Properly save and restore RA and Mips16 callee save registers S0,S1

[oota-llvm.git] / lib / Target / Mips / Mips16FrameLowering.cpp

diff --git a/lib/Target/Mips/Mips16FrameLowering.cpp b/lib/Target/Mips/Mips16FrameLowering.cpp
index 030042f2e8326f4ec0703010b40acd4b591dbf9f..b2583f73d06c37624246ab815a475dc8099448f0 100644 (file)
--- a/lib/Target/Mips/Mips16FrameLowering.cpp
+++ b/lib/Target/Mips/Mips16FrameLowering.cpp
@@ -66,7 +66,42 @@ spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                           MachineBasicBlock::iterator MI,
                           const std::vector<CalleeSavedInfo> &CSI,
                           const TargetRegisterInfo *TRI) const {
-  // FIXME: implement.
+  MachineFunction *MF = MBB.getParent();
+  MachineBasicBlock *EntryBlock = MF->begin();
+  const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
+
+  //
+  // Registers RA, S0,S1 are the callee saved registers and they
+  // will be saved with the "save" instruction
+  // during emitPrologue
+  //
+  for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
+    // Add the callee-saved register as live-in. Do not add if the register is
+    // RA and return address is taken, because it has already been added in
+    // method MipsTargetLowering::LowerRETURNADDR.
+    // It's killed at the spill, unless the register is RA and return address
+    // is taken.
+    unsigned Reg = CSI[i].getReg();
+    bool IsRAAndRetAddrIsTaken = (Reg == Mips::RA)
+      && MF->getFrameInfo()->isReturnAddressTaken();
+    if (!IsRAAndRetAddrIsTaken)
+      EntryBlock->addLiveIn(Reg);
+  }
+
+  return true;
+}
+
+bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
+                                          MachineBasicBlock::iterator MI,
+                                       const std::vector<CalleeSavedInfo> &CSI,
+                                       const TargetRegisterInfo *TRI) const {
+  //
+  // Registers RA,S0,S1 are the callee saved registers and they will be restored
+  // with the restore instruction during emitEpilogue.
+  // We need to override this virtual function, otherwise llvm will try and
+  // restore the registers on it's on from the stack.
+  //
+
   return true;
 }
 
@@ -79,6 +114,9 @@ Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
 void Mips16FrameLowering::
 processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                      RegScavenger *RS) const {
+  MF.getRegInfo().setPhysRegUsed(Mips::RA);
+  MF.getRegInfo().setPhysRegUsed(Mips::S0);
+  MF.getRegInfo().setPhysRegUsed(Mips::S1);
 }
 
 const MipsFrameLowering *