[WebAssembly] Return ArrayRef's rather than const std::vector&

[sbc100]

Summary

From working on lld I've learned this is generally the
preferred way for several reasons (e.g. more concise, improves
encapsulation).

[sbc100]

• revert parts

include/llvm/BinaryFormat/Wasm.h

 struct WasmLocalDecl {
   int32_t Type;
   uint32_t Count;
 };
 
 struct WasmFunction {
   std::vector<WasmLocalDecl> Locals;
   ArrayRef<uint8_t> Body;
+  size_t CodeSectionOffset;
+  size_t Size;
 };
 
 struct WasmDataSegment {
   uint32_t MemoryIndex;
   WasmInitExpr Offset;
   ArrayRef<uint8_t> Content;
   StringRef Name;
   uint32_t Alignment;

include/llvm/Object/Wasm.h

public:
   const wasm::WasmObjectHeader &getHeader() const;
   const WasmSymbol &getWasmSymbol(const DataRefImpl &Symb) const;
   const WasmSymbol &getWasmSymbol(const SymbolRef &Symbol) const;
   const WasmSection &getWasmSection(const SectionRef &Section) const;
   const wasm::WasmRelocation &getWasmRelocation(const RelocationRef& Ref) const;
 
   static bool classof(const Binary *v) { return v->isWasm(); }
 
-  const std::vector<wasm::WasmSignature>& types() const { return Signatures; }
-  const std::vector<uint32_t>& functionTypes() const { return FunctionTypes; }
-  const std::vector<wasm::WasmImport>& imports() const { return Imports; }
-  const std::vector<wasm::WasmTable>& tables() const { return Tables; }
-  const std::vector<wasm::WasmLimits>& memories() const { return Memories; }
-  const std::vector<wasm::WasmGlobal>& globals() const { return Globals; }
-  const std::vector<wasm::WasmExport>& exports() const { return Exports; }
+  ArrayRef<wasm::WasmSignature> types() const { return Signatures; }
+  ArrayRef<uint32_t> functionTypes() const { return FunctionTypes; }
+  ArrayRef<wasm::WasmImport> imports() const { return Imports; }
+  ArrayRef<wasm::WasmTable> tables() const { return Tables; }
+  ArrayRef<wasm::WasmLimits> memories() const { return Memories; }
+  ArrayRef<wasm::WasmGlobal> globals() const { return Globals; }
+  ArrayRef<wasm::WasmExport> exports() const { return Exports; }
   const wasm::WasmLinkingData& linkingData() const { return LinkingData; }
-
-  uint32_t getNumberOfSymbols() const {
-    return Symbols.size();
-  }
-
-  const std::vector<wasm::WasmElemSegment>& elements() const {
-    return ElemSegments;
-  }
-
-  const std::vector<WasmSegment>& dataSegments() const {
-    return DataSegments;
-  }
-
-  const std::vector<wasm::WasmFunction>& functions() const { return Functions; }
+  uint32_t getNumberOfSymbols() const { return Symbols.size(); }
+  ArrayRef<wasm::WasmElemSegment> elements() const { return ElemSegments; }
+  ArrayRef<WasmSegment> dataSegments() const { return DataSegments; }
+  ArrayRef<wasm::WasmFunction> functions() const { return Functions; }
   const ArrayRef<uint8_t>& code() const { return CodeSection; }
   uint32_t startFunction() const { return StartFunction; }
 
   void moveSymbolNext(DataRefImpl &Symb) const override;
 
   uint32_t getSymbolFlags(DataRefImpl Symb) const override;
 
   basic_symbol_iterator symbol_begin() const override;

lib/Object/WasmObjectFile.cpp

 
 Error WasmObjectFile::parseCodeSection(const uint8_t *Ptr, const uint8_t *End) {
   uint32_t FunctionCount = readVaruint32(Ptr);
   if (FunctionCount != FunctionTypes.size()) {
     return make_error<GenericBinaryError>("Invalid function count",
                                           object_error::parse_failed);
   }
 
+  const uint8_t *CodeSectionStart = Ptr;
   CodeSection = ArrayRef<uint8_t>(Ptr, End - Ptr);
 
   while (FunctionCount--) {
     wasm::WasmFunction Function;
-    uint32_t FunctionSize = readVaruint32(Ptr);
-    const uint8_t *FunctionEnd = Ptr + FunctionSize;
+    Function.CodeSectionOffset = Ptr - CodeSectionStart;
+    Function.Size = readVaruint32(Ptr);
+    const uint8_t *FunctionEnd = Ptr + Function.Size;
 
     uint32_t NumLocalDecls = readVaruint32(Ptr);
     Function.Locals.reserve(NumLocalDecls);
     while (NumLocalDecls--) {
       wasm::WasmLocalDecl Decl;
       Decl.Count = readVaruint32(Ptr);
       Decl.Type = readVarint7(Ptr);
       Function.Locals.push_back(Decl);