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 SectionHeader = 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 = ArrayRef<SectionHeader>{
  34         reinterpret_cast<const SectionHeader *>(c + 1), c->nsects};
  35     for (const SectionHeader &secHead : sectionHeaders) {
  36       StringRef sectname(secHead.sectname,
  37                          strnlen(secHead.sectname, sizeof(secHead.sectname)));
  38       StringRef segname(secHead.segname,
  39                         strnlen(secHead.segname, sizeof(secHead.segname)));
  40       if ((segname == segment_names::data &&
  41            sectname == section_names::objcCatList) ||
  42           (segname == segment_names::text &&
  43            sectname.startswith(section_names::swift))) {
  44         return true;
  45       }
  46     }
  47   }
  48   return false;
  49 }
  50
  51 static bool objectHasObjCSection(MemoryBufferRef mb) {
  52   if (target->wordSize == 8)
  53     return ::objectHasObjCSection<LP64>(mb);
  54   else
  55     return ::objectHasObjCSection<ILP32>(mb);
  56 }
  57
  58 bool macho::hasObjCSection(MemoryBufferRef mb) {
  59   switch (identify_magic(mb.getBuffer())) {
  60   case file_magic::macho_object:
  61     return objectHasObjCSection(mb);
  62   case file_magic::bitcode:
  63     return check(isBitcodeContainingObjCCategory(mb));
  64   default:
  65     return false;
  66   }
  67 }