add support for external symbols.  The mc instprinter  can now handle
reasonable code like Codegen/ARM/2009-02-27-SpillerBug.ll, producing 
identical output except for superior formatting of constant pool entries.

llvm-svn: 84582
diff --git a/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.cpp b/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.cpp
index 2520b2c..757164e 100644
--- a/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.cpp
+++ b/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.cpp
@@ -54,6 +54,22 @@
   return Ctx.GetOrCreateSymbol(Name.str());
 }
 
+MCSymbol *ARMMCInstLower::
+GetExternalSymbolSymbol(const MachineOperand &MO) const {
+  SmallString<128> Name;
+  Name += Printer.MAI->getGlobalPrefix();
+  Name += MO.getSymbolName();
+  
+  // FIXME: HANDLE PLT references how??
+  switch (MO.getTargetFlags()) {
+  default: assert(0 && "Unknown target flag on GV operand");
+  case 0: break;
+  }
+  
+  return Ctx.GetOrCreateSymbol(Name.str());
+}
+
+
 
 MCSymbol *ARMMCInstLower::
 GetJumpTableSymbol(const MachineOperand &MO) const {
@@ -133,11 +149,9 @@
     case MachineOperand::MO_GlobalAddress:
       MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
       break;
-#if 0
     case MachineOperand::MO_ExternalSymbol:
       MCOp = LowerSymbolOperand(MO, GetExternalSymbolSymbol(MO));
       break;
-#endif
     case MachineOperand::MO_JumpTableIndex:
       MCOp = LowerSymbolOperand(MO, GetJumpTableSymbol(MO));
       break;
diff --git a/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.h b/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.h
index 1b73e81..383d30d 100644
--- a/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.h
+++ b/llvm/lib/Target/ARM/AsmPrinter/ARMMCInstLower.h
@@ -40,7 +40,7 @@
 
   //MCSymbol *GetPICBaseSymbol() const;
   MCSymbol *GetGlobalAddressSymbol(const MachineOperand &MO) const;
-  //MCSymbol *GetExternalSymbolSymbol(const MachineOperand &MO) const;
+  MCSymbol *GetExternalSymbolSymbol(const MachineOperand &MO) const;
   MCSymbol *GetJumpTableSymbol(const MachineOperand &MO) const;
   MCSymbol *GetConstantPoolIndexSymbol(const MachineOperand &MO) const;
   MCOperand LowerSymbolOperand(const MachineOperand &MO, MCSymbol *Sym) const;