tick-sample.h

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// Copyright 2013 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef V8_PROFILER_TICK_SAMPLE_H_
#define V8_PROFILER_TICK_SAMPLE_H_
 
#include "include/v8-unwinder.h"
#include "src/base/platform/time.h"
#include "src/common/globals.h"
 
namespace v8 {
namespace internal {
 
class Isolate;
 
// TickSample captures the information collected for each sample.
struct V8_EXPORT TickSample {
  // Internal profiling (with --prof + tools/$OS-tick-processor) wants to
  // include the runtime function we're calling. Externally exposed tick
  // samples don't care.
  enum RecordCEntryFrame { kIncludeCEntryFrame, kSkipCEntryFrame };
 
  TickSample() {}
 
  void Init(Isolate* isolate, const v8::RegisterState& state,
            RecordCEntryFrame record_c_entry_frame, bool update_stats,
            bool use_simulator_reg_state = true,
            base::TimeDelta sampling_interval = base::TimeDelta(),
            const std::optional<uint64_t> trace_id = std::nullopt);
  static bool GetStackSample(Isolate* isolate, v8::RegisterState* state,
                             RecordCEntryFrame record_c_entry_frame,
                             void** frames, size_t frames_limit,
                             v8::SampleInfo* sample_info,
                             StateTag* out_state = nullptr,
                             bool use_simulator_reg_state = true);
 
  void print() const;
 
  static constexpr unsigned kMaxFramesCountLog2 = 8;
  static constexpr unsigned kMaxFramesCount = (1 << kMaxFramesCountLog2) - 1;
 
  void* pc = nullptr;  // Instruction pointer.
  union {
    void* tos;  // Top stack value (*sp).
    void* external_callback_entry = nullptr;
  };
  void* context = nullptr;          // Address of the incumbent native context.
  void* embedder_context = nullptr;  // Address of the embedder native context.
 
  base::TimeTicks timestamp;
  base::TimeDelta sampling_interval_;  // Sampling interval used to capture.
 
  StateTag state = OTHER;  // The state of the VM.
  EmbedderStateTag embedder_state = EmbedderStateTag::EMPTY;
 
  uint16_t frames_count = 0;  // Number of captured frames.
  static_assert(sizeof(frames_count) * kBitsPerByte >= kMaxFramesCountLog2);
  bool has_external_callback = false;
  // Whether the sample should update aggregated stats.
  bool update_stats_ = true;
  // An identifier to associate the sample with a trace event.
  std::optional<uint64_t> trace_id_;
 
  void* stack[kMaxFramesCount];  // Call stack.
};
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_PROFILER_TICK_SAMPLE_H_