index, Vector<const byte> instructions, int stack_slots,
int tagged_parameter_slots, int safepoint_table_offset,
int handler_table_offset, int constant_pool_offset,
int code_comments_offset, int unpadded_binary_size,
Vector<const byte> protected_instructions_data,
Vector<const byte> reloc_info, Vector<const byte> source_position_table,
WasmCode::Kind kind, ExecutionTier tier);
// Adds anonymous code for testing purposes.
WasmCode* AddCodeForTesting(Handle<Code> code);
// Use {UseLazyStub} to setup lazy compilation per function. It will use the
// existing {WasmCode::kWasmCompileLazy} runtime stub and populate the jump
// table with trampolines accordingly.
void UseLazyStub(uint32_t func_index);
// Creates a snapshot of the current state of the code table. This is useful
// to get a consistent view of the table (e.g. used by the serializer).
std::vector<WasmCode*> SnapshotCodeTable() const;
WasmCode* GetCode(uint32_t index) const;
bool HasCode(uint32_t index) const;
bool HasCodeWithTier(uint32_t index, ExecutionTier tier) const;
void SetWasmSourceMap(std::unique_ptr<WasmModuleSourceMap> source_map);
WasmModuleSourceMap* GetWasmSourceMap() const;
Address jump_table_start() const {
return main_jump_table_ ? main_jump_table_->instruction_start()
: kNullAddress;
uint32_t GetJumpTableOffset(uint32_t func_index) const;
// Returns the canonical target to call for the given function (the slot in
// the first jump table).
Address GetCallTargetForFunction(uint32_t func_index) const;
struct JumpTablesRef {
const Address jump_table_start = kNullAddress;
const Address far_jump_table_start = kNullAddress;
bool is_valid() const { return far_jump_table_start != kNullAddress; }
// Finds the jump tables that should be used for given code region. This
// information is then passed to {GetNearCallTargetForFunction} and
// {GetNearRuntimeStubEntry} to avoid the overhead of looking this information
// up there. Return an empty struct if no suitable jump tables exist.
JumpTablesRef FindJumpTablesForRegion(base::AddressRegion) const;
// Similarly to {GetCallTargetForFunction}, but uses the jump table previously
// looked up via {FindJumpTablesForRegion}.
Address GetNearCallTargetForFunction(uint32_t func_index,
const JumpTablesRef&) const;
// Get a runtime stub entry (which is a far jump table slot) in the jump table
// previously looked up via {FindJumpTablesForRegion}.
Address GetNearRuntimeStubEntry(WasmCode::RuntimeStubId index,
const JumpTablesRef&) const;
// Reverse lookup from a given call target (which must be a jump table slot)
// to a function index.
uint32_t GetFunctionIndexFromJumpTableSlot(Address slot_address) const;
bool SetExecutable(bool executable) {
return code_allocator_.SetExecutable(executable);
// For cctests, where we build both WasmModule and the runtime objects
// on the fly, and bypass the instance builder pipeline.
void ReserveCodeTableForTesting(uint32_t max_functions);
void LogWasmCodes(Isolate* isolate);
CompilationState* compilation_state() { return compilation_state_.get(); }
// Create a {CompilationEnv} object for compilation. The caller has to ensure
// that the {WasmModule} pointer stays valid while the {CompilationEnv} is
// being used.
CompilationEnv CreateCompilationEnv() const;
uint32_t num_functions() const {
return module_->num_declared_functions + module_->num_imported_functions;
uint32_t num_imported_functions() const {
return module_->num_imported_functions;
UseTrapHandler use_trap_handler() const { return use_trap_handler_; }
void set_lazy_compile_frozen(bool frozen) { lazy_compile_frozen_ = frozen; }
bool lazy_compile_frozen() const { return lazy_compile_frozen_; }
Vector<const uint8_t> wire_bytes() const {
return std::atomic_load(&wire_bytes_)->as_vector();
const WasmModule* module() const { return module_.get(); }
std::shared_ptr<const WasmModule> shared_module() const { return module_; }
size_t committed_code_space() const {
return code_allocator_.committed_code_space();
size_t generated_code_size() const {
return code_allocator_.generated_code_size();
size_t liftoff_bailout_count() const { return liftoff_bailout_count_.load(); }
size_t liftoff_code_size() const { return liftoff_code_size_.load(); }
size_t turbofan_code_size() const { return turbofan_code_size_.load(); }
WasmEngine* engine() const { return engine_; }
bool HasWireBytes() const {
auto wire_bytes = std::atomic_load(&wire_bytes_);
return wire_bytes && !wire_bytes->empty();
void SetWireBytes(OwnedVector<const uint8_t> wire_bytes);
WasmCode* Lookup(Address) const;
WasmImportWrapperCache* import_wrapper_cache() const {
return import_wrapper_cache_.get();
const WasmFeatures& enabled_features() const { return enabled_features_; }
// Returns the runtime stub id that corresponds to the given address (which
// must be a far jump table slot). Returns {kRuntimeStubCount} on failure.
