1 files changed, 50 insertions, 1 deletions

diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h
index dd56e72f914..188e2c65243 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldMachOX86_64.h
@@ -39,6 +39,10 @@ public:
       static_cast<const MachOObjectFile &>(BaseObjT);
     MachO::any_relocation_info RelInfo =
         Obj.getRelocation(RelI->getRawDataRefImpl());
+    uint32_t RelType = Obj.getAnyRelocationType(RelInfo);
+
+    if (RelType == MachO::X86_64_RELOC_SUBTRACTOR)
+      return processSubtractRelocation(SectionID, RelI, Obj, ObjSectionToID);
 
     assert(!Obj.isRelocationScattered(RelInfo) &&
            "Scattered relocations not supported on X86_64");
@@ -91,9 +95,17 @@ public:
     case MachO::X86_64_RELOC_BRANCH:
       writeBytesUnaligned(Value + RE.Addend, LocalAddress, 1 << RE.Size);
       break;
+    case MachO::X86_64_RELOC_SUBTRACTOR: {
+      uint64_t SectionABase = Sections[RE.Sections.SectionA].LoadAddress;
+      uint64_t SectionBBase = Sections[RE.Sections.SectionB].LoadAddress;
+      assert((Value == SectionABase || Value == SectionBBase) &&
+             "Unexpected SUBTRACTOR relocation value.");
+      Value = SectionABase - SectionBBase + RE.Addend;
+      writeBytesUnaligned(Value, LocalAddress, 1 << RE.Size);
+      break;
+    }
     case MachO::X86_64_RELOC_GOT_LOAD:
     case MachO::X86_64_RELOC_GOT:
-    case MachO::X86_64_RELOC_SUBTRACTOR:
     case MachO::X86_64_RELOC_TLV:
       Error("Relocation type not implemented yet!");
     }
@@ -130,6 +142,43 @@ private:
                              MachO::X86_64_RELOC_UNSIGNED, RE.Addend, true, 2);
     resolveRelocation(TargetRE, (uint64_t)Addr);
   }
+
+  relocation_iterator
+  processSubtractRelocation(unsigned SectionID, relocation_iterator RelI,
+                            const ObjectFile &BaseObjT,
+                            ObjSectionToIDMap &ObjSectionToID) {
+    const MachOObjectFile &Obj =
+        static_cast<const MachOObjectFile&>(BaseObjT);
+    MachO::any_relocation_info RE =
+        Obj.getRelocation(RelI->getRawDataRefImpl());
+
+    unsigned Size = Obj.getAnyRelocationLength(RE);
+    uint64_t Offset = RelI->getOffset();
+    ErrorOr<StringRef> SubtrahendNameOrErr = RelI->getSymbol()->getName();
+    if (auto EC = SubtrahendNameOrErr.getError())
+      report_fatal_error(EC.message());
+    auto SubtrahendI = GlobalSymbolTable.find(*SubtrahendNameOrErr);
+    unsigned SectionBID = SubtrahendI->second.getSectionID();
+    uint64_t SectionBOffset = SubtrahendI->second.getOffset();
+
+    ++RelI;
+    ErrorOr<StringRef> MinuendNameOrErr = RelI->getSymbol()->getName();
+    if (auto EC = MinuendNameOrErr.getError())
+      report_fatal_error(EC.message());
+    auto MinuendI = GlobalSymbolTable.find(*MinuendNameOrErr);
+    unsigned SectionAID = MinuendI->second.getSectionID();
+    uint64_t SectionAOffset = MinuendI->second.getOffset();
+
+    uint64_t Addend = SectionAOffset - SectionBOffset;
+    RelocationEntry R(SectionID, Offset, MachO::X86_64_RELOC_SUBTRACTOR, Addend,
+                      SectionAID, SectionAOffset, SectionBID, SectionBOffset,
+                      false, Size);
+
+    addRelocationForSection(R, SectionAID);
+
+    return ++RelI;
+  }
+
 };
 }