--- a/lld/MachO/InputSection.cpp	Mon May 25 11:55:54 2020 +0900
+++ b/lld/MachO/InputSection.cpp	Tue Jun 08 06:07:14 2021 +0900
@@ -7,12 +7,16 @@
 //===----------------------------------------------------------------------===//
 
 #include "InputSection.h"
+#include "InputFiles.h"
 #include "OutputSegment.h"
 #include "Symbols.h"
+#include "SyntheticSections.h"
 #include "Target.h"
+#include "Writer.h"
 #include "lld/Common/Memory.h"
 #include "llvm/Support/Endian.h"
 
+using namespace llvm;
 using namespace llvm::MachO;
 using namespace llvm::support;
 using namespace lld;
@@ -24,27 +28,86 @@
   return parent->fileOff + outSecFileOff;
 }
 
+uint64_t InputSection::getFileSize() const {
+  return isZeroFill(flags) ? 0 : getSize();
+}
+
 uint64_t InputSection::getVA() const { return parent->addr + outSecOff; }
 
+static uint64_t resolveSymbolVA(const Symbol *sym, uint8_t type) {
+  const RelocAttrs &relocAttrs = target->getRelocAttrs(type);
+  if (relocAttrs.hasAttr(RelocAttrBits::BRANCH))
+    return sym->resolveBranchVA();
+  else if (relocAttrs.hasAttr(RelocAttrBits::GOT))
+    return sym->resolveGotVA();
+  else if (relocAttrs.hasAttr(RelocAttrBits::TLV))
+    return sym->resolveTlvVA();
+  return sym->getVA();
+}
+
 void InputSection::writeTo(uint8_t *buf) {
-  if (!data.empty())
-    memcpy(buf, data.data(), data.size());
+  assert(!shouldOmitFromOutput());
+
+  if (getFileSize() == 0)
+    return;
+
+  memcpy(buf, data.data(), data.size());
 
-  for (Reloc &r : relocs) {
-    uint64_t va = 0;
-    if (auto *s = r.target.dyn_cast<Symbol *>()) {
-      if (auto *dylibSymbol = dyn_cast<DylibSymbol>(s)) {
-        va = target->getDylibSymbolVA(*dylibSymbol, r.type);
-      } else {
-        va = s->getVA();
+  for (size_t i = 0; i < relocs.size(); i++) {
+    const Reloc &r = relocs[i];
+    uint8_t *loc = buf + r.offset;
+    uint64_t referentVA = 0;
+    if (target->hasAttr(r.type, RelocAttrBits::SUBTRAHEND)) {
+      const Symbol *fromSym = r.referent.get<Symbol *>();
+      const Reloc &minuend = relocs[++i];
+      uint64_t minuendVA;
+      if (const Symbol *toSym = minuend.referent.dyn_cast<Symbol *>())
+        minuendVA = toSym->getVA();
+      else {
+        auto *referentIsec = minuend.referent.get<InputSection *>();
+        assert(!referentIsec->shouldOmitFromOutput());
+        minuendVA = referentIsec->getVA();
       }
-    } else if (auto *isec = r.target.dyn_cast<InputSection *>()) {
-      va = isec->getVA();
-    }
+      referentVA = minuendVA - fromSym->getVA() + minuend.addend;
+    } else if (auto *referentSym = r.referent.dyn_cast<Symbol *>()) {
+      if (target->hasAttr(r.type, RelocAttrBits::LOAD) &&
+          !referentSym->isInGot())
+        target->relaxGotLoad(loc, r.type);
+      referentVA = resolveSymbolVA(referentSym, r.type);
 
-    uint64_t val = va + r.addend;
-    if (r.pcrel)
-      val -= getVA() + r.offset;
-    target->relocateOne(buf + r.offset, r.type, val);
+      if (isThreadLocalVariables(flags)) {
+        // References from thread-local variable sections are treated as offsets
+        // relative to the start of the thread-local data memory area, which
+        // is initialized via copying all the TLV data sections (which are all
+        // contiguous).
+        if (isa<Defined>(referentSym))
+          referentVA -= firstTLVDataSection->addr;
+      }
+    } else if (auto *referentIsec = r.referent.dyn_cast<InputSection *>()) {
+      assert(!referentIsec->shouldOmitFromOutput());
+      referentVA = referentIsec->getVA();
+    }
+    target->relocateOne(loc, r, referentVA + r.addend, getVA() + r.offset);
   }
 }
+
+bool macho::isCodeSection(const InputSection *isec) {
+  uint32_t type = isec->flags & SECTION_TYPE;
+  if (type != S_REGULAR && type != S_COALESCED)
+    return false;
+
+  uint32_t attr = isec->flags & SECTION_ATTRIBUTES_USR;
+  if (attr == S_ATTR_PURE_INSTRUCTIONS)
+    return true;
+
+  if (isec->segname == segment_names::text)
+    return StringSwitch<bool>(isec->name)
+        .Cases(section_names::textCoalNt, section_names::staticInit, true)
+        .Default(false);
+
+  return false;
+}
+
+std::string lld::toString(const InputSection *isec) {
+  return (toString(isec->file) + ":(" + isec->name + ")").str();
+}