[WebAssembly] MC: Refactor relocation handling

[sbc100]

Summary

The change cleans up and unifies the handling of relocation
entries in WasmObjectWriter. Type index relocation are no
longer handled seperately.

The only exteranlly visible change should be that type
index relocations are not longer grouped at the end.

[sbc100]

Add reset method

[sbc100]

• remove newline

[jgravelle-google]

Overall looks reasonable to me? Take that for what it's worth.

lib/MC/WasmObjectWriter.cpp

515

Why drop the assert message?

[sbc100]

• create hasAddend

lib/MC/WasmObjectWriter.cpp

515

It was not accurate. I could update it but it pretty self explanatory already, and not something that a random dev or user would ever see. In fact it ended being more clear to create a method this this. What do you think?

[jgravelle-google]

lib/MC/WasmObjectWriter.cpp

515

Oo that is clearer, nice.

[sbc100]

@sunfish could you take a quick look?

[sunfish]

Sounds good.

lib/MC/WasmObjectWriter.cpp

class WasmObjectWriter : public MCObjectWriter {
   std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter;
 
   // Relocations for fixing up references in the code section.
   std::vector<WasmRelocationEntry> CodeRelocations;
 
   // Relocations for fixing up references in the data section.
   std::vector<WasmRelocationEntry> DataRelocations;
 
-  // Fixups for call_indirect type indices.
-  std::vector<WasmRelocationEntry> TypeIndexFixups;
-
   // Index values to use for fixing up call_indirect type indices.
-  std::vector<uint32_t> TypeIndexFixupTypes;
+  // Maps function symbols to the index of the type of the function
+  DenseMap<const MCSymbolWasm *, uint32_t> TypeIndices;
+
+  DenseMap<const MCSymbolWasm *, uint32_t> SymbolIndices;
+
+  DenseMap<WasmFunctionType, int32_t, WasmFunctionTypeDenseMapInfo>
+      FunctionTypeIndices;
 
   // TargetObjectWriter wrappers.
   bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
   unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
                         const MCFixup &Fixup, bool IsPCRel) const {
     return TargetObjectWriter->getRelocType(Ctx, Target, Fixup, IsPCRel);
   }
 
   void startSection(SectionBookkeeping &Section, unsigned SectionId,
                     const char *Name = nullptr);
   void endSection(SectionBookkeeping &Section);
 
 public:
   WasmObjectWriter(MCWasmObjectTargetWriter *MOTW, raw_pwrite_stream &OS)
       : MCObjectWriter(OS, /*IsLittleEndian=*/true), TargetObjectWriter(MOTW) {}
 
 private:
   ~WasmObjectWriter() override;
 
+  void reset() override {
+    CodeRelocations.clear();
+    DataRelocations.clear();
+    TypeIndices.clear();
+    SymbolIndices.clear();
+    FunctionTypeIndices.clear();
+    MCObjectWriter::reset();
+  }
+
   void writeHeader(const MCAssembler &Asm);
 
   void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
                         const MCFragment *Fragment, const MCFixup &Fixup,
                         MCValue Target, bool &IsPCRel,
                         uint64_t &FixedValue) override;
 
   void executePostLayoutBinding(MCAssembler &Asm,
private:
   void writeImportSection(const SmallVector<WasmImport, 4> &Imports);
   void writeFunctionSection(const SmallVector<WasmFunction, 4> &Functions);
   void writeTableSection(const SmallVector<uint32_t, 4> &TableElems);
   void writeMemorySection(const SmallVector<char, 0> &DataBytes);
   void writeGlobalSection(const SmallVector<WasmGlobal, 4> &Globals);
   void writeExportSection(const SmallVector<WasmExport, 4> &Exports);
   void writeElemSection(const SmallVector<uint32_t, 4> &TableElems);
   void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
-                        DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices,
                         const SmallVector<WasmFunction, 4> &Functions);
   uint64_t
-  writeDataSection(const SmallVector<char, 0> &DataBytes,
-                   DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices);
+  writeDataSection(const SmallVector<char, 0> &DataBytes);
   void writeNameSection(const SmallVector<WasmFunction, 4> &Functions,
                         const SmallVector<WasmImport, 4> &Imports,
                         uint32_t NumFuncImports);
-  void writeCodeRelocSection(
-      DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices);
-  void writeDataRelocSection(
-      DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices,
-      uint64_t DataSectionHeaderSize);
+  void writeCodeRelocSection();
+  void writeDataRelocSection(uint64_t DataSectionHeaderSize);
   void writeLinkingMetaDataSection(bool HasStackPointer,
                                    uint32_t StackPointerGlobal);
+
+  void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
+                        uint64_t ContentsOffset);
+
+  void writeRelocations(ArrayRef<WasmRelocationEntry> Relocations,
+                        uint64_t HeaderSize);
+  uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry);
 };
 
 } // end anonymous namespace
 
 WasmObjectWriter::~WasmObjectWriter() {}
 
 // Return the padding size to write a 32-bit value into a 5-byte ULEB128.
 static unsigned PaddingFor5ByteULEB128(uint32_t X) {
void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
 
   if (SymA) {
     if (ViaWeakRef)
       llvm_unreachable("weakref used in reloc not yet implemented");
     else
       SymA->setUsedInReloc();
   }
 
-  if (RefA) {
-    if (RefA->getKind() == MCSymbolRefExpr::VK_WebAssembly_TYPEINDEX) {
-      assert(C == 0);
-      WasmRelocationEntry Rec(FixupOffset, SymA, C,
-                              wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB,
-                              &FixupSection);
-      TypeIndexFixups.push_back(Rec);
-      return;
-    }
-  }
-
   unsigned Type = getRelocType(Ctx, Target, Fixup, IsPCRel);
-
   WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection);
 
   if (FixupSection.hasInstructions())
     CodeRelocations.push_back(Rec);
   else
     DataRelocations.push_back(Rec);
 }
 
static uint32_t ProvisionalValue(const WasmRelocationEntry &RelEntry) {
   uint64_t Address = Section.getSectionOffset() + RelEntry.Addend;
 
   // Ignore overflow. LLVM allows address arithmetic to silently wrap.
   uint32_t Value = Address;
 
   return Value;
 }
 
+uint32_t WasmObjectWriter::getRelocationIndexValue(
+    const WasmRelocationEntry &RelEntry) {
+  switch (RelEntry.Type) {
+  case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
+  case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
+  case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB:
+  case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB:
+  case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32:
+    assert(SymbolIndices.count(RelEntry.Symbol));
+    return SymbolIndices[RelEntry.Symbol];
+  case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
+    assert(TypeIndices.count(RelEntry.Symbol));
+    return TypeIndices[RelEntry.Symbol];
+  default:
+    llvm_unreachable("invalid relocation type");
+  }
+}
+
+
 // Apply the portions of the relocation records that we can handle ourselves
 // directly.
-static void ApplyRelocations(
-    ArrayRef<WasmRelocationEntry> Relocations,
-    raw_pwrite_stream &Stream,
-    DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices,
-    uint64_t ContentsOffset)
-{
+void WasmObjectWriter::applyRelocations(
+    ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset) {
+  raw_pwrite_stream &Stream = getStream();
   for (const WasmRelocationEntry &RelEntry : Relocations) {
     uint64_t Offset = ContentsOffset +
                       RelEntry.FixupSection->getSectionOffset() +
                       RelEntry.Offset;
-    switch (RelEntry.Type) {
-    case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB: {
-      assert(SymbolIndices.count(RelEntry.Symbol));
-      uint32_t Index = SymbolIndices[RelEntry.Symbol];
-      assert(RelEntry.Addend == 0);
-
-      WritePatchableLEB(Stream, Index, Offset);
-      break;
-    }
-    case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB: {
-      assert(SymbolIndices.count(RelEntry.Symbol));
-      uint32_t Index = SymbolIndices[RelEntry.Symbol];
-      assert(RelEntry.Addend == 0);
 
