/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * 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_Safepoints_h
#define jit_Safepoints_h

#include "mozilla/Attributes.h"

#include <stddef.h>
#include <stdint.h>

#include "jit/BitSet.h"
#include "jit/CompactBuffer.h"
#include "jit/RegisterSets.h"

namespace js {
namespace jit {

class CodeLocationLabel;
class IonScript;
class SafepointIndex;
struct SafepointSlotEntry;
class TempAllocator;

class LAllocation;
class LSafepoint;

static const uint32_t INVALID_SAFEPOINT_OFFSET = uint32_t(-1);

class SafepointWriter {
  CompactBufferWriter stream_;
  BitSet frameSlots_;
  BitSet argumentSlots_;

 public:
  explicit SafepointWriter(uint32_t slotCount, uint32_t argumentCount);
  [[nodiscard]] bool init(TempAllocator& alloc);

 private:
  // A safepoint entry is written in the order these functions appear.
  uint32_t startEntry();

  void writeOsiCallPointOffset(uint32_t osiPointOffset);
  void writeGcRegs(LSafepoint* safepoint);
  void writeGcSlots(LSafepoint* safepoint);
  void writeValueSlots(LSafepoint* safepoint);

  void writeSlotsOrElementsSlots(LSafepoint* safepoint);

#ifdef JS_NUNBOX32
  void writeNunboxParts(LSafepoint* safepoint);
#endif

  void endEntry();

 public:
  void encode(LSafepoint* safepoint);

  size_t size() const { return stream_.length(); }
  const uint8_t* buffer() const { return stream_.buffer(); }
  bool oom() const { return stream_.oom(); }
};

class SafepointReader {
  CompactBufferReader stream_;
  uint32_t frameSlots_;
  uint32_t argumentSlots_;
  uint32_t currentSlotChunk_;
  bool currentSlotsAreStack_;
  uint32_t nextSlotChunkNumber_;
  uint32_t osiCallPointOffset_;
  GeneralRegisterSet gcSpills_;
  GeneralRegisterSet valueSpills_;
  GeneralRegisterSet slotsOrElementsSpills_;
  GeneralRegisterSet allGprSpills_;
  FloatRegisterSet allFloatSpills_;
  uint32_t nunboxSlotsRemaining_;
  uint32_t slotsOrElementsSlotsRemaining_;

 private:
  void advanceFromGcRegs();
  void advanceFromGcSlots();
  void advanceFromValueSlots();
  void advanceFromNunboxSlots();
  [[nodiscard]] bool getSlotFromBitmap(SafepointSlotEntry* entry);

 public:
  SafepointReader(IonScript* script, const SafepointIndex* si);

  static CodeLocationLabel InvalidationPatchPoint(IonScript* script,
                                                  const SafepointIndex* si);

  uint32_t osiCallPointOffset() const { return osiCallPointOffset_; }
  LiveGeneralRegisterSet gcSpills() const {
    return LiveGeneralRegisterSet(gcSpills_);
  }
  LiveGeneralRegisterSet slotsOrElementsSpills() const {
    return LiveGeneralRegisterSet(slotsOrElementsSpills_);
  }
  LiveGeneralRegisterSet valueSpills() const {
    return LiveGeneralRegisterSet(valueSpills_);
  }
  LiveGeneralRegisterSet allGprSpills() const {
    return LiveGeneralRegisterSet(allGprSpills_);
  }
  LiveFloatRegisterSet allFloatSpills() const {
    return LiveFloatRegisterSet(allFloatSpills_);
  }
  uint32_t osiReturnPointOffset() const;

  // Returns true if a slot was read, false if there are no more slots.
  [[nodiscard]] bool getGcSlot(SafepointSlotEntry* entry);

  // Returns true if a slot was read, false if there are no more value slots.
  [[nodiscard]] bool getValueSlot(SafepointSlotEntry* entry);

  // Returns true if a nunbox slot was read, false if there are no more
  // nunbox slots.
  [[nodiscard]] bool getNunboxSlot(LAllocation* type, LAllocation* payload);

  // Returns true if a slot was read, false if there are no more slots.
  [[nodiscard]] bool getSlotsOrElementsSlot(SafepointSlotEntry* entry);
};

}  // namespace jit
}  // namespace js

#endif /* jit_Safepoints_h */