// 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/module-compiler.h"

#include <algorithm>

#include <atomic>

#include <memory>

#include <queue>

#include "src/api/api-inl.h"

#include "src/base/enum-set.h"

#include "src/base/fpu.h"

#include "src/base/platform/mutex.h"

#include "src/base/platform/semaphore.h"

#include "src/base/platform/time.h"

#include "src/codegen/compiler.h"

#include "src/compiler/wasm-compiler.h"

#include "src/debug/debug.h"

#include "src/handles/global-handles-inl.h"

#include "src/logging/counters-scopes.h"

#include "src/logging/metrics.h"

#include "src/tracing/trace-event.h"

#include "src/wasm/code-space-access.h"

#include "src/wasm/compilation-environment-inl.h"

#include "src/wasm/jump-table-assembler.h"

#include "src/wasm/module-decoder.h"

#include "src/wasm/pgo.h"

#include "src/wasm/std-object-sizes.h"

#include "src/wasm/streaming-decoder.h"

#include "src/wasm/wasm-code-manager.h"

#include "src/wasm/wasm-code-pointer-table-inl.h"

#include "src/wasm/wasm-engine.h"

#include "src/wasm/wasm-feature-flags.h"

#include "src/wasm/wasm-import-wrapper-cache.h"

#include "src/wasm/wasm-js.h"

#include "src/wasm/wasm-limits.h"

#include "src/wasm/wasm-objects-inl.h"

#include "src/wasm/wasm-result.h"

#include "src/wasm/wasm-serialization.h"

#define TRACE_COMPILE(...) \

do { \

if (v8_flags.trace_wasm_compiler) PrintF(__VA_ARGS__); \

} while (false)

#define TRACE_STREAMING(...) \

do { \

if (v8_flags.trace_wasm_streaming) PrintF(__VA_ARGS__); \

} while (false)

#define TRACE_LAZY(...) \

do { \

if (v8_flags.trace_wasm_lazy_compilation) PrintF(__VA_ARGS__); \

} while (false)

namespace v8::internal::wasm {

namespace {

enum class CompileStrategy : uint8_t {

// Compiles functions on first use. In this case, execution will block until

// the function's baseline is reached and top tier compilation starts in

// background (if applicable).

// Lazy compilation can help to reduce startup time and code size at the risk

// of blocking execution.

kLazy,

// Compiles baseline ahead of execution and starts top tier compilation in

// background (if applicable).

kEager,

// Marker for default strategy.

kDefault = kEager,

};

class CompilationStateImpl;

class CompilationUnitBuilder;

class V8_NODISCARD BackgroundCompileScope {

public:

explicit BackgroundCompileScope(std::weak_ptr<NativeModule> native_module)

: native_module_(native_module.lock()) {}

NativeModule* native_module() const {

DCHECK(native_module_);

return native_module_.get();

}

inline CompilationStateImpl* compilation_state() const;

bool cancelled() const;

private:

// Keep the native module alive while in this scope.

std::shared_ptr<NativeModule> native_module_;

};

enum CompilationTier { kBaseline = 0, kTopTier = 1, kNumTiers = kTopTier + 1 };

// A set of work-stealing queues (vectors of units). Each background compile

// task owns one of the queues and steals from all others once its own queue

// runs empty.

class CompilationUnitQueues {

public:

// Public API for QueueImpl.

struct Queue {

bool ShouldPublish(int num_processed_units) const;

};

explicit CompilationUnitQueues(int num_imported_functions,

int num_declared_functions)

: num_imported_functions_(num_imported_functions),

num_declared_functions_(num_declared_functions) {

// Add one first queue, to add units to.

queues_.emplace_back(std::make_unique<QueueImpl>(0));

#if !defined(__cpp_lib_atomic_value_initialization) || \

__cpp_lib_atomic_value_initialization < 201911L

for (auto& atomic_counter : num_units_) {

std::atomic_init(&atomic_counter, size_t{0});

}

#endif

top_tier_compiled_ =

std::make_unique<std::atomic<bool>[]>(num_declared_functions);

#if !defined(__cpp_lib_atomic_value_initialization) || \

__cpp_lib_atomic_value_initialization < 201911L

for (int i = 0; i < num_declared_functions; i++) {

std::atomic_init(&top_tier_compiled_.get()[i], false);

}

#endif

}

Queue* GetQueueForTask(int task_id) {

int required_queues = task_id + 1;

{

base::MutexGuard queues_guard{&queues_mutex_};

if (V8_LIKELY(static_cast<int>(queues_.size()) >= required_queues)) {

return queues_[task_id].get();

}

}

// Otherwise increase the number of queues.

base::MutexGuard queues_guard{&queues_mutex_};

int num_queues = static_cast<int>(queues_.size());

while (num_queues < required_queues) {

int steal_from = num_queues + 1;

queues_.emplace_back(std::make_unique<QueueImpl>(steal_from));

++num_queues;

}

// Update the {publish_limit}s of all queues.

