lld/MachO/ObjC.cpp

   1 //===- ObjC.cpp -----------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "ObjC.h"
  10 #include "InputFiles.h"
  11 #include "InputSection.h"
  12 #include "OutputSegment.h"
  13 #include "Target.h"
  14
  15 #include "llvm/BinaryFormat/MachO.h"
  16 #include "llvm/Bitcode/BitcodeReader.h"
  17
  18 using namespace llvm;
  19 using namespace llvm::MachO;
  20 using namespace lld;
  21 using namespace lld::macho;
  22
  23 template <class LP> static bool objectHasObjCSection(MemoryBufferRef mb) {
  24   using Section = typename LP::section;
  25
  26   auto *hdr =
  27       reinterpret_cast<const typename LP::mach_header *>(mb.getBufferStart());
  28   if (hdr->magic != LP::magic)
  29     return false;
  30
  31   if (const auto *c =
  32           findCommand<typename LP::segment_command>(hdr, LP::segmentLCType)) {
  33     auto sectionHeaders =
  34         ArrayRef<Section>{reinterpret_cast<const Section *>(c + 1), c->nsects};
  35     for (const Section &sec : sectionHeaders) {
  36       StringRef sectname(sec.sectname,
  37                          strnlen(sec.sectname, sizeof(sec.sectname)));
  38       StringRef segname(sec.segname, strnlen(sec.segname, sizeof(sec.segname)));
  39       if ((segname == segment_names::data &&
  40            sectname == section_names::objcCatList) ||
  41           (segname == segment_names::text &&
  42            sectname == section_names::swift)) {
  43         return true;
  44       }
  45     }
  46   }
  47   return false;
  48 }
  49
  50 static bool objectHasObjCSection(MemoryBufferRef mb) {
  51   if (target->wordSize == 8)
  52     return ::objectHasObjCSection<LP64>(mb);
  53   else
  54     return ::objectHasObjCSection<ILP32>(mb);
  55 }
  56
  57 bool macho::hasObjCSection(MemoryBufferRef mb) {
  58   switch (identify_magic(mb.getBuffer())) {
  59   case file_magic::macho_object:
  60     return objectHasObjCSection(mb);
  61   case file_magic::bitcode:
  62     return check(isBitcodeContainingObjCCategory(mb));
  63   default:
  64     return false;
  65   }
  66 }