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dart/sdk/e5e85af5a1141ed11fe2a94de6502ebbcd66ae69/./runtime/vm/profiler.cc
blob: 16cebc350720c5598a9cd3b0d5e08a705ade71f5 [file]
// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/profiler.h"
#include <utility>
#include "platform/address_sanitizer.h"
#include "platform/atomic.h"
#include "platform/memory_sanitizer.h"
#include "platform/thread_sanitizer.h"
#include "platform/utils.h"
#if defined(SUPPORT_PERFETTO)
#include "third_party/perfetto/protos/perfetto/trace/profiling/profile_packet.pbzero.h"
#endif
#include "vm/allocation.h"
#include "vm/code_patcher.h"
#if !defined(DART_PRECOMPILED_RUNTIME)
#include "vm/compiler/compiler_state.h"
#endif
#include "vm/debugger.h"
#include "vm/globals.h"
#include "vm/heap/safepoint.h"
#if defined(DART_PRECOMPILED_RUNTIME)
#include "vm/image_snapshot.h"
#endif
#include "vm/instructions.h"
#include "vm/isolate.h"
#include "vm/json_stream.h"
#include "vm/lockers.h"
#include "vm/message_handler.h"
#include "vm/native_symbol.h"
#include "vm/object.h"
#include "vm/object_store.h"
#include "vm/os.h"
#if defined(SUPPORT_PERFETTO)
#include "vm/perfetto_utils.h"
#endif
#include "vm/profiler_service.h"
#include "vm/reusable_handles.h"
#include "vm/signal_handler.h"
#include "vm/simulator.h"
#include "vm/stack_frame.h"
#include "vm/timeline.h"
#include "vm/version.h"
namespace dart {
static constexpr intptr_t kMaxSamplesPerTick = 4;
DEFINE_FLAG(bool, trace_profiled_isolates, false, "Trace profiled isolates.");
DEFINE_FLAG(int,
profile_period,
1000,
"Time between profiler samples in microseconds. Minimum 50.");
DEFINE_FLAG(int,
max_profile_depth,
Sample::kPCArraySizeInWords* kMaxSamplesPerTick,
"Maximum number stack frames walked. Minimum 2. Maximum 255.");
DEFINE_FLAG(bool, profile_vm, false, "Always collect native stack traces.");
DEFINE_FLAG(bool,
profile_vm_allocation,
false,
"Collect native stack traces when tracing Dart allocations.");
DEFINE_FLAG(
int,
sample_buffer_duration,
0,
"Defines the size of the profiler sample buffer to contain at least "
"N seconds of samples at a given sample rate. If not provided, the "
"default is ~4 seconds. Large values will greatly increase memory "
"consumption.");
DEFINE_FLAG(
bool,
profile_startup,
false,
"Make the profiler discard new samples once the profiler sample buffer is "
"full. When this flag is not set, the profiler sample buffer is used as a "
"ring buffer, meaning that once it is full, new samples start overwriting "
"the oldest ones. This flag itself does not enable the profiler; the "
"profiler must be enabled separately, e.g. with --profiler.");
#if defined(DART_INCLUDE_STACK_DUMPER)
ProfilerCounters Profiler::counters_ = {};
static void DumpStackFrame(uword pc, uword fp, const char* name, uword offset) {
OS::PrintErr(" pc 0x%" Pp " fp 0x%" Pp " %s+0x%" Px "\n", pc, fp, name,
offset);
}
void DumpStackFrame(intptr_t frame_index, uword pc, uword fp) {
uword start = 0;
// The pc for all frames except the top frame is a return address, which can
// belong to a different inlining interval than the call. Subtract one to get
// the symbolization for the call.
uword lookup_pc = frame_index == 0 ? pc : pc - 1;
if (auto const name =
NativeSymbolResolver::LookupSymbolName(lookup_pc, &start)) {
DumpStackFrame(pc, fp, name, pc - start);
NativeSymbolResolver::FreeSymbolName(name);
return;
}
const char* dso_name;
uword dso_base;
if (NativeSymbolResolver::LookupSharedObject(pc, &dso_base, &dso_name)) {
DumpStackFrame(pc, fp, dso_name, pc - dso_base);
NativeSymbolResolver::FreeSymbolName(dso_name);
return;
}
#if !defined(DART_PRECOMPILED_RUNTIME)
// This relies on heap iteration, which might fail if we're crashing because
// of heap corruption. A nested crash symbolizing a JIT frame will prevent
// seeing all caller frames, so only do this when we aren't able to use the
// safer StackFrameIterator.
Thread* thread = Thread::Current();
bool symbolize_jit_code =
(thread != nullptr) &&
(thread->execution_state() != Thread::kThreadInNative) &&
(thread->execution_state() != Thread::kThreadInVM);
if (symbolize_jit_code) {
Code result;
result = Code::FindCodeUnsafe(lookup_pc);
if (!result.IsNull()) {
DumpStackFrame(
pc, fp,
result.QualifiedName(NameFormattingParams(Object::kInternalName)),
pc - result.PayloadStart());
return;
}
}
#endif
OS::PrintErr(" pc 0x%" Pp " fp 0x%" Pp " Unknown symbol\n", pc, fp);
}
class ProfilerStackWalker : public ValueObject {
public:
ProfilerStackWalker(Sample* head_sample, Isolate* isolate)
: sample_(head_sample),
isolate_(isolate),
frame_index_(0),
total_frames_(0) {
if (sample_ == nullptr) {
ASSERT(isolate_ == nullptr);
} else {
ASSERT(isolate_ != nullptr);
ASSERT(sample_->head_sample());
}
}
bool Append(uword pc, uword fp) {
if (sample_ == nullptr) {
DumpStackFrame(frame_index_, pc, fp);
frame_index_++;
total_frames_++;
return true;
}
#if defined(DART_INCLUDE_PROFILER)
if (total_frames_ >= Profiler::CurrentConfig().max_depth) {
sample_->set_truncated_trace(true);
return false;
}
ASSERT(sample_ != nullptr);
if (frame_index_ == Sample::kPCArraySizeInWords) {
Sample* new_sample = SampleBlock::ReserveSampleAndLink(sample_, isolate_);
if (new_sample == nullptr) {
// Could not reserve new sample- mark this as truncated.
sample_->set_truncated_trace(true);
return false;
}
frame_index_ = 0;
sample_ = new_sample;
}
ASSERT(frame_index_ < Sample::kPCArraySizeInWords);
sample_->SetAt(frame_index_, pc);
frame_index_++;
total_frames_++;
return true;
#else
UNREACHABLE();
return false;
#endif
}
protected:
Sample* sample_;
Isolate* const isolate_;
intptr_t frame_index_;
intptr_t total_frames_;
};
// MSAN/ASAN are unaware of frames initialized by generated code.
// ProfilerNativeStackWalker may also read a random slot in the stack if a
// function on the stack doesn't use frame pointers and puts something that
// looks like a stack address into the FP register.
NO_SANITIZE_ADDRESS
NO_SANITIZE_MEMORY
static uword* LoadStackSlot(uword* ptr) {
return reinterpret_cast<uword*>(*ptr);
}
// Clang on Windows inlines the load from LoadStackSlot and still applies the
// sanitizer instrumentation to the load in callers.
#if defined(DART_HOST_OS_WINDOWS)
#define WINDOWS_EXTRA_NO_SANITIZE_ADDRESS NO_SANITIZE_ADDRESS
#else
#define WINDOWS_EXTRA_NO_SANITIZE_ADDRESS
#endif
// The layout of C stack frames.
#if defined(HOST_ARCH_IA32) || defined(HOST_ARCH_X64) || \
defined(HOST_ARCH_ARM) || defined(HOST_ARCH_ARM64)
// +-------------+
// | saved IP/LR |
// +-------------+
// | saved FP | <- FP
// +-------------+
static constexpr intptr_t kHostSavedCallerPcSlotFromFp = 1;
static constexpr intptr_t kHostSavedCallerFpSlotFromFp = 0;
#elif defined(HOST_ARCH_RISCV32) || defined(HOST_ARCH_RISCV64)
// +-------------+
// | | <- FP
// +-------------+
// | saved RA |
// +-------------+
// | saved FP |
// +-------------+
static constexpr intptr_t kHostSavedCallerPcSlotFromFp = -1;
static constexpr intptr_t kHostSavedCallerFpSlotFromFp = -2;
#else
#error What architecture?
#endif
// If the VM is compiled without frame pointers (which is the default on
// recent GCC versions with optimizing enabled) the stack walking code may
// fail.
//
class ProfilerNativeStackWalker : public ProfilerStackWalker {
public:
ProfilerNativeStackWalker(ProfilerCounters* counters,
Sample* sample,
Isolate* isolate,
uword stack_lower,
uword stack_upper,
uword pc,
uword fp)
: ProfilerStackWalker(sample, isolate),
counters_(counters),
stack_upper_(stack_upper),
original_pc_(pc),
original_fp_(fp),
lower_bound_(stack_lower) {}
WINDOWS_EXTRA_NO_SANITIZE_ADDRESS
void walk() {
Append(original_pc_, original_fp_);
uword* pc = reinterpret_cast<uword*>(original_pc_);
uword* fp = reinterpret_cast<uword*>(original_fp_);
uword* previous_fp = fp;
if (!ValidFramePointer(fp)) {
counters_->incomplete_sample_fp_bounds.fetch_add(1);
return;
}
while (true) {
pc = CallerPC(fp);
previous_fp = fp;
fp = CallerFP(fp);
if (fp == nullptr) {
return;
}
if (fp <= previous_fp) {
// Frame pointer did not move to a higher address.
counters_->incomplete_sample_fp_step.fetch_add(1);
return;
}
if (!ValidFramePointer(fp)) {
// Frame pointer is outside of isolate stack boundary.
counters_->incomplete_sample_fp_bounds.fetch_add(1);
return;
}
const uword pc_value = reinterpret_cast<uword>(pc);
if ((pc_value + 1) < pc_value) {
// It is not uncommon to encounter an invalid pc as we
// traverse a stack frame. Most of these we can tolerate. If
// the pc is so large that adding one to it will cause an
// overflow it is invalid and it will cause headaches later
// while we are building the profile. Discard it.
counters_->incomplete_sample_bad_pc.fetch_add(1);
return;
}
// Move the lower bound up.
lower_bound_ = reinterpret_cast<uword>(fp);
if (!Append(pc_value, reinterpret_cast<uword>(fp))) {
return;
}
}
}
private:
WINDOWS_EXTRA_NO_SANITIZE_ADDRESS
uword* CallerPC(uword* fp) const {
ASSERT(fp != nullptr);
return LoadStackSlot(fp + kHostSavedCallerPcSlotFromFp);
}
WINDOWS_EXTRA_NO_SANITIZE_ADDRESS
uword* CallerFP(uword* fp) const {
ASSERT(fp != nullptr);
return LoadStackSlot(fp + kHostSavedCallerFpSlotFromFp);
}
bool ValidFramePointer(uword* fp) const {
if (fp == nullptr) {
return false;
}
if (!Utils::IsAligned(fp, kWordSize)) {
return false;
}
uword cursor = reinterpret_cast<uword>(fp);
cursor += sizeof(fp);
bool r = (cursor >= lower_bound_) && (cursor < stack_upper_);
return r;
}
ProfilerCounters* const counters_;
const uword stack_upper_;
const uword original_pc_;
const uword original_fp_;
uword lower_bound_;
};
static bool GetAndValidateCurrentThreadStackBounds(uintptr_t fp,
uintptr_t sp,
uword* stack_lower,
uword* stack_upper) {
ASSERT(stack_lower != nullptr);
ASSERT(stack_upper != nullptr);
if (!OSThread::GetCurrentStackBounds(stack_lower, stack_upper)) {
return false;
}
if ((*stack_lower == 0) || (*stack_upper == 0) ||
(*stack_lower >= *stack_upper)) {
return false; // Bad bounds.
}
if ((sp < *stack_lower) || (sp >= *stack_upper)) {
return false; // Bad SP.
}
if ((fp < *stack_lower) || (fp >= *stack_upper)) {
return false; // Bad FP.
}
// On Windows, touching more than one page beyond sp will fault.
*stack_lower = sp;
return true;
}
void Profiler::DumpStackTrace(void* context) {
if (context == nullptr) {
DumpStackTrace(/*for_crash=*/true);
return;
}
#if defined(DART_HOST_OS_LINUX) || defined(DART_HOST_OS_MACOS) || \
defined(DART_HOST_OS_ANDROID)
ucontext_t* ucontext = reinterpret_cast<ucontext_t*>(context);
mcontext_t mcontext = ucontext->uc_mcontext;
uword pc = SignalHandler::GetProgramCounter(mcontext);
uword fp = SignalHandler::GetFramePointer(mcontext);
uword sp = SignalHandler::GetCStackPointer(mcontext);
DumpStackTrace(sp, fp, pc, /*for_crash=*/true);
#elif defined(DART_HOST_OS_WINDOWS)
CONTEXT* ctx = reinterpret_cast<CONTEXT*>(context);
#if defined(HOST_ARCH_IA32)
uword pc = static_cast<uword>(ctx->Eip);
uword fp = static_cast<uword>(ctx->Ebp);
uword sp = static_cast<uword>(ctx->Esp);
#elif defined(HOST_ARCH_X64)
uword pc = static_cast<uword>(ctx->Rip);
uword fp = static_cast<uword>(ctx->Rbp);
uword sp = static_cast<uword>(ctx->Rsp);
#elif defined(HOST_ARCH_ARM)
uword pc = static_cast<uword>(ctx->Pc);
uword fp = static_cast<uword>(ctx->R11);
uword sp = static_cast<uword>(ctx->Sp);
#elif defined(HOST_ARCH_ARM64)
uword pc = static_cast<uword>(ctx->Pc);
uword fp = static_cast<uword>(ctx->Fp);
uword sp = static_cast<uword>(ctx->Sp);
#else
#error Unsupported architecture.
#endif
DumpStackTrace(sp, fp, pc, /*for_crash=*/true);
#else
// TODO(fschneider): Add support for more platforms.
// Do nothing on unsupported platforms.
#endif
}
// We need the call to DumpStackTrace to be a non-tail call and this function to
// not get the shrink wrap optimization, otherwise the frame from which we start
// our stack walk may be clobbered before the stack walk begins.
#ifdef _MSC_VER
#pragma optimize("", off)
#elif __clang__
__attribute__((optnone))
#elif __GNUC__
__attribute__((optimize(0)))
#endif
void Profiler::DumpStackTrace(bool for_crash) {
uintptr_t sp = OSThread::GetCurrentStackPointer();
uintptr_t fp = GET_FP_REGISTER();
uintptr_t pc = OS::GetProgramCounter();
DumpStackTrace(sp, fp, pc, for_crash);
}
#ifdef _MSC_VER
#pragma optimize("", on)
#endif
static void DumpCompilerState(Thread* thread) {
#if !defined(DART_PRECOMPILED_RUNTIME)
if (thread != nullptr && thread->execution_state() == Thread::kThreadInVM &&
thread->HasCompilerState()) {
thread->compiler_state().ReportCrash();
}
#endif
}
void Profiler::DumpStackTrace(uword sp, uword fp, uword pc, bool for_crash) {
if (for_crash) {
// Allow only one stack trace to prevent recursively printing stack traces
// if we hit an assert while printing the stack.
static RelaxedAtomic<uintptr_t> started_dump = 0;
if (started_dump.fetch_add(1u) != 0) {
OS::PrintErr("Aborting reentrant request for stack trace.\n");
return;
}
}
auto thread = Thread::Current(); // nullptr if no current isolate.
auto isolate = thread == nullptr ? nullptr : thread->isolate();
auto isolate_group = thread == nullptr ? nullptr : thread->isolate_group();
auto source = isolate_group == nullptr ? nullptr : isolate_group->source();
const char* isolate_group_name =
isolate_group == nullptr ? "(nil)" : isolate_group->source()->name;
const char* isolate_name = isolate == nullptr ? "(nil)" : isolate->name();
#ifdef SUPPORT_TIMELINE
const intptr_t thread_id =
OSThread::ThreadIdToIntPtr(OSThread::GetCurrentThreadTraceId());
#else
const intptr_t thread_id = -1;
#endif
OS::PrintErr("version=%s\n", Version::String());
OS::PrintErr("pid=%" Pd ", thread=%" Pd
", isolate_group=%s(%p), isolate=%s(%p)\n",
static_cast<intptr_t>(OS::ProcessId()), thread_id,
isolate_group_name, isolate_group, isolate_name, isolate);
#if defined(DART_COMPRESSED_POINTERS)
const char kCompressedPointers[] = "yes";
#else
const char kCompressedPointers[] = "no";
#endif
#if defined(DART_INCLUDE_SIMULATOR)
const char kUsingSimulator[] = "yes";
#else
const char kUsingSimulator[] = "no";
#endif
OS::PrintErr("os=%s, arch=%s, comp=%s, sim=%s\n", kHostOperatingSystemName,
kTargetArchitectureName, kCompressedPointers, kUsingSimulator);
OS::PrintErr(
"isolate_instructions=%" Px ", vm_instructions=0\n",
source == nullptr ? 0 : reinterpret_cast<uword>(source->snapshot_text));
OS::PrintErr("fp=%" Px ", sp=%" Px ", pc=%" Px "\n", fp, sp, pc);
uword stack_lower = 0;
uword stack_upper = 0;
if (!GetAndValidateCurrentThreadStackBounds(fp, sp, &stack_lower,
&stack_upper)) {
OS::PrintErr(
"Stack dump aborted because "
"GetAndValidateCurrentThreadStackBounds failed.\n");
if (pc != 0) { // At the very least dump the top frame.
DumpStackFrame(0, pc, fp);
}
DumpCompilerState(thread);
return;
}
ProfilerNativeStackWalker native_stack_walker(
&counters_, nullptr, nullptr, stack_lower, stack_upper, pc, fp);
native_stack_walker.walk();
OS::PrintErr("-- End of DumpStackTrace\n");
if (thread != nullptr) {
if (thread->execution_state() == Thread::kThreadInNative) {
TransitionNativeToVM transition(thread);
StackFrame::DumpCurrentTrace();
} else if (thread->execution_state() == Thread::kThreadInVM) {
StackFrame::DumpCurrentTrace();
} else if (thread->execution_state() == Thread::kThreadInGenerated) {
// No exit frame, walk from the crash's registers.
#if defined(DART_DYNAMIC_MODULES)
if (thread->vm_tag() == VMTag::kDartInterpretedTagId) {
Interpreter* interpreter = thread->interpreter();
sp = interpreter->get_sp();
fp = interpreter->get_fp();
pc = interpreter->get_pc();
StackFrame::DumpCurrentTrace(sp, fp, pc);
}
#endif // defined(DART_DYNAMIC_MODULES)
if (thread->vm_tag() == VMTag::kDartTagId) {
StackFrame::DumpCurrentTrace(sp, fp, pc);
}
}
}
DumpCompilerState(thread);
}
#endif // defined(DART_INCLUDE_STACK_DUMPER)
#if defined(DART_INCLUDE_PROFILER)
Monitor* Profiler::monitor_ = nullptr;
Profiler::Config Profiler::config_ = {.enabled = false,
.period_us = 0,
.max_depth = 0};
RelaxedAtomic<bool> Profiler::running_ = false;
SampleBlockBuffer* Profiler::sample_block_buffer_ = nullptr;
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
bool SampleBlockProcessor::initialized_ = false;
bool SampleBlockProcessor::shutdown_ = false;
bool SampleBlockProcessor::drain_ = false;
bool SampleBlockProcessor::thread_running_ = false;
ThreadJoinId SampleBlockProcessor::processor_thread_id_ =
OSThread::kInvalidThreadJoinId;
Monitor* SampleBlockProcessor::monitor_ = nullptr;
#endif
void Profiler::Init() {
monitor_ = new Monitor();
ThreadInterrupter::Init();
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
SampleBlockProcessor::Init();
#endif
SetConfig({});
}
void Profiler::Cleanup() {
{
SafepointMonitorLocker lock(monitor_);
StopLocked();
}
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
SampleBlockProcessor::Cleanup();
#endif
ThreadInterrupter::Cleanup();
delete monitor_;
}
namespace {
Profiler::Config NormalizeConfig(const Profiler::Config& config) {
const intptr_t kMinimumDepth = 2;
const intptr_t kMaximumDepth = 255;
const intptr_t kMinimumProfilePeriodUs = 50;
return {
.enabled = config.enabled,
.period_us = Utils::Maximum(kMinimumProfilePeriodUs, config.period_us),
.max_depth = Utils::Minimum(
kMaximumDepth,
Utils::Maximum(kMinimumDepth, config.max_depth.load())),
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
.stream_to_timeline = config.stream_to_timeline,
#endif
};
}
} // namespace
void Profiler::SetConfig(const Profiler::Config& config) {
SafepointMonitorLocker lock(monitor_);
const auto new_config = NormalizeConfig(config);
const auto old_config = config_;
config_ = new_config;
if (new_config.enabled != old_config.enabled) {
// Update running state.
if (new_config.enabled) {
StartLocked();
} else {
StopLocked();
}
} else if (old_config.enabled) {
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
if (new_config.stream_to_timeline != old_config.stream_to_timeline) {
if (new_config.stream_to_timeline) {
SampleBlockProcessor::Startup();
} else {
SampleBlockProcessor::Shutdown();
}
}
#endif
// Check if we need to reconfigure a running profiler.
//
// Note: this will not resize the sampling buffer, you
// need to stop and restart the profiler to resize it.
if (new_config.period_us != old_config.period_us) {
ThreadInterrupter::SetInterruptPeriod(new_config.period_us);
}
// Profiling thread will automatically pickup a change in
// config_.max_depth, but to resize underlying buffer
// you need to start and stop the profiler.
}
}
void Profiler::StartLocked() {
RELEASE_ASSERT(!running_);
// The profiler may have been shutdown previously, in which case the sample
// buffer will have already been initialized. However it might be too small.
const intptr_t sample_buffer_capacity = CalculateSampleBufferCapacity();
if (sample_block_buffer_ != nullptr &&
sample_buffer_capacity > sample_block_buffer_->Capacity()) {
delete sample_block_buffer_;
sample_block_buffer_ = nullptr;
}
if (sample_block_buffer_ == nullptr) {
sample_block_buffer_ = new SampleBlockBuffer(sample_buffer_capacity);
}
ThreadInterrupter::SetInterruptPeriod(config_.period_us);
ThreadInterrupter::Startup();
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
if (config_.stream_to_timeline) {
SampleBlockProcessor::Startup();
}
#endif
running_ = true;
}
class SampleBlockCleanupVisitor : public IsolateVisitor {
public:
SampleBlockCleanupVisitor() = default;
virtual ~SampleBlockCleanupVisitor() = default;
void VisitIsolate(Isolate* isolate) {
isolate->set_current_allocation_sample_block(nullptr);
isolate->set_current_sample_block(nullptr);
}
};
void Profiler::StopLocked() {
if (!running_) {
return;
}
ThreadInterrupter::Shutdown();
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
SampleBlockProcessor::Shutdown();
#endif
SampleBlockCleanupVisitor visitor;
Isolate::VisitIsolates(&visitor);
running_ = false;
}
intptr_t Profiler::CalculateSampleBufferCapacity() {
if (FLAG_sample_buffer_duration <= 0) {
return SampleBlockBuffer::kDefaultBlockCount;
}
// Deeper stacks require more than a single Sample object to be represented
// correctly. These samples are chained, so we need to determine the worst
// case sample chain length for a single stack.
//
// We use the fact that `ceil((float)a / (float)b) == (a + b - 1) / b` when
// `a` and `b` are positive integers below.
const intptr_t max_sample_chain_length =
(config_.max_depth + Sample::kPCArraySizeInWords - 1) /
Sample::kPCArraySizeInWords;
const intptr_t kMicrosPerSec = 1000000;
const intptr_t samples_per_second = kMicrosPerSec / config_.period_us;
const intptr_t sample_count = FLAG_sample_buffer_duration *
samples_per_second * max_sample_chain_length;
return (sample_count / SampleBlock::kSamplesPerBlock) + 1;
}
SampleBlockBuffer::SampleBlockBuffer(intptr_t blocks,
intptr_t samples_per_block) {
const intptr_t size = Utils::RoundUp(
blocks * samples_per_block * sizeof(Sample), VirtualMemory::PageSize());
const bool executable = false;
memory_ = VirtualMemory::Allocate(size, executable, "dart-profiler");
if (memory_ == nullptr) {
OUT_OF_MEMORY();
}
sample_buffer_ = reinterpret_cast<Sample*>(memory_->address());
blocks_ = new SampleBlock[blocks];
for (intptr_t i = 0; i < blocks; ++i) {
blocks_[i].Init(&sample_buffer_[i * samples_per_block], samples_per_block);
}
capacity_ = blocks;
cursor_ = 0;
}
SampleBlockBuffer::~SampleBlockBuffer() {
delete[] blocks_;
blocks_ = nullptr;
delete memory_;
memory_ = nullptr;
capacity_ = 0;
cursor_ = 0;
}
SampleBlock* SampleBlockBuffer::ReserveSampleBlock() {
intptr_t capacity = capacity_;
intptr_t start = cursor_.fetch_add(1) % capacity;
intptr_t i = start;
do {
SampleBlock* block = &blocks_[i];
if (block->TryAllocateFree()) {
return block;
}
i = (i + 1) % capacity;
} while (i != start);
if (FLAG_profile_startup) {
// There are no free blocks and [FLAG_profile_startup] is set, so we stop
// recording samples.
return nullptr;
} else {
// There are no free blocks and [FLAG_profile_startup] is not set, so we
// reuse a completed block if one is available.
i = start;
do {
SampleBlock* block = &blocks_[i];
if (block->TryAllocateCompleted()) {
return block;
}
i = (i + 1) % capacity;
} while (i != start);
return nullptr;
}
}
void SampleBlockBuffer::FreeCompletedBlocks() {
for (intptr_t i = 0; i < capacity_; i++) {
blocks_[i].FreeCompleted();
}
}
static void FlushSampleBlocks(Isolate* isolate) {
ASSERT(isolate != nullptr);
bool flushed = false;
SampleBlock* block = isolate->exchange_current_sample_block(nullptr);
if (block != nullptr) {
block->MarkCompleted();
flushed = true;
}
block = isolate->exchange_current_allocation_sample_block(nullptr);
if (block != nullptr) {
// Allocation samples are collected synchronously.
