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// Copyright 2022 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/pgo.h"
#include "src/wasm/decoder.h"
#include "src/wasm/wasm-module-builder.h" // For {ZoneBuffer}.
namespace v8::internal::wasm {
constexpr uint8_t kFunctionExecutedBit = 1 << 0;
constexpr uint8_t kFunctionTieredUpBit = 1 << 1;
class ProfileGenerator {
public:
ProfileGenerator(const WasmModule* module,
const uint32_t* tiering_budget_array)
: module_(module),
type_feedback_mutex_guard_(&module->type_feedback.mutex),
tiering_budget_array_(tiering_budget_array) {}
base::OwnedVector<uint8_t> GetProfileData() {
ZoneBuffer buffer{&zone_};
SerializeTypeFeedback(buffer);
SerializeTieringInfo(buffer);
return base::OwnedVector<uint8_t>::Of(buffer);
}
private:
void SerializeTypeFeedback(ZoneBuffer& buffer) {
std::unordered_map<uint32_t, FunctionTypeFeedback>& feedback_for_function =
module_->type_feedback.feedback_for_function;
// Get an ordered list of function indexes, so we generate deterministic
// data.
std::vector<uint32_t> ordered_function_indexes;
ordered_function_indexes.reserve(feedback_for_function.size());
for (const auto& entry : feedback_for_function) {
// Skip functions for which we have no feedback.
if (entry.second.feedback_vector.empty()) continue;
ordered_function_indexes.push_back(entry.first);
}
std::sort(ordered_function_indexes.begin(), ordered_function_indexes.end());
buffer.write_u32v(static_cast<uint32_t>(ordered_function_indexes.size()));
for (const uint32_t func_index : ordered_function_indexes) {
buffer.write_u32v(func_index);
// Serialize {feedback_vector}.
const FunctionTypeFeedback& feedback =
feedback_for_function.at(func_index);
buffer.write_u32v(static_cast<uint32_t>(feedback.feedback_vector.size()));
for (const CallSiteFeedback& call_site_feedback :
feedback.feedback_vector) {
int cases = call_site_feedback.num_cases();
buffer.write_i32v(cases);
for (int i = 0; i < cases; ++i) {
buffer.write_i32v(call_site_feedback.function_index(i));
buffer.write_i32v(call_site_feedback.call_count(i));
}
}
// Serialize {call_targets}.
buffer.write_u32v(static_cast<uint32_t>(feedback.call_targets.size()));
for (uint32_t call_target : feedback.call_targets) {
buffer.write_u32v(call_target);
}
}
}
void SerializeTieringInfo(ZoneBuffer& buffer) {
std::unordered_map<uint32_t, FunctionTypeFeedback>& feedback_for_function =
module_->type_feedback.feedback_for_function;
const uint32_t initial_budget = v8_flags.wasm_tiering_budget;
for (uint32_t declared_index = 0;
declared_index < module_->num_declared_functions; ++declared_index) {
uint32_t func_index = declared_index + module_->num_imported_functions;
auto feedback_it = feedback_for_function.find(func_index);
int prio = feedback_it == feedback_for_function.end()
? 0
: feedback_it->second.tierup_priority;
DCHECK_LE(0, prio);
uint32_t remaining_budget = tiering_budget_array_[declared_index];
DCHECK_GE(initial_budget, remaining_budget);
bool was_tiered_up = prio > 0;
bool was_executed = was_tiered_up || remaining_budget != initial_budget;
// TODO(13209): Make this less V8-specific for productionization.
buffer.write_u8((was_executed ? kFunctionExecutedBit : 0) |
(was_tiered_up ? kFunctionTieredUpBit : 0));
}
}
private:
const WasmModule* module_;
AccountingAllocator allocator_;
Zone zone_{&allocator_, "wasm::ProfileGenerator"};
base::MutexGuard type_feedback_mutex_guard_;
const uint32_t* const tiering_budget_array_;
};
void DeserializeTypeFeedback(Decoder& decoder, WasmModule* module) {
std::unordered_map<uint32_t, FunctionTypeFeedback>& feedback_for_function =
module->type_feedback.feedback_for_function;
uint32_t num_entries = decoder.consume_u32v("num function entries");
CHECK_LE(num_entries, module->num_declared_functions);
for (uint32_t missing_entries = num_entries; missing_entries > 0;
--missing_entries) {
uint32_t function_index = decoder.consume_u32v("function index");
CHECK(!feedback_for_function.count(function_index));
FunctionTypeFeedback& feedback = feedback_for_function[function_index];
// Deserialize {feedback_vector}.
