[DebugInfo] Allow getDebugThreadLocalSymbol to return MCExpr

This allows getDebugThreadLocalSymbol to return a generic MCExpr
instead of just a MCSymbolRefExpr.

This is in preparation for supporting debug info for TLS variables
on PowerPC, where we need to describe the variable location using
a more complex expression than just MCSymbolRefExpr.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185460 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/X86/X86TargetObjectFile.cpp

@@ -48,7 +48,7 @@ X86LinuxTargetObjectFile::Initialize(MCContext &Ctx, const TargetMachine &TM) {
   InitializeELF(TM.Options.UseInitArray);
 }
 
-const MCSymbolRefExpr *
+const MCExpr *
 X86LinuxTargetObjectFile::getDebugThreadLocalSymbol(
     const MCSymbol *Sym) const {
   return MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext());