/// Changes operand OpNum in MI the refer the PhysReg, considering subregs. This
/// may invalidate any operand pointers. Return true if the operand kills its
/// register.
bool RegAllocFast::setPhysReg(MachineInstr &MI, MachineOperand &MO,
MCPhysReg PhysReg) {
bool Dead = MO.isDead();
if (!MO.getSubReg()) {
MO.setReg(PhysReg);
MO.setIsRenamable(true);
return MO.isKill() || Dead;
}
// Handle subregister index.
MO.setReg(PhysReg ? TRI->getSubReg(PhysReg, MO.getSubReg()) : 0);
MO.setIsRenamable(true);
MO.setSubReg(0);
// A kill flag implies killing the full register. Add corresponding super
// register kill.
if (MO.isKill()) {
MI.addRegisterKilled(PhysReg, TRI, true);
return true;
}
// A <def,read-undef> of a sub-register requires an implicit def of the full
// register.
if (MO.isDef() && MO.isUndef())
MI.addRegisterDefined(PhysReg, TRI);
return Dead;
}
void RegAllocFast::allocVirtRegUndef(MachineOperand &MO) {
assert(MO.isUndef() && "expected undef use");
unsigned VirtReg = MO.getReg();
assert(TargetRegisterInfo::isVirtualRegister(VirtReg) && "Expected virtreg");
LiveRegMap::const_iterator LRI = findLiveVirtReg(VirtReg);
MCPhysReg PhysReg;
if (LRI != LiveVirtRegs.end() && LRI->PhysReg) {
PhysReg = LRI->PhysReg;
} else {
const TargetRegisterClass &RC = *MRI->getRegClass(VirtReg);
ArrayRef<MCPhysReg> AllocationOrder = RegClassInfo.getOrder(&RC);
assert(!AllocationOrder.empty() && "Allocation order must not be empty");
PhysReg = AllocationOrder[0];
}
unsigned SubRegIdx = MO.getSubReg();
if (SubRegIdx != 0) {
PhysReg = TRI->getSubReg(PhysReg, SubRegIdx);
MO.setSubReg(0);
}
MO.setReg(PhysReg);
MO.setIsRenamable(true);
}