+    switch (RelEntry.Type) {
+    case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
+    case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
+    case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB: {
+      uint32_t Index = getRelocationIndexValue(RelEntry);
       WritePatchableSLEB(Stream, Index, Offset);
       break;
     }
     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB: {
       uint32_t Value = ProvisionalValue(RelEntry);
-
       WritePatchableSLEB(Stream, Value, Offset);
       break;
     }
     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB: {
       uint32_t Value = ProvisionalValue(RelEntry);
-
       WritePatchableLEB(Stream, Value, Offset);
       break;
     }
     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32: {
-      assert(SymbolIndices.count(RelEntry.Symbol));
-      uint32_t Index = SymbolIndices[RelEntry.Symbol];
-      assert(RelEntry.Addend == 0);
-
+      uint32_t Index = getRelocationIndexValue(RelEntry);
       WriteI32(Stream, Index, Offset);
       break;
     }
     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32: {
       uint32_t Value = ProvisionalValue(RelEntry);
-
       WriteI32(Stream, Value, Offset);
       break;
     }
     default:
-      break;
+      llvm_unreachable("unsupported relocation type");
     }
   }
 }
 
 // Write out the portions of the relocation records that the linker will
 // need to handle.
-static void
-WriteRelocations(ArrayRef<WasmRelocationEntry> Relocations,
-                 raw_pwrite_stream &Stream,
-                 DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices,
-                 uint64_t HeaderSize) {
-  for (const WasmRelocationEntry RelEntry : Relocations) {
-    encodeULEB128(RelEntry.Type, Stream);
+void WasmObjectWriter::writeRelocations(
+    ArrayRef<WasmRelocationEntry> Relocations, uint64_t HeaderSize) {
+  raw_pwrite_stream &Stream = getStream();
+  for (const WasmRelocationEntry& RelEntry : Relocations) {
 
     uint64_t Offset = RelEntry.Offset +
                       RelEntry.FixupSection->getSectionOffset() + HeaderSize;
-    assert(SymbolIndices.count(RelEntry.Symbol));
-    uint32_t Index = SymbolIndices[RelEntry.Symbol];
-    int64_t Addend = RelEntry.Addend;
+    uint32_t Index = getRelocationIndexValue(RelEntry);
+
+    encodeULEB128(RelEntry.Type, Stream);
+    encodeULEB128(Offset, Stream);
+    encodeULEB128(Index, Stream);
 
     switch (RelEntry.Type) {
     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
-      encodeULEB128(Offset, Stream);
-      encodeULEB128(Index, Stream);
-      assert(Addend == 0 && "addends not supported for functions");
+    case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
+      assert(RelEntry.Addend == 0);
       break;
     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB:
     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB:
     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32:
-      encodeULEB128(Offset, Stream);
-      encodeULEB128(Index, Stream);
-      encodeSLEB128(Addend, Stream);
+      encodeSLEB128(RelEntry.Addend, Stream);
       break;
     default:
       llvm_unreachable("unsupported relocation type");
     }
   }
 }
 
-// Write out the the type relocation records that the linker will
-// need to handle.
-static void WriteTypeRelocations(
-    ArrayRef<WasmRelocationEntry> TypeIndexFixups,
-    ArrayRef<uint32_t> TypeIndexFixupTypes,
-    raw_pwrite_stream &Stream)
-{
-  for (size_t i = 0, e = TypeIndexFixups.size(); i < e; ++i) {
-    const WasmRelocationEntry &Fixup = TypeIndexFixups[i];
-    uint32_t Type = TypeIndexFixupTypes[i];
-
-    assert(Fixup.Type == wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB);
-    assert(Fixup.Addend == 0);
-
-    uint64_t Offset = Fixup.Offset +
-                      Fixup.FixupSection->getSectionOffset();
-
-    encodeULEB128(Fixup.Type, Stream);
-    encodeULEB128(Offset, Stream);
-    encodeULEB128(Type, Stream);
-  }
-}
-
 void WasmObjectWriter::writeTypeSection(
     const SmallVector<WasmFunctionType, 4> &FunctionTypes) {
   if (FunctionTypes.empty())
     return;
 
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_TYPE);
 
void WasmObjectWriter::writeElemSection(
   for (uint32_t Elem : TableElems)
     encodeULEB128(Elem, getStream());
 
   endSection(Section);
 }
 
 void WasmObjectWriter::writeCodeSection(
     const MCAssembler &Asm, const MCAsmLayout &Layout,
-    DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices,
     const SmallVector<WasmFunction, 4> &Functions) {
   if (Functions.empty())
     return;
 
