[WebAssembly] Remove some unused code and tidy logging. NFC.

[ncw]

Summary

A few bits split out of D41954, to go in before

lib/MC/WasmObjectWriter.cpp

 #if !defined(NDEBUG)
 raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
   Rel.print(OS);
   return OS;
 }
 #endif
 
 class WasmObjectWriter : public MCObjectWriter {
-  /// Helper struct for containing some precomputed information on symbols.
-  struct WasmSymbolData {
-    const MCSymbolWasm *Symbol;
-    StringRef Name;
-
-    // Support lexicographic sorting.
-    bool operator<(const WasmSymbolData &RHS) const { return Name < RHS.Name; }
-  };
-
   /// The target specific Wasm writer instance.
   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;
for (MCSection &Sec : Asm) {
     auto &Section = static_cast<MCSectionWasm &>(Sec);
     if (!Section.isWasmData())
       continue;
 
     // .init_array sections are handled specially elsewhere.
     if (cast<MCSectionWasm>(Sec).getSectionName().startswith(".init_array"))
       continue;
 
+    uint32_t SegmentIndex = DataSegments.size();
     DataSize = alignTo(DataSize, Section.getAlignment());
     DataSegments.emplace_back();
     WasmDataSegment &Segment = DataSegments.back();
     Segment.Name = Section.getSectionName();
     Segment.Offset = DataSize;
     Segment.Section = &Section;
     addData(Segment.Data, Section);
     Segment.Alignment = Section.getAlignment();
     Segment.Flags = 0;
     DataSize += Segment.Data.size();
     Section.setMemoryOffset(Segment.Offset);
 
     if (const MCSymbolWasm *C = Section.getGroup()) {
       Comdats[C->getName()].emplace_back(
-          WasmComdatEntry{wasm::WASM_COMDAT_DATA,
-                          static_cast<uint32_t>(DataSegments.size()) - 1});
+          WasmComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex});
     }
   }
 
   // Handle regular defined and undefined symbols.
   for (const MCSymbol &S : Asm.symbols()) {
     // Ignore unnamed temporary symbols, which aren't ever exported, imported,
     // or used in relocations.
     if (S.isTemporary() && S.getName().empty())
       continue;
 
     const auto &WS = static_cast<const MCSymbolWasm &>(S);
     DEBUG(dbgs() << "MCSymbol: '" << S << "'"
-                 << " isDefined=" << S.isDefined() << " isExternal="
-                 << S.isExternal() << " isTemporary=" << S.isTemporary()
+                 << " isDefined=" << S.isDefined()
+                 << " isExternal=" << S.isExternal()
+                 << " isTemporary=" << S.isTemporary()
                  << " isFunction=" << WS.isFunction()
                  << " isWeak=" << WS.isWeak()
                  << " isHidden=" << WS.isHidden()
                  << " isVariable=" << WS.isVariable() << "\n");
 
     if (WS.isWeak() || WS.isHidden()) {
       uint32_t Flags = (WS.isWeak() ? wasm::WASM_SYMBOL_BINDING_WEAK : 0) |
           (WS.isHidden() ? wasm::WASM_SYMBOL_VISIBILITY_HIDDEN : 0);
auto HandleReloc = [&](const WasmRelocationEntry &Rel) {
       if (Rel.Type != wasm::R_WEBASSEMBLY_TABLE_INDEX_I32 &&
           Rel.Type != wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB)
         return;
       assert(Rel.Symbol->isFunction());
       const MCSymbolWasm* WS = ResolveSymbol(*Rel.Symbol);
       uint32_t SymbolIndex = SymbolIndices[WS];
       uint32_t TableIndex = TableElems.size() + kInitialTableOffset;
       if (TableIndices.try_emplace(WS, TableIndex).second) {
-        DEBUG(dbgs() << "  -> adding to table: " << TableElems.size() << "\n");
+        DEBUG(dbgs() << "  -> adding " << WS->getName() << " to table: " <<
+              TableElems.size() << "\n");
         TableElems.push_back(SymbolIndex);
       }
     };
 
     for (const WasmRelocationEntry &RelEntry : CodeRelocations)
       HandleReloc(RelEntry);
     for (const WasmRelocationEntry &RelEntry : DataRelocations)
       HandleReloc(RelEntry);