llvm/clang/lib/CodeGen/Address.h

//===-- Address.h - An aligned address -------------------------*- 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
//
//===----------------------------------------------------------------------===//
//
// This class provides a simple wrapper for a pair of a pointer and an
// alignment.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CLANG_LIB_CODEGEN_ADDRESS_H
#define LLVM_CLANG_LIB_CODEGEN_ADDRESS_H

#include "CGPointerAuthInfo.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/Type.h"
#include "llvm/ADT/PointerIntPair.h"
#include "llvm/IR/Constants.h"
#include "llvm/Support/MathExtras.h"

namespace clang {
namespace CodeGen {

class Address;
class CGBuilderTy;
class CodeGenFunction;
class CodeGenModule;

// Indicates whether a pointer is known not to be null.
enum KnownNonNull_t { … };

/// An abstract representation of an aligned address. This is designed to be an
/// IR-level abstraction, carrying just the information necessary to perform IR
/// operations on an address like loads and stores.  In particular, it doesn't
/// carry C type information or allow the representation of things like
/// bit-fields; clients working at that level should generally be using
/// `LValue`.
/// The pointer contained in this class is known to be unsigned.
class RawAddress { … };

/// Like RawAddress, an abstract representation of an aligned address, but the
/// pointer contained in this class is possibly signed.
///
/// This is designed to be an IR-level abstraction, carrying just the
/// information necessary to perform IR operations on an address like loads and
/// stores.  In particular, it doesn't carry C type information or allow the
/// representation of things like bit-fields; clients working at that level
/// should generally be using `LValue`.
///
/// An address may be either *raw*, meaning that it's an ordinary machine
/// pointer, or *signed*, meaning that the pointer carries an embedded
/// pointer-authentication signature. Representing signed pointers directly in
/// this abstraction allows the authentication to be delayed as long as possible
/// without forcing IRGen to use totally different code paths for signed and
/// unsigned values or to separately propagate signature information through
/// every API that manipulates addresses. Pointer arithmetic on signed addresses
/// (e.g. drilling down to a struct field) is accumulated into a separate offset
/// which is applied when the address is finally accessed.
class Address { … };

inline RawAddress::RawAddress(Address Addr)
    : … { … }

/// A specialization of Address that requires the address to be an
/// LLVM Constant.
class ConstantAddress : public RawAddress { … };
}

// Present a minimal LLVM-like casting interface.
template <class U> inline U cast(CodeGen::Address addr) { … }
template <class U> inline bool isa(CodeGen::Address addr) { … }

}

#endif