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_CODE);
 
   encodeULEB128(Functions.size(), getStream());
for (const WasmFunction &Func : Functions) {
     encodeULEB128(Size, getStream());
 
     FuncSection.setSectionOffset(getStream().tell() -
                                  Section.ContentsOffset);
 
     Asm.writeSectionData(&FuncSection, Layout);
   }
 
-  // Apply the type index fixups for call_indirect etc. instructions.
-  for (size_t i = 0, e = TypeIndexFixups.size(); i < e; ++i) {
-    uint32_t Type = TypeIndexFixupTypes[i];
-    unsigned Padding = PaddingFor5ByteULEB128(Type);
-
-    const WasmRelocationEntry &Fixup = TypeIndexFixups[i];
-    assert(Fixup.Addend == 0);
-    assert(Fixup.Type == wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB);
-    uint64_t Offset = Fixup.Offset +
-                      Fixup.FixupSection->getSectionOffset();
-
-    uint8_t Buffer[16];
-    unsigned SizeLen = encodeULEB128(Type, Buffer, Padding);
-    assert(SizeLen == 5);
-    getStream().pwrite((char *)Buffer, SizeLen,
-                       Section.ContentsOffset + Offset);
-  }
-
   // Apply fixups.
-  ApplyRelocations(CodeRelocations, getStream(), SymbolIndices,
-                   Section.ContentsOffset);
+  applyRelocations(CodeRelocations, Section.ContentsOffset);
 
   endSection(Section);
 }
 
 uint64_t WasmObjectWriter::writeDataSection(
-    const SmallVector<char, 0> &DataBytes,
-    DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices) {
+    const SmallVector<char, 0> &DataBytes) {
   if (DataBytes.empty())
     return 0;
 
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_DATA);
 
   encodeULEB128(1, getStream()); // count
   encodeULEB128(0, getStream()); // memory index
   write8(wasm::WASM_OPCODE_I32_CONST);
   encodeSLEB128(0, getStream()); // offset
   write8(wasm::WASM_OPCODE_END);
   encodeULEB128(DataBytes.size(), getStream()); // size
   uint32_t HeaderSize = getStream().tell() - Section.ContentsOffset;
   writeBytes(DataBytes); // data
 
   // Apply fixups.
-  ApplyRelocations(DataRelocations, getStream(), SymbolIndices,
-                   Section.ContentsOffset + HeaderSize);
+  applyRelocations(DataRelocations, Section.ContentsOffset + HeaderSize);
 
   endSection(Section);
   return HeaderSize;
 }
 
 void WasmObjectWriter::writeNameSection(
     const SmallVector<WasmFunction, 4> &Functions,
     const SmallVector<WasmImport, 4> &Imports,
for (const WasmFunction &Func : Functions) {
     writeBytes(Func.Sym->getName());
     ++Index;
   }
 
   endSection(SubSection);
   endSection(Section);
 }
 
-void WasmObjectWriter::writeCodeRelocSection(
-    DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices) {
+void WasmObjectWriter::writeCodeRelocSection() {
   // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
   // for descriptions of the reloc sections.
 
   if (CodeRelocations.empty())
     return;
 
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.CODE");
 
   encodeULEB128(wasm::WASM_SEC_CODE, getStream());
-  encodeULEB128(CodeRelocations.size() + TypeIndexFixups.size(), getStream());
+  encodeULEB128(CodeRelocations.size(), getStream());
 
-  WriteRelocations(CodeRelocations, getStream(), SymbolIndices, 0);
-  WriteTypeRelocations(TypeIndexFixups, TypeIndexFixupTypes, getStream());
+  writeRelocations(CodeRelocations, 0);
 
   endSection(Section);
 }
 
-void WasmObjectWriter::writeDataRelocSection(
-    DenseMap<const MCSymbolWasm *, uint32_t> &SymbolIndices,
-    uint64_t DataSectionHeaderSize) {
+void WasmObjectWriter::writeDataRelocSection(uint64_t DataSectionHeaderSize) {
   // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
   // for descriptions of the reloc sections.
 
   if (DataRelocations.empty())
     return;
 
