Make AliasedSymbol able to handle MCTargetExpr. They can get here if
a weakref is used with a VariantKind.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118798 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/ELFObjectWriter.cpp b/lib/MC/ELFObjectWriter.cpp
index f84164d..93ea77a 100644
--- a/lib/MC/ELFObjectWriter.cpp
+++ b/lib/MC/ELFObjectWriter.cpp
@@ -470,10 +470,23 @@
   const MCSymbol *S = &Symbol;
   while (S->isVariable()) {
     const MCExpr *Value = S->getVariableValue();
-    if (Value->getKind() != MCExpr::SymbolRef)
+    MCExpr::ExprKind Kind = Value->getKind();
+    switch (Kind) {
+    case MCExpr::SymbolRef: {
+      const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
+      S = &Ref->getSymbol();
+      break;
+    }
+    case MCExpr::Target: {
+      const MCTargetExpr *TExp = static_cast<const MCTargetExpr*>(Value);
+      MCValue Res;
+      TExp->EvaluateAsRelocatableImpl(Res, NULL);
+      S = &Res.getSymA()->getSymbol();
+      break;
+    }
+    default:
       return *S;
-    const MCSymbolRefExpr *Ref = static_cast<const MCSymbolRefExpr*>(Value);
-    S = &Ref->getSymbol();
+    }
   }
   return *S;
 }