- if (MachineDominatorTree *MDT =
- P->getAnalysisIfAvailable<MachineDominatorTree>()) {
- // Update dominator information.
- MachineDomTreeNode *SucccDTNode = MDT->getNode(Succ);
-
- bool IsNewIDom = true;
- for (const_pred_iterator PI = Succ->pred_begin(), E = Succ->pred_end();
- PI != E; ++PI) {
- MachineBasicBlock *PredBB = *PI;
- if (PredBB == NMBB)
- continue;
- if (!MDT->dominates(SucccDTNode, MDT->getNode(PredBB))) {
- IsNewIDom = false;
- break;
+ if (LIS) {
+ // After splitting the edge and updating SlotIndexes, live intervals may be
+ // in one of two situations, depending on whether this block was the last in
+ // the function. If the original block was the last in the function, all live
+ // intervals will end prior to the beginning of the new split block. If the
+ // original block was not at the end of the function, all live intervals will
+ // extend to the end of the new split block.
+
+ bool isLastMBB =
+ std::next(MachineFunction::iterator(NMBB)) == getParent()->end();
+
+ SlotIndex StartIndex = Indexes->getMBBEndIdx(this);
+ SlotIndex PrevIndex = StartIndex.getPrevSlot();
+ SlotIndex EndIndex = Indexes->getMBBEndIdx(NMBB);
+
+ // Find the registers used from NMBB in PHIs in Succ.
+ SmallSet<unsigned, 8> PHISrcRegs;
+ for (MachineBasicBlock::instr_iterator
+ I = Succ->instr_begin(), E = Succ->instr_end();
+ I != E && I->isPHI(); ++I) {
+ for (unsigned ni = 1, ne = I->getNumOperands(); ni != ne; ni += 2) {
+ if (I->getOperand(ni+1).getMBB() == NMBB) {
+ MachineOperand &MO = I->getOperand(ni);
+ unsigned Reg = MO.getReg();
+ PHISrcRegs.insert(Reg);
+ if (MO.isUndef())
+ continue;
+
+ LiveInterval &LI = LIS->getInterval(Reg);
+ VNInfo *VNI = LI.getVNInfoAt(PrevIndex);
+ assert(VNI && "PHI sources should be live out of their predecessors.");
+ LI.addSegment(LiveInterval::Segment(StartIndex, EndIndex, VNI));
+ }