// We want background threads to publish regularly (to avoid contention when

// they are all publishing at the end). On the other side, each publishing

// has some overhead (part of it for synchronizing between threads), so it

// should not happen *too* often. Thus aim for 4-8 publishes per thread, but

// distribute it such that publishing is likely to happen at different

// times.

int units_per_thread = num_declared_functions_ / num_queues;

int min = std::max(10, units_per_thread / 8);

int queue_id = 0;

for (auto& queue : queues_) {

// Set a limit between {min} and {2*min}, but not smaller than {10}.

int limit = min + (min * queue_id / num_queues);

queue->publish_limit.store(limit, std::memory_order_relaxed);

++queue_id;

}

return queues_[task_id].get();

}

std::optional<WasmCompilationUnit> GetNextUnit(Queue* queue,

CompilationTier tier) {

DCHECK_LT(tier, CompilationTier::kNumTiers);

if (auto unit = GetNextUnitOfTier(queue, tier)) {

[[maybe_unused]] size_t old_units_count =

num_units_[tier].fetch_sub(1, std::memory_order_relaxed);

DCHECK_LE(1, old_units_count);

return unit;

}

return {};

}

void AddUnits(base::Vector<WasmCompilationUnit> baseline_units,

base::Vector<WasmCompilationUnit> top_tier_units,

const WasmModule* module) {

DCHECK_LT(0, baseline_units.size() + top_tier_units.size());

// Add to the individual queues in a round-robin fashion. No special care is

// taken to balance them; they will be balanced by work stealing.

QueueImpl* queue;

{

int queue_to_add = next_queue_to_add.load(std::memory_order_relaxed);

base::MutexGuard queues_guard{&queues_mutex_};

while (!next_queue_to_add.compare_exchange_weak(

queue_to_add, next_task_id(queue_to_add, queues_.size()),

std::memory_order_relaxed)) {

// Retry with updated {queue_to_add}.

}

queue = queues_[queue_to_add].get();

}

base::MutexGuard guard(&queue->mutex);

std::optional<base::MutexGuard> big_units_guard;

for (auto pair :

{std::make_pair(CompilationTier::kBaseline, baseline_units),

std::make_pair(CompilationTier::kTopTier, top_tier_units)}) {

int tier = pair.first;

base::Vector<WasmCompilationUnit> units = pair.second;

if (units.empty()) continue;

num_units_[tier].fetch_add(units.size(), std::memory_order_relaxed);

for (WasmCompilationUnit unit : units) {

size_t func_size = module->functions[unit.func_index()].code.length();

if (func_size <= kBigUnitsLimit) {

queue->units[tier].push_back(unit);

} else {

if (!big_units_guard) {

big_units_guard.emplace(&big_units_queue_.mutex);

}

big_units_queue_.has_units[tier].store(true,

std::memory_order_relaxed);

big_units_queue_.units[tier].emplace(func_size, unit);

}

}

}

}

void AddTopTierPriorityUnit(WasmCompilationUnit unit, size_t priority) {

base::MutexGuard queues_guard{&queues_mutex_};

// Add to the individual queues in a round-robin fashion. No special care is

// taken to balance them; they will be balanced by work stealing.

// Priorities should only be seen as a hint here; without balancing, we

// might pop a unit with lower priority from one queue while other queues

// still hold higher-priority units.

// Since updating priorities in a std::priority_queue is difficult, we just

// add new units with higher priorities, and use the

// {CompilationUnitQueues::top_tier_compiled_} array to discard units for

// functions which are already being compiled.

int queue_to_add = next_queue_to_add.load(std::memory_order_relaxed);

while (!next_queue_to_add.compare_exchange_weak(

queue_to_add, next_task_id(queue_to_add, queues_.size()),

std::memory_order_relaxed)) {

// Retry with updated {queue_to_add}.