WasmCode::RuntimeStubId GetRuntimeStubId(Address runtime_stub_target) const;
// Sample the current code size of this modules to the given counters.
enum CodeSamplingTime : int8_t { kAfterBaseline, kAfterTopTier, kSampling };
void SampleCodeSize(Counters*, CodeSamplingTime) const;
V8_WARN_UNUSED_RESULT std::unique_ptr<WasmCode> AddCompiledCode(
V8_WARN_UNUSED_RESULT std::vector<std::unique_ptr<WasmCode>> AddCompiledCode(
// Set a new tiering state, but don't trigger any recompilation yet; use
// {RecompileForTiering} for that. The two steps are split because In some
// scenarios we need to drop locks before triggering recompilation.
void SetTieringState(TieringState);
// Check whether this modules is tiered down for debugging.
bool IsTieredDown();
// Fully recompile this module in the tier set previously via
// {SetTieringState}. The calling thread contributes to compilation and only
// returns once recompilation is done.
void RecompileForTiering();
// Find all functions that need to be recompiled for a new tier. Note that
// compilation jobs might run concurrently, so this method only considers the
// compilation state of this native module at the time of the call.
// Returns a vector of function indexes to recompile.
std::vector<int> FindFunctionsToRecompile(TieringState);
// Free a set of functions of this module. Uncommits whole pages if possible.
// The given vector must be ordered by the instruction start address, and all
// {WasmCode} objects must not be used any more.
// Should only be called via {WasmEngine::FreeDeadCode}, so the engine can do
// its accounting.
void FreeCode(Vector<WasmCode* const>);
// Retrieve the number of separately reserved code spaces for this module.
size_t GetNumberOfCodeSpacesForTesting() const;
// Check whether there is DebugInfo for this NativeModule.
bool HasDebugInfo() const;
// Get or create the debug info for this NativeModule.
DebugInfo* GetDebugInfo();
uint32_t* num_liftoff_function_calls_array() {
return num_liftoff_function_calls_.get();
friend class WasmCode;
friend class WasmCodeAllocator;
friend class WasmCodeManager;
friend class NativeModuleModificationScope;
struct CodeSpaceData {
base::AddressRegion region;
WasmCode* jump_table;
WasmCode* far_jump_table;
// Private constructor, called via {WasmCodeManager::NewNativeModule()}.
NativeModule(WasmEngine* engine, const WasmFeatures& enabled_features,
VirtualMemory code_space,
std::shared_ptr<const WasmModule> module,
std::shared_ptr<Counters> async_counters,
std::shared_ptr<NativeModule>* shared_this);
std::unique_ptr<WasmCode> AddCodeWithCodeSpace(
int index, const CodeDesc& desc, int stack_slots,
int tagged_parameter_slots,
Vector<const byte> protected_instructions_data,
Vector<const byte> source_position_table, WasmCode::Kind kind,
ExecutionTier tier, ForDebugging for_debugging,
Vector<uint8_t> code_space, const JumpTablesRef& jump_tables_ref);
WasmCode* CreateEmptyJumpTableInRegion(
int jump_table_size, base::AddressRegion,
const WasmCodeAllocator::OptionalLock&);
void UpdateCodeSize(size_t, ExecutionTier, ForDebugging);
// Hold the {allocation_mutex_} when calling one of these methods.
