-MachineInstr *InsertNewPHI(MachineBasicBlock *BB, const TargetRegisterClass *RC,
- MachineRegisterInfo *MRI, const TargetInstrInfo *TII) {
+unsigned LookForIdenticalPHI(MachineBasicBlock *BB,
+ SmallVector<std::pair<MachineBasicBlock*, unsigned>, 8> &PredValues) {
+ if (BB->empty())
+ return 0;
+
+ MachineBasicBlock::iterator I = BB->front();
+ if (!I->isPHI())
+ return 0;
+
+ AvailableValsTy AVals;
+ for (unsigned i = 0, e = PredValues.size(); i != e; ++i)
+ AVals[PredValues[i].first] = PredValues[i].second;
+ while (I != BB->end() && I->isPHI()) {
+ bool Same = true;
+ for (unsigned i = 1, e = I->getNumOperands(); i != e; i += 2) {
+ unsigned SrcReg = I->getOperand(i).getReg();
+ MachineBasicBlock *SrcBB = I->getOperand(i+1).getMBB();
+ if (AVals[SrcBB] != SrcReg) {
+ Same = false;
+ break;
+ }
+ }
+ if (Same)
+ return I->getOperand(0).getReg();
+ ++I;
+ }
+ return 0;
+}
+
+/// InsertNewDef - Insert an empty PHI or IMPLICIT_DEF instruction which define
+/// a value of the given register class at the start of the specified basic
+/// block. It returns the virtual register defined by the instruction.
+static
+MachineInstr *InsertNewDef(unsigned Opcode,
+ MachineBasicBlock *BB, MachineBasicBlock::iterator I,
+ const TargetRegisterClass *RC,
+ MachineRegisterInfo *MRI, const TargetInstrInfo *TII) {