Position Independent Code (PIC) support [2]

- Added a function to hold the stack location 
  where GP must be stored during LowerCALL
- AsmPrinter now emits directives based on
  relocation type
- PIC_ set to default relocation type (same as GCC)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42779 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/Mips/MipsMachineFunction.h

@@ -33,6 +33,11 @@ private:
   /// the Return Address must be saved
   int RAStackOffset;
 
+  /// When PIC is used the GP must be saved on the stack
+  /// on the function prologue, so a reference to its stack
+  /// location must be kept.
+  int GPStackOffset;
+
   /// MipsFIHolder - Holds a FrameIndex and it's Stack Pointer Offset
   struct MipsFIHolder {
 
@@ -69,6 +74,9 @@ public:
   int getRAStackOffset() const { return RAStackOffset; }
   void setRAStackOffset(int Off) { RAStackOffset = Off; }
 
+  int getGPStackOffset() const { return GPStackOffset; }
+  void setGPStackOffset(int Off) { GPStackOffset = Off; }
+
   int getTopSavedRegOffset() const { 
     return (RAStackOffset > FPStackOffset) ? 
            (RAStackOffset) : (FPStackOffset);