block->MarkCompleted();
flushed = true;
}
if (flushed) {
isolate->TrySetHasCompletedBlocks();
}
}
ProcessedSampleBuffer* SampleBlockBuffer::BuildProcessedSampleBuffer(
Isolate* isolate,
SampleFilter* filter,
ProcessedSampleBuffer* buffer) {
ASSERT(isolate != nullptr);
Thread* thread = Thread::Current();
Zone* zone = thread->zone();
if (buffer == nullptr) {
buffer = new (zone) ProcessedSampleBuffer();
}
FlushSampleBlocks(isolate);
for (intptr_t i = 0; i < capacity_; ++i) {
SampleBlock* block = &blocks_[i];
if (block->TryAcquireStreaming(isolate)) {
block->BuildProcessedSampleBuffer(filter, buffer);
if (filter->take_samples()) {
block->StreamingToFree();
} else {
block->StreamingToCompleted();
}
}
}
return buffer;
}
Sample* SampleBlock::ReserveSample() {
intptr_t slot = cursor_.fetch_add(1u);
if (slot < capacity_) {
return At(slot);
}
return nullptr;
}
Sample* SampleBlock::ReserveSampleAndLink(Sample* previous, Isolate* isolate) {
ASSERT(previous != nullptr);
SampleBlockBuffer* buffer = Profiler::sample_block_buffer();
ASSERT(isolate != nullptr);
Sample* next = previous->is_allocation_sample()
? buffer->ReserveAllocationSample(isolate)
: buffer->ReserveCPUSample(isolate);
if (next == nullptr) {
return nullptr; // No blocks left, so drop sample.
}
next->Init(previous->port(), previous->timestamp(), previous->tid());
next->set_head_sample(false);
// Mark that previous continues at next.
previous->SetContinuation(next);
return next;
}
Sample* SampleBlockBuffer::ReserveCPUSample(Isolate* isolate) {
return ReserveSampleImpl(isolate, false);
}
Sample* SampleBlockBuffer::ReserveAllocationSample(Isolate* isolate) {
return ReserveSampleImpl(isolate, true);
}
Sample* SampleBlockBuffer::ReserveSampleImpl(Isolate* isolate,
bool allocation_sample) {
SampleBlock* block = allocation_sample
? isolate->current_allocation_sample_block()
: isolate->current_sample_block();
Sample* sample = nullptr;
if (block != nullptr) {
sample = block->ReserveSample();
}
if (sample != nullptr) {
return sample;
}
SampleBlock* next = ReserveSampleBlock();
if (next == nullptr) {
// We're out of blocks to reserve. Drop the sample.
return nullptr;
}
next->set_owner(isolate);
if (allocation_sample) {
isolate->set_current_allocation_sample_block(next);
} else {
isolate->set_current_sample_block(next);
}
if (block != nullptr) {
block->MarkCompleted();
if (!Isolate::IsSystemIsolate(isolate)) {
isolate->TrySetHasCompletedBlocks();
}
}
return next->ReserveSample();
}
// Attempts to find the true return address when a Dart frame is being setup
// or torn down.
// NOTE: Architecture specific implementations below.
class ReturnAddressLocator : public ValueObject {
public:
ReturnAddressLocator(Sample* sample, const Code& code)
: stack_buffer_(sample->GetStackBuffer()),
pc_(sample->pc()),
code_(Code::ZoneHandle(code.ptr())) {
ASSERT(!code_.IsNull());
ASSERT(code_.ContainsInstructionAt(pc()));
}
ReturnAddressLocator(uword pc,
RelaxedAtomic<uword>* stack_buffer,
const Code& code)
: stack_buffer_(stack_buffer),
pc_(pc),
code_(Code::ZoneHandle(code.ptr())) {
ASSERT(!code_.IsNull());
ASSERT(code_.ContainsInstructionAt(pc_));
}
uword pc() { return pc_; }
// Returns false on failure.
bool LocateReturnAddress(uword* return_address);
// Returns offset into code object.
intptr_t RelativePC() {
ASSERT(pc() >= code_.PayloadStart());
return static_cast<intptr_t>(pc() - code_.PayloadStart());
}
uint8_t* CodePointer(intptr_t offset) {
const intptr_t size = code_.Size();
ASSERT(offset < size);
uint8_t* code_pointer = reinterpret_cast<uint8_t*>(code_.PayloadStart());
code_pointer += offset;
return code_pointer;
}
uword StackAt(intptr_t i) {
ASSERT(i >= 0);
ASSERT(i < Sample::kStackBufferSizeInWords);
return stack_buffer_[i];
}
private:
RelaxedAtomic<uword>* stack_buffer_;
uword pc_;
const Code& code_;
};
#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
bool ReturnAddressLocator::LocateReturnAddress(uword* return_address) {
ASSERT(return_address != nullptr);
const intptr_t offset = RelativePC();
ASSERT(offset >= 0);
const intptr_t size = code_.Size();
ASSERT(offset < size);
const intptr_t prologue_offset = code_.GetPrologueOffset();
if (offset < prologue_offset) {
// Before the prologue, return address is at the top of the stack.
// TODO(johnmccutchan): Some intrinsics and stubs do not conform to the
// expected stack layout. Use a more robust solution for those code objects.
*return_address = StackAt(0);
return true;
}
// Detect if we are:
// push ebp <--- here
// mov ebp, esp
// on X64 the register names are different but the sequence is the same.
ProloguePattern pp(pc());
if (pp.IsValid()) {
// Stack layout:
// 0 RETURN ADDRESS.
*return_address = StackAt(0);
return true;
}
// Detect if we are:
// push ebp
// mov ebp, esp <--- here
// on X64 the register names are different but the sequence is the same.
SetFramePointerPattern sfpp(pc());
if (sfpp.IsValid()) {
// Stack layout:
// 0 CALLER FRAME POINTER
// 1 RETURN ADDRESS
*return_address = StackAt(1);
return true;
}
// Detect if we are:
// ret <--- here
ReturnPattern rp(pc());
if (rp.IsValid()) {
// Stack layout:
// 0 RETURN ADDRESS.
*return_address = StackAt(0);
return true;
}
return false;
}
#elif defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64) || \
defined(TARGET_ARCH_RISCV32) || defined(TARGET_ARCH_RISCV64)
bool ReturnAddressLocator::LocateReturnAddress(uword* return_address) {
ASSERT(return_address != nullptr);
return false;
}
#else
#error ReturnAddressLocator implementation missing for this architecture.
#endif
bool SampleFilter::TimeFilterSample(Sample* sample) {
if ((time_origin_micros_ == -1) || (time_extent_micros_ == -1)) {
// No time filter passed in, always pass.
return true;
}
const int64_t timestamp = sample->timestamp();
int64_t delta = timestamp - time_origin_micros_;
return (delta >= 0) && (delta <= time_extent_micros_);
}
bool SampleFilter::TaskFilterSample(Sample* sample) {
const intptr_t task = static_cast<intptr_t>(sample->thread_task());
if (thread_task_mask_ == kNoTaskFilter) {
return true;
}
return (task & thread_task_mask_) != 0;
}
ClearProfileVisitor::ClearProfileVisitor(Isolate* isolate)
: SampleVisitor(isolate->main_port()) {}
void ClearProfileVisitor::VisitSample(Sample* sample) {
sample->Clear();
}
// Executing Dart code, walk the stack.
class ProfilerDartStackWalker : public ProfilerStackWalker {
public:
ProfilerDartStackWalker(Thread* thread,
Sample* sample,
Isolate* isolate,
uword pc,
uword fp)
: ProfilerStackWalker(sample, isolate),
thread_(thread),
pc_(reinterpret_cast<uword*>(pc)),
fp_(reinterpret_cast<uword*>(fp)) {}
void WalkFromExitFrame() {
// Can't be in the middle of a prologue. Won't need an SP or LR fixup.
sample_->set_exit_frame_sample(true);
// Skip exit frame.
pc_ = CallerPC();
fp_ = CallerFP();
walk();
}
void WalkFromTopFrame(uword sp, uword lr) {
const bool is_interpreted_frame = IsInterpretedFrame();
const bool is_entry_frame =
#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
StubCode::InInvocationStub(thread_, Stack(sp, 0),
is_interpreted_frame) ||
StubCode::InInvocationStub(thread_, Stack(sp, 1), is_interpreted_frame);
#elif defined(TARGET_ARCH_ARM) && defined(DART_INCLUDE_SIMULATOR)
StubCode::InInvocationStub(thread_, reinterpret_cast<uword>(pc_),
is_interpreted_frame) ||
StubCode::InInvocationStub(thread_, lr, is_interpreted_frame);
#else
StubCode::InInvocationStub(thread_, lr, is_interpreted_frame);
#endif
if (is_entry_frame) {
// During the prologue of a function, CallerPC will return the caller's
// caller. For most frames, the missing PC will be added during profile
// processing. However, during this stack walk, it can cause us to fail
// to identify the entry frame and lead the stack walk into the weeds.
