DXR is a code search and navigation tool aimed at making sense of large projects. It supports full-text and regex searches as well as structural queries.

Line Code
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * vim: set ts=8 sts=4 et sw=4 tw=99:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef js_ProfilingFrameIterator_h
#define js_ProfilingFrameIterator_h

#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"

#include "js/GCAPI.h"
#include "js/TypeDecls.h"
#include "js/Utility.h"

namespace js {
class Activation;
namespace jit {
class JitActivation;
class JSJitProfilingFrameIterator;
class JitcodeGlobalEntry;
}  // namespace jit
namespace wasm {
class ProfilingFrameIterator;
}  // namespace wasm
}  // namespace js

namespace JS {

struct ForEachTrackedOptimizationAttemptOp;
struct ForEachTrackedOptimizationTypeInfoOp;

// This iterator can be used to walk the stack of a thread suspended at an
// arbitrary pc. To provide accurate results, profiling must have been enabled
// (via EnableRuntimeProfilingStack) before executing the callstack being
// unwound.
//
// Note that the caller must not do anything that could cause GC to happen while
// the iterator is alive, since this could invalidate Ion code and cause its
// contents to become out of date.
class MOZ_NON_PARAM JS_PUBLIC_API ProfilingFrameIterator {
 public:
  enum class Kind : bool { JSJit, Wasm };

 private:
  JSContext* cx_;
  mozilla::Maybe<uint64_t> samplePositionInProfilerBuffer_;
  js::Activation* activation_;
  Kind kind_;

  static const unsigned StorageSpace = 8 * sizeof(void*);
  alignas(void*) unsigned char storage_[StorageSpace];

  void* storage() { return storage_; }
  const void* storage() const { return storage_; }

  js::wasm::ProfilingFrameIterator& wasmIter() {
    MOZ_ASSERT(!done());
    MOZ_ASSERT(isWasm());
    return *static_cast<js::wasm::ProfilingFrameIterator*>(storage());
  }
  const js::wasm::ProfilingFrameIterator& wasmIter() const {
    MOZ_ASSERT(!done());
    MOZ_ASSERT(isWasm());
    return *static_cast<const js::wasm::ProfilingFrameIterator*>(storage());
  }

  js::jit::JSJitProfilingFrameIterator& jsJitIter() {
    MOZ_ASSERT(!done());
    MOZ_ASSERT(isJSJit());
    return *static_cast<js::jit::JSJitProfilingFrameIterator*>(storage());
  }

  const js::jit::JSJitProfilingFrameIterator& jsJitIter() const {
    MOZ_ASSERT(!done());
    MOZ_ASSERT(isJSJit());
    return *static_cast<const js::jit::JSJitProfilingFrameIterator*>(storage());
  }

  void settleFrames();
  void settle();

 public:
  struct RegisterState {
    RegisterState() : pc(nullptr), sp(nullptr), fp(nullptr), lr(nullptr) {}
    void* pc;
    void* sp;
    void* fp;
    void* lr;
  };

  ProfilingFrameIterator(
      JSContext* cx, const RegisterState& state,
      const mozilla::Maybe<uint64_t>& samplePositionInProfilerBuffer =
          mozilla::Nothing());
  ~ProfilingFrameIterator();
  void operator++();
  bool done() const { return !activation_; }

  // Assuming the stack grows down (we do), the return value:
  //  - always points into the stack
  //  - is weakly monotonically increasing (may be equal for successive frames)
  //  - will compare greater than newer native and psuedo-stack frame addresses
  //    and less than older native and psuedo-stack frame addresses
  void* stackAddress() const;

  enum FrameKind { Frame_Baseline, Frame_Ion, Frame_Wasm };

  struct Frame {
    FrameKind kind;
    void* stackAddress;
    void* returnAddress;
    void* activation;
    const char* label;
  } JS_HAZ_GC_INVALIDATED;

  bool isWasm() const;
  bool isJSJit() const;

  uint32_t extractStack(Frame* frames, uint32_t offset, uint32_t end) const;

  mozilla::Maybe<Frame> getPhysicalFrameWithoutLabel() const;

 private:
  mozilla::Maybe<Frame> getPhysicalFrameAndEntry(
      js::jit::JitcodeGlobalEntry* entry) const;

  void iteratorConstruct(const RegisterState& state);
  void iteratorConstruct();
  void iteratorDestroy();
  bool iteratorDone();
} JS_HAZ_GC_INVALIDATED;

