MCSymbolMachO.h

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//===- MCSymbolMachO.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 LLVM_MC_MCSYMBOLMACHO_H
#define LLVM_MC_MCSYMBOLMACHO_H
 
#include "llvm/ADT/Twine.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCSymbolTableEntry.h"
 
namespace llvm {
class MCSymbolMachO : public MCSymbol {
  /// We store the value for the 'desc' symbol field in the
  /// lowest 16 bits of the implementation defined flags.
  enum MachOSymbolFlags : uint16_t { // See <mach-o/nlist.h>.
    SF_DescFlagsMask                        = 0xFFFF,
 
    // Reference type flags.
    SF_ReferenceTypeMask                    = 0x0007,
    SF_ReferenceTypeUndefinedNonLazy        = 0x0000,
    SF_ReferenceTypeUndefinedLazy           = 0x0001,
    SF_ReferenceTypeDefined                 = 0x0002,
    SF_ReferenceTypePrivateDefined          = 0x0003,
    SF_ReferenceTypePrivateUndefinedNonLazy = 0x0004,
    SF_ReferenceTypePrivateUndefinedLazy    = 0x0005,
 
    // Other 'desc' flags.
    SF_ThumbFunc                            = 0x0008,
    SF_NoDeadStrip                          = 0x0020,
    SF_WeakReference                        = 0x0040,
    SF_WeakDefinition                       = 0x0080,
    SF_SymbolResolver                       = 0x0100,
    SF_AltEntry                             = 0x0200,
    SF_Cold                                 = 0x0400,
 
    // Common alignment
    SF_CommonAlignmentMask                  = 0xF0FF,
    SF_CommonAlignmentShift                 = 8
  };
 
public:
  MCSymbolMachO(const MCSymbolTableEntry *Name, bool isTemporary)
      : MCSymbol(SymbolKindMachO, Name, isTemporary) {}
 
  bool isPrivateExtern() const { return IsPrivateExtern; }
  void setPrivateExtern(bool Value) { IsPrivateExtern = Value; }
 
  // Reference type methods.
 
  void clearReferenceType() const {
    modifyFlags(0, SF_ReferenceTypeMask);
  }
 
  void setReferenceTypeUndefinedLazy(bool Value) const {
    modifyFlags(Value ? SF_ReferenceTypeUndefinedLazy : 0,
                SF_ReferenceTypeUndefinedLazy);
  }
 
  // Other 'desc' methods.
 
  void setThumbFunc() const {
    modifyFlags(SF_ThumbFunc, SF_ThumbFunc);
  }
 
  bool isNoDeadStrip() const {
    return getFlags() & SF_NoDeadStrip;
  }
  void setNoDeadStrip() const {
    modifyFlags(SF_NoDeadStrip, SF_NoDeadStrip);
  }
 
  bool isWeakReference() const {
    return getFlags() & SF_WeakReference;
  }
  void setWeakReference() const {
    modifyFlags(SF_WeakReference, SF_WeakReference);
  }
 
  bool isWeakDefinition() const {
    return getFlags() & SF_WeakDefinition;
  }
  void setWeakDefinition() const {
    modifyFlags(SF_WeakDefinition, SF_WeakDefinition);
  }
 
  bool isSymbolResolver() const {
    return getFlags() & SF_SymbolResolver;
  }
  void setSymbolResolver() const {
    modifyFlags(SF_SymbolResolver, SF_SymbolResolver);
  }
 
  void setAltEntry() const {
    modifyFlags(SF_AltEntry, SF_AltEntry);
  }
 
  bool isAltEntry() const {
    return getFlags() & SF_AltEntry;
  }
 
  void setCold() const { modifyFlags(SF_Cold, SF_Cold); }
 
  bool isCold() const { return getFlags() & SF_Cold; }
 
  void setDesc(unsigned Value) const {
    assert(Value == (Value & SF_DescFlagsMask) &&
           "Invalid .desc value!");
    setFlags(Value & SF_DescFlagsMask);
  }
 
  // Check whether a particular symbol is visible to the linker and is required
  // in the symbol table, or whether it can be discarded by the assembler. This
  // also effects whether the assembler treats the label as potentially defining
  // a separate atom.
  bool isSymbolLinkerVisible() const {
    // Non-temporary labels should always be visible to the linker.
    if (!isTemporary())
      return true;
 
    return isUsedInReloc();
  }
 
  /// Get the encoded value of the flags as they will be emitted in to
  /// the MachO binary
  uint16_t getEncodedFlags(bool EncodeAsAltEntry) const {
    uint16_t Flags = getFlags();
 
    // Common alignment is packed into the 'desc' bits.
    if (isCommon()) {
      if (MaybeAlign MaybeAlignment = getCommonAlignment()) {
        Align Alignment = *MaybeAlignment;
        unsigned Log2Size = Log2(Alignment);
        if (Log2Size > 15)
          report_fatal_error("invalid 'common' alignment '" +
                                 Twine(Alignment.value()) + "' for '" +
                                 getName() + "'",
                             false);
        Flags = (Flags & SF_CommonAlignmentMask) |
                (Log2Size << SF_CommonAlignmentShift);
      }
    }
 
    if (EncodeAsAltEntry)
      Flags |= SF_AltEntry;
 
    return Flags;
  }
 
  static bool classof(const MCSymbol *S) { return S->isMachO(); }
};
}
 
#endif