/// computeLiveInRegUnits - Precompute the live ranges of any register units
/// that are live-in to an ABI block somewhere. Register values can appear
/// without a corresponding def when entering the entry block or a landing pad.
///
void LiveIntervals::computeLiveInRegUnits() {
RegUnitIntervals.resize(TRI->getNumRegUnits());
DEBUG(dbgs() << "Computing live-in reg-units in ABI blocks.\n");
// Keep track of the intervals allocated.
SmallVector<LiveInterval*, 8> NewIntvs;
// Check all basic blocks for live-ins.
for (MachineFunction::const_iterator MFI = MF->begin(), MFE = MF->end();
MFI != MFE; ++MFI) {
const MachineBasicBlock *MBB = MFI;
// We only care about ABI blocks: Entry + landing pads.
if ((MFI != MF->begin() && !MBB->isLandingPad()) || MBB->livein_empty())
continue;
// Create phi-defs at Begin for all live-in registers.
SlotIndex Begin = Indexes->getMBBStartIdx(MBB);
DEBUG(dbgs() << Begin << "\tBB#" << MBB->getNumber());
for (MachineBasicBlock::livein_iterator LII = MBB->livein_begin(),
LIE = MBB->livein_end(); LII != LIE; ++LII) {
for (MCRegUnitIterator Units(*LII, TRI); Units.isValid(); ++Units) {
unsigned Unit = *Units;
LiveInterval *Intv = RegUnitIntervals[Unit];
if (!Intv) {
Intv = RegUnitIntervals[Unit] = new LiveInterval(Unit, HUGE_VALF);
NewIntvs.push_back(Intv);
}
VNInfo *VNI = Intv->createDeadDef(Begin, getVNInfoAllocator());
(void)VNI;
DEBUG(dbgs() << ' ' << PrintRegUnit(Unit, TRI) << '#' << VNI->id);
}
}
DEBUG(dbgs() << '\n');
}
DEBUG(dbgs() << "Created " << NewIntvs.size() << " new intervals.\n");
// Compute the 'normal' part of the intervals.
for (unsigned i = 0, e = NewIntvs.size(); i != e; ++i)
computeRegUnitInterval(NewIntvs[i]);
}