}

{

auto* queue = queues_[queue_to_add].get();

base::MutexGuard guard(&queue->mutex);

queue->top_tier_priority_units.emplace(priority, unit);

num_priority_units_.fetch_add(1, std::memory_order_relaxed);

num_units_[CompilationTier::kTopTier].fetch_add(

1, std::memory_order_relaxed);

}

}

// Get the current number of units in the queue for |tier|. This is only a

// momentary snapshot, it's not guaranteed that {GetNextUnit} returns a unit

// if this method returns non-zero.

size_t GetSizeForTier(CompilationTier tier) const {

DCHECK_LT(tier, CompilationTier::kNumTiers);

return num_units_[tier].load(std::memory_order_relaxed);

}

void AllowAnotherTopTierJob(uint32_t func_index) {

top_tier_compiled_[declared_function_index(func_index)].store(

false, std::memory_order_relaxed);

}

size_t EstimateCurrentMemoryConsumption() const;

private:

// Functions bigger than {kBigUnitsLimit} will be compiled first, in ascending

// order of their function body size.

static constexpr size_t kBigUnitsLimit = 4096;

struct BigUnit {

BigUnit(size_t func_size, WasmCompilationUnit unit)

: func_size{func_size}, unit(unit) {}

size_t func_size;

WasmCompilationUnit unit;

bool operator<(const BigUnit& other) const {

return func_size < other.func_size;

}

};

struct TopTierPriorityUnit {

TopTierPriorityUnit(int priority, WasmCompilationUnit unit)

: priority(priority), unit(unit) {}

size_t priority;

WasmCompilationUnit unit;

bool operator<(const TopTierPriorityUnit& other) const {

return priority < other.priority;

}

};

struct BigUnitsQueue {

BigUnitsQueue() {

#if !defined(__cpp_lib_atomic_value_initialization) || \

__cpp_lib_atomic_value_initialization < 201911L

for (auto& atomic : has_units) std::atomic_init(&atomic, false);

#endif

}

mutable base::Mutex mutex;

// Can be read concurrently to check whether any elements are in the queue.

std::atomic<bool> has_units[CompilationTier::kNumTiers];

// Protected by {mutex}:

std::priority_queue<BigUnit> units[CompilationTier::kNumTiers];

};

struct QueueImpl : public Queue {

explicit QueueImpl(int next_steal_task_id)

: next_steal_task_id(next_steal_task_id) {}

// Number of units after which the task processing this queue should publish

// compilation results. Updated (reduced, using relaxed ordering) when new

// queues are allocated. If there is only one thread running, we can delay

// publishing arbitrarily.

std::atomic<int> publish_limit{kMaxInt};

base::Mutex mutex;

// All fields below are protected by {mutex}.

std::vector<WasmCompilationUnit> units[CompilationTier::kNumTiers];

std::priority_queue<TopTierPriorityUnit> top_tier_priority_units;

int next_steal_task_id;

};

int next_task_id(int task_id, size_t num_queues) const {

int next = task_id + 1;

return next == static_cast<int>(num_queues) ? 0 : next;

}

std::optional<WasmCompilationUnit> GetNextUnitOfTier(Queue* public_queue,

int tier) {

QueueImpl* queue = static_cast<QueueImpl*>(public_queue);

// First check whether there is a priority unit. Execute that first.

if (tier == CompilationTier::kTopTier) {

if (auto unit = GetTopTierPriorityUnit(queue)) {

return unit;

}

}

// Then check whether there is a big unit of that tier.

if (auto unit = GetBigUnitOfTier(tier)) return unit;

// Finally check whether our own queue has a unit of the wanted tier. If

// so, return it, otherwise get the task id to steal from.

int steal_task_id;

{

base::MutexGuard mutex_guard(&queue->mutex);

if (!queue->units[tier].empty()) {

auto unit = queue->units[tier].back();

queue->units[tier].pop_back();

return unit;

}

steal_task_id = queue->next_steal_task_id;

}

// Try to steal from all other queues. If this succeeds, return one of the

// stolen units.

{

base::MutexGuard guard{&queues_mutex_};

for (size_t steal_trials = 0; steal_trials < queues_.size();

++steal_trials, ++steal_task_id) {

if (steal_task_id >= static_cast<int>(queues_.size())) {

steal_task_id = 0;

}

if (auto unit = StealUnitsAndGetFirst(queue, steal_task_id, tier)) {

return unit;

}

}

}

// If we reach here, we didn't find any unit of the requested tier.

return {};

}

std::optional<WasmCompilationUnit> GetBigUnitOfTier(int tier) {

// Fast path without locking.

if (!big_units_queue_.has_units[tier].load(std::memory_order_relaxed)) {

return {};

}

base::MutexGuard guard(&big_units_queue_.mutex);

if (big_units_queue_.units[tier].empty()) return {};

WasmCompilationUnit unit = big_units_queue_.units[tier].top().unit;

big_units_queue_.units[tier].pop();

if (big_units_queue_.units[tier].empty()) {

big_units_queue_.has_units[tier].store(false, std::memory_order_relaxed);

}

return unit;

}

std::optional<WasmCompilationUnit> GetTopTierPriorityUnit(QueueImpl* queue) {

// Fast path without locking.