// Do not continue the stalk walk since this might be a false positive
// from a Smi or unboxed value.
sample_->set_ignore_sample(true);
return;
}
walk();
}
private:
void walk() {
for (;;) {
// Skip entry frame.
if (StubCode::InInvocationStub(thread_, reinterpret_cast<uword>(pc_),
IsInterpretedFrame())) {
pc_ = nullptr;
fp_ = ExitLink();
if (fp_ == nullptr) {
break; // End of Dart stack.
}
// Skip exit frame.
pc_ = CallerPC();
fp_ = CallerFP();
// At least one frame between exit and next entry frame.
RELEASE_ASSERT(!StubCode::InInvocationStub(
thread_, reinterpret_cast<uword>(pc_), IsInterpretedFrame()));
}
if (!Append(reinterpret_cast<uword>(pc_), reinterpret_cast<uword>(fp_))) {
break; // Sample is full.
}
pc_ = CallerPC();
fp_ = CallerFP();
}
}
bool IsInterpretedFrame() const {
#if defined(DART_DYNAMIC_MODULES)
Interpreter* interpreter = thread_->interpreter();
return (interpreter != nullptr) &&
interpreter->HasFrame(reinterpret_cast<uword>(fp_));
#else
return false;
#endif
}
uword* CallerPC() const {
ASSERT(fp_ != nullptr);
uword* caller_pc_ptr =
fp_ + (IsInterpretedFrame() ? kKBCSavedCallerPcSlotFromFp
: kSavedCallerPcSlotFromFp);
return LoadStackSlot(caller_pc_ptr);
}
uword* CallerFP() const {
ASSERT(fp_ != nullptr);
uword* caller_fp_ptr =
fp_ + (IsInterpretedFrame() ? kKBCSavedCallerFpSlotFromFp
: kSavedCallerFpSlotFromFp);
return LoadStackSlot(caller_fp_ptr);
}
uword* ExitLink() const {
ASSERT(fp_ != nullptr);
uword* exit_link_ptr =
fp_ + (IsInterpretedFrame() ? kKBCExitLinkSlotFromEntryFp
: kExitLinkSlotFromEntryFp);
return LoadStackSlot(exit_link_ptr);
}
uword Stack(uword sp, intptr_t index) const {
ASSERT(sp != 0);
return reinterpret_cast<uword>(
LoadStackSlot(reinterpret_cast<uword*>(sp) + index));
}
Thread* const thread_;
uword* pc_;
uword* fp_;
};
static void CopyStackBuffer(Sample* sample, uword sp_addr) {
#if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
ASSERT(sample != nullptr);
uword* sp = reinterpret_cast<uword*>(sp_addr);
RelaxedAtomic<uword>* buffer = sample->GetStackBuffer();
if (sp != nullptr) {
for (intptr_t i = 0; i < Sample::kStackBufferSizeInWords; i++) {
buffer[i] = reinterpret_cast<uword>(LoadStackSlot(sp));
sp++;
}
}
#endif
}
static Sample* SetupSample(Thread* thread,
bool allocation_sample,
ThreadId tid) {
ASSERT(thread != nullptr);
Isolate* isolate = thread->isolate();
SampleBlockBuffer* buffer = Profiler::sample_block_buffer();
Sample* sample = allocation_sample ? buffer->ReserveAllocationSample(isolate)
: buffer->ReserveCPUSample(isolate);
if (sample == nullptr) {
return nullptr;
}
sample->Init(isolate->main_port(), OS::GetCurrentMonotonicMicros(), tid);
uword vm_tag = thread->vm_tag();
#if defined(DART_INCLUDE_SIMULATOR)
// When running in the simulator, the runtime entry function address
// (stored as the vm tag) is the address of a redirect function.
// Attempt to find the real runtime entry function address and use that.
if (FLAG_use_simulator) {
uword redirect_vm_tag = Simulator::FunctionForRedirect(vm_tag);
if (redirect_vm_tag != 0) {
vm_tag = redirect_vm_tag;
}
}
#endif
sample->set_vm_tag(vm_tag);
sample->set_user_tag(thread->user_tag());
sample->set_thread_task(thread->task_kind());
return sample;
}
void Profiler::SampleAllocation(Thread* thread,
intptr_t cid,
uint32_t identity_hash) {
ASSERT(thread != nullptr);
OSThread* os_thread = thread->os_thread();
ASSERT(os_thread != nullptr);
Isolate* isolate = thread->isolate();
if (isolate == nullptr) {
return;
}
Sample* sample =
SetupSample(thread, /*allocation_sample=*/true, os_thread->trace_id());
if (sample == nullptr) {
// We were unable to assign a sample for this allocation.
counters_.sample_allocation_failure++;
return;
}
sample->SetAllocationCid(cid);
sample->set_allocation_identity_hash(identity_hash);
if (FLAG_profile_vm_allocation) {
uintptr_t fp = GET_FP_REGISTER();
uintptr_t pc = OS::GetProgramCounter();
uword stack_lower = os_thread->stack_limit();
uword stack_upper = os_thread->stack_base();
if ((stack_lower >= stack_upper) || (stack_lower == 0) ||
(stack_upper == 0) || (fp < stack_lower) || (fp >= stack_upper)) {
counters_.single_frame_sample_get_and_validate_stack_bounds.fetch_add(1);
return;
}
ProfilerNativeStackWalker native_stack_walker(
&counters_, sample, isolate, stack_lower, stack_upper, pc, fp);
native_stack_walker.walk();
} else if (thread->HasExitedDartCode()) {
uintptr_t fp = thread->top_exit_frame_info();
uintptr_t pc = 0;
ProfilerDartStackWalker dart_exit_stack_walker(thread, sample, isolate, pc,
fp);
dart_exit_stack_walker.WalkFromExitFrame();
} else {
// Fall back.
uintptr_t pc = OS::GetProgramCounter();
sample->SetAt(0, pc);
}
}
void Profiler::SampleThreadSingleFrame(Thread* thread,
Sample* sample,
uintptr_t pc) {
ASSERT(thread != nullptr);
OSThread* os_thread = thread->os_thread();
ASSERT(os_thread != nullptr);
ASSERT(Profiler::sample_block_buffer() != nullptr);
#if !defined(PRODUCT)
Isolate* isolate = thread->isolate();
// Increment counter for vm tag.
VMTagCounters* counters = isolate->vm_tag_counters();
ASSERT(counters != nullptr);
if (thread->IsDartMutatorThread()) {
counters->Increment(sample->vm_tag());
}
#endif
// Write the single pc value.
sample->SetAt(0, pc);
}
void ReleaseToCurrentBlock(Isolate* isolate) {
#if defined(DART_HOST_OS_MACOS) || defined(DART_HOST_OS_WINDOWS) || \
defined(DART_HOST_OS_FUCHSIA)
// The sample is collected by a different thread. The sample appears all at
// once from the profiled thread's point of view. Establish the isolate
// flushing its own current block happens-after the most recent sample
// written in that block by dumping a dependency through the current block.
// TSAN doesn't otherwise know this is already true because it doesn't have
// special treatment for thread_suspend/resume.
SampleBlock* block = isolate->current_sample_block();
isolate->exchange_current_sample_block(block);
#elif defined(DART_HOST_OS_LINUX) || defined(DART_HOST_OS_ANDROID)
// The sample is collected by a signal handler on the same thread being
// sampled.
#else
#error What kind of sampler?
#endif
}
void Profiler::SampleThread(Thread* thread,
const InterruptedThreadState& state) {
ASSERT(thread != nullptr);
OSThread* os_thread = thread->os_thread();
ASSERT(os_thread != nullptr);
Isolate* isolate = thread->isolate();
// Double check if interrupts are disabled after the thread interrupter
// decided to send a signal.
if (!os_thread->ThreadInterruptsEnabled()) {
return;
}
// Thread is not doing VM work.
if (thread->task_kind() == Thread::kUnknownTask) {
counters_.bail_out_unknown_task.fetch_add(1);
return;
}
if (isolate == nullptr) {
counters_.bail_out_check_isolate.fetch_add(1);
return;
}
if (StubCode::InJumpToFrameStub(thread, state.pc)) {
// The JumpToFrame stub manually adjusts the stack pointer, frame
// pointer, and some isolate state. It is not safe to walk the
// stack when executing this stub.
counters_.bail_out_jump_to_exception_handler.fetch_add(1);
return;
}
if (thread->IsDeoptimizing()) {
counters_.bail_out_deoptimizing.fetch_add(1);
return;
}
// Setup sample.
