[WebAssembly] Move direct call tracking from member to local. NFC.

[sbc100]

Summary

This data structure is only needed temporarily while symbols are being
created.

This is a followup on rL361678.

[ruiu]

LGTM

wasm/InputFiles.h

public:
   MutableArrayRef<Symbol *> getMutableSymbols() { return Symbols; }
 
 protected:
   InputFile(Kind K, MemoryBufferRef M) : MB(M), FileKind(K) {}
   MemoryBufferRef MB;
 
   // List of all symbols referenced or defined by this file.
   std::vector<Symbol *> Symbols;
-  // Bool for each symbol, true if called directly.  This allows us to implement
-  // a weaker form of signature checking where undefined functions that are not
-  // called directly (i.e. only address taken) don't have to match the defined
-  // function's signature.  We cannot do this for directly called functions
-  // because those signatures are checked at validation times.
-  // See https://bugs.llvm.org/show_bug.cgi?id=40412
-  std::vector<bool> SymbolIsCalledDirectly;
 
 private:
   const Kind FileKind;
 };
 
 // .a file (ar archive)
 class ArchiveFile : public InputFile {
 public:

wasm/InputFiles.cpp

for (const WasmElemSegment &Seg : WasmObj->elements()) {
     for (uint32_t Index = 0; Index < Seg.Functions.size(); Index++) {
 
       uint32_t FunctionIndex = Seg.Functions[Index];
       TableEntries[FunctionIndex] = Offset + Index;
     }
   }
 
   uint32_t SectionIndex = 0;
-  SymbolIsCalledDirectly.resize(WasmObj->getNumberOfSymbols(), false);
+
+  // Bool for each symbol, true if called directly.  This allows us to implement
+  // a weaker form of signature checking where undefined functions that are not
+  // called directly (i.e. only address taken) don't have to match the defined
+  // function's signature.  We cannot do this for directly called functions
+  // because those signatures are checked at validation times.
+  // See https://bugs.llvm.org/show_bug.cgi?id=40412
+  std::vector<bool> IsCalledDirectly(WasmObj->getNumberOfSymbols(), false);
   for (const SectionRef &Sec : WasmObj->sections()) {
     const WasmSection &Section = WasmObj->getWasmSection(Sec);
     // Wasm objects can have at most one code and one data section.
     if (Section.Type == WASM_SEC_CODE) {
       assert(!CodeSection);
       CodeSection = &Section;
     } else if (Section.Type == WASM_SEC_DATA) {
       assert(!DataSection);
       DataSection = &Section;
     } else if (Section.Type == WASM_SEC_CUSTOM) {
       CustomSections.emplace_back(make<InputSection>(Section, this));
       CustomSections.back()->setRelocations(Section.Relocations);
       CustomSectionsByIndex[SectionIndex] = CustomSections.back();
     }
     SectionIndex++;
     // Scans relocations to dermine determine if a function symbol is called
     // directly
     for (const WasmRelocation &Reloc : Section.Relocations)
       if (Reloc.Type == R_WASM_FUNCTION_INDEX_LEB)
-        SymbolIsCalledDirectly[Reloc.Index] = true;
+        IsCalledDirectly[Reloc.Index] = true;
   }
 
   TypeMap.resize(getWasmObj()->types().size());
   TypeIsUsed.resize(getWasmObj()->types().size(), false);
 
   ArrayRef<StringRef> Comdats = WasmObj->linkingData().Comdats;
   for (unsigned I = 0; I < Comdats.size(); ++I)
     if (IgnoreComdats)
if (WasmSym.isDefined()) {
       // createDefined may fail if the symbol is comdat excluded in which case
       // we fall back to creating an undefined symbol
       if (Symbol *D = createDefined(WasmSym)) {
         Symbols.push_back(D);
         continue;
       }
     }
     size_t Idx = Symbols.size();
-    Symbols.push_back(createUndefined(WasmSym, SymbolIsCalledDirectly[Idx]));
+    Symbols.push_back(createUndefined(WasmSym, IsCalledDirectly[Idx]));
   }
 }
 
 bool ObjFile::isExcludedByComdat(InputChunk *Chunk) const {
   uint32_t C = Chunk->getComdat();
   if (C == UINT32_MAX)
     return false;
   return !KeptComdats[C];