   SectionBookkeeping Section;
   startSection(Section, wasm::WASM_SEC_CUSTOM, "reloc.DATA");
 
   encodeULEB128(wasm::WASM_SEC_DATA, getStream());
   encodeULEB128(DataRelocations.size(), getStream());
 
-  WriteRelocations(DataRelocations, getStream(), SymbolIndices,
-                   DataSectionHeaderSize);
+  writeRelocations(DataRelocations, DataSectionHeaderSize);
 
   endSection(Section);
 }
 
 void WasmObjectWriter::writeLinkingMetaDataSection(
     bool HasStackPointer, uint32_t StackPointerGlobal) {
   if (!HasStackPointer)
     return;

 }
 
 void WasmObjectWriter::writeObject(MCAssembler &Asm,
                                    const MCAsmLayout &Layout) {
   MCContext &Ctx = Asm.getContext();
   wasm::ValType PtrType = is64Bit() ? wasm::ValType::I64 : wasm::ValType::I32;
 
   // Collect information from the available symbols.
-  DenseMap<WasmFunctionType, int32_t, WasmFunctionTypeDenseMapInfo>
-      FunctionTypeIndices;
   SmallVector<WasmFunctionType, 4> FunctionTypes;
   SmallVector<WasmFunction, 4> Functions;
   SmallVector<uint32_t, 4> TableElems;
   SmallVector<WasmGlobal, 4> Globals;
   SmallVector<WasmImport, 4> Imports;
   SmallVector<WasmExport, 4> Exports;
-  DenseMap<const MCSymbolWasm *, uint32_t> SymbolIndices;
   SmallPtrSet<const MCSymbolWasm *, 4> IsAddressTaken;
   unsigned NumFuncImports = 0;
   unsigned NumGlobalImports = 0;
   SmallVector<char, 0> DataBytes;
   uint32_t StackPointerGlobal = 0;
   bool HasStackPointer = false;
 
   // Populate the IsAddressTaken set.
if (WS.isExternal()) {
       else
         Export.Kind = wasm::WASM_EXTERNAL_GLOBAL;
 
       Exports.push_back(Export);
     }
   }
 
   // Add types for indirect function calls.
-  for (const WasmRelocationEntry &Fixup : TypeIndexFixups) {
-    assert(Fixup.Addend == 0);
-    assert(Fixup.Type == wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB);
+  for (const WasmRelocationEntry &Fixup : CodeRelocations) {
+    if (Fixup.Type != wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB)
+      continue;
 
     WasmFunctionType F;
     F.Returns = Fixup.Symbol->getReturns();
     F.Params = Fixup.Symbol->getParams();
     auto Pair =
         FunctionTypeIndices.insert(std::make_pair(F, FunctionTypes.size()));
     if (Pair.second)
       FunctionTypes.push_back(F);
 
-    TypeIndexFixupTypes.push_back(Pair.first->second);
+    TypeIndices[Fixup.Symbol] = Pair.first->second;
   }
 
   // Write out the Wasm header.
   writeHeader(Asm);
 
   writeTypeSection(FunctionTypes);
   writeImportSection(Imports);
   writeFunctionSection(Functions);
   writeTableSection(TableElems);
   writeMemorySection(DataBytes);
   writeGlobalSection(Globals);
   writeExportSection(Exports);
   // TODO: Start Section
   writeElemSection(TableElems);
-  writeCodeSection(Asm, Layout, SymbolIndices, Functions);
-  uint64_t DataSectionHeaderSize = writeDataSection(DataBytes, SymbolIndices);
+  writeCodeSection(Asm, Layout, Functions);
+  uint64_t DataSectionHeaderSize = writeDataSection(DataBytes);
   writeNameSection(Functions, Imports, NumFuncImports);
-  writeCodeRelocSection(SymbolIndices);
-  writeDataRelocSection(SymbolIndices, DataSectionHeaderSize);
+  writeCodeRelocSection();
+  writeDataRelocSection(DataSectionHeaderSize);
   writeLinkingMetaDataSection(HasStackPointer, StackPointerGlobal);
 
   // TODO: Translate the .comment section to the output.
   // TODO: Translate debug sections to the output.
 }
 