Sample* sample =
SetupSample(thread, /*allocation_sample=*/false, os_thread->trace_id());
if (sample == nullptr) {
// We were unable to assign a sample for this profiler tick.
counters_.sample_allocation_failure++;
return;
}
#if !defined(PRODUCT)
// Increment counter for vm tag.
VMTagCounters* counters = isolate->vm_tag_counters();
ASSERT(counters != nullptr);
if (thread->IsDartMutatorThread()) {
counters->Increment(sample->vm_tag());
}
#endif
if (FLAG_profile_vm) {
uintptr_t sp = state.csp;
uintptr_t fp = state.fp;
uintptr_t pc = state.pc;
uword stack_lower = os_thread->stack_limit();
uword stack_upper = os_thread->stack_base();
if ((fp < stack_lower) || (fp >= stack_upper) || (sp < stack_lower) ||
(sp >= stack_upper)) {
counters_.single_frame_sample_get_and_validate_stack_bounds.fetch_add(1);
SampleThreadSingleFrame(thread, sample, pc);
ReleaseToCurrentBlock(isolate);
return;
}
// On Windows, touching more than one page beyond sp will fault.
stack_lower = sp;
counters_.stack_walker_native.fetch_add(1);
ProfilerNativeStackWalker native_stack_walker(
&counters_, sample, isolate, stack_lower, stack_upper, pc, fp);
native_stack_walker.walk();
} else if (thread->HasExitedDartCode()) {
uintptr_t fp = thread->top_exit_frame_info();
uintptr_t pc = 0;
counters_.stack_walker_dart_exit.fetch_add(1);
ProfilerDartStackWalker dart_stack_walker(thread, sample, isolate, pc, fp);
dart_stack_walker.WalkFromExitFrame();
} else if (thread->IsExecutingDartCode()) {
uintptr_t sp = state.dsp;
uintptr_t fp = state.fp;
uintptr_t pc = state.pc;
uintptr_t lr = state.lr;
#if defined(DART_INCLUDE_SIMULATOR)
if (FLAG_use_simulator) {
Simulator* simulator = thread->simulator();
sp = simulator->get_register(SPREG);
fp = simulator->get_register(FPREG);
pc = simulator->get_pc();
lr = simulator->get_lr();
}
#endif
#if defined(DART_DYNAMIC_MODULES)
if (thread->vm_tag() == VMTag::kDartInterpretedTagId) {
sp = 0;
pc = thread->interpreter()->get_pc();
fp = thread->interpreter()->get_fp();
lr = 0;
RELEASE_ASSERT(thread->interpreter()->HasFrame(fp));
}
#endif
// We can only trust the stack pointer if we are executing Dart code.
// See http://dartbug.com/20421 for details.
CopyStackBuffer(sample, sp);
counters_.stack_walker_dart_exit.fetch_add(1);
ProfilerDartStackWalker dart_stack_walker(thread, sample, isolate, pc, fp);
dart_stack_walker.WalkFromTopFrame(sp, lr);
} else {
counters_.stack_walker_none.fetch_add(1);
sample->SetAt(0, state.pc);
}
ReleaseToCurrentBlock(isolate);
}
CodeDescriptor::CodeDescriptor(const AbstractCode code) : code_(code) {}
uword CodeDescriptor::Start() const {
return code_.PayloadStart();
}
uword CodeDescriptor::Size() const {
return code_.Size();
}
int64_t CodeDescriptor::CompileTimestamp() const {
return code_.compile_timestamp();
}
CodeLookupTable::CodeLookupTable(Thread* thread) {
Build(thread);
}
class CodeLookupTableBuilder : public ObjectVisitor {
public:
explicit CodeLookupTableBuilder(CodeLookupTable* table) : table_(table) {
ASSERT(table_ != nullptr);
}
~CodeLookupTableBuilder() {}
void VisitObject(ObjectPtr raw_obj) override {
if (raw_obj->IsCode() && !Code::IsUnknownDartCode(Code::RawCast(raw_obj))) {
table_->Add(Code::Handle(Code::RawCast(raw_obj)));
} else if (raw_obj->IsBytecode()) {
table_->Add(Bytecode::Handle(Bytecode::RawCast(raw_obj)));
}
}
private:
CodeLookupTable* table_;
};
void CodeLookupTable::Build(Thread* thread) {
ASSERT(thread != nullptr);
// Clear.
code_objects_.Clear();
thread->CheckForSafepoint();
// Add all found Code objects.
if (FLAG_precompiled_mode) {
const GrowableObjectArray& tables = GrowableObjectArray::Handle(
IsolateGroup::Current()->object_store()->instructions_tables());
InstructionsTable& table = InstructionsTable::Handle();
Array& codes = Array::Handle();
for (intptr_t i = 0; i < tables.Length(); i++) {
table ^= tables.At(i);
codes = table.code_objects();
for (intptr_t j = 0; j < codes.Length(); j++) {
Code& code = Code::Handle(); // Separate handle for each.
code ^= codes.At(j);
if (!Code::IsUnknownDartCode(code.ptr())) {
Add(code);
}
}
}
} else {
TimelineBeginEndScope tl(Timeline::GetIsolateStream(),
"CodeLookupTable::Build HeapIterationScope");
HeapIterationScope iteration(thread);
CodeLookupTableBuilder cltb(this);
iteration.IterateOldObjects(&cltb);
}
thread->CheckForSafepoint();
// Sort by entry.
code_objects_.Sort(CodeDescriptor::Compare);
#if defined(DEBUG)
if (length() <= 1) {
return;
}
ASSERT(FindCode(0) == nullptr);
ASSERT(FindCode(~0) == nullptr);
// Sanity check that we don't have duplicate entries and that the entries
// are sorted.
for (intptr_t i = 0; i < length() - 1; i++) {
const CodeDescriptor* a = At(i);
const CodeDescriptor* b = At(i + 1);
ASSERT(a->Start() < b->Start());
ASSERT(FindCode(a->Start()) == a);
ASSERT(FindCode(b->Start()) == b);
ASSERT(FindCode(a->Start() + a->Size() - 1) == a);
ASSERT(FindCode(b->Start() + b->Size() - 1) == b);
}
#endif
}
void CodeLookupTable::Add(const Object& code) {
ASSERT(!code.IsNull());
ASSERT(code.IsCode() || code.IsBytecode());
CodeDescriptor* cd = new CodeDescriptor(AbstractCode(code.ptr()));
code_objects_.Add(cd);
}
const CodeDescriptor* CodeLookupTable::FindCode(uword pc) const {
intptr_t first = 0;
intptr_t count = length();
while (count > 0) {
intptr_t current = first;
intptr_t step = count / 2;
current += step;
const CodeDescriptor* cd = At(current);
if (pc >= cd->Start()) {
first = ++current;
count -= step + 1;
} else {
count = step;
}
}
// First points to the first code object whose entry is greater than PC.
// That means the code object we need to check is first - 1.
if (first == 0) {
return nullptr;
}
first--;
ASSERT(first >= 0);
ASSERT(first < length());
const CodeDescriptor* cd = At(first);
if (cd->Contains(pc)) {
return cd;
}
return nullptr;
}
ProcessedSampleBuffer* SampleBuffer::BuildProcessedSampleBuffer(
SampleFilter* filter,
ProcessedSampleBuffer* buffer) {
Thread* thread = Thread::Current();
Zone* zone = thread->zone();
if (buffer == nullptr) {
buffer = new (zone) ProcessedSampleBuffer();
}
const intptr_t length = capacity();
for (intptr_t i = 0; i < length; i++) {
thread->CheckForSafepoint();
Sample* sample = At(i);
if (sample->ignore_sample()) {
// Bad sample.
continue;
}
if (!sample->head_sample()) {
// An inner sample in a chain of samples.
continue;
}
if (sample->timestamp() == 0) {
// Empty.
continue;
}
if (sample->At(0) == 0) {
// No frames.
continue;
}
if (filter != nullptr) {
// If we're requesting all the native allocation samples, we don't care
// whether or not we're in the same isolate as the sample.
if (sample->port() != filter->port()) {
// Another isolate.
continue;
}
if (!filter->TimeFilterSample(sample)) {
// Did not pass time filter.
continue;
}
if (!filter->TaskFilterSample(sample)) {
// Did not pass task filter.
continue;
}
if (!filter->FilterSample(sample)) {
// Did not pass filter.
