[WebAssembly] objdump: Don't assume all relocations have symbols

llvm/trunk/test/tools/llvm-objdump/WebAssembly/relocations.test

 ; RUN: llc -mtriple=wasm32-unknown-unknown-wasm -filetype=obj %s -o - | llvm-objdump -r - | FileCheck %s
 
-@foo1 = hidden global i32 1, align 4
-@foo2 = hidden global i32 1, align 4
-@bar = hidden global i32* @foo2, align 4
+@foo = external global i32, align 4
+@bar = global i32* @foo, align 4
+
+define void @make_call(void ()* nocapture %func) {
+entry:
+  call void %func()
+  ret void
+}
+
+; CHECK:      RELOCATION RECORDS FOR [CODE]:
+; CHECK-NEXT: 00000006 R_WEBASSEMBLY_TYPE_INDEX_LEB 1+0
 
 ; CHECK:      RELOCATION RECORDS FOR [DATA]:
-; CHECK-NEXT: 00000018 R_WEBASSEMBLY_MEMORY_ADDR_I32 foo2+0
+; CHECK-NEXT: 00000006 R_WEBASSEMBLY_MEMORY_ADDR_I32 foo+0

llvm/trunk/tools/llvm-objdump/llvm-objdump.cpp

 
 static std::error_code getRelocationValueString(const WasmObjectFile *Obj,
                                                 const RelocationRef &RelRef,
                                                 SmallVectorImpl<char> &Result) {
   const wasm::WasmRelocation& Rel = Obj->getWasmRelocation(RelRef);
   symbol_iterator SI = RelRef.getSymbol();
   std::string fmtbuf;
   raw_string_ostream fmt(fmtbuf);
-  Expected<StringRef> SymNameOrErr = SI->getName();
-  if (!SymNameOrErr) {
+  if (SI == Obj->symbol_end()) {
+    // Not all wasm relocations have symbols associated with them.
+    // In particular R_WEBASSEMBLY_TYPE_INDEX_LEB.
     fmt << Rel.Index;
   } else {
+    Expected<StringRef> SymNameOrErr = SI->getName();
+    if (!SymNameOrErr)
+      return errorToErrorCode(SymNameOrErr.takeError());
     StringRef SymName = *SymNameOrErr;
     Result.append(SymName.begin(), SymName.end());
   }
   fmt << (Rel.Addend < 0 ? "" : "+") << Rel.Addend;
   fmt.flush();
   Result.append(fmtbuf.begin(), fmtbuf.end());
   return std::error_code();
 }