 MCObjectWriter *llvm::createWasmObjectWriter(MCWasmObjectTargetWriter *MOTW,
                                              raw_pwrite_stream &OS) {
   return new WasmObjectWriter(MOTW, OS);
 }

lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp

static bool IsFunctionExpr(const MCExpr *Expr) {
 
   if (const MCUnaryExpr *UnOp =
           dyn_cast<MCUnaryExpr>(Expr))
     return IsFunctionExpr(UnOp->getSubExpr());
 
   return false;
 }
 
+static bool IsFunctionType(const MCValue &Target) {
+  const MCSymbolRefExpr *RefA = Target.getSymA();
+  return RefA && RefA->getKind() == MCSymbolRefExpr::VK_WebAssembly_TYPEINDEX;
+}
+
 unsigned WebAssemblyWasmObjectWriter::getRelocType(MCContext &Ctx,
                                                    const MCValue &Target,
                                                    const MCFixup &Fixup,
                                                    bool IsPCRel) const {
   // WebAssembly functions are not allocated in the data address space. To
   // resolve a pointer to a function, we must use a special relocation type.
   bool IsFunction = IsFunctionExpr(Fixup.getValue());
 
   assert(!IsPCRel);
   switch (unsigned(Fixup.getKind())) {
   case WebAssembly::fixup_code_sleb128_i32:
     if (IsFunction)
       return wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB;
     return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB;
   case WebAssembly::fixup_code_sleb128_i64:
     llvm_unreachable("fixup_sleb128_i64 not implemented yet");
   case WebAssembly::fixup_code_uleb128_i32:
+    if (IsFunctionType(Target))
+      return wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB;
     if (IsFunction)
       return wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB;
     return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB;
   case FK_Data_4:
     if (IsFunction)
       return wasm::R_WEBASSEMBLY_TABLE_INDEX_I32;
     return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32;
   case FK_Data_8:

test/MC/WebAssembly/reloc-code.ll

 ; CHECK-NEXT:     }
 ; CHECK-NEXT:     Relocation {
 ; CHECK-NEXT:       Type: R_WEBASSEMBLY_GLOBAL_ADDR_LEB (3)
 ; CHECK-NEXT:       Offset: 0x14
 ; CHECK-NEXT:       Index: 0x1
 ; CHECK-NEXT:       Addend: 0
 ; CHECK-NEXT:     }
 ; CHECK-NEXT:     Relocation {
-; CHECK-NEXT:       Type: R_WEBASSEMBLY_FUNCTION_INDEX_LEB (0)
-; CHECK-NEXT:       Offset: 0x2D
-; CHECK-NEXT:       Index: 0x0
-; CHECK-NEXT:     }
-; CHECK-NEXT:     Relocation {
-; CHECK-NEXT:       Type: R_WEBASSEMBLY_FUNCTION_INDEX_LEB (0)
-; CHECK-NEXT:       Offset: 0x34
-; CHECK-NEXT:       Index: 0x1
-; CHECK-NEXT:     }
-; CHECK-NEXT:     Relocation {
 ; CHECK-NEXT:       Type: R_WEBASSEMBLY_TYPE_INDEX_LEB (6)
 ; CHECK-NEXT:       Offset: 0x1A
 ; CHECK-NEXT:       Index: 0x1
 ; CHECK-NEXT:     }
 ; CHECK-NEXT:     Relocation {
 ; CHECK-NEXT:       Type: R_WEBASSEMBLY_TYPE_INDEX_LEB (6)
 ; CHECK-NEXT:       Offset: 0x24
 ; CHECK-NEXT:       Index: 0x0
 ; CHECK-NEXT:     }
+; CHECK-NEXT:     Relocation {
+; CHECK-NEXT:       Type: R_WEBASSEMBLY_FUNCTION_INDEX_LEB (0)
+; CHECK-NEXT:       Offset: 0x2D
+; CHECK-NEXT:       Index: 0x0
+; CHECK-NEXT:     }
+; CHECK-NEXT:     Relocation {
+; CHECK-NEXT:       Type: R_WEBASSEMBLY_FUNCTION_INDEX_LEB (0)
+; CHECK-NEXT:       Offset: 0x34
+; CHECK-NEXT:       Index: 0x1
+; CHECK-NEXT:     }
 ; CHECK-NEXT:   }
 ; CHECK-NEXT: ]