Lower RETURNADDR node in Mips backend.

Patch by Sasa Stankovic.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160031 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index ca002c0..6858d84 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -806,6 +806,7 @@ LowerOperation(SDValue Op, SelectionDAG &DAG) const
     case ISD::FCOPYSIGN:          return LowerFCOPYSIGN(Op, DAG);
     case ISD::FABS:               return LowerFABS(Op, DAG);
     case ISD::FRAMEADDR:          return LowerFRAMEADDR(Op, DAG);
+    case ISD::RETURNADDR:         return LowerRETURNADDR(Op, DAG);
     case ISD::MEMBARRIER:         return LowerMEMBARRIER(Op, DAG);
     case ISD::ATOMIC_FENCE:       return LowerATOMIC_FENCE(Op, DAG);
     case ISD::SHL_PARTS:          return LowerShiftLeftParts(Op, DAG);
@@ -2009,6 +2010,23 @@ LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const {
   return FrameAddr;
 }
 
+SDValue MipsTargetLowering::LowerRETURNADDR(SDValue Op,
+                                            SelectionDAG &DAG) const {
+  // check the depth
+  assert((cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue() == 0) &&
+         "Return address can be determined only for current frame.");
+
+  MachineFunction &MF = DAG.getMachineFunction();
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  EVT VT = Op.getValueType();
+  unsigned RA = IsN64 ? Mips::RA_64 : Mips::RA;
+  MFI->setReturnAddressIsTaken(true);
+
+  // Return RA, which contains the return address. Mark it an implicit live-in.
+  unsigned Reg = MF.addLiveIn(RA, getRegClassFor(VT));
+  return DAG.getCopyFromReg(DAG.getEntryNode(), Op.getDebugLoc(), Reg, VT);
+}
+
 // TODO: set SType according to the desired memory barrier behavior.
 SDValue
 MipsTargetLowering::LowerMEMBARRIER(SDValue Op, SelectionDAG &DAG) const {