Remove the unused string section symbol parameter from DwarfFile::emitStrings

And since it /looked/ like the DwarfStrSectionSym was unused, I tried
removing it - but then it turned out that DwarfStringPool was
reconstructing the same label (and expecting it to have already been
emitted) and uses that.

So I kept it around, but wanted to pass it in to users - since it seemed
a bit silly for DwarfStringPool to have it passed in and returned but
itself have no use for it. The only two users don't handle strings in
both .dwo and .o files so they only ever need the one symbol - no need
to keep it (and have an unused symbol) in the DwarfStringPool used for
fission/.dwo.

Refactor a bunch of accelerator table usage to remove duplication so I
didn't have to touch 4-5 callers.

llvm-svn: 217628
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
index e9527c4..a9cbdba 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfAccelTable.cpp
@@ -174,7 +174,8 @@
 // Walk through the buckets and emit the full data for each element in
 // the bucket. For the string case emit the dies and the various offsets.
 // Terminate each HashData bucket with 0.
-void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfFile *D) {
+void DwarfAccelTable::EmitData(AsmPrinter *Asm, DwarfFile *D,
+                               MCSymbol *StrSym) {
   uint64_t PrevHash = UINT64_MAX;
   for (size_t i = 0, e = Buckets.size(); i < e; ++i) {
     for (HashList::const_iterator HI = Buckets[i].begin(),
@@ -183,8 +184,7 @@
       // Remember to emit the label for our offset.
       Asm->OutStreamer.EmitLabel((*HI)->Sym);
       Asm->OutStreamer.AddComment((*HI)->Str);
-      Asm->EmitSectionOffset((*HI)->Data.StrSym,
-                             D->getStringPool().getSectionSymbol());
+      Asm->EmitSectionOffset((*HI)->Data.StrSym, StrSym);
       Asm->OutStreamer.AddComment("Num DIEs");
       Asm->EmitInt32((*HI)->Data.Values.size());
       for (HashDataContents *HD : (*HI)->Data.Values) {
@@ -206,7 +206,8 @@
 }
 
 // Emit the entire data structure to the output file.
-void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin, DwarfFile *D) {
+void DwarfAccelTable::Emit(AsmPrinter *Asm, MCSymbol *SecBegin, DwarfFile *D,
+                           MCSymbol *StrSym) {
   // Emit the header.
   EmitHeader(Asm);
 
@@ -220,7 +221,7 @@
   EmitOffsets(Asm, SecBegin);
 
   // Emit the hash data.
-  EmitData(Asm, D);
+  EmitData(Asm, D, StrSym);
 }
 
 #ifndef NDEBUG