JS_FRIEND_API bool IsProfilingEnabledForContext(JSContext* cx);

/**
 * After each sample run, this method should be called with the current buffer
 * position at which the buffer contents start. This will update the
 * corresponding field on the JSRuntime.
 *
 * See the field |profilerSampleBufferRangeStart| on JSRuntime for documentation
 * about what this value is used for.
 */
JS_FRIEND_API void SetJSContextProfilerSampleBufferRangeStart(
    JSContext* cx, uint64_t rangeStart);

class ProfiledFrameRange;

// A handle to the underlying JitcodeGlobalEntry, so as to avoid repeated
// lookups on JitcodeGlobalTable.
class MOZ_STACK_CLASS ProfiledFrameHandle {
  friend class ProfiledFrameRange;

  JSRuntime* rt_;
  js::jit::JitcodeGlobalEntry& entry_;
  void* addr_;
  void* canonicalAddr_;
  const char* label_;
  uint32_t depth_;
  mozilla::Maybe<uint8_t> optsIndex_;

  ProfiledFrameHandle(JSRuntime* rt, js::jit::JitcodeGlobalEntry& entry,
                      void* addr, const char* label, uint32_t depth);

  void updateHasTrackedOptimizations();

 public:
  const char* label() const { return label_; }
  uint32_t depth() const { return depth_; }
  bool hasTrackedOptimizations() const { return optsIndex_.isSome(); }
  void* canonicalAddress() const { return canonicalAddr_; }

  JS_PUBLIC_API ProfilingFrameIterator::FrameKind frameKind() const;
  JS_PUBLIC_API void forEachOptimizationAttempt(
      ForEachTrackedOptimizationAttemptOp& op, JSScript** scriptOut,
      jsbytecode** pcOut) const;

  JS_PUBLIC_API void forEachOptimizationTypeInfo(
      ForEachTrackedOptimizationTypeInfoOp& op) const;
};

class ProfiledFrameRange {
 public:
  class Iter final {
   public:
    Iter(const ProfiledFrameRange& range, uint32_t index)
        : range_(range), index_(index) {}

    JS_PUBLIC_API ProfiledFrameHandle operator*() const;

    // Provide the bare minimum of iterator methods that are needed for
    // C++ ranged for loops.
    Iter& operator++() {
      ++index_;
      return *this;
    }
    bool operator==(const Iter& rhs) { return index_ == rhs.index_; }
    bool operator!=(const Iter& rhs) { return !(*this == rhs); }

   private:
    const ProfiledFrameRange& range_;
    uint32_t index_;
  };

  Iter begin() const { return Iter(*this, 0); }
  Iter end() const { return Iter(*this, depth_); }

 private:
  friend JS_PUBLIC_API ProfiledFrameRange GetProfiledFrames(JSContext* cx,
                                                            void* addr);

  ProfiledFrameRange(JSRuntime* rt, void* addr,
                     js::jit::JitcodeGlobalEntry* entry)
      : rt_(rt), addr_(addr), entry_(entry), depth_(0) {}

  JSRuntime* rt_;
  void* addr_;
  js::jit::JitcodeGlobalEntry* entry_;
  // Assume maximum inlining depth is <64
  const char* labels_[64];
  uint32_t depth_;
};

// Returns a range that can be iterated over using C++ ranged for loops.
JS_PUBLIC_API ProfiledFrameRange GetProfiledFrames(JSContext* cx, void* addr);

}  // namespace JS

#endif /* js_ProfilingFrameIterator_h */