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Simplify LiveIntervals::shrinkToUses() a bit by using the new extendInBlock(). 

llvm-svn: 126806
This commit is contained in:
Jakob Stoklund Olesen 2011-03-02 00:33:03 +00:00
parent 81eb18df34
commit f3c6e9211c
1 changed files with 19 additions and 31 deletions
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50
llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
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@ -781,46 +781,34 @@ void LiveIntervals::shrinkToUses(LiveInterval *li) {
NewLI.addRange(LiveRange(VNI->def, VNI->def.getNextSlot(), VNI));
}
// Keep track of the PHIs that are in use.
SmallPtrSet<VNInfo*, 8> UsedPHIs;
// Extend intervals to reach all uses in WorkList.
while (!WorkList.empty()) {
SlotIndex Idx = WorkList.back().first;
VNInfo *VNI = WorkList.back().second;
WorkList.pop_back();
// Extend the live range for VNI to be live at Idx.
LiveInterval::iterator I = NewLI.find(Idx);
// Already got it?
if (I != NewLI.end() && I->start <= Idx) {
assert(I->valno == VNI && "Unexpected existing value number");
continue;
}
// Is there already a live range in the block containing Idx?
const MachineBasicBlock *MBB = getMBBFromIndex(Idx);
SlotIndex BlockStart = getMBBStartIdx(MBB);
DEBUG(dbgs() << "Shrink: Use val#" << VNI->id << " at " << Idx
<< " in BB#" << MBB->getNumber() << '@' << BlockStart);
if (I != NewLI.begin() && (--I)->end > BlockStart) {
assert(I->valno == VNI && "Wrong reaching def");
DEBUG(dbgs() << " extend [" << I->start << ';' << I->end << ")\n");
// Is this the first use of a PHIDef in its defining block?
if (VNI->isPHIDef() && I->end == VNI->def.getNextSlot()) {
// The PHI is live, make sure the predecessors are live-out.
for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
SlotIndex Stop = getMBBEndIdx(*PI).getPrevSlot();
VNInfo *PVNI = li->getVNInfoAt(Stop);
// A predecessor is not required to have a live-out value for a PHI.
if (PVNI) {
assert(PVNI->hasPHIKill() && "Missing hasPHIKill flag");
WorkList.push_back(std::make_pair(Stop, PVNI));
}
// Extend the live range for VNI to be live at Idx.
if (VNInfo *ExtVNI = NewLI.extendInBlock(BlockStart, Idx)) {
assert(ExtVNI == VNI && "Unexpected existing value number");
// Is this a PHIDef we haven't seen before?
if (!VNI->isPHIDef() || !UsedPHIs.insert(VNI))
continue;
// The PHI is live, make sure the predecessors are live-out.
for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
PE = MBB->pred_end(); PI != PE; ++PI) {
SlotIndex Stop = getMBBEndIdx(*PI).getPrevSlot();
VNInfo *PVNI = li->getVNInfoAt(Stop);
// A predecessor is not required to have a live-out value for a PHI.
if (PVNI) {
assert(PVNI->hasPHIKill() && "Missing hasPHIKill flag");
WorkList.push_back(std::make_pair(Stop, PVNI));
}
}
// Extend the live range in the block to include Idx.
NewLI.addRange(LiveRange(I->end, Idx.getNextSlot(), VNI));
continue;
}