if (num_priority_units_.load(std::memory_order_relaxed) == 0) {

return {};

}

int steal_task_id;

{

base::MutexGuard mutex_guard(&queue->mutex);

while (!queue->top_tier_priority_units.empty()) {

auto unit = queue->top_tier_priority_units.top().unit;

queue->top_tier_priority_units.pop();

num_priority_units_.fetch_sub(1, std::memory_order_relaxed);

if (!top_tier_compiled_[declared_function_index(unit.func_index())]

.exchange(true, std::memory_order_relaxed)) {

return unit;

}

num_units_[CompilationTier::kTopTier].fetch_sub(

1, std::memory_order_relaxed);

}

steal_task_id = queue->next_steal_task_id;

}

// Try to steal from all other queues. If this succeeds, return one of the

// stolen units.

{

base::MutexGuard guard{&queues_mutex_};

for (size_t steal_trials = 0; steal_trials < queues_.size();

++steal_trials, ++steal_task_id) {

if (steal_task_id >= static_cast<int>(queues_.size())) {

steal_task_id = 0;

}

if (auto unit = StealTopTierPriorityUnit(queue, steal_task_id)) {

return unit;

}

}

}

return {};

}

// Steal units of {wanted_tier} from {steal_from_task_id} to {queue}. Return

// first stolen unit (rest put in queue of {task_id}), or {nullopt} if

// {steal_from_task_id} had no units of {wanted_tier}.

// Hold a shared lock on {queues_mutex_} when calling this method.

std::optional<WasmCompilationUnit> StealUnitsAndGetFirst(

QueueImpl* queue, int steal_from_task_id, int wanted_tier) {

auto* steal_queue = queues_[steal_from_task_id].get();

// Cannot steal from own queue.

if (steal_queue == queue) return {};

std::vector<WasmCompilationUnit> stolen;

std::optional<WasmCompilationUnit> returned_unit;

{

base::MutexGuard guard(&steal_queue->mutex);

auto* steal_from_vector = &steal_queue->units[wanted_tier];

if (steal_from_vector->empty()) return {};

size_t remaining = steal_from_vector->size() / 2;

auto steal_begin = steal_from_vector->begin() + remaining;

returned_unit = *steal_begin;

stolen.assign(steal_begin + 1, steal_from_vector->end());

steal_from_vector->erase(steal_begin, steal_from_vector->end());

}

base::MutexGuard guard(&queue->mutex);

auto* target_queue = &queue->units[wanted_tier];

target_queue->insert(target_queue->end(), stolen.begin(), stolen.end());

queue->next_steal_task_id = steal_from_task_id + 1;

return returned_unit;

}

// Steal one priority unit from {steal_from_task_id} to {task_id}. Return

// stolen unit, or {nullopt} if {steal_from_task_id} had no priority units.

// Hold a shared lock on {queues_mutex_} when calling this method.

std::optional<WasmCompilationUnit> StealTopTierPriorityUnit(

QueueImpl* queue, int steal_from_task_id) {

auto* steal_queue = queues_[steal_from_task_id].get();

// Cannot steal from own queue.

if (steal_queue == queue) return {};

std::optional<WasmCompilationUnit> returned_unit;

{

base::MutexGuard guard(&steal_queue->mutex);

while (true) {

if (steal_queue->top_tier_priority_units.empty()) return {};

auto unit = steal_queue->top_tier_priority_units.top().unit;

steal_queue->top_tier_priority_units.pop();

num_priority_units_.fetch_sub(1, std::memory_order_relaxed);

if (!top_tier_compiled_[declared_function_index(unit.func_index())]

.exchange(true, std::memory_order_relaxed)) {

returned_unit = unit;

break;

}

num_units_[CompilationTier::kTopTier].fetch_sub(

1, std::memory_order_relaxed);

}

}

base::MutexGuard guard(&queue->mutex);

queue->next_steal_task_id = steal_from_task_id + 1;

return returned_unit;

}

int declared_function_index(int func_index) const {

DCHECK_LE(num_imported_functions_, func_index);

DCHECK_LT(func_index, num_imported_functions_ + num_declared_functions_);

return func_index - num_imported_functions_;

}

// {queues_mutex_} protectes {queues_};

mutable base::Mutex queues_mutex_;

std::vector<std::unique_ptr<QueueImpl>> queues_;

const int num_imported_functions_;

const int num_declared_functions_;

BigUnitsQueue big_units_queue_;

std::atomic<size_t> num_units_[CompilationTier::kNumTiers];

std::atomic<size_t> num_priority_units_{0};

std::unique_ptr<std::atomic<bool>[]> top_tier_compiled_;

std::atomic<int> next_queue_to_add{0};

