js/public/ProfilingFrameIterator.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=8 sts=4 et sw=4 tw=99:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef js_ProfilingFrameIterator_h
   8 #define js_ProfilingFrameIterator_h
   9
  10 #include "mozilla/Alignment.h"
  11
  12 #include <stdint.h>
  13
  14 #include "js/Utility.h"
  15
  16 class JSAtom;
  17 struct JSRuntime;
  18
  19 namespace js {
  20     class Activation;
  21     class AsmJSProfilingFrameIterator;
  22 }
  23
  24 namespace JS {
  25
  26 // This iterator can be used to walk the stack of a thread suspended at an
  27 // arbitrary pc. To provide acurate results, profiling must have been enabled
  28 // (via EnableRuntimeProfilingStack) before executing the callstack being
  29 // unwound.
  30 class JS_PUBLIC_API(ProfilingFrameIterator)
  31 {
  32     js::Activation* activation_;
  33
  34     static const unsigned StorageSpace = 6 * sizeof(void*);
  35     mozilla::AlignedStorage<StorageSpace> storage_;
  36     js::AsmJSProfilingFrameIterator& asmJSIter() {
  37         MOZ_ASSERT(!done());
  38         return *reinterpret_cast<js::AsmJSProfilingFrameIterator*>(storage_.addr());
  39     }
  40     const js::AsmJSProfilingFrameIterator& asmJSIter() const {
  41         MOZ_ASSERT(!done());
  42         return *reinterpret_cast<const js::AsmJSProfilingFrameIterator*>(storage_.addr());
  43     }
  44
  45     void settle();
  46
  47   public:
  48     struct RegisterState
  49     {
  50         RegisterState() : pc(nullptr), sp(nullptr), lr(nullptr) {}
  51         void* pc;
  52         void* sp;
  53         void* lr;
  54     };
  55
  56     ProfilingFrameIterator(JSRuntime* rt, const RegisterState& state);
  57     ~ProfilingFrameIterator();
  58     void operator++();
  59     bool done() const { return !activation_; }
  60
  61     // Assuming the stack grows down (we do), the return value:
  62     //  - always points into the stack
  63     //  - is weakly monotonically increasing (may be equal for successive frames)
  64     //  - will compare greater than newer native and psuedo-stack frame addresses
  65     //    and less than older native and psuedo-stack frame addresses
  66     void* stackAddress() const;
  67
  68     // Return a label suitable for regexp-matching as performed by
  69     // browser/devtools/profiler/cleopatra/js/parserWorker.js
  70     const char* label() const;
  71
  72   private:
  73     void iteratorConstruct(const RegisterState& state);
  74     void iteratorConstruct();
  75     void iteratorDestroy();
  76     bool iteratorDone();
  77 };
  78
  79 } // namespace JS
  80
  81 #endif  /* js_ProfilingFrameIterator_h */