[MCDwarf] Change emitListsTableHeaderStart to use a reference and fold Start/End symbols generation into it

[MaskRay]

Summary

Apply @dblaikie's suggestions in post-commit review for D75375

[dblaikie]

Thanks! (fine to commit things like this without precommit review & just link to the commit in response to the previous post-review feedback)

[MaskRay]

Fold TableStart/TableEnd into emitListsTableHeaderStart()

[dblaikie]

Looks good - thanks!

llvm/include/llvm/MC/MCDwarf.h

 class MCStreamer;
 class MCSymbol;
 class raw_ostream;
 class SMLoc;
 class SourceMgr;
 
 namespace mcdwarf {
 // Emit the common part of the DWARF 5 range/locations list tables header.
-void emitListsTableHeaderStart(MCStreamer *S, MCSymbol *TableStart,
-                               MCSymbol *TableEnd);
+MCSymbol *emitListsTableHeaderStart(MCStreamer &S);
 } // namespace mcdwarf
 
 /// Instances of this class represent the name of the dwarf .file directive and
 /// its associated dwarf file number in the MC file. MCDwarfFile's are created
 /// and uniqued by the MCContext class. In Dwarf 4 file numbers start from 1;
 /// i.e. the entry with file number 1 is the first element in the vector of
 /// DwarfFiles and there is no MCDwarfFile with file number 0. In Dwarf 5 file
 /// numbers start from 0, with the MCDwarfFile with file number 0 being the

llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

void DwarfDebug::emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry,
   emitDebugLocEntry(Streamer, Entry, CU);
 }
 
 // Emit the header of a DWARF 5 range list table list table. Returns the symbol
 // that designates the end of the table for the caller to emit when the table is
 // complete.
 static MCSymbol *emitRnglistsTableHeader(AsmPrinter *Asm,
                                          const DwarfFile &Holder) {
-  MCSymbol *TableStart = Asm->createTempSymbol("debug_rnglist_table_start");
-  MCSymbol *TableEnd = Asm->createTempSymbol("debug_rnglist_table_end");
-  mcdwarf::emitListsTableHeaderStart(Asm->OutStreamer.get(), TableStart,
-                                     TableEnd);
+  MCSymbol *TableEnd = mcdwarf::emitListsTableHeaderStart(*Asm->OutStreamer);
 
   Asm->OutStreamer->AddComment("Offset entry count");
   Asm->emitInt32(Holder.getRangeLists().size());
   Asm->OutStreamer->emitLabel(Holder.getRnglistsTableBaseSym());
 
   for (const RangeSpanList &List : Holder.getRangeLists())
     Asm->emitLabelDifference(List.Label, Holder.getRnglistsTableBaseSym(), 4);
 
   return TableEnd;
 }
 
 // Emit the header of a DWARF 5 locations list table. Returns the symbol that
 // designates the end of the table for the caller to emit when the table is
 // complete.
 static MCSymbol *emitLoclistsTableHeader(AsmPrinter *Asm,
                                          const DwarfDebug &DD) {
-  MCSymbol *TableStart = Asm->createTempSymbol("debug_loclist_table_start");
-  MCSymbol *TableEnd = Asm->createTempSymbol("debug_loclist_table_end");
-  mcdwarf::emitListsTableHeaderStart(Asm->OutStreamer.get(), TableStart,
-                                     TableEnd);
+  MCSymbol *TableEnd = mcdwarf::emitListsTableHeaderStart(*Asm->OutStreamer);
 
   const auto &DebugLocs = DD.getDebugLocs();
 
   Asm->OutStreamer->AddComment("Offset entry count");
   Asm->emitInt32(DebugLocs.getLists().size());
   Asm->OutStreamer->emitLabel(DebugLocs.getSym());
 
   for (const auto &List : DebugLocs.getLists())

llvm/lib/MC/MCDwarf.cpp

 #include <cassert>
 #include <cstdint>
 #include <string>
 #include <utility>
 #include <vector>
 
 using namespace llvm;
 
-void mcdwarf::emitListsTableHeaderStart(MCStreamer *S, MCSymbol *TableStart,
-                                        MCSymbol *TableEnd) {
-  S->AddComment("Length");
-  S->emitAbsoluteSymbolDiff(TableEnd, TableStart, 4);
-  S->emitLabel(TableStart);
-  S->AddComment("Version");
-  S->emitInt16(S->getContext().getDwarfVersion());
-  S->AddComment("Address size");
-  S->emitInt8(S->getContext().getAsmInfo()->getCodePointerSize());
-  S->AddComment("Segment selector size");
-  S->emitInt8(0);
+MCSymbol *mcdwarf::emitListsTableHeaderStart(MCStreamer &S) {
+  MCSymbol *Start =
+      S.getContext().createTempSymbol("debug_list_header_start", true, true);
+  MCSymbol *End =
+      S.getContext().createTempSymbol("debug_list_header_end", true, true);
+  S.AddComment("Length");
+  S.emitAbsoluteSymbolDiff(End, Start, 4);
+  S.emitLabel(Start);
+  S.AddComment("Version");
+  S.emitInt16(S.getContext().getDwarfVersion());
+  S.AddComment("Address size");
+  S.emitInt8(S.getContext().getAsmInfo()->getCodePointerSize());
+  S.AddComment("Segment selector size");
+  S.emitInt8(0);
+  return End;
 }
 
 /// Manage the .debug_line_str section contents, if we use it.
 class llvm::MCDwarfLineStr {
   MCSymbol *LineStrLabel = nullptr;
   StringTableBuilder LineStrings{StringTableBuilder::DWARF};
   bool UseRelocs = false;
 
static MCSymbol *emitGenDwarfRanges(MCStreamer *MCOS) {
   auto &Sections = context.getGenDwarfSectionSyms();
 
   const MCAsmInfo *AsmInfo = context.getAsmInfo();
   int AddrSize = AsmInfo->getCodePointerSize();
   MCSymbol *RangesSymbol;
 
   if (MCOS->getContext().getDwarfVersion() >= 5) {
     MCOS->SwitchSection(context.getObjectFileInfo()->getDwarfRnglistsSection());
-    MCSymbol *StartSymbol =
-        context.createTempSymbol("debug_rnglists_start", true, true);
-    MCSymbol *EndSymbol =
-        context.createTempSymbol("debug_rnglists_end", true, true);
-    mcdwarf::emitListsTableHeaderStart(MCOS, StartSymbol, EndSymbol);
+    MCSymbol *EndSymbol = mcdwarf::emitListsTableHeaderStart(*MCOS);
     MCOS->AddComment("Offset entry count");
     MCOS->emitInt32(0);
     RangesSymbol = context.createTempSymbol("debug_rnglist0_start", true, true);
     MCOS->emitLabel(RangesSymbol);
     for (MCSection *Sec : Sections) {
       const MCSymbol *StartSymbol = Sec->getBeginSymbol();
       const MCSymbol *EndSymbol = Sec->getEndSymbol(context);
       const MCExpr *SectionStartAddr = MCSymbolRefExpr::create(