Files
sdk/runtime/vm/profiler.cc
T
Ryan Macnak d36adbacaf [vm] Remove the VM isolate.
The former contents of the VM isolate are now included into each isolate group. This makes each isolate group's heap independent, and in particular allows each heap to be allocated to a separate pointer cage (not done in this CL).

The duplicated stubs that allowed PC relative calls are removed, since the originals can now be the target of PC relative calls.

The bootstrapping needing to load an AppJIT or AppAOT snapshot is reduced to allocating the oddballs. The code is entirely dropped in the AOT runtime, but the JIT runtime still has it to allow for flags to affect the compilation of the stub code. Further refactoring might be able to remove this for the JIT runtime too, with only gen_snapshot knowing how to bootstrap.

Class serialization no longer distinguishes predefined classes.

The page containing null is marked as never-evacuate. null, false and true must not move because the compiler relies on their low bits having certain patterns for some optimizations. (Previously, the entire VM isolate heap never moved.)

Compaction is disabled for IA32. Due to register pressure, some stub calls must not use a scratch register and embed the address of Code.

The page containing the call-through-safepoint stub is frozen when running with --write-protect-code and the stub is created at runtime (instead of loaded from an AppJIT or AppAOT snapshot). This stub must remain executable even during a safepoint, as a foreign call might during return during a safepoint and only block after the stub directs it to the runtime.

The snapshot symbols are renamed to kDartSnapshotData and kDartSnapshotText. There is no need to distinguish the VM isolate's snapshot, and snaphots are per isolate group not per isolate. Aliases with the old names are added to ease migration.

Some global flags that were automatically set based on the VM isolate's snapshot are now isolate group flags and automatically set by the isolate group's snapshot.

TEST=ci
Change-Id: Iee82016057d609112e9b021d178fc3d4d18b5044
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/500621
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>
SLSA-Policy-Verified: SLSA Policy Verification Service <devtools-gerritcodereview-exitgate@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
2026-05-18 11:35:03 -07:00

2160 lines
66 KiB
C++

// 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.
}
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;
const bool compressed = false;
memory_ =
VirtualMemory::Allocate(size, executable, compressed, "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);
#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 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)) {
counters_.single_frame_sample_get_and_validate_stack_bounds.fetch_add(1);
SampleThreadSingleFrame(thread, sample, pc);
ReleaseToCurrentBlock(isolate);
return;
}
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 = isolate->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 Image 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_);
}
void Profiler::IsolateShutdown(Isolate* isolate) {
FlushSampleBlocks(isolate);
NOT_IN_PRECOMPILED(Timeline::DrainCompletedSampleBlocksIntoRecorder(isolate));
}
void Profiler::IsolateGroupShutdown(IsolateGroup* isolate_group) {
#if defined(SUPPORT_TIMELINE)
if (config_.enabled && config_.stream_to_timeline) {
Timeline::NotifyAboutIsolateGroupShutdown(isolate_group);
}
#endif // defined(SUPPORT_TIMELINE)
}
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