lib/CodeGen/ModuloSchedule.cpp

1271   // Map from <LoopReg, InitReg> to phi register for all created phis. Note that
1272   // this map is only used when InitReg is non-undef.
1274   // Map from LoopReg to phi register where the InitReg is undef.
1280   // Insert a phi that carries LoopReg from the loop body and InitReg otherwise.
1281   // If InitReg is not given it is chosen arbitrarily. It will either be undef
1283   Register phi(Register LoopReg, std::optional<Register> InitReg = {},
1468 Register KernelRewriter::phi(Register LoopReg, std::optional<Register> InitReg,
1471   if (InitReg) {
1472     auto I = Phis.find({LoopReg, *InitReg});
1482   // InitReg is either undef or no existing phi takes InitReg as input. Try and
1487     if (!InitReg)
1491     // Found a phi taking undef as input, so rewrite it to take InitReg.
1493     MI->getOperand(1).setReg(*InitReg);
1494     Phis.insert({{LoopReg, *InitReg}, R});
1496         MRI.constrainRegClass(R, MRI.getRegClass(*InitReg));
1507   if (InitReg) {
1509         MRI.constrainRegClass(R, MRI.getRegClass(*InitReg));
1514       .addReg(InitReg ? *InitReg : undef(RC))
1518   if (!InitReg)
1521     Phis[{LoopReg, *InitReg}] = R;