};

size_t CompilationUnitQueues::EstimateCurrentMemoryConsumption() const {

UPDATE_WHEN_CLASS_CHANGES(CompilationUnitQueues, 176);

UPDATE_WHEN_CLASS_CHANGES(QueueImpl, 112);

UPDATE_WHEN_CLASS_CHANGES(BigUnitsQueue, 88);

// Not including sizeof(CompilationUnitQueues) because that's included in

// sizeof(CompilationStateImpl).

size_t result = 0;

{

base::MutexGuard mutex_guard(&queues_mutex_);

result += ContentSize(queues_) + queues_.size() * sizeof(QueueImpl);

for (const auto& q : queues_) {

base::MutexGuard guard(&q->mutex);

result += ContentSize(*q->units);

result += q->top_tier_priority_units.size() * sizeof(TopTierPriorityUnit);

}

}

{

base::MutexGuard lock(&big_units_queue_.mutex);

result += big_units_queue_.units[0].size() * sizeof(BigUnit);

result += big_units_queue_.units[1].size() * sizeof(BigUnit);

}

// For {top_tier_compiled_}.

result += sizeof(std::atomic<bool>) * num_declared_functions_;

return result;

}

bool CompilationUnitQueues::Queue::ShouldPublish(

int num_processed_units) const {

auto* queue = static_cast<const QueueImpl*>(this);

return num_processed_units >=

queue->publish_limit.load(std::memory_order_relaxed);

}

// The {CompilationStateImpl} keeps track of the compilation state of the

// owning NativeModule, i.e. which functions are left to be compiled.

// It contains a task manager to allow parallel and asynchronous background

// compilation of functions.

// Its public interface {CompilationState} lives in compilation-environment.h.

class CompilationStateImpl {

public:

CompilationStateImpl(const std::shared_ptr<NativeModule>& native_module,

WasmDetectedFeatures detected_features);

~CompilationStateImpl() {

if (baseline_compile_job_->IsValid()) {

baseline_compile_job_->CancelAndDetach();

}

if (top_tier_compile_job_->IsValid()) {

top_tier_compile_job_->CancelAndDetach();

}

}

// Call right after the constructor, after the {compilation_state_} field in

// the {NativeModule} has been initialized.

void InitCompileJob();

// {kCancelUnconditionally}: Cancel all compilation.

// {kCancelInitialCompilation}: Cancel all compilation if initial (baseline)

// compilation is not finished yet.

enum CancellationPolicy { kCancelUnconditionally, kCancelInitialCompilation };

void CancelCompilation(CancellationPolicy);

bool cancelled() const;

// Apply eager tier-up to the initial compilation progress, updating all

// internal fields accordingly.

void ApplyEagerTierUpToInitialProgress(size_t hint_idx);

// Apply a compilation priority hint to initial compilation progress,

// updating all internal fields accordingly.

void ApplyCompilationPriorityToInitialProgress(size_t hint_idx,

CompilationPriority priority);

// Use PGO information to choose a better initial compilation progress

// (tiering decisions).

void ApplyPgoInfoToInitialProgress(ProfileInformation* pgo_info);

// Apply PGO information to a fully initialized compilation state. Also

// trigger compilation as needed.

void ApplyPgoInfoLate(ProfileInformation* pgo_info);

// Initialize compilation progress. Set compilation tiers to expect for

// baseline and top tier compilation. Must be set before

// {CommitCompilationUnits} is invoked which triggers background compilation.

void InitializeCompilationProgress(ProfileInformation* pgo_info);

void InitializeCompilationProgressAfterDeserialization(

base::Vector<const int> lazy_functions,

base::Vector<const int> eager_functions);

// Initializes compilation units based on the information encoded in the

// {compilation_progress_}.

void InitializeCompilationUnits(

std::unique_ptr<CompilationUnitBuilder> builder);

// Adds compilation units for another function to the

// {CompilationUnitBuilder}. This function is the streaming compilation

// equivalent to {InitializeCompilationUnits}.

void InitializeCompilationUnitForSingleFunction(

CompilationUnitBuilder* builder, int func_index);

// Add the callback to be called on compilation events. Needs to be

// set before {CommitCompilationUnits} is run to ensure that it receives all

// events. The callback object must support being deleted from any thread.

void AddCallback(std::unique_ptr<CompilationEventCallback> callback);

// Inserts new functions to compile and kicks off compilation.

void CommitCompilationUnits(base::Vector<WasmCompilationUnit> baseline_units,

base::Vector<WasmCompilationUnit> top_tier_units);

void CommitTopTierCompilationUnit(WasmCompilationUnit);

void AddTopTierPriorityCompilationUnit(WasmCompilationUnit, size_t);

