/* -*- 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 jit_BaselineDebugModeOSR_h
#define jit_BaselineDebugModeOSR_h

#include "jit/BaselineFrame.h"
#include "jit/BaselineIC.h"
#include "jit/BaselineJIT.h"
#include "jit/JSJitFrameIter.h"

#include "vm/Debugger.h"

namespace js {
namespace jit {

// Note that this file and the corresponding .cpp implement debug mode
// on-stack recompilation. This is to be distinguished from ordinary
// Baseline->Ion OSR, which is used to jump into compiled loops.

//
// A volatile location due to recompilation of an on-stack baseline script
// (e.g., for debug mode toggling).
//
// It is usually used in fallback stubs which may trigger on-stack
// recompilation by calling out into the VM. Example use:
//
//     DebugModeOSRVolatileStub<FallbackStubT*> stub(frame, stub_)
//
//     // Call out to the VM
//     // Other effectful operations like TypeScript::Monitor
//
//     if (stub.invalid())
//         return true;
//
//     // First use of stub after VM call.
//
template <typename T>
class DebugModeOSRVolatileStub {
  ICStubCompiler::Engine engine_;
  T stub_;
  BaselineFrame* frame_;
  uint32_t pcOffset_;

 public:
  DebugModeOSRVolatileStub(ICStubCompiler::Engine engine, BaselineFrame* frame,
                           ICFallbackStub* stub)
      : engine_(engine),
        stub_(static_cast<T>(stub)),
        frame_(frame),
        pcOffset_(stub->icEntry()->pcOffset()) {}

  DebugModeOSRVolatileStub(BaselineFrame* frame, ICFallbackStub* stub)
      : engine_(ICStubCompiler::Engine::Baseline),
        stub_(static_cast<T>(stub)),
        frame_(frame),
        pcOffset_(stub->icEntry()->pcOffset()) {}

  bool invalid() const {
    if (engine_ == ICStubCompiler::Engine::IonSharedIC) return stub_->invalid();
    MOZ_ASSERT(!frame_->isHandlingException());
    ICEntry& entry =
        frame_->script()->baselineScript()->icEntryFromPCOffset(pcOffset_);
    return stub_ != entry.fallbackStub();
  }

  operator const T&() const {
    MOZ_ASSERT(!invalid());
    return stub_;
  }
  T operator->() const {
    MOZ_ASSERT(!invalid());
    return stub_;
  }
  T* address() {
    MOZ_ASSERT(!invalid());
    return &stub_;
  }
  const T* address() const {
    MOZ_ASSERT(!invalid());
    return &stub_;
  }
  T& get() {
    MOZ_ASSERT(!invalid());
    return stub_;
  }
  const T& get() const {
    MOZ_ASSERT(!invalid());
    return stub_;
  }

  bool operator!=(const T& other) const {
    MOZ_ASSERT(!invalid());
    return stub_ != other;
  }
  bool operator==(const T& other) const {
    MOZ_ASSERT(!invalid());
    return stub_ == other;
  }
};

//
// A JitFrameIter that updates internal JSJitFrameIter in case of
// recompilation of an on-stack baseline script.
//

class DebugModeOSRVolatileJitFrameIter : public JitFrameIter {
  DebugModeOSRVolatileJitFrameIter** stack;
  DebugModeOSRVolatileJitFrameIter* prev;

 public:
  explicit DebugModeOSRVolatileJitFrameIter(JSContext* cx)
      : JitFrameIter(cx->activation()->asJit(),
                     /* mustUnwindActivation */ true) {
    stack = &cx->liveVolatileJitFrameIter_.ref();
    prev = *stack;
    *stack = this;
  }

  ~DebugModeOSRVolatileJitFrameIter() {
    MOZ_ASSERT(*stack == this);
    *stack = prev;
  }

  static void forwardLiveIterators(const CooperatingContext& target,
                                   uint8_t* oldAddr, uint8_t* newAddr);
};

//
// Auxiliary info to help the DebugModeOSRHandler fix up state.
//
struct BaselineDebugModeOSRInfo {
  uint8_t* resumeAddr;
  jsbytecode* pc;
  PCMappingSlotInfo slotInfo;
  ICEntry::Kind frameKind;

  // Filled in by SyncBaselineDebugModeOSRInfo.
  uintptr_t stackAdjust;
  Value valueR0;
  Value valueR1;

  BaselineDebugModeOSRInfo(jsbytecode* pc, ICEntry::Kind kind)
      : resumeAddr(nullptr),
        pc(pc),
        slotInfo(0),
        frameKind(kind),
        stackAdjust(0),
        valueR0(UndefinedValue()),
        valueR1(UndefinedValue()) {}

  void popValueInto(PCMappingSlotInfo::SlotLocation loc, Value* vp);
};

MOZ_MUST_USE bool RecompileOnStackBaselineScriptsForDebugMode(
    JSContext* cx, const Debugger::ExecutionObservableSet& obs,
    Debugger::IsObserving observing);

}  // namespace jit
}  // namespace js

#endif  // jit_BaselineDebugModeOSR_h
