[WebAssembly] Added R_WASM_FUNCTION_OFFSET_I64 for use with DWARF DW_AT_low_pc

Needed for wasm64, see discussion in https://reviews.llvm.org/D91203

Differential Revision: https://reviews.llvm.org/D91395

Author: aardappel

lld/wasm/InputChunks.cpp

@@ -97,6 +97,7 @@ void InputChunk::verifyRelocTargets() const {
       break;
     case R_WASM_TABLE_INDEX_I64:
     case R_WASM_MEMORY_ADDR_I64:
+    case R_WASM_FUNCTION_OFFSET_I64:
       existingValue = read64le(loc);
       break;
     default:
@@ -176,6 +177,7 @@ void InputChunk::writeTo(uint8_t *buf) const {
       break;
     case R_WASM_TABLE_INDEX_I64:
     case R_WASM_MEMORY_ADDR_I64:
+    case R_WASM_FUNCTION_OFFSET_I64:
       write64le(loc, value);
       break;
     default:

lld/wasm/InputFiles.cpp

@@ -124,6 +124,7 @@ uint64_t ObjFile::calcNewAddend(const WasmRelocation &reloc) const {
   case R_WASM_MEMORY_ADDR_I32:
   case R_WASM_MEMORY_ADDR_I64:
   case R_WASM_FUNCTION_OFFSET_I32:
+  case R_WASM_FUNCTION_OFFSET_I64:
     return reloc.Addend;
   case R_WASM_SECTION_OFFSET_I32:
     return getSectionSymbol(reloc.Index)->section->outputOffset + reloc.Addend;
@@ -171,7 +172,8 @@ uint64_t ObjFile::calcExpectedValue(const WasmRelocation &reloc) const {
     else
       llvm_unreachable("unknown init expr opcode");
   }
-  case R_WASM_FUNCTION_OFFSET_I32: {
+  case R_WASM_FUNCTION_OFFSET_I32:
+  case R_WASM_FUNCTION_OFFSET_I64: {
     const WasmSymbol &sym = wasmObj->syms()[reloc.Index];
     InputFunction *f =
         functions[sym.Info.ElementIndex - wasmObj->getNumImportedFunctions()];
@@ -258,7 +260,8 @@ uint64_t ObjFile::calcNewValue(const WasmRelocation &reloc) const {
     return sym->getGOTIndex();
   case R_WASM_EVENT_INDEX_LEB:
     return getEventSymbol(reloc.Index)->getEventIndex();
-  case R_WASM_FUNCTION_OFFSET_I32: {
+  case R_WASM_FUNCTION_OFFSET_I32:
+  case R_WASM_FUNCTION_OFFSET_I64: {
     auto *f = cast<DefinedFunction>(sym);
     return f->function->outputOffset +
            (f->function->getFunctionCodeOffset() + reloc.Addend);

llvm/include/llvm/BinaryFormat/WasmRelocs.def

@@ -24,3 +24,4 @@ WASM_RELOC(R_WASM_TABLE_INDEX_SLEB64,     18)
 WASM_RELOC(R_WASM_TABLE_INDEX_I64,        19)
 WASM_RELOC(R_WASM_TABLE_NUMBER_LEB,       20)
 WASM_RELOC(R_WASM_MEMORY_ADDR_TLS_SLEB,   21)
+WASM_RELOC(R_WASM_FUNCTION_OFFSET_I64,    22)

llvm/lib/BinaryFormat/Wasm.cpp

@@ -50,6 +50,7 @@ bool llvm::wasm::relocTypeHasAddend(uint32_t Type) {
   case R_WASM_MEMORY_ADDR_I64:
   case R_WASM_MEMORY_ADDR_TLS_SLEB:
   case R_WASM_FUNCTION_OFFSET_I32:
+  case R_WASM_FUNCTION_OFFSET_I64:
   case R_WASM_SECTION_OFFSET_I32:
     return true;
   default:

llvm/lib/MC/WasmObjectWriter.cpp

@@ -478,6 +478,7 @@ void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
   // Currently only supported for for metadata sections.
   // See: test/MC/WebAssembly/blockaddress.ll
   if (Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
+      Type == wasm::R_WASM_FUNCTION_OFFSET_I64 ||
       Type == wasm::R_WASM_SECTION_OFFSET_I32) {
     if (!FixupSection.getKind().isMetadata())
       report_fatal_error("relocations for function or section offsets are "
@@ -564,6 +565,7 @@ WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry,
     assert(WasmIndices.count(RelEntry.Symbol) > 0 && "symbol not found in wasm index space");
     return WasmIndices[RelEntry.Symbol];
   case wasm::R_WASM_FUNCTION_OFFSET_I32:
+  case wasm::R_WASM_FUNCTION_OFFSET_I64:
   case wasm::R_WASM_SECTION_OFFSET_I32: {
     const auto &Section =
         static_cast<const MCSectionWasm &>(RelEntry.Symbol->getSection());
@@ -680,6 +682,7 @@ void WasmObjectWriter::applyRelocations(
       break;
     case wasm::R_WASM_TABLE_INDEX_I64:
     case wasm::R_WASM_MEMORY_ADDR_I64:
+    case wasm::R_WASM_FUNCTION_OFFSET_I64:
       patchI64(Stream, Value, Offset);
       break;
     case wasm::R_WASM_TABLE_INDEX_SLEB:

