options.h

//===-- options.h -----------------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef SCUDO_OPTIONS_H_
#define SCUDO_OPTIONS_H_

#include "atomic_helpers.h"
#include "common.h"

namespace scudo {

enum class OptionBit {
  MayReturnNull,
  FillContents0of2,
  FillContents1of2,
  DeallocTypeMismatch,
  DeleteSizeMismatch,
  TrackAllocationStacks,
  UseOddEvenTags,
  UseMemoryTagging,
};

struct Options {
  u32 Val;

  bool get(OptionBit Opt) const { return Val & (1U << static_cast<u32>(Opt)); }

  FillContentsMode getFillContentsMode() const {
    return static_cast<FillContentsMode>(
        (Val >> static_cast<u32>(OptionBit::FillContents0of2)) & 3);
  }
};

struct AtomicOptions {
  atomic_u32 Val;

public:
  Options load() const {
    return Options{atomic_load(&Val, memory_order_relaxed)};
  }

  void clear(OptionBit Opt) {
    atomic_fetch_and(&Val, ~(1U << static_cast<u32>(Opt)),
                     memory_order_relaxed);
  }

  void set(OptionBit Opt) {
    atomic_fetch_or(&Val, 1U << static_cast<u32>(Opt), memory_order_relaxed);
  }

  void setFillContentsMode(FillContentsMode FillContents) {
    while (1) {
      u32 Opts = atomic_load(&Val, memory_order_relaxed);
      u32 NewOpts = Opts;
      NewOpts &= ~(3U << static_cast<u32>(OptionBit::FillContents0of2));
      NewOpts |= static_cast<u32>(FillContents)
                 << static_cast<u32>(OptionBit::FillContents0of2);
      if (atomic_compare_exchange_strong(&Val, &Opts, NewOpts,
                                         memory_order_relaxed))
        break;
    }
  }
};

} // namespace scudo

#endif // SCUDO_OPTIONS_H_