+bool MipsDAGToDAGISel::ReplaceUsesWithZeroReg(MachineRegisterInfo *MRI,
+ const MachineInstr& MI) {
+ unsigned DstReg = 0, ZeroReg = 0;
+
+ // Check if MI is "addiu $dst, $zero, 0" or "daddiu $dst, $zero, 0".
+ if ((MI.getOpcode() == Mips::ADDiu) &&
+ (MI.getOperand(1).getReg() == Mips::ZERO) &&
+ (MI.getOperand(2).getImm() == 0)) {
+ DstReg = MI.getOperand(0).getReg();
+ ZeroReg = Mips::ZERO;
+ } else if ((MI.getOpcode() == Mips::DADDiu) &&
+ (MI.getOperand(1).getReg() == Mips::ZERO_64) &&
+ (MI.getOperand(2).getImm() == 0)) {
+ DstReg = MI.getOperand(0).getReg();
+ ZeroReg = Mips::ZERO_64;
+ }
+
+ if (!DstReg)
+ return false;
+
+ // Replace uses with ZeroReg.
+ for (MachineRegisterInfo::use_iterator U = MRI->use_begin(DstReg),
+ E = MRI->use_end(); U != E; ++U) {
+ MachineOperand &MO = U.getOperand();
+ MachineInstr *MI = MO.getParent();
+
+ // Do not replace if it is a phi's operand or is tied to def operand.
+ if (MI->isPHI() || MI->isRegTiedToDefOperand(U.getOperandNo()))
+ continue;
+
+ MO.setReg(ZeroReg);
+ }
+
+ return true;
+}
+
+void MipsDAGToDAGISel::ProcessFunctionAfterISel(MachineFunction &MF) {
+ InitGlobalBaseReg(MF);
+
+ MachineRegisterInfo *MRI = &MF.getRegInfo();
+
+ for (MachineFunction::iterator MFI = MF.begin(), MFE = MF.end(); MFI != MFE;
+ ++MFI)
+ for (MachineBasicBlock::iterator I = MFI->begin(); I != MFI->end(); ++I)
+ ReplaceUsesWithZeroReg(MRI, *I);
+}
+