llvm/lib/Object/RelocationResolver.cpp

@@ -566,6 +566,7 @@ static bool supportsWasm64(uint64_t Type) {
   case wasm::R_WASM_MEMORY_ADDR_I64:
   case wasm::R_WASM_TABLE_INDEX_SLEB64:
   case wasm::R_WASM_TABLE_INDEX_I64:
+  case wasm::R_WASM_FUNCTION_OFFSET_I64:
     return true;
   default:
     return supportsWasm32(Type);
@@ -601,6 +602,7 @@ static uint64_t resolveWasm64(RelocationRef R, uint64_t S, uint64_t A) {
   case wasm::R_WASM_MEMORY_ADDR_I64:
   case wasm::R_WASM_TABLE_INDEX_SLEB64:
   case wasm::R_WASM_TABLE_INDEX_I64:
+  case wasm::R_WASM_FUNCTION_OFFSET_I64:
     // For wasm section, its offset at 0 -- ignoring Value
     return A;
   default:

llvm/lib/Object/WasmObjectFile.cpp

@@ -876,6 +876,12 @@ Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
                                               object_error::parse_failed);
       Reloc.Addend = readVarint32(Ctx);
       break;
+    case wasm::R_WASM_FUNCTION_OFFSET_I64:
+      if (!isValidFunctionSymbol(Reloc.Index))
+        return make_error<GenericBinaryError>("Bad relocation function index",
+                                              object_error::parse_failed);
+      Reloc.Addend = readVarint64(Ctx);
+      break;
     case wasm::R_WASM_SECTION_OFFSET_I32:
       if (!isValidSectionSymbol(Reloc.Index))
         return make_error<GenericBinaryError>("Bad relocation section index",
@@ -903,7 +909,8 @@ Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
         Reloc.Type == wasm::R_WASM_GLOBAL_INDEX_I32)
       Size = 4;
     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I64 ||
-        Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I64)
+        Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I64 ||
+        Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I64)
       Size = 8;
     if (Reloc.Offset + Size > EndOffset)
       return make_error<GenericBinaryError>("Bad relocation offset",

llvm/lib/ObjectYAML/WasmEmitter.cpp

@@ -547,6 +547,7 @@ void WasmWriter::writeRelocSection(raw_ostream &OS, WasmYAML::Section &Sec,
     case wasm::R_WASM_MEMORY_ADDR_I32:
     case wasm::R_WASM_MEMORY_ADDR_I64:
     case wasm::R_WASM_FUNCTION_OFFSET_I32:
+    case wasm::R_WASM_FUNCTION_OFFSET_I64:
     case wasm::R_WASM_SECTION_OFFSET_I32:
       encodeULEB128(Reloc.Addend, OS);
     }

llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCAsmInfo.cpp

@@ -23,9 +23,7 @@ WebAssemblyMCAsmInfo::~WebAssemblyMCAsmInfo() = default; // anchor.
 
 WebAssemblyMCAsmInfo::WebAssemblyMCAsmInfo(const Triple &T,
                                            const MCTargetOptions &Options) {
-  CalleeSaveStackSlotSize = T.isArch64Bit() ? 8 : 4;
-  // So far this is used for DWARF DW_AT_low_pc which is always 32-bit in Wasm.
-  CodePointerSize = 4;
+  CodePointerSize = CalleeSaveStackSlotSize = T.isArch64Bit() ? 8 : 4;
 
   // TODO: What should MaxInstLength be?
 

llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyWasmObjectWriter.cpp

@@ -131,7 +131,7 @@ unsigned WebAssemblyWasmObjectWriter::getRelocType(const MCValue &Target,
     if (auto Section = static_cast<const MCSectionWasm *>(
             getFixupSection(Fixup.getValue()))) {
       if (Section->getKind().isText())
-        llvm_unreachable("unimplemented R_WASM_FUNCTION_OFFSET_I64");
+        return wasm::R_WASM_FUNCTION_OFFSET_I64;
       else if (!Section->isWasmData())
         llvm_unreachable("unimplemented R_WASM_SECTION_OFFSET_I64");
     }