// {slot_index} is the index in the declared functions, i.e. function index
// minus the number of imported functions.
void PatchJumpTablesLocked(uint32_t slot_index, Address target);
void PatchJumpTableLocked(const CodeSpaceData&, uint32_t slot_index,
Address target);
// Called by the {WasmCodeAllocator} to register a new code space.
void AddCodeSpace(base::AddressRegion,
const WasmCodeAllocator::OptionalLock&);
// Hold the {allocation_mutex_} when calling {PublishCodeLocked}.
WasmCode* PublishCodeLocked(std::unique_ptr<WasmCode>);
// {WasmCodeAllocator} manages all code reservations and allocations for this
// {NativeModule}.
WasmCodeAllocator code_allocator_;
// Features enabled for this module. We keep a copy of the features that
// were enabled at the time of the creation of this native module,
// to be consistent across asynchronous compilations later.
const WasmFeatures enabled_features_;
// The decoded module, stored in a shared_ptr such that background compile
// tasks can keep this alive.
std::shared_ptr<const WasmModule> module_;
std::unique_ptr<WasmModuleSourceMap> source_map_;
// Wire bytes, held in a shared_ptr so they can be kept alive by the
// {WireBytesStorage}, held by background compile tasks.
std::shared_ptr<OwnedVector<const uint8_t>> wire_bytes_;
// The first allocated jump table. Always used by external calls (from JS).
// Wasm calls might use one of the other jump tables stored in
// {code_space_data_}.
WasmCode* main_jump_table_ = nullptr;
// The first allocated far jump table.
WasmCode* main_far_jump_table_ = nullptr;
// Lazy compile stub table, containing entries to jump to the
// {WasmCompileLazy} builtin, passing the function index.
WasmCode* lazy_compile_table_ = nullptr;
// The compilation state keeps track of compilation tasks for this module.
// Note that its destructor blocks until all tasks are finished/aborted and
// hence needs to be destructed first when this native module dies.
std::unique_ptr<CompilationState> compilation_state_;
// A cache of the import wrappers, keyed on the kind and signature.
std::unique_ptr<WasmImportWrapperCache> import_wrapper_cache_;
// Array to handle number of function calls.
std::unique_ptr<uint32_t[]> num_liftoff_function_calls_;
// This mutex protects concurrent calls to {AddCode} and friends.
mutable base::Mutex allocation_mutex_;
// Protected by {allocation_mutex_}:
// Holds all allocated code objects. For lookup based on pc, the key is the
// instruction start address of the value.
std::map<Address, std::unique_ptr<WasmCode>> owned_code_;
// Table of the latest code object per function, updated on initial
// compilation and tier up. The number of entries is
// {WasmModule::num_declared_functions}, i.e. there are no entries for
// imported functions.
std::unique_ptr<WasmCode*[]> code_table_;
// Data (especially jump table) per code space.
std::vector<CodeSpaceData> code_space_data_;
// Debug information for this module. You only need to hold the allocation
// mutex while getting the {DebugInfo} pointer, or initializing this field.
// Further accesses to the {DebugInfo} do not need to be protected by the
// mutex.
std::unique_ptr<DebugInfo> debug_info_;
TieringState tiering_state_ = kTieredUp;
// End of fields protected by {allocation_mutex_}.
WasmEngine* const engine_;
int modification_scope_depth_ = 0;
UseTrapHandler use_trap_handler_ = kNoTrapHandler;
bool lazy_compile_frozen_ = false;
std::atomic<size_t> liftoff_bailout_count_{0};
std::atomic<size_t> liftoff_code_size_{0};
std::atomic<size_t> turbofan_code_size_{0};
class V8_EXPORT_PRIVATE WasmCodeManager final {
explicit WasmCodeManager(size_t max_committed);
WasmCodeManager(const WasmCodeManager&) = delete;
WasmCodeManager& operator=(const WasmCodeManager&) = delete;
#ifdef DEBUG
~WasmCodeManager() {
// No more committed code space.