uint32_t feedback_vector_size =
decoder.consume_u32v("feedback vector size");
feedback.feedback_vector.resize(feedback_vector_size);
for (CallSiteFeedback& feedback : feedback.feedback_vector) {
int num_cases = decoder.consume_i32v("num cases");
if (num_cases == 0) continue; // no feedback
if (num_cases == 1) { // monomorphic
int called_function_index = decoder.consume_i32v("function index");
int call_count = decoder.consume_i32v("call count");
feedback = CallSiteFeedback{called_function_index, call_count};
} else { // polymorphic
auto* polymorphic = new CallSiteFeedback::PolymorphicCase[num_cases];
for (int i = 0; i < num_cases; ++i) {
polymorphic[i].function_index =
decoder.consume_i32v("function index");
polymorphic[i].absolute_call_frequency =
decoder.consume_i32v("call count");
}
feedback = CallSiteFeedback{polymorphic, num_cases};
}
}
// Deserialize {call_targets}.
uint32_t num_call_targets = decoder.consume_u32v("num call targets");
feedback.call_targets =
base::OwnedVector<uint32_t>::NewForOverwrite(num_call_targets);
for (uint32_t& call_target : feedback.call_targets) {
call_target = decoder.consume_u32v("call target");
}
}
}
std::unique_ptr<ProfileInformation> DeserializeTieringInformation(
Decoder& decoder, WasmModule* module) {
std::vector<uint32_t> executed_functions;
std::vector<uint32_t> tiered_up_functions;
uint32_t start = module->num_imported_functions;
uint32_t end = start + module->num_declared_functions;
for (uint32_t func_index = start; func_index < end; ++func_index) {
uint8_t tiering_info = decoder.consume_u8("tiering info");
CHECK_EQ(0, tiering_info & ~3);
bool was_executed = tiering_info & kFunctionExecutedBit;
bool was_tiered_up = tiering_info & kFunctionTieredUpBit;
if (was_tiered_up) tiered_up_functions.push_back(func_index);
if (was_executed) executed_functions.push_back(func_index);
}
return std::make_unique<ProfileInformation>(std::move(executed_functions),
std::move(tiered_up_functions));
}
std::unique_ptr<ProfileInformation> RestoreProfileData(
WasmModule* module, base::Vector<uint8_t> profile_data) {
Decoder decoder{profile_data.begin(), profile_data.end()};
DeserializeTypeFeedback(decoder, module);
std::unique_ptr<ProfileInformation> pgo_info =
DeserializeTieringInformation(decoder, module);
CHECK(decoder.ok());
CHECK_EQ(decoder.pc(), decoder.end());
return pgo_info;
}
void DumpProfileToFile(const WasmModule* module,
base::Vector<const uint8_t> wire_bytes,
uint32_t* tiering_budget_array) {
CHECK(!wire_bytes.empty());
// File are named `profile-wasm-<hash>`.
// We use the same hash as for reported scripts, to make it easier to
// correlate files to wasm modules (see {CreateWasmScript}).
uint32_t hash = static_cast<uint32_t>(GetWireBytesHash(wire_bytes));
base::EmbeddedVector<char, 32> filename;
SNPrintF(filename, "profile-wasm-%08x", hash);
ProfileGenerator profile_generator{module, tiering_budget_array};
base::OwnedVector<uint8_t> profile_data = profile_generator.GetProfileData();
PrintF("Dumping Wasm PGO data to file '%s' (%zu bytes)\n", filename.begin(),
profile_data.size());
if (FILE* file = base::OS::FOpen(filename.begin(), "wb")) {
size_t written = fwrite(profile_data.begin(), 1, profile_data.size(), file);
CHECK_EQ(profile_data.size(), written);
base::Fclose(file);
}
}
std::unique_ptr<ProfileInformation> LoadProfileFromFile(
WasmModule* module, base::Vector<const uint8_t> wire_bytes) {
CHECK(!wire_bytes.empty());
// File are named `profile-wasm-<hash>`.
// We use the same hash as for reported scripts, to make it easier to
// correlate files to wasm modules (see {CreateWasmScript}).
uint32_t hash = static_cast<uint32_t>(GetWireBytesHash(wire_bytes));
base::EmbeddedVector<char, 32> filename;
SNPrintF(filename, "profile-wasm-%08x", hash);
FILE* file = base::OS::FOpen(filename.begin(), "rb");
if (!file) {
PrintF("No Wasm PGO data found: Cannot open file '%s'\n", filename.begin());
return {};
}
fseek(file, 0, SEEK_END);
size_t size = ftell(file);
rewind(file);
PrintF("Loading Wasm PGO data from file '%s' (%zu bytes)\n", filename.begin(),
size);
base::OwnedVector<uint8_t> profile_data =
base::OwnedVector<uint8_t>::NewForOverwrite(size);
for (size_t read = 0; read < size;) {
read += fread(profile_data.begin() + read, 1, size - read, file);
CHECK(!ferror(file));
}
base::Fclose(file);
return RestoreProfileData(module, profile_data.as_vector());
}
} // namespace v8::internal::wasm
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