CompilationUnitQueues::Queue* GetQueueForCompileTask(int task_id);

std::optional<WasmCompilationUnit> GetNextCompilationUnit(

CompilationUnitQueues::Queue*, CompilationTier tier);

void OnFinishedUnits(base::Vector<WasmCode*>);

void OnCompilationStopped(WasmDetectedFeatures detected);

void SchedulePublishCompilationResults(

std::vector<UnpublishedWasmCode> unpublished_code, CompilationTier tier);

WasmDetectedFeatures detected_features() const {

return detected_features_.load(std::memory_order_relaxed);

}

// Update the set of detected features; returns all features that were not

// detected before.

V8_WARN_UNUSED_RESULT WasmDetectedFeatures

UpdateDetectedFeatures(WasmDetectedFeatures);

size_t NumOutstandingCompilations(CompilationTier tier) const;

void SetError();

void WaitForBaselineCompileJob();

void TierUpAllFunctions();

void AllowAnotherTopTierJob(uint32_t func_index) {

compilation_unit_queues_.AllowAnotherTopTierJob(func_index);

// Reset the stored priority; otherwise triggers might be ignored if the

// priority is not bumped to the next power of two.

TypeFeedbackStorage* feedback = &native_module_->module()->type_feedback;

base::MutexGuard mutex_guard(&feedback->mutex);

feedback->feedback_for_function[func_index].tierup_priority = 0;

}

void AllowAnotherTopTierJobForAllFunctions() {

const WasmModule* module = native_module_->module();

uint32_t fn_start = module->num_imported_functions;

uint32_t fn_end = fn_start + module->num_declared_functions;

base::MutexGuard mutex_guard(&module->type_feedback.mutex);

std::unordered_map<uint32_t, FunctionTypeFeedback>& feedback_map =

module->type_feedback.feedback_for_function;

for (uint32_t i = fn_start; i < fn_end; i++) {

compilation_unit_queues_.AllowAnotherTopTierJob(i);

// Reset the stored priority; otherwise triggers might be ignored if the

// priority is not bumped to the next power of two.

if (auto it = feedback_map.find(i); it != feedback_map.end()) {

it->second.tierup_priority = 0;

}

}

}

bool failed() const {

return compile_failed_.load(std::memory_order_relaxed);

}

bool baseline_compilation_finished() const {

base::MutexGuard guard(&callbacks_mutex_);

return outstanding_baseline_units_ == 0;

}

void SetWireBytesStorage(

std::shared_ptr<WireBytesStorage> wire_bytes_storage) {

base::MutexGuard guard(&mutex_);

wire_bytes_storage_ = std::move(wire_bytes_storage);

}

std::shared_ptr<WireBytesStorage> GetWireBytesStorage() const {

base::MutexGuard guard(&mutex_);

DCHECK_NOT_NULL(wire_bytes_storage_);

return wire_bytes_storage_;

}

void set_compilation_id(int compilation_id) {

DCHECK_EQ(compilation_id_, kInvalidCompilationID);

compilation_id_ = compilation_id;

}

size_t EstimateCurrentMemoryConsumption() const;

// Called from the delayed task to trigger caching if the timeout

// (--wasm-caching-timeout-ms) has passed since the last top-tier compilation.

// This either triggers caching or re-schedules the task if more code has

// been compiled to the top tier in the meantime.

void TriggerCachingAfterTimeout();

std::vector<WasmCode*> PublishCode(base::Vector<UnpublishedWasmCode> codes);

private:

// Trigger callbacks according to the internal counters below

// (outstanding_...).

// Hold the {callbacks_mutex_} when calling this method.

void TriggerOutstandingCallbacks();

// Trigger an exact set of callbacks. Hold the {callbacks_mutex_} when calling

// this method.

void TriggerCallbacks(base::EnumSet<CompilationEvent>);

void PublishCompilationResults(

std::vector<UnpublishedWasmCode> unpublished_code);

NativeModule* const native_module_;

std::weak_ptr<NativeModule> const native_module_weak_;

// Compilation error, atomically updated. This flag can be updated and read

// using relaxed semantics.

std::atomic<bool> compile_failed_{false};

// True if compilation was cancelled and worker threads should return. This

// flag can be updated and read using relaxed semantics.

std::atomic<bool> compile_cancelled_{false};

CompilationUnitQueues compilation_unit_queues_;

// This mutex protects all information of this {CompilationStateImpl} which is

// being accessed concurrently.

mutable base::Mutex mutex_;

// The compile job handles, initialized right after construction of

// {CompilationStateImpl}.

std::unique_ptr<JobHandle> baseline_compile_job_;

std::unique_ptr<JobHandle> top_tier_compile_job_;

// The compilation id to identify trace events linked to this compilation.

static constexpr int kInvalidCompilationID = -1;

int compilation_id_ = kInvalidCompilationID;

// Features detected to be used in this module. Features can be detected

// as a module is being compiled.

std::atomic<WasmDetectedFeatures> detected_features_;

//////////////////////////////////////////////////////////////////////////////

// Protected by {mutex_}:

// Abstraction over the storage of the wire bytes. Held in a shared_ptr so

// that background compilation jobs can keep the storage alive while

// compiling.

std::shared_ptr<WireBytesStorage> wire_bytes_storage_;

// End of fields protected by {mutex_}.

//////////////////////////////////////////////////////////////////////////////

// This mutex protects the callbacks vector, and the counters used to

// determine which callbacks to call. The counters plus the callbacks

// themselves need to be synchronized to ensure correct order of events.

mutable base::Mutex callbacks_mutex_;

//////////////////////////////////////////////////////////////////////////////

// Protected by {callbacks_mutex_}:

// Callbacks to be called on compilation events.

std::vector<std::unique_ptr<CompilationEventCallback>> callbacks_;

// Events that already happened.

base::EnumSet<CompilationEvent> finished_events_;

int outstanding_baseline_units_ = 0;

// The amount of generated top tier code since the last

// {kFinishedCompilationChunk} event.

size_t bytes_since_last_chunk_ = 0;

// One byte per declared function, see bitfields defined below.

// This vector is initialized once to the right size, updates are *usually*

// protected by the {callbacks_mutes_}, with exceptions during

// initialization (see comment in

// {CompilationStateImpl::InitializeCompilationUnitForSingleFunction}).

base::OwnedVector<uint8_t> compilation_progress_;

// The timestamp of the last top-tier compilation.

// This field is updated on every publishing of top-tier code, and is reset

// once caching is triggered. Hence it also informs whether a caching task is

// currently being scheduled (whenever this is set).

base::TimeTicks last_top_tier_compilation_timestamp_;

// End of fields protected by {callbacks_mutex_}.

//////////////////////////////////////////////////////////////////////////////

struct PublishState {

// {mutex_} protects {publish_queue_} and {publisher_running_}.

base::Mutex mutex_;

std::vector<UnpublishedWasmCode> publish_queue_;

bool publisher_running_ = false;

};

PublishState publish_state_[CompilationTier::kNumTiers];

// Encoding of fields in the {compilation_progress_} vector.

using RequiredBaselineTierField = base::BitField8<ExecutionTier, 0, 2>;

using RequiredTopTierField = base::BitField8<ExecutionTier, 2, 2>;

using ReachedTierField = base::BitField8<ExecutionTier, 4, 2>;

};

CompilationStateImpl* Impl(CompilationState* compilation_state) {

return reinterpret_cast<CompilationStateImpl*>(compilation_state);

}

const CompilationStateImpl* Impl(const CompilationState* compilation_state) {

return reinterpret_cast<const CompilationStateImpl*>(compilation_state);

}

CompilationStateImpl* BackgroundCompileScope::compilation_state() const {

DCHECK(native_module_);

return Impl(native_module_->compilation_state());

}

size_t CompilationStateImpl::EstimateCurrentMemoryConsumption() const {

UPDATE_WHEN_CLASS_CHANGES(CompilationStateImpl, 448);

size_t result = sizeof(CompilationStateImpl);

{

base::MutexGuard guard{&mutex_};

result += compilation_unit_queues_.EstimateCurrentMemoryConsumption();

}

// To read the size of {callbacks_} and {compilation_progress_}, we'd

// need to acquire the {callbacks_mutex_}, which can cause deadlocks

// when that mutex is already held elsewhere and another thread calls

// into this function. So we rely on heuristics and informed guesses

// instead: {compilation_progress_} contains an entry for every declared

// function in the module...

result += sizeof(uint8_t) * native_module_->module()->num_declared_functions;

// ...and there are typically no more than a handful of {callbacks_}.

constexpr size_t kAssumedNumberOfCallbacks = 4;

constexpr size_t size_of_vector =

kAssumedNumberOfCallbacks *

sizeof(std::unique_ptr<CompilationEventCallback>);

// Concrete subclasses of CompilationEventCallback will be bigger, but we

// can't know that here.

constexpr size_t size_of_payload =

kAssumedNumberOfCallbacks * sizeof(CompilationEventCallback);

result += size_of_vector + size_of_payload;

if (v8_flags.trace_wasm_offheap_memory) {

PrintF("CompilationStateImpl: %zu\n", result);

}

return result;

}

bool BackgroundCompileScope::cancelled() const {

return native_module_ == nullptr ||

Impl(native_module_->compilation_state())->cancelled();

}

} // namespace

//////////////////////////////////////////////////////

// PIMPL implementation of {CompilationState}.

CompilationState::~CompilationState() { Impl(this)->~CompilationStateImpl(); }

void CompilationState::InitCompileJob() { Impl(this)->InitCompileJob(); }

void CompilationState::CancelCompilation() {

Impl(this)->CancelCompilation(CompilationStateImpl::kCancelUnconditionally);

}

void CompilationState::CancelInitialCompilation() {

Impl(this)->CancelCompilation(

CompilationStateImpl::kCancelInitialCompilation);

}

void CompilationState::SetError() { Impl(this)->SetError(); }

void CompilationState::SetWireBytesStorage(

std::shared_ptr<WireBytesStorage> wire_bytes_storage) {

Impl(this)->SetWireBytesStorage(std::move(wire_bytes_storage));

}

std::shared_ptr<WireBytesStorage> CompilationState::GetWireBytesStorage()

const {

return Impl(this)->GetWireBytesStorage();

}

void CompilationState::AddCallback(

std::unique_ptr<CompilationEventCallback> callback) {

return Impl(this)->AddCallback(std::move(callback));

}

void CompilationState::TierUpAllFunctions() {

Impl(this)->TierUpAllFunctions();

}

void CompilationState::AllowAnotherTopTierJob(uint32_t func_index) {

Impl(this)->AllowAnotherTopTierJob(func_index);

}

void CompilationState::AllowAnotherTopTierJobForAllFunctions() {

Impl(this)->AllowAnotherTopTierJobForAllFunctions();

}

void CompilationState::InitializeAfterDeserialization(

base::Vector<const int> lazy_functions,

base::Vector<const int> eager_functions) {

Impl(this)->InitializeCompilationProgressAfterDeserialization(

lazy_functions, eager_functions);

}

bool CompilationState::failed() const { return Impl(this)->failed(); }

bool CompilationState::baseline_compilation_finished() const {

return Impl(this)->baseline_compilation_finished();

}

void CompilationState::set_compilation_id(int compilation_id) {

Impl(this)->set_compilation_id(compilation_id);

}

size_t CompilationState::EstimateCurrentMemoryConsumption() const {

return Impl(this)->EstimateCurrentMemoryConsumption();

}

std::vector<WasmCode*> CompilationState::PublishCode(

base::Vector<UnpublishedWasmCode> unpublished_code) {

return Impl(this)->PublishCode(unpublished_code);

}

// static

std::unique_ptr<CompilationState> CompilationState::New(

const std::shared_ptr<NativeModule>& native_module,

WasmDetectedFeatures detected_features) {

return std::unique_ptr<CompilationState>(reinterpret_cast<CompilationState*>(

new CompilationStateImpl(native_module, detected_features)));

}

WasmDetectedFeatures CompilationState::detected_features() const {

return Impl(this)->detected_features();

}

WasmDetectedFeatures CompilationState::UpdateDetectedFeatures(

WasmDetectedFeatures detected_features) {

return Impl(this)->UpdateDetectedFeatures(detected_features);

}

// End of PIMPL implementation of {CompilationState}.

//////////////////////////////////////////////////////

namespace {

struct ExecutionTierPair {

ExecutionTier baseline_tier;

ExecutionTier top_tier;

};

// Pass the debug state as a separate parameter to avoid data races: the debug

// state may change between its use here and its use at the call site. To have

// a consistent view on the debug state, the caller reads the debug state once

// and then passes it to this function.

ExecutionTierPair GetDefaultTiersPerModule(NativeModule* native_module,

DebugState is_in_debug_state,

bool lazy_module) {

const WasmModule* module = native_module->module();

if (lazy_module) {

return {ExecutionTier::kNone, ExecutionTier::kNone};

}

if (is_asmjs_module(module)) {

DCHECK(!is_in_debug_state);

return {ExecutionTier::kTurbofan, ExecutionTier::kTurbofan};

}

if (is_in_debug_state) {

return {ExecutionTier::kLiftoff, ExecutionTier::kLiftoff};

}

ExecutionTier baseline_tier =

v8_flags.liftoff ? ExecutionTier::kLiftoff : ExecutionTier::kTurbofan;

bool eager_tier_up = !v8_flags.wasm_dynamic_tiering && v8_flags.wasm_tier_up;

ExecutionTier top_tier =

eager_tier_up ? ExecutionTier::kTurbofan : baseline_tier;