DCHECK_EQ(0, total_committed_code_space_.load());
#if defined(V8_OS_WIN64)
bool CanRegisterUnwindInfoForNonABICompliantCodeRange() const;
#endif // V8_OS_WIN64
NativeModule* LookupNativeModule(Address pc) const;
WasmCode* LookupCode(Address pc) const;
size_t committed_code_space() const {
return total_committed_code_space_.load();
// Estimate the needed code space for a Liftoff function based on the size of
// the function body (wasm byte code).
static size_t EstimateLiftoffCodeSize(int body_size);
// Estimate the needed code space from a completely decoded module.
static size_t EstimateNativeModuleCodeSize(const WasmModule* module,
bool include_liftoff);
// Estimate the needed code space from the number of functions and total code
// section length.
static size_t EstimateNativeModuleCodeSize(int num_functions,
int num_imported_functions,
int code_section_length,
bool include_liftoff);
// Estimate the size of meta data needed for the NativeModule, excluding
// generated code. This data still be stored on the C++ heap.
static size_t EstimateNativeModuleMetaDataSize(const WasmModule* module);
friend class WasmCodeAllocator;
friend class WasmEngine;
std::shared_ptr<NativeModule> NewNativeModule(
WasmEngine* engine, Isolate* isolate,
const WasmFeatures& enabled_features, size_t code_size_estimate,
std::shared_ptr<const WasmModule> module);
V8_WARN_UNUSED_RESULT VirtualMemory TryAllocate(size_t size,
void* hint = nullptr);
void Commit(base::AddressRegion);
void Decommit(base::AddressRegion);
void FreeNativeModule(Vector<VirtualMemory> owned_code,
size_t committed_size);
void AssignRange(base::AddressRegion, NativeModule*);
const size_t max_committed_code_space_;
std::atomic<size_t> total_committed_code_space_{0};
// If the committed code space exceeds {critical_committed_code_space_}, then
// we trigger a GC before creating the next module. This value is set to the
// currently committed space plus 50% of the available code space on creation
// and updated after each GC.
std::atomic<size_t> critical_committed_code_space_;
mutable base::Mutex native_modules_mutex_;
// Protected by {native_modules_mutex_}:
std::map<Address, std::pair<Address, NativeModule*>> lookup_map_;
// End of fields protected by {native_modules_mutex_}.
// Within the scope, the native_module is writable and not executable.
// At the scope's destruction, the native_module is executable and not writable.
// The states inside the scope and at the scope termination are irrespective of
// native_module's state when entering the scope.
// We currently mark the entire module's memory W^X:
// - for AOT, that's as efficient as it can be.
// - for Lazy, we don't have a heuristic for functions that may need patching,
// and even if we did, the resulting set of pages may be fragmented.
// Currently, we try and keep the number of syscalls low.
// - similar argument for debug time.
class NativeModuleModificationScope final {
explicit NativeModuleModificationScope(NativeModule* native_module);
NativeModule* native_module_;
// {WasmCodeRefScope}s form a perfect stack. New {WasmCode} pointers generated
// by e.g. creating new code or looking up code by its address are added to the
// top-most {WasmCodeRefScope}.
class V8_EXPORT_PRIVATE WasmCodeRefScope {
WasmCodeRefScope(const WasmCodeRefScope&) = delete;
WasmCodeRefScope& operator=(const WasmCodeRefScope&) = delete;
// Register a {WasmCode} reference in the current {WasmCodeRefScope}. Fails if
// there is no current scope.
static void AddRef(WasmCode*);
WasmCodeRefScope* const previous_scope_;
std::unordered_set<WasmCode*> code_ptrs_;
// Similarly to a global handle, a {GlobalWasmCodeRef} stores a single
// ref-counted pointer to a {WasmCode} object.
class GlobalWasmCodeRef {
explicit GlobalWasmCodeRef(WasmCode* code,
std::shared_ptr<NativeModule> native_module)
: code_(code), native_module_(std::move(native_module)) {
GlobalWasmCodeRef(const GlobalWasmCodeRef&) = delete;
GlobalWasmCodeRef& operator=(const GlobalWasmCodeRef&) = delete;
~GlobalWasmCodeRef() { WasmCode::DecrementRefCount({&code_, 1}); }
// Get a pointer to the contained {WasmCode} object. This is only guaranteed
// to exist as long as this {GlobalWasmCodeRef} exists.
WasmCode* code() const { return code_; }
WasmCode* const code_;
// Also keep the {NativeModule} alive.
const std::shared_ptr<NativeModule> native_module_;
const char* GetRuntimeStubName(WasmCode::RuntimeStubId);
} // namespace wasm
} // namespace internal
} // namespace v8