continue;
}
}
buffer->Add(BuildProcessedSample(sample, buffer->code_lookup_table()));
}
return buffer;
}
#if defined(SUPPORT_PERFETTO) && defined(DART_PRECOMPILED_RUNTIME)
class PerfettoPerfSampleWriter : public ValueObject {
public:
PerfettoPerfSampleWriter(
int64_t from_micros,
int64_t to_micros,
perfetto_utils::InternedDataBuilder& interned_data_builder,
void* file,
Dart_FileWriteCallback write_bytes)
: from_micros_(from_micros),
to_micros_(to_micros),
file_(file),
write_bytes_(write_bytes),
interned_data_builder_(interned_data_builder) {
CollectMappings();
}
~PerfettoPerfSampleWriter() {
for (auto m : mappings_) {
delete m;
}
}
struct SnapshotMapping : public MallocAllocated {
uint32_t iid;
uword start;
uword end;
const char* path;
Dart_Port isolate_group_id;
bool is_root_unit;
bool Contains(uword pc) { return start < pc && pc <= end; }
};
void CollectMappings() {
IsolateGroup::ForEach([&](IsolateGroup* group) {
const auto group_source = group->source();
const auto isolate_group_instructions =
reinterpret_cast<uword>(group_source->snapshot_text);
const TextImage isolate_group_image(isolate_group_instructions);
group->heap()->old_space()->ForEachImagePage([&](Page* page) {
if (page->is_executable()) {
mappings_.Add(new SnapshotMapping{
.start = page->object_start(),
.end = page->object_end(),
.path = group->source()->script_uri,
.isolate_group_id = group->id(),
.is_root_unit =
(page->object_start() ==
reinterpret_cast<uword>(isolate_group_image.object_start())),
});
}
});
});
mappings_.Sort([](auto a, auto b) -> int {
if ((*a)->start < (*b)->start) return -1;
if ((*a)->start > (*b)->start) return 1;
return 0;
});
// Remove duplicated mappings.
intptr_t j = 0;
for (intptr_t i = 0; i < mappings_.length(); i++) {
if (j > 0 && mappings_[j - 1]->start == mappings_[i]->start) {
delete mappings_[i];
} else {
mappings_[j++] = mappings_[i];
}
}
mappings_.SetLength(j);
}
void WriteSamples(SampleBuffer* buffer) {
const intptr_t length = buffer->capacity();
for (intptr_t i = 0; i < length; i++) {
Sample* sample = buffer->At(i);
if (sample->ignore_sample()) {
// Bad sample.
continue;
}
if (!sample->head_sample()) {
// An inner sample in a chain of samples.
continue;
}
if (sample->timestamp() == 0) {
// Empty.
continue;
}
if (sample->At(0) == 0) {
// No frames.
continue;
}
if (sample->is_allocation_sample()) {
continue;
}
auto timestamp = sample->timestamp();
if (from_micros_ > timestamp || to_micros_ < timestamp) {
continue;
}
WriteSample(sample);
}
}
std::pair<uint32_t, uint64_t> FindMapping(uword pc) {
const auto lower_bound =
std::lower_bound(mappings_.begin(), mappings_.end(), pc,
[](auto m, auto pc) { return m->end < pc; });
if (lower_bound == mappings_.end() || !(*lower_bound)->Contains(pc)) {
return std::make_pair(0, pc);
}
const auto m = *lower_bound;
return std::make_pair(InternMapping(m), pc - m->start);
}
uint32_t InternMapping(SnapshotMapping* m) {
if (m->iid == 0) {
// When Perfetto is matching ModuleSymbols to a corresponding mapping,
// it uses both path and build_id for matching (and both of them are
// used as opaque identifiers). We use this to support deferred units:
// all mappings corresponding to an isolate group have the same build-id
// (which is based on isolate group id) while path is based on the script
// uri with address of the mapping appended for non-root units - this
// makes the combination of path+build_id unique for each unit including
// the root one.
//
// Additionally we make sure to prepend "/" to the path if it does not
// start with "/" to compensation for similar logic in Perfetto:
// Mapping.path_string_ids is an array of path components, to construct
// mappings path from path components Perfetto joins them with "/"
// and prepends "/" if there is no leading slash (see [1]). To normalize
// paths between Mapping and ModuleSymbols we simply ensure that path
// here always starts with "/".
//
// [1]: https://github.com/google/perfetto/blob/a3e107ec803c876a870205f89c1e37742184b598/src/trace_processor/importers/proto/profile_packet_utils.cc#L24-L38
const char* path = m->path;
if (!m->is_root_unit) {
Utils::SNPrint(&name_buf_[0], ARRAY_SIZE(name_buf_),
"%s%s(%016" Px64 ")", m->path[0] == '/' ? "" : "/",
m->path, static_cast<uint64_t>(m->start));
path = name_buf_;
} else if (m->path[0] != '/') {
Utils::SNPrint(&name_buf_[0], ARRAY_SIZE(name_buf_), "/%s", m->path);
path = name_buf_;
}
const auto path_id = interned_data_builder_.mapping_paths().Intern(path);
const auto build_id_iid =
interned_data_builder_.InternSyntheticBuildIdForIsolateGroup(
m->isolate_group_id);
m->iid = interned_data_builder_.mappings().Intern({
.start = m->start,
.end = m->end,
.path_string = path_id,
.build_id = build_id_iid,
});
}
return m->iid;
}
void WriteSample(Sample* sample) {
WriteClockSnapshotPacket();
// Walk the sampled PCs and intern the stack.
callstack_.Clear();
Sample* current = sample;
bool unknown_mappings = false;
intptr_t pc_adjustment = 0;
while (current != nullptr) {
for (intptr_t i = 0; i < Sample::kPCArraySizeInWords; i++) {
if (current->At(i) == 0) {
break;
}
const uword pc = current->At(i) + pc_adjustment;
const auto [mapping_iid, rel_pc] = FindMapping(pc);
const auto frame_iid = interned_data_builder_.frames().Intern({
.rel_pc = rel_pc,
.mapping_iid = mapping_iid,
});
if (mapping_iid == 0) {
unknown_mappings = true;
// Eagerly symbolize native frames.
const auto& frame =
interned_data_builder_.frames().GetByIid(frame_iid);
if (frame.function_name_iid == 0) {
const auto name_iid =
interned_data_builder_.function_names().Intern(
LookupNativeName(pc));
const_cast<perfetto_utils::InternedDataBuilder::Frame&>(frame)
.function_name_iid = name_iid;
}
}
callstack_.Add(frame_iid);
pc_adjustment = -1;
}
current = current->Next();
}
if (unknown_mappings) {
interned_data_builder_.MarkNeedUnknownMapping();
}
// Perfetto UI requires callstack frames to be in caller-first order, while
// profiler records samples in callee-first order.
callstack_.Reverse();
const auto callstack_iid = interned_data_builder_.callstacks().Intern(
{&callstack_[0], callstack_.length()});
perfetto_utils::SetTrustedPacketSequenceId(packet_.get());
perfetto_utils::SetTimestampAndMonotonicClockId(packet_.get(),
sample->timestamp());
auto& perf_sample = *packet_->set_perf_sample();
perf_sample.set_pid(pid_);
perf_sample.set_tid(OSThread::ThreadIdToIntPtr(sample->tid()));
perf_sample.set_callstack_iid(callstack_iid);
interned_data_builder_.AttachInternedDataTo(packet_.get());
perfetto_utils::WritePacketBytes(&packet_, [this](auto bytes, auto size) {
write_bytes_(bytes, size, file_);
});
packet_.Reset();
}
private:
void WriteClockSnapshotPacket() {
if (clock_snapshot_written_) {
return;
}
perfetto_utils::PopulateClockSnapshotPacket(packet_.get());
perfetto_utils::WritePacketBytes(&packet_, [this](auto bytes, auto size) {
write_bytes_(bytes, size, file_);
});
packet_.Reset();
clock_snapshot_written_ = true;
}
char* LookupNativeName(uword pc) {
uword start;
if (auto const name = NativeSymbolResolver::LookupSymbolName(pc, &start)) {
Utils::SNPrint(&name_buf_[0], ARRAY_SIZE(name_buf_),
"[Native] %s+0x%" Px "", name, pc - start);
NativeSymbolResolver::FreeSymbolName(name);
return &name_buf_[0];
}
uword dso_base;
const char* dso_name;
if (NativeSymbolResolver::LookupSharedObject(pc, &dso_base, &dso_name)) {
uword dso_offset = pc - dso_base;
Utils::SNPrint(&name_buf_[0], ARRAY_SIZE(name_buf_),
"[Native] %s+0x%" Px "", dso_name, dso_offset);
NativeSymbolResolver::FreeSymbolName(dso_name);
return &name_buf_[0];
} else {
Utils::SNPrint(&name_buf_[0], ARRAY_SIZE(name_buf_), "[Native] %" Px "",
pc);
return &name_buf_[0];
}
}
int64_t from_micros_;
int64_t to_micros_;
void* file_;
Dart_FileWriteCallback write_bytes_;
const intptr_t pid_ = OS::ProcessId();
MallocGrowableArray<SnapshotMapping*> mappings_;
char name_buf_[1024];
perfetto_utils::InternedDataBuilder& interned_data_builder_;
bool clock_snapshot_written_ = false;
protozero::HeapBuffered<perfetto::protos::pbzero::TracePacket> packet_;
MallocGrowableArray<uint64_t> callstack_{128};
};
void SampleBlockBuffer::WritePerfetto(
int64_t from_micros,
int64_t to_micros,
perfetto_utils::InternedDataBuilder& interned_data_builder,
void* file,
Dart_FileWriteCallback write_bytes) {
PerfettoPerfSampleWriter writer(from_micros, to_micros, interned_data_builder,
file, write_bytes);
for (intptr_t i = 0; i < capacity_; ++i) {
SampleBlock* block = &blocks_[i];
if (block->TryAcquireStreaming(/*isolate=*/nullptr)) {
writer.WriteSamples(block);
block->StreamingToFree(); // We consumed samples.
}
}
}
#endif
ProcessedSample* SampleBuffer::BuildProcessedSample(
Sample* sample,
const CodeLookupTable& clt) {
Thread* thread = Thread::Current();
Zone* zone = thread->zone();
ProcessedSample* processed_sample = new (zone) ProcessedSample();
// Copy state bits from sample.
processed_sample->set_timestamp(sample->timestamp());
processed_sample->set_tid(sample->tid());
processed_sample->set_vm_tag(sample->vm_tag());
processed_sample->set_user_tag(sample->user_tag());
if (sample->is_allocation_sample()) {
processed_sample->set_allocation_cid(sample->allocation_cid());
processed_sample->set_allocation_identity_hash(
sample->allocation_identity_hash());
}
processed_sample->set_first_frame_executing(!sample->exit_frame_sample());
// Copy stack trace from sample(s).
bool truncated = false;
for (Sample* current = sample; current != nullptr;
current = current->Next()) {
for (intptr_t i = 0; i < Sample::kPCArraySizeInWords; i++) {
if (current->At(i) == 0) {
break;
}
processed_sample->Add(current->At(i));
}
truncated = truncated || current->truncated_trace();
}
if (!sample->exit_frame_sample()) {
processed_sample->FixupCaller(clt, /*pc_marker=*/0,
sample->GetStackBuffer());
}
processed_sample->set_truncated(truncated);
return processed_sample;
}
ProcessedSample::ProcessedSample()
: pcs_(Sample::kPCArraySizeInWords),
timestamp_(0),
vm_tag_(0),
user_tag_(0),
allocation_cid_(-1),
allocation_identity_hash_(0),
truncated_(false) {}
void ProcessedSample::FixupCaller(const CodeLookupTable& clt,
uword pc_marker,
RelaxedAtomic<uword>* stack_buffer) {
const CodeDescriptor* cd = clt.FindCode(At(0));
if (cd == nullptr) {
// No Dart code.
return;
}
if (cd->CompileTimestamp() > timestamp()) {
// Code compiled after sample. Ignore.
return;
}
CheckForMissingDartFrame(clt, cd, pc_marker, stack_buffer);
}
void ProcessedSample::CheckForMissingDartFrame(
const CodeLookupTable& clt,
const CodeDescriptor* cd,
uword pc_marker,
RelaxedAtomic<uword>* stack_buffer) {
ASSERT(cd != nullptr);
if (cd->code().IsBytecode()) {
// Bytecode frame build is atomic from the profiler's perspective,
// there are no missing frames.
return;
}
const Code& code = Code::Handle(Code::RawCast(cd->code().ptr()));
ASSERT(!code.IsNull());
// Some stubs (and intrinsics) do not push a frame onto the stack leaving
// the frame pointer in the caller.
//
// PC -> STUB
// FP -> DART3 <-+
// DART2 <-| <- TOP FRAME RETURN ADDRESS.
// DART1 <-|
// .....
//
// In this case, traversing the linked stack frames will not collect a PC
// inside DART3. The stack will incorrectly be: STUB, DART2, DART1.
// In Dart code, after pushing the FP onto the stack, an IP in the current
// function is pushed onto the stack as well. This stack slot is called
// the PC marker. We can use the PC marker to insert DART3 into the stack
// so that it will correctly be: STUB, DART3, DART2, DART1. Note the
// inserted PC may not accurately reflect the true return address into DART3.
// The pc marker is our current best guess of a return address.
uword return_address = pc_marker;
// Attempt to find a better return address.
ReturnAddressLocator ral(At(0), stack_buffer, code);
if (!ral.LocateReturnAddress(&return_address)) {
ASSERT(return_address == pc_marker);
if (code.GetPrologueOffset() == 0) {
// Code has the prologue at offset 0. The frame is already setup and
// can be trusted.
return;
}
// Could not find a better return address than the pc_marker.
if (code.ContainsInstructionAt(return_address)) {
// PC marker is in the same code as pc, no missing frame.
return;
}
}
if (clt.FindCode(return_address) == nullptr) {
// Return address is not from a Dart code object. Do not insert.
return;
}
if (return_address != 0) {
InsertAt(1, return_address);
}
}
ProcessedSampleBuffer::ProcessedSampleBuffer()
: code_lookup_table_(new CodeLookupTable(Thread::Current())) {
ASSERT(code_lookup_table_ != nullptr);
}
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
void SampleBlockProcessor::Init() {
ASSERT(!initialized_);
monitor_ = new Monitor();
initialized_ = true;
shutdown_ = true;
drain_ = false;
}
void SampleBlockProcessor::Cleanup() {
Shutdown();
initialized_ = false;
delete monitor_;
}
void SampleBlockProcessor::Startup() {
ASSERT(initialized_);
ASSERT(processor_thread_id_ == OSThread::kInvalidThreadJoinId);
SafepointMonitorLocker startup_ml(monitor_);
shutdown_ = false;
drain_ = false;
OSThread::Start("Dart Profiler SampleBlockProcessor", ThreadMain, 0);
while (!thread_running_) {
startup_ml.Wait();
}
ASSERT(processor_thread_id_ != OSThread::kInvalidThreadJoinId);
}
void SampleBlockProcessor::Shutdown() {
{
SafepointMonitorLocker shutdown_ml(monitor_);
if (shutdown_) {
// Already shutdown.
return;
}
shutdown_ = true;
shutdown_ml.Notify();
ASSERT(initialized_);
}
// Join the thread.
ASSERT(processor_thread_id_ != OSThread::kInvalidThreadJoinId);
auto thread = Thread::Current();
if (thread != nullptr) {
TransitionVMToBlocked transition(thread);
OSThread::Join(processor_thread_id_);
} else {
OSThread::Join(processor_thread_id_);
}
processor_thread_id_ = OSThread::kInvalidThreadJoinId;
ASSERT(!thread_running_);
}
#endif // defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
void Profiler::IsolateShutdown(Isolate* isolate) {
FlushSampleBlocks(isolate);
NOT_IN_PRECOMPILED(Timeline::DrainCompletedSampleBlocksIntoRecorder(isolate));
}
void Profiler::IsolateGroupShutdown(IsolateGroup* isolate_group) {
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
if (config_.enabled && config_.stream_to_timeline) {
Timeline::NotifyAboutIsolateGroupShutdown(isolate_group);
}
#endif // defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
}
#if defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO)
void SampleBlockProcessor::ThreadMain(uword parameters) {
ASSERT(initialized_);
{
// Signal to main thread we are ready.
MonitorLocker startup_ml(monitor_);
OSThread* os_thread = OSThread::Current();
ASSERT(os_thread != nullptr);
processor_thread_id_ = OSThread::GetCurrentThreadJoinId(os_thread);
thread_running_ = true;
startup_ml.Notify();
}
MonitorLocker wait_ml(monitor_);
// Wakeup every 100ms.
const int64_t wakeup_interval = 1000 * 100;
while (true) {
wait_ml.WaitMicros(wakeup_interval);
#if defined(DART_PRECOMPILED_RUNTIME)
// If shutting down flush all sample blocks from all isolates.
if (shutdown_) {
IsolateGroup::ForEach([&](IsolateGroup* group) {
const bool kBypassSafepoint = false;
Thread::EnterIsolateGroupAsHelper(group, Thread::kSampleBlockTask,
kBypassSafepoint);
group->ForEachIsolate(
[&](Isolate* isolate) { FlushSampleBlocks(isolate); });
Thread::ExitIsolateGroupAsHelper(kBypassSafepoint);
});
}
Timeline::DrainCompletedSampleBlocksIntoRecorder();
#else
IsolateGroup::ForEach([&](IsolateGroup* group) {
const bool kBypassSafepoint = false;
Thread::EnterIsolateGroupAsHelper(group, Thread::kSampleBlockTask,
kBypassSafepoint);
group->ForEachIsolate([&](Isolate* isolate) {
if (shutdown_) {
FlushSampleBlocks(isolate);
}
if (isolate->TakeHasCompletedBlocks()) {
Timeline::DrainCompletedSampleBlocksIntoRecorder(isolate);
}
});
Thread::ExitIsolateGroupAsHelper(kBypassSafepoint);
});
#endif
if (shutdown_) {
break;
}
}
// Signal to main thread we are exiting.
thread_running_ = false;
}
#endif
#endif // defined(DART_INCLUDE_PROFILER)
} // namespace dart