v8-unwinder.h

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// Copyright 2021 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 INCLUDE_V8_UNWINDER_H_
#define INCLUDE_V8_UNWINDER_H_
 
#include <memory>
 
#include "v8-embedder-state-scope.h"  // NOLINT(build/include_directory)
#include "v8config.h"                 // NOLINT(build/include_directory)
 
namespace v8 {
// Holds the callee saved registers needed for the stack unwinder. It is the
// empty struct if no registers are required. Implemented in
// include/v8-unwinder-state.h.
struct CalleeSavedRegisters;
 
// A RegisterState represents the current state of registers used
// by the sampling profiler API.
struct V8_EXPORT RegisterState {
  RegisterState();
  ~RegisterState();
  RegisterState(const RegisterState& other);
  RegisterState& operator=(const RegisterState& other);
 
  void* pc;  // Instruction pointer.
  void* sp;  // Stack pointer.
  void* fp;  // Frame pointer.
  void* lr;  // Link register (or nullptr on platforms without a link register).
  // Callee saved registers (or null if no callee saved registers were stored)
  std::unique_ptr<CalleeSavedRegisters> callee_saved;
};
 
// A StateTag represents a possible state of the VM.
// LINT.IfChange
enum StateTag : uint16_t {
  JS,
  GC,
  PARSER,
  BYTECODE_COMPILER,
  COMPILER,
  OTHER,
  EXTERNAL,
  ATOMICS_WAIT,
  IDLE,
  IDLE_EXTERNAL,
  LOGGING,
};
// LINT.ThenChange(../tools/profile.mjs, ../tools/tickprocessor.mjs)
 
constexpr bool IsExternal(StateTag state) {
  return state == EXTERNAL || state == IDLE_EXTERNAL;
}
 
constexpr bool IsIdle(StateTag state) {
  return state == IDLE || state == IDLE_EXTERNAL;
}
 
// The output structure filled up by GetStackSample API function.
struct SampleInfo {
  size_t frames_count;              // Number of frames collected.
  void* external_callback_entry;    // External callback address if VM is
                                    // executing an external callback.
  void* context;                    // Incumbent native context address.
  void* embedder_context;           // Native context address for embedder state
  StateTag vm_state;                // Current VM state.
  EmbedderStateTag embedder_state;  // Current Embedder state
};
 
struct MemoryRange {
  const void* start = nullptr;
  size_t length_in_bytes = 0;
};
 
struct JSEntryStub {
  MemoryRange code;
};
 
struct JSEntryStubs {
  JSEntryStub js_entry_stub;
  JSEntryStub js_construct_entry_stub;
  JSEntryStub js_run_microtasks_entry_stub;
};
 
class V8_EXPORT Unwinder {
 public:
  static bool TryUnwindV8Frames(const JSEntryStubs& entry_stubs,
                                size_t code_pages_length,
                                const MemoryRange* code_pages,
                                RegisterState* register_state,
                                const void* stack_base);
 
  static bool PCIsInV8(size_t code_pages_length, const MemoryRange* code_pages,
                       void* pc);
};
 
}  // namespace v8
 
#endif  // INCLUDE_V8_UNWINDER_H_