--- a/lld/MachO/InputSection.h	Mon May 25 11:55:54 2020 +0900
+++ b/lld/MachO/InputSection.h	Tue Jun 08 06:07:14 2021 +0900
@@ -9,40 +9,28 @@
 #ifndef LLD_MACHO_INPUT_SECTION_H
 #define LLD_MACHO_INPUT_SECTION_H
 
+#include "Config.h"
+#include "Relocations.h"
+
 #include "lld/Common/LLVM.h"
 #include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/PointerUnion.h"
 #include "llvm/BinaryFormat/MachO.h"
 
 namespace lld {
 namespace macho {
 
 class InputFile;
-class InputSection;
 class OutputSection;
-class Symbol;
-
-struct Reloc {
-  uint8_t type;
-  bool pcrel;
-  // The offset from the start of the subsection that this relocation belongs
-  // to.
-  uint32_t offset;
-  // Adding this offset to the address of the target symbol or subsection gives
-  // the destination that this relocation refers to.
-  uint64_t addend;
-  llvm::PointerUnion<Symbol *, InputSection *> target;
-};
 
 class InputSection {
 public:
   virtual ~InputSection() = default;
-  virtual size_t getSize() const { return data.size(); }
-  virtual uint64_t getFileSize() const { return getSize(); }
+  virtual uint64_t getSize() const { return data.size(); }
+  uint64_t getFileSize() const;
   uint64_t getFileOffset() const;
   uint64_t getVA() const;
 
-  virtual void writeTo(uint8_t *buf);
+  void writeTo(uint8_t *buf);
 
   InputFile *file = nullptr;
   StringRef name;
@@ -54,14 +42,111 @@
 
   uint32_t align = 1;
   uint32_t flags = 0;
+  uint32_t callSiteCount = 0;
+  bool isFinal = false; // is address assigned?
+
+  // How many symbols refer to this InputSection.
+  uint32_t numRefs = 0;
+
+  // With subsections_via_symbols, most symbols have their own InputSection,
+  // and for weak symbols (e.g. from inline functions), only the
+  // InputSection from one translation unit will make it to the output,
+  // while all copies in other translation units are coalesced into the
+  // first and not copied to the output.
+  bool wasCoalesced = false;
+
+  bool isCoalescedWeak() const { return wasCoalesced && numRefs == 0; }
+  bool shouldOmitFromOutput() const { return !live || isCoalescedWeak(); }
+
+  bool live = !config->deadStrip;
 
   ArrayRef<uint8_t> data;
   std::vector<Reloc> relocs;
 };
 
+inline uint8_t sectionType(uint32_t flags) {
+  return flags & llvm::MachO::SECTION_TYPE;
+}
+
+inline bool isZeroFill(uint32_t flags) {
+  return llvm::MachO::isVirtualSection(sectionType(flags));
+}
+
+inline bool isThreadLocalVariables(uint32_t flags) {
+  return sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_VARIABLES;
+}
+
+// These sections contain the data for initializing thread-local variables.
+inline bool isThreadLocalData(uint32_t flags) {
+  return sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_REGULAR ||
+         sectionType(flags) == llvm::MachO::S_THREAD_LOCAL_ZEROFILL;
+}
+
+inline bool isDebugSection(uint32_t flags) {
+  return (flags & llvm::MachO::SECTION_ATTRIBUTES_USR) ==
+         llvm::MachO::S_ATTR_DEBUG;
+}
+
+bool isCodeSection(const InputSection *);
+
 extern std::vector<InputSection *> inputSections;
 
+namespace section_names {
+
+constexpr const char authGot[] = "__auth_got";
+constexpr const char authPtr[] = "__auth_ptr";
+constexpr const char binding[] = "__binding";
+constexpr const char bitcodeBundle[] = "__bundle";
+constexpr const char cfString[] = "__cfstring";
+constexpr const char codeSignature[] = "__code_signature";
+constexpr const char common[] = "__common";
+constexpr const char compactUnwind[] = "__compact_unwind";
+constexpr const char data[] = "__data";
+constexpr const char debugAbbrev[] = "__debug_abbrev";
+constexpr const char debugInfo[] = "__debug_info";
+constexpr const char debugStr[] = "__debug_str";
+constexpr const char ehFrame[] = "__eh_frame";
+constexpr const char export_[] = "__export";
+constexpr const char functionStarts[] = "__func_starts";
+constexpr const char got[] = "__got";
+constexpr const char header[] = "__mach_header";
+constexpr const char indirectSymbolTable[] = "__ind_sym_tab";
+constexpr const char const_[] = "__const";
+constexpr const char lazySymbolPtr[] = "__la_symbol_ptr";
+constexpr const char lazyBinding[] = "__lazy_binding";
+constexpr const char moduleInitFunc[] = "__mod_init_func";
+constexpr const char moduleTermFunc[] = "__mod_term_func";
+constexpr const char nonLazySymbolPtr[] = "__nl_symbol_ptr";
+constexpr const char objcCatList[] = "__objc_catlist";
+constexpr const char objcClassList[] = "__objc_classlist";
+constexpr const char objcConst[] = "__objc_const";
+constexpr const char objcImageInfo[] = "__objc_imageinfo";
+constexpr const char objcNonLazyCatList[] = "__objc_nlcatlist";
+constexpr const char objcNonLazyClassList[] = "__objc_nlclslist";
+constexpr const char objcProtoList[] = "__objc_protolist";
+constexpr const char pageZero[] = "__pagezero";
+constexpr const char pointers[] = "__pointers";
+constexpr const char rebase[] = "__rebase";
+constexpr const char staticInit[] = "__StaticInit";
+constexpr const char stringTable[] = "__string_table";
+constexpr const char stubHelper[] = "__stub_helper";
+constexpr const char stubs[] = "__stubs";
+constexpr const char swift[] = "__swift";
+constexpr const char symbolTable[] = "__symbol_table";
+constexpr const char textCoalNt[] = "__textcoal_nt";
+constexpr const char text[] = "__text";
+constexpr const char threadPtrs[] = "__thread_ptrs";
+constexpr const char threadVars[] = "__thread_vars";
+constexpr const char unwindInfo[] = "__unwind_info";
+constexpr const char weakBinding[] = "__weak_binding";
+constexpr const char zeroFill[] = "__zerofill";
+
+} // namespace section_names
+
 } // namespace macho
+
+std::string toString(const macho::InputSection *);
+
 } // namespace lld
 
 #endif