// Copyright 2025 The Abseil Authors

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     https://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#ifndef ABSL_DEBUGGING_INTERNAL_ADDRESSES_H_

#define ABSL_DEBUGGING_INTERNAL_ADDRESSES_H_

#include <stdint.h>

#include "absl/base/config.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace debugging_internal {

// Removes any metadata (tag bits) from the given pointer, converting it into a

// user-readable address.

inline uintptr_t StripPointerMetadata(uintptr_t ptr) {

#if defined(__aarch64__)

  // When PAC-RET (-mbranch-protection=pac-ret) is enabled, return addresses

  // stored on the stack will be signed, which means that pointer bits outside

  // of the virtual address range are potentially set. Since the stacktrace code

  // is expected to return normal code pointers, this function clears those

  // bits.

  register uintptr_t x30 __asm__("x30") = ptr;

  // The normal instruction for clearing PAC bits is XPACI, but for

  // compatibility with ARM platforms that do not support pointer

  // authentication, we use the hint space instruction XPACLRI instead. Hint

  // space instructions behave as NOPs on unsupported platforms.

#define ABSL_XPACLRI_HINT "hint #0x7;"

  asm(ABSL_XPACLRI_HINT : "+r"(x30));  // asm("xpaclri" : "+r"(x30));

#undef ABSL_XPACLRI_HINT

  return x30;

#else

  return ptr;

#endif

}

inline uintptr_t StripPointerMetadata(void* ptr) {

  return StripPointerMetadata(reinterpret_cast<uintptr_t>(ptr));

}

}  // namespace debugging_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_DEBUGGING_INTERNAL_ADDRESSES_H_