5 files changed, 63 insertions, 23 deletions
diff --git a/lib/Target/Mips/MipsISelDAGToDAG.cpp b/lib/Target/Mips/MipsISelDAGToDAG.cpp
index f05ac702ccdd..53de1bbea66e 100644
--- a/lib/Target/Mips/MipsISelDAGToDAG.cpp
+++ b/lib/Target/Mips/MipsISelDAGToDAG.cpp
@@ -70,7 +70,19 @@ private:
   // Include the pieces autogenerated from the target description.
   #include "MipsGenDAGISel.inc"
 
-  SDValue getGlobalBaseReg();
+  /// getTargetMachine - Return a reference to the TargetMachine, casted
+  /// to the target-specific type.
+  const MipsTargetMachine &getTargetMachine() {
+    return static_cast<const MipsTargetMachine &>(TM);
+  }
+
+  /// getInstrInfo - Return a reference to the TargetInstrInfo, casted
+  /// to the target-specific type.
+  const MipsInstrInfo *getInstrInfo() {
+    return getTargetMachine().getInstrInfo();
+  }
+
+  SDNode *getGlobalBaseReg();
   SDNode *Select(SDValue N);
 
   // Complex Pattern.
@@ -116,19 +128,10 @@ InstructionSelect()
 
 /// getGlobalBaseReg - Output the instructions required to put the
 /// GOT address into a register.
-SDValue MipsDAGToDAGISel::getGlobalBaseReg() {
-  MachineFunction* MF = BB->getParent();
-  unsigned GP = 0;
-  for(MachineRegisterInfo::livein_iterator ii = MF->getRegInfo().livein_begin(),
-        ee = MF->getRegInfo().livein_end(); ii != ee; ++ii)
-    if (ii->first == Mips::GP) {
-      GP = ii->second;
-      break;
-    }
-  assert(GP && "GOT PTR not in liveins");
-  // FIXME is there a sensible place to get debug info for this?
-  return CurDAG->getCopyFromReg(CurDAG->getEntryNode(), 
-                                DebugLoc::getUnknownLoc(), GP, MVT::i32);
+SDNode *MipsDAGToDAGISel::getGlobalBaseReg() {
+  MachineFunction *MF = BB->getParent();
+  unsigned GlobalBaseReg = getInstrInfo()->getGlobalBaseReg(MF);
+  return CurDAG->getRegister(GlobalBaseReg, TLI.getPointerTy()).getNode();
 }
 
 /// ComplexPattern used on MipsInstrInfo
@@ -321,11 +324,8 @@ Select(SDValue N)
     }
 
     // Get target GOT address.
-    case ISD::GLOBAL_OFFSET_TABLE: {
-      SDValue Result = getGlobalBaseReg();
-      ReplaceUses(N, Result);
-      return NULL;
-    }
+    case ISD::GLOBAL_OFFSET_TABLE:
+      return getGlobalBaseReg();
 
     /// Handle direct and indirect calls when using PIC. On PIC, when 
     /// GOT is smaller than about 64k (small code) the GA target is 
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 9281940019a9..4517cfc96a43 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -941,9 +941,6 @@ LowerFORMAL_ARGUMENTS(SDValue Op, SelectionDAG &DAG)
 
   unsigned StackReg = MF.getTarget().getRegisterInfo()->getFrameRegister(MF);
 
-  // GP must be live into PIC and non-PIC call target.
-  AddLiveIn(MF, Mips::GP, Mips::CPURegsRegisterClass);
-
   // Assign locations to all of the incoming arguments.
   SmallVector<CCValAssign, 16> ArgLocs;
   CCState CCInfo(CC, isVarArg, getTargetMachine(), ArgLocs);
diff --git a/lib/Target/Mips/MipsInstrInfo.cpp b/lib/Target/Mips/MipsInstrInfo.cpp
index 6225fa9c9884..92af973b0d21 100644
--- a/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/lib/Target/Mips/MipsInstrInfo.cpp
@@ -13,8 +13,10 @@
 
 #include "MipsInstrInfo.h"
 #include "MipsTargetMachine.h"
+#include "MipsMachineFunction.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "MipsGenInstrInfo.inc"
 
 using namespace llvm;
@@ -621,3 +623,30 @@ ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const
   Cond[0].setImm(GetOppositeBranchCondition((Mips::CondCode)Cond[0].getImm()));
   return false;
 }
+
+/// getGlobalBaseReg - Return a virtual register initialized with the
+/// the global base register value. Output instructions required to
+/// initialize the register in the function entry block, if necessary.
+///
+unsigned MipsInstrInfo::getGlobalBaseReg(MachineFunction *MF) const {
+  MipsFunctionInfo *MipsFI = MF->getInfo<MipsFunctionInfo>();
+  unsigned GlobalBaseReg = MipsFI->getGlobalBaseReg();
+  if (GlobalBaseReg != 0)
+    return GlobalBaseReg;
+
+  // Insert the set of GlobalBaseReg into the first MBB of the function
+  MachineBasicBlock &FirstMBB = MF->front();
+  MachineBasicBlock::iterator MBBI = FirstMBB.begin();
+  MachineRegisterInfo &RegInfo = MF->getRegInfo();
+  const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
+
+  GlobalBaseReg = RegInfo.createVirtualRegister(Mips::CPURegsRegisterClass);
+  bool Ok = TII->copyRegToReg(FirstMBB, MBBI, GlobalBaseReg, Mips::GP,
+                              Mips::CPURegsRegisterClass,
+                              Mips::CPURegsRegisterClass);
+  assert(Ok && "Couldn't assign to global base register!");
+  RegInfo.addLiveIn(Mips::GP);
+
+  MipsFI->setGlobalBaseReg(GlobalBaseReg);
+  return GlobalBaseReg;
+}
diff --git a/lib/Target/Mips/MipsInstrInfo.h b/lib/Target/Mips/MipsInstrInfo.h
index 334244e6601a..6655c6749fdf 100644
--- a/lib/Target/Mips/MipsInstrInfo.h
+++ b/lib/Target/Mips/MipsInstrInfo.h
@@ -216,6 +216,12 @@ public:
   /// Insert nop instruction when hazard condition is found
   virtual void insertNoop(MachineBasicBlock &MBB, 
                           MachineBasicBlock::iterator MI) const;
+
+  /// getGlobalBaseReg - Return a virtual register initialized with the
+  /// the global base register value. Output instructions required to
+  /// initialize the register in the function entry block, if necessary.
+  ///
+  unsigned getGlobalBaseReg(MachineFunction *MF) const;
 };
 
 }
diff --git a/lib/Target/Mips/MipsMachineFunction.h b/lib/Target/Mips/MipsMachineFunction.h
index b95394ec81ce..ac3cdfd38e16 100644
--- a/lib/Target/Mips/MipsMachineFunction.h
+++ b/lib/Target/Mips/MipsMachineFunction.h
@@ -75,11 +75,16 @@ private:
   /// holds the virtual register into which the sret argument is passed.
   unsigned SRetReturnReg;
 
+  /// GlobalBaseReg - keeps track of the virtual register initialized for
+  /// use as the global base register. This is used for PIC in some PIC
+  /// relocation models.
+  unsigned GlobalBaseReg;
+
 public:
   MipsFunctionInfo(MachineFunction& MF) 
   : FPStackOffset(0), RAStackOffset(0), CPUTopSavedRegOff(0), 
     FPUTopSavedRegOff(0), GPHolder(-1,-1), HasLoadArgs(false), 
-    HasStoreVarArgs(false), SRetReturnReg(0)
+    HasStoreVarArgs(false), SRetReturnReg(0), GlobalBaseReg(0)
   {}
 
   int getFPStackOffset() const { return FPStackOffset; }
@@ -124,6 +129,9 @@ public:
 
   unsigned getSRetReturnReg() const { return SRetReturnReg; }
   void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
+
+  unsigned getGlobalBaseReg() const { return GlobalBaseReg; }
+  void setGlobalBaseReg(unsigned Reg) { GlobalBaseReg = Reg; }
 };